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Anatomy_Gray_200	Anatomy_Gray	Each spinal nerve divides, as it emerges from an intervertebral foramen, into two major branches: a small posterior ramus and a much larger anterior ramus (Fig. 2.61): The posterior rami innervate only intrinsic back muscles (the epaxial muscles) and an associated narrow strip of skin on the back. The anterior rami innervate most other skeletal muscles (the hypaxial muscles) of the body, including those of the limbs and trunk, and most remaining areas of the skin, except for certain regions of the head. Near the point of division into anterior and posterior rami, each spinal nerve gives rise to two to four small recurrent meningeal (sinuvertebral) nerves (see Fig. 2.59). These nerves reenter the intervertebral foramen to supply dura, ligaments, intervertebral discs, and blood vessels. All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by anterior rami.	Anatomy_Gray. Each spinal nerve divides, as it emerges from an intervertebral foramen, into two major branches: a small posterior ramus and a much larger anterior ramus (Fig. 2.61): The posterior rami innervate only intrinsic back muscles (the epaxial muscles) and an associated narrow strip of skin on the back. The anterior rami innervate most other skeletal muscles (the hypaxial muscles) of the body, including those of the limbs and trunk, and most remaining areas of the skin, except for certain regions of the head. Near the point of division into anterior and posterior rami, each spinal nerve gives rise to two to four small recurrent meningeal (sinuvertebral) nerves (see Fig. 2.59). These nerves reenter the intervertebral foramen to supply dura, ligaments, intervertebral discs, and blood vessels. All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by anterior rami.
Anatomy_Gray_201	Anatomy_Gray	All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by anterior rami. Because the spinal cord is much shorter than the vertebral column, the roots of spinal nerves become longer and pass more obliquely from the cervical to coccygeal regions of the vertebral canal (Fig. 2.62). In adults, the spinal cord terminates at a level approximately between vertebrae LI and LII, but this can range between vertebra TXII and the disc between vertebrae LII and LIII. Consequently, posterior and anterior roots forming spinal nerves emerging between vertebrae in the lower regions of the vertebral column are connected to the spinal cord at higher vertebral levels. Below the end of the spinal cord, the posterior and anterior roots of lumbar, sacral, and coccygeal nerves pass inferiorly to reach their exit points from the vertebral canal. This terminal cluster of roots is the cauda equina. Nomenclature of spinal nerves	Anatomy_Gray. All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by anterior rami. Because the spinal cord is much shorter than the vertebral column, the roots of spinal nerves become longer and pass more obliquely from the cervical to coccygeal regions of the vertebral canal (Fig. 2.62). In adults, the spinal cord terminates at a level approximately between vertebrae LI and LII, but this can range between vertebra TXII and the disc between vertebrae LII and LIII. Consequently, posterior and anterior roots forming spinal nerves emerging between vertebrae in the lower regions of the vertebral column are connected to the spinal cord at higher vertebral levels. Below the end of the spinal cord, the posterior and anterior roots of lumbar, sacral, and coccygeal nerves pass inferiorly to reach their exit points from the vertebral canal. This terminal cluster of roots is the cauda equina. Nomenclature of spinal nerves
Anatomy_Gray_202	Anatomy_Gray	Nomenclature of spinal nerves There are approximately 31 pairs of spinal nerves (Fig. 2.62), named according to their position with respect to associated vertebrae: eight cervical nerves—C1 to C8, twelve thoracic nerves—T1 to T12, five lumbar nerves—L1 to L5, five sacral nerves—S1 to S5, one coccygeal nerve—Co. The first cervical nerve (C1) emerges from the vertebral canal between the skull and vertebra CI (Fig. 2.63). Therefore cervical nerves C2 to C7 also emerge from the vertebral canal above their respective vertebrae. Because there are only seven cervical vertebrae, C8 emerges between vertebrae CVII and TI. As a consequence, all remaining spinal nerves, beginning with T1, emerge from the vertebral canal below their respective vertebrae.	Anatomy_Gray. Nomenclature of spinal nerves There are approximately 31 pairs of spinal nerves (Fig. 2.62), named according to their position with respect to associated vertebrae: eight cervical nerves—C1 to C8, twelve thoracic nerves—T1 to T12, five lumbar nerves—L1 to L5, five sacral nerves—S1 to S5, one coccygeal nerve—Co. The first cervical nerve (C1) emerges from the vertebral canal between the skull and vertebra CI (Fig. 2.63). Therefore cervical nerves C2 to C7 also emerge from the vertebral canal above their respective vertebrae. Because there are only seven cervical vertebrae, C8 emerges between vertebrae CVII and TI. As a consequence, all remaining spinal nerves, beginning with T1, emerge from the vertebral canal below their respective vertebrae.
Anatomy_Gray_203	Anatomy_Gray	Surface features of the back are used to locate muscle groups for testing peripheral nerves, to determine regions of the vertebral column, and to estimate the approximate position of the inferior end of the spinal cord. They are also used to locate organs that occur posteriorly in the thorax and abdomen. Absence of lateral curvatures When viewed from behind, the normal vertebral column has no lateral curvatures. The vertical skin furrow between muscle masses on either side of the midline is straight (Fig. 2.64). in the sagittal plane When viewed from the side, the normal vertebral column has primary curvatures in the thoracic and sacral/coccygeal regions and secondary curvatures in the cervical and lumbar regions (Fig. 2.65). The primary curvatures are concave anteriorly. The secondary curvatures are concave posteriorly.	Anatomy_Gray. Surface features of the back are used to locate muscle groups for testing peripheral nerves, to determine regions of the vertebral column, and to estimate the approximate position of the inferior end of the spinal cord. They are also used to locate organs that occur posteriorly in the thorax and abdomen. Absence of lateral curvatures When viewed from behind, the normal vertebral column has no lateral curvatures. The vertical skin furrow between muscle masses on either side of the midline is straight (Fig. 2.64). in the sagittal plane When viewed from the side, the normal vertebral column has primary curvatures in the thoracic and sacral/coccygeal regions and secondary curvatures in the cervical and lumbar regions (Fig. 2.65). The primary curvatures are concave anteriorly. The secondary curvatures are concave posteriorly.
Anatomy_Gray_204	Anatomy_Gray	A number of readily palpable bony features provide useful landmarks for defining muscles and for locating structures associated with the vertebral column. Among these features are the external occipital protuberance, the scapula, and the iliac crest (Fig. 2.66). The external occipital protuberance is palpable in the midline at the back of the head just superior to the hairline. The spine, medial border, and inferior angle of the scapula are often visible and are easily palpable. The iliac crest is palpable along its entire length, from the anterior superior iliac spine at the lower lateral margin of the anterior abdominal wall to the posterior superior iliac spine near the base of the back. The position of the posterior superior iliac spine is often visible as a “sacral dimple” just lateral to the midline. How to identify specific vertebral	Anatomy_Gray. A number of readily palpable bony features provide useful landmarks for defining muscles and for locating structures associated with the vertebral column. Among these features are the external occipital protuberance, the scapula, and the iliac crest (Fig. 2.66). The external occipital protuberance is palpable in the midline at the back of the head just superior to the hairline. The spine, medial border, and inferior angle of the scapula are often visible and are easily palpable. The iliac crest is palpable along its entire length, from the anterior superior iliac spine at the lower lateral margin of the anterior abdominal wall to the posterior superior iliac spine near the base of the back. The position of the posterior superior iliac spine is often visible as a “sacral dimple” just lateral to the midline. How to identify specific vertebral
Anatomy_Gray_205	Anatomy_Gray	How to identify specific vertebral Identification of vertebral spinous processes (Fig. 2.67A) can be used to differentiate between regions of the vertebral column and facilitate visualizing the position of deeper structures, such as the inferior ends of the spinal cord and subarachnoid space. The spinous process of vertebra CII can be identified through deep palpation as the most superior bony protuberance in the midline inferior to the skull. Most of the other spinous processes, except for that of vertebra CVII, are not readily palpable because they are obscured by soft tissue. The spinous process of CVII is usually visible as a prominent eminence in the midline at the base of the neck (Fig. 2.67B), particularly when the neck is flexed. Extending between CVII and the external occipital protuberance of the skull is the ligamentum nuchae, which is readily apparent as a longitudinal ridge when the neck is flexed (Fig. 2.67C).	Anatomy_Gray. How to identify specific vertebral Identification of vertebral spinous processes (Fig. 2.67A) can be used to differentiate between regions of the vertebral column and facilitate visualizing the position of deeper structures, such as the inferior ends of the spinal cord and subarachnoid space. The spinous process of vertebra CII can be identified through deep palpation as the most superior bony protuberance in the midline inferior to the skull. Most of the other spinous processes, except for that of vertebra CVII, are not readily palpable because they are obscured by soft tissue. The spinous process of CVII is usually visible as a prominent eminence in the midline at the base of the neck (Fig. 2.67B), particularly when the neck is flexed. Extending between CVII and the external occipital protuberance of the skull is the ligamentum nuchae, which is readily apparent as a longitudinal ridge when the neck is flexed (Fig. 2.67C).
Anatomy_Gray_206	Anatomy_Gray	Extending between CVII and the external occipital protuberance of the skull is the ligamentum nuchae, which is readily apparent as a longitudinal ridge when the neck is flexed (Fig. 2.67C). Inferior to the spinous process of CVII is the spinous process of TI, which is also usually visible as a midline protuberance. Often it is more prominent than the spinous process of CVII (Fig. 2.67A,B). The root of the spine of the scapula is at the same level as the spinous process of vertebra TIII, and the inferior angle of the scapula is level with the spinous process of vertebra TVII (Fig. 2.67A). The spinous process of vertebra TXII is level with the midpoint of a vertical line between the inferior angle of the scapula and the iliac crest (Fig. 2.67A).	Anatomy_Gray. Extending between CVII and the external occipital protuberance of the skull is the ligamentum nuchae, which is readily apparent as a longitudinal ridge when the neck is flexed (Fig. 2.67C). Inferior to the spinous process of CVII is the spinous process of TI, which is also usually visible as a midline protuberance. Often it is more prominent than the spinous process of CVII (Fig. 2.67A,B). The root of the spine of the scapula is at the same level as the spinous process of vertebra TIII, and the inferior angle of the scapula is level with the spinous process of vertebra TVII (Fig. 2.67A). The spinous process of vertebra TXII is level with the midpoint of a vertical line between the inferior angle of the scapula and the iliac crest (Fig. 2.67A).
Anatomy_Gray_207	Anatomy_Gray	The spinous process of vertebra TXII is level with the midpoint of a vertical line between the inferior angle of the scapula and the iliac crest (Fig. 2.67A). A horizontal line between the highest point of the iliac crest on each side crosses through the spinous process of vertebra LIV. The LIII and LV vertebral spinous processes can be palpated above and below the LIV spinous process, respectively (Fig. 2.67A). The sacral dimples that mark the position of the posterior superior iliac spine are level with the SII vertebral spinous process (Fig. 2.67A). The tip of the coccyx is palpable at the base of the vertebral column between the gluteal masses (Fig. 2.67A).	Anatomy_Gray. The spinous process of vertebra TXII is level with the midpoint of a vertical line between the inferior angle of the scapula and the iliac crest (Fig. 2.67A). A horizontal line between the highest point of the iliac crest on each side crosses through the spinous process of vertebra LIV. The LIII and LV vertebral spinous processes can be palpated above and below the LIV spinous process, respectively (Fig. 2.67A). The sacral dimples that mark the position of the posterior superior iliac spine are level with the SII vertebral spinous process (Fig. 2.67A). The tip of the coccyx is palpable at the base of the vertebral column between the gluteal masses (Fig. 2.67A).
Anatomy_Gray_208	Anatomy_Gray	The tip of the coccyx is palpable at the base of the vertebral column between the gluteal masses (Fig. 2.67A). The tips of the vertebral spinous processes do not always lie in the same horizontal plane as their corresponding vertebral bodies. In thoracic regions, the spinous processes are long and sharply sloped downward so that their tips lie at the level of the vertebral body below. In other words, the tip of the TIII vertebral spinous process lies at vertebral level TIV. In lumbar and sacral regions, the spinous processes are generally shorter and less sloped than in thoracic regions, and their palpable tips more closely reflect the position of their corresponding vertebral bodies. As a consequence, the palpable end of the spinous process of vertebra LIV lies at approximately the LIV vertebral level. Visualizing the inferior ends of the spinal cord and subarachnoid space	Anatomy_Gray. The tip of the coccyx is palpable at the base of the vertebral column between the gluteal masses (Fig. 2.67A). The tips of the vertebral spinous processes do not always lie in the same horizontal plane as their corresponding vertebral bodies. In thoracic regions, the spinous processes are long and sharply sloped downward so that their tips lie at the level of the vertebral body below. In other words, the tip of the TIII vertebral spinous process lies at vertebral level TIV. In lumbar and sacral regions, the spinous processes are generally shorter and less sloped than in thoracic regions, and their palpable tips more closely reflect the position of their corresponding vertebral bodies. As a consequence, the palpable end of the spinous process of vertebra LIV lies at approximately the LIV vertebral level. Visualizing the inferior ends of the spinal cord and subarachnoid space
Anatomy_Gray_209	Anatomy_Gray	Visualizing the inferior ends of the spinal cord and subarachnoid space The spinal cord does not occupy the entire length of the vertebral canal. Normally in adults, it terminates at the level of the disc between vertebrae LI and LII; however, it may end as high as TXII or as low as the disc between vertebrae LII and LIII. The subarachnoid space ends at approximately the level of vertebra SII (Fig. 2.68A).	Anatomy_Gray. Visualizing the inferior ends of the spinal cord and subarachnoid space The spinal cord does not occupy the entire length of the vertebral canal. Normally in adults, it terminates at the level of the disc between vertebrae LI and LII; however, it may end as high as TXII or as low as the disc between vertebrae LII and LIII. The subarachnoid space ends at approximately the level of vertebra SII (Fig. 2.68A).
Anatomy_Gray_210	Anatomy_Gray	Because the subarachnoid space can be accessed in the lower lumbar region without endangering the spinal cord, it is important to be able to identify the position of the lumbar vertebral spinous processes. The LIV vertebral spinous process is level with a horizontal line between the highest points on the iliac crests. In the lumbar region, the palpable ends of the vertebral spinous processes lie opposite their corresponding vertebral bodies. The subarachnoid space can be accessed between vertebral levels LIII and LIV and between LIV and LV without endangering the spinal cord (Fig. 2.68B). The subarachnoid space ends at vertebral level SII, which is level with the sacral dimples marking the posterior superior iliac spines.	Anatomy_Gray. Because the subarachnoid space can be accessed in the lower lumbar region without endangering the spinal cord, it is important to be able to identify the position of the lumbar vertebral spinous processes. The LIV vertebral spinous process is level with a horizontal line between the highest points on the iliac crests. In the lumbar region, the palpable ends of the vertebral spinous processes lie opposite their corresponding vertebral bodies. The subarachnoid space can be accessed between vertebral levels LIII and LIV and between LIV and LV without endangering the spinal cord (Fig. 2.68B). The subarachnoid space ends at vertebral level SII, which is level with the sacral dimples marking the posterior superior iliac spines.
Anatomy_Gray_211	Anatomy_Gray	A number of intrinsic and extrinsic muscles of the back can readily be observed and palpated. The largest of these are the trapezius and latissimus dorsi muscles (Fig. 2.69A and 2.69B). Retracting the scapulae toward the midline can accentuate the rhomboid muscles (Fig. 2.69C), which lie deep to the trapezius muscle. The erector spinae muscles are visible as two longitudinal columns separated by a furrow in the midline (Fig. 2.69A). Fig. 2.1 Skeletal framework of the back. Fig. 2.2 Curvatures of the vertebral column. Cervical curvature(secondary curvature)Thoracic curvature(primary curvature)Lumbar curvature(secondary curvature)Sacral/coccygeal curvature(primary curvature)Gravity lineConcave primarycurvature of backEarly embryoAdultSomites Fig. 2.3 Back movements. Fig. 2.4 Nervous system. Fig. 2.5 Vertebrae. Fig. 2.6 A typical vertebra. A. Superior view. B. Lateral view. Fig. 2.7 Back muscles. A. Extrinsic muscles. B. Intrinsic muscles.	Anatomy_Gray. A number of intrinsic and extrinsic muscles of the back can readily be observed and palpated. The largest of these are the trapezius and latissimus dorsi muscles (Fig. 2.69A and 2.69B). Retracting the scapulae toward the midline can accentuate the rhomboid muscles (Fig. 2.69C), which lie deep to the trapezius muscle. The erector spinae muscles are visible as two longitudinal columns separated by a furrow in the midline (Fig. 2.69A). Fig. 2.1 Skeletal framework of the back. Fig. 2.2 Curvatures of the vertebral column. Cervical curvature(secondary curvature)Thoracic curvature(primary curvature)Lumbar curvature(secondary curvature)Sacral/coccygeal curvature(primary curvature)Gravity lineConcave primarycurvature of backEarly embryoAdultSomites Fig. 2.3 Back movements. Fig. 2.4 Nervous system. Fig. 2.5 Vertebrae. Fig. 2.6 A typical vertebra. A. Superior view. B. Lateral view. Fig. 2.7 Back muscles. A. Extrinsic muscles. B. Intrinsic muscles.
Anatomy_Gray_212	Anatomy_Gray	Fig. 2.4 Nervous system. Fig. 2.5 Vertebrae. Fig. 2.6 A typical vertebra. A. Superior view. B. Lateral view. Fig. 2.7 Back muscles. A. Extrinsic muscles. B. Intrinsic muscles. Deep groupSerratus posteriorinferiorSerratus posteriorsuperiorSuboccipitalLevator scapulaeSpleniusRhomboid minorSuperficial groupABIntermediate groupIntrinsic musclesTrue back muscles innervated by posterior rami of spinal nervesRhomboid majorSpinalisIliocostalisErector spinaeLongissimusLatissimusdorsiTrapeziusExtrinsic musclesInnervated by anterior rami of spinal nerves or cranial nerve XI (trapezius) Fig. 2.8 Vertebral canal. Spinal cordPia materSubarachnoid spaceDura materArachnoid materAnterior ramusPosterior ramusPosition of spinal ganglionTransverseprocessSpinousprocessPosterior longitudinalligamentAnterior internal vertebralvenous plexusIntervertebral discExtradural spaceExtradural fatVertebral body Fig. 2.9 Spinal nerves (transverse section). Fig. 2.10 Relationships of the back to other regions.	Anatomy_Gray. Fig. 2.4 Nervous system. Fig. 2.5 Vertebrae. Fig. 2.6 A typical vertebra. A. Superior view. B. Lateral view. Fig. 2.7 Back muscles. A. Extrinsic muscles. B. Intrinsic muscles. Deep groupSerratus posteriorinferiorSerratus posteriorsuperiorSuboccipitalLevator scapulaeSpleniusRhomboid minorSuperficial groupABIntermediate groupIntrinsic musclesTrue back muscles innervated by posterior rami of spinal nervesRhomboid majorSpinalisIliocostalisErector spinaeLongissimusLatissimusdorsiTrapeziusExtrinsic musclesInnervated by anterior rami of spinal nerves or cranial nerve XI (trapezius) Fig. 2.8 Vertebral canal. Spinal cordPia materSubarachnoid spaceDura materArachnoid materAnterior ramusPosterior ramusPosition of spinal ganglionTransverseprocessSpinousprocessPosterior longitudinalligamentAnterior internal vertebralvenous plexusIntervertebral discExtradural spaceExtradural fatVertebral body Fig. 2.9 Spinal nerves (transverse section). Fig. 2.10 Relationships of the back to other regions.
Anatomy_Gray_213	Anatomy_Gray	Fig. 2.9 Spinal nerves (transverse section). Fig. 2.10 Relationships of the back to other regions. Cervical region• supports and moves head• transmits spinal cord and vertebral arteries between head and neck Thoracic region• support for thoraxLumbar region• support for abdomenSacral region• transmits weight to lower limbs through pelvic bones• framework for posterior aspect of pelvisVertebral arteries travelin transverse processes ofC6-C1, then pass throughforamen magnum Fig. 2.11 Vertebral canal, spinal cord, and spinal nerves. 1121110112233445595678412345678123C8T1T2T3T4T5T6T7T8T9T10T11T12L1L2L3L4L5S1S2S3S4S5CoC7C6C5C4Cervicalenlargement(of spinal cord)C2C3C1SubarachnoidspaceLumbosacralenlargement(of spinal cord)Arachnoid materEnd of spinalcord at LI–LIIvertebraeEnd ofsubarachnoidspace–sacralvertebra IIDura materPedicles ofvertebraeSpinalganglion Fig. 2.12 Intervertebral foramina. Fig. 2.13 Dermatomes innervated by posterior rami of spinal nerves.	Anatomy_Gray. Fig. 2.9 Spinal nerves (transverse section). Fig. 2.10 Relationships of the back to other regions. Cervical region• supports and moves head• transmits spinal cord and vertebral arteries between head and neck Thoracic region• support for thoraxLumbar region• support for abdomenSacral region• transmits weight to lower limbs through pelvic bones• framework for posterior aspect of pelvisVertebral arteries travelin transverse processes ofC6-C1, then pass throughforamen magnum Fig. 2.11 Vertebral canal, spinal cord, and spinal nerves. 1121110112233445595678412345678123C8T1T2T3T4T5T6T7T8T9T10T11T12L1L2L3L4L5S1S2S3S4S5CoC7C6C5C4Cervicalenlargement(of spinal cord)C2C3C1SubarachnoidspaceLumbosacralenlargement(of spinal cord)Arachnoid materEnd of spinalcord at LI–LIIvertebraeEnd ofsubarachnoidspace–sacralvertebra IIDura materPedicles ofvertebraeSpinalganglion Fig. 2.12 Intervertebral foramina. Fig. 2.13 Dermatomes innervated by posterior rami of spinal nerves.
Anatomy_Gray_214	Anatomy_Gray	Fig. 2.12 Intervertebral foramina. Fig. 2.13 Dermatomes innervated by posterior rami of spinal nerves. C2C3C4T2T3T4T5T6T7T8T9L5S1S2S4S3S5, Co*The dorsal rami of L4 and L5 may not have cutaneousbranches and may therefore not be represented asdermatomes on the backL4L3L2L1T11T12T10 Fig. 2.14 Vertebrae. Fig. 2.15 Radiograph of cervical region of vertebral column. A. Anteroposterior view. B. Lateral view. ARib IICIISpinous process of CVII Vertebralbody of CIIILocation ofintervertebral discVertebra prominens(spinous process of CVII)Posterior tubercleof CI (atlas)B Fig. 2.16 Radiograph of thoracic region of vertebral column. A. Anteroposterior view. B. Lateral view. RibPedicleLocation of intervertebral discSpinous processTransverse processVertebral bodyA BIntervertebral foramenVertebral bodyLocation of intervertebral disc Fig. 2.17 Radiograph of lumbar region of vertebral column. A. Anteroposterior view. B. Lateral view. RibTransverse processPedicleSpinous process of LIVA	Anatomy_Gray. Fig. 2.12 Intervertebral foramina. Fig. 2.13 Dermatomes innervated by posterior rami of spinal nerves. C2C3C4T2T3T4T5T6T7T8T9L5S1S2S4S3S5, Co*The dorsal rami of L4 and L5 may not have cutaneousbranches and may therefore not be represented asdermatomes on the backL4L3L2L1T11T12T10 Fig. 2.14 Vertebrae. Fig. 2.15 Radiograph of cervical region of vertebral column. A. Anteroposterior view. B. Lateral view. ARib IICIISpinous process of CVII Vertebralbody of CIIILocation ofintervertebral discVertebra prominens(spinous process of CVII)Posterior tubercleof CI (atlas)B Fig. 2.16 Radiograph of thoracic region of vertebral column. A. Anteroposterior view. B. Lateral view. RibPedicleLocation of intervertebral discSpinous processTransverse processVertebral bodyA BIntervertebral foramenVertebral bodyLocation of intervertebral disc Fig. 2.17 Radiograph of lumbar region of vertebral column. A. Anteroposterior view. B. Lateral view. RibTransverse processPedicleSpinous process of LIVA
Anatomy_Gray_215	Anatomy_Gray	Fig. 2.17 Radiograph of lumbar region of vertebral column. A. Anteroposterior view. B. Lateral view. RibTransverse processPedicleSpinous process of LIVA Location ofintervertebral discVertebral body of LIIIIntervertebral foramenB Fig. 2.18 Development of the vertebrae. Fig. 2.19 Typical vertebra. Fig. 2.20 Regional vertebrae. A. Typical cervical vertebra. B. Atlas and axis. C. Typical thoracic vertebra. D. Typical lumbar vertebra. E. Sacrum. F. Coccyx.	Anatomy_Gray. Fig. 2.17 Radiograph of lumbar region of vertebral column. A. Anteroposterior view. B. Lateral view. RibTransverse processPedicleSpinous process of LIVA Location ofintervertebral discVertebral body of LIIIIntervertebral foramenB Fig. 2.18 Development of the vertebrae. Fig. 2.19 Typical vertebra. Fig. 2.20 Regional vertebrae. A. Typical cervical vertebra. B. Atlas and axis. C. Typical thoracic vertebra. D. Typical lumbar vertebra. E. Sacrum. F. Coccyx.
Anatomy_Gray_216	Anatomy_Gray	E. Sacrum. F. Coccyx. Transverse processDensDensForamen transversariumSuperior viewSuperior viewSuperior viewPosterior viewPosterosuperior viewBAnterior tuberclePosterior tubercleAnterior archLateral massPosterior archFacet for densFacet for occipital condyleImpressionsfor alarligamentsAlarligamentsTectorial membrane (upper partof posterior longitudinal ligament)PosteriorlongitudinalligamentFacets forattachment ofalar ligamentsAtlas (CI vertebra)Atlas (CI vertebra) and Axis (CII vertebra)Atlas (CIvertebra)and Axis(CII vertebra)and baseof skullAxis (CII vertebra)Transverse ligament of atlasTransverse ligament of atlasVertebral bodyTransverse processTransverseprocessSpinousprocessMammillaryprocessSpinousprocessSuperior viewLateral viewSuperior viewFacet for articulationwith tubercle ofits own ribDemifacet for articulationwith head of rib belowDemifacet for articulationwith head of its own ribCDApical ligamentof densInferior longitudinalband of cruciformligament	Anatomy_Gray. E. Sacrum. F. Coccyx. Transverse processDensDensForamen transversariumSuperior viewSuperior viewSuperior viewPosterior viewPosterosuperior viewBAnterior tuberclePosterior tubercleAnterior archLateral massPosterior archFacet for densFacet for occipital condyleImpressionsfor alarligamentsAlarligamentsTectorial membrane (upper partof posterior longitudinal ligament)PosteriorlongitudinalligamentFacets forattachment ofalar ligamentsAtlas (CI vertebra)Atlas (CI vertebra) and Axis (CII vertebra)Atlas (CIvertebra)and Axis(CII vertebra)and baseof skullAxis (CII vertebra)Transverse ligament of atlasTransverse ligament of atlasVertebral bodyTransverse processTransverseprocessSpinousprocessMammillaryprocessSpinousprocessSuperior viewLateral viewSuperior viewFacet for articulationwith tubercle ofits own ribDemifacet for articulationwith head of rib belowDemifacet for articulationwith head of its own ribCDApical ligamentof densInferior longitudinalband of cruciformligament
Anatomy_Gray_217	Anatomy_Gray	Anterior viewDorsolateral viewPosterior viewFacet for articulation with pelvic boneEFAnterior sacral foraminaPosterior sacral foraminaCoccygeal cornuIncomplete sacral canal Fig. 2.21 Radiograph showing CI (atlas) and CII (axis) vertebrae. Open mouth, anteroposterior (odontoid peg) view. Superior articularfacet of CIIDensInferior articular faceton lateral mass of CI Fig. 2.22 Intervertebral foramen. Fig. 2.23 Spaces between adjacent vertebral arches in the lumbar region. Fig. 2.24 T1-weighted MR image in the sagittal plane demonstrating a lumbosacral myelomeningocele. There is an absence of laminae and spinous processes in the lumbosacral region. Fig. 2.25 Radiograph of the lumbar region of the vertebral column demonstrating a wedge fracture of the L1 vertebra. This condition is typically seen in patients with osteoporosis.	Anatomy_Gray. Anterior viewDorsolateral viewPosterior viewFacet for articulation with pelvic boneEFAnterior sacral foraminaPosterior sacral foraminaCoccygeal cornuIncomplete sacral canal Fig. 2.21 Radiograph showing CI (atlas) and CII (axis) vertebrae. Open mouth, anteroposterior (odontoid peg) view. Superior articularfacet of CIIDensInferior articular faceton lateral mass of CI Fig. 2.22 Intervertebral foramen. Fig. 2.23 Spaces between adjacent vertebral arches in the lumbar region. Fig. 2.24 T1-weighted MR image in the sagittal plane demonstrating a lumbosacral myelomeningocele. There is an absence of laminae and spinous processes in the lumbosacral region. Fig. 2.25 Radiograph of the lumbar region of the vertebral column demonstrating a wedge fracture of the L1 vertebra. This condition is typically seen in patients with osteoporosis.
Anatomy_Gray_218	Anatomy_Gray	Fig. 2.25 Radiograph of the lumbar region of the vertebral column demonstrating a wedge fracture of the L1 vertebra. This condition is typically seen in patients with osteoporosis. Fig. 2.26 Radiograph of the lumbar region of the vertebral column demonstrating three intrapedicular needles, all of which have been placed into the middle of the vertebral bodies. The high-density material is radiopaque bone cement, which has been injected as a liquid that will harden. Fig. 2.27 Severe scoliosis. A. Radiograph, anteroposterior view. B. Volume-rendered CT, anterior view. Fig. 2.28 Sagittal CT showing kyphosis. Fig. 2.29 Variations in vertebral number. A. Fused vertebral bodies of cervical vertebrae. B. Hemivertebra. C. Axial slice MRI through the LV vertebra. The iliolumbar ligament runs from the tip of the LV vertebra transverse process to the iliac crest. Fused bodies of cervical vertebraeA HemivertebraPartial lumbarization of first sacral vertebraB	Anatomy_Gray. Fig. 2.25 Radiograph of the lumbar region of the vertebral column demonstrating a wedge fracture of the L1 vertebra. This condition is typically seen in patients with osteoporosis. Fig. 2.26 Radiograph of the lumbar region of the vertebral column demonstrating three intrapedicular needles, all of which have been placed into the middle of the vertebral bodies. The high-density material is radiopaque bone cement, which has been injected as a liquid that will harden. Fig. 2.27 Severe scoliosis. A. Radiograph, anteroposterior view. B. Volume-rendered CT, anterior view. Fig. 2.28 Sagittal CT showing kyphosis. Fig. 2.29 Variations in vertebral number. A. Fused vertebral bodies of cervical vertebrae. B. Hemivertebra. C. Axial slice MRI through the LV vertebra. The iliolumbar ligament runs from the tip of the LV vertebra transverse process to the iliac crest. Fused bodies of cervical vertebraeA HemivertebraPartial lumbarization of first sacral vertebraB
Anatomy_Gray_219	Anatomy_Gray	Fused bodies of cervical vertebraeA HemivertebraPartial lumbarization of first sacral vertebraB Fig. 2.30 A. MRI of a spine with multiple collapsed vertebrae due to diffuse metastatic myeloma infiltration. B1, B2. Positron emission tomography CT (PETCT) study detecting cancer cells in the spine that have high glucose metabolism. Fig. 2.31 Intervertebral joints. Anulus fibrosusNucleus pulposusLayer of hyalinecartilage Fig. 2.32 Zygapophysial joints. Fig. 2.33 Uncovertebral joint. Fig. 2.34 Disc protrusion. T2-weighted magnetic resonance images of the lumbar region of the vertebral column. A. Sagittal plane. B. Axial plane. Fig. 2.35 Anterior and posterior longitudinal ligaments of vertebral column. Fig. 2.36 Ligamenta flava. Fig. 2.37 Supraspinous ligament and ligamentum nuchae. Fig. 2.38 Interspinous ligaments. Fig. 2.39 Axial slice MRI through the lumbar spine demonstrating bilateral hypertrophy of the ligamentum flavum.	Anatomy_Gray. Fused bodies of cervical vertebraeA HemivertebraPartial lumbarization of first sacral vertebraB Fig. 2.30 A. MRI of a spine with multiple collapsed vertebrae due to diffuse metastatic myeloma infiltration. B1, B2. Positron emission tomography CT (PETCT) study detecting cancer cells in the spine that have high glucose metabolism. Fig. 2.31 Intervertebral joints. Anulus fibrosusNucleus pulposusLayer of hyalinecartilage Fig. 2.32 Zygapophysial joints. Fig. 2.33 Uncovertebral joint. Fig. 2.34 Disc protrusion. T2-weighted magnetic resonance images of the lumbar region of the vertebral column. A. Sagittal plane. B. Axial plane. Fig. 2.35 Anterior and posterior longitudinal ligaments of vertebral column. Fig. 2.36 Ligamenta flava. Fig. 2.37 Supraspinous ligament and ligamentum nuchae. Fig. 2.38 Interspinous ligaments. Fig. 2.39 Axial slice MRI through the lumbar spine demonstrating bilateral hypertrophy of the ligamentum flavum.
Anatomy_Gray_220	Anatomy_Gray	Fig. 2.38 Interspinous ligaments. Fig. 2.39 Axial slice MRI through the lumbar spine demonstrating bilateral hypertrophy of the ligamentum flavum. Fig. 2.40 Radiograph of lumbar region of vertebral column, oblique view (“Scottie dog”). A. Normal radiograph of lumbar region of vertebral column, oblique view. In this view, the transverse process (nose), pedicle (eye), superior articular process (ear), inferior articular process (front leg), and pars interarticularis (neck) resemble a dog. A fracture of the pars interarticularis is visible as a break in the neck of the dog, or the appearance of a collar. B. Fracture of pars interarticularis. C. CT of lumbar spine shows fracture of the LV pars interarticularis. Fig. 2.41 A. Anterior lumbar interbody fusion (ALIF). B. Posterior lumbar interbody fusion (PLIF). Fig. 2.42 Superficial group of back muscles—trapezius and latissimus dorsi.	Anatomy_Gray. Fig. 2.38 Interspinous ligaments. Fig. 2.39 Axial slice MRI through the lumbar spine demonstrating bilateral hypertrophy of the ligamentum flavum. Fig. 2.40 Radiograph of lumbar region of vertebral column, oblique view (“Scottie dog”). A. Normal radiograph of lumbar region of vertebral column, oblique view. In this view, the transverse process (nose), pedicle (eye), superior articular process (ear), inferior articular process (front leg), and pars interarticularis (neck) resemble a dog. A fracture of the pars interarticularis is visible as a break in the neck of the dog, or the appearance of a collar. B. Fracture of pars interarticularis. C. CT of lumbar spine shows fracture of the LV pars interarticularis. Fig. 2.41 A. Anterior lumbar interbody fusion (ALIF). B. Posterior lumbar interbody fusion (PLIF). Fig. 2.42 Superficial group of back muscles—trapezius and latissimus dorsi.
Anatomy_Gray_221	Anatomy_Gray	Fig. 2.41 A. Anterior lumbar interbody fusion (ALIF). B. Posterior lumbar interbody fusion (PLIF). Fig. 2.42 Superficial group of back muscles—trapezius and latissimus dorsi. Spinous process of CVIIAcromionSpine of scapulaIliac crestGreater occipital nerve(posterior ramus of C2)Third occipital nerve(posterior ramus of C3)Medial branches of posterior ramiLateral branches of posterior ramiTrapeziusLatissimus dorsiThoracolumbar fascia Fig. 2.43 Superficial group of back muscles—trapezius and latissimus dorsi, with rhomboid major, rhomboid minor, and levator scapulae located deep to trapezius in the superior part of the back. Fig. 2.44 Innervation and blood supply of trapezius. TrapeziusLatissimus dorsiRhomboid minorRhomboid majorLevator scapulaeAccessory nerve [XI]Superficial branch of transverse cervical artery Fig. 2.45 Rhomboid muscles and levator scapulae. Fig. 2.46 Innervation and blood supply of the rhomboid muscles.	Anatomy_Gray. Fig. 2.41 A. Anterior lumbar interbody fusion (ALIF). B. Posterior lumbar interbody fusion (PLIF). Fig. 2.42 Superficial group of back muscles—trapezius and latissimus dorsi. Spinous process of CVIIAcromionSpine of scapulaIliac crestGreater occipital nerve(posterior ramus of C2)Third occipital nerve(posterior ramus of C3)Medial branches of posterior ramiLateral branches of posterior ramiTrapeziusLatissimus dorsiThoracolumbar fascia Fig. 2.43 Superficial group of back muscles—trapezius and latissimus dorsi, with rhomboid major, rhomboid minor, and levator scapulae located deep to trapezius in the superior part of the back. Fig. 2.44 Innervation and blood supply of trapezius. TrapeziusLatissimus dorsiRhomboid minorRhomboid majorLevator scapulaeAccessory nerve [XI]Superficial branch of transverse cervical artery Fig. 2.45 Rhomboid muscles and levator scapulae. Fig. 2.46 Innervation and blood supply of the rhomboid muscles.
Anatomy_Gray_222	Anatomy_Gray	Fig. 2.45 Rhomboid muscles and levator scapulae. Fig. 2.46 Innervation and blood supply of the rhomboid muscles. Dorsal scapular nerveTrapeziusLatissimus dorsiRhomboid minorRhomboid majorLevator scapulaeSuperficial branch of transverse cervical arteryDeep branch of transverse cervical artery Fig. 2.47 Intermediate group of back muscles—serratus posterior muscles. Fig. 2.48 Thoracolumbar fascia and the deep back muscles (transverse section). Fig. 2.49 Deep group of back muscles—spinotransversales muscles (splenius capitis and splenius cervicis). Fig. 2.50 Deep group of back muscles—erector spinae muscles. Spinous process of CVIIIliac crestSplenius capitisLongissimus capitis Ligamentum nuchaeLongissimus thoracisLongissimus cervicisSpinalis thoracisSpinalisIliocostalis lumborum Iliocostalis thoracisIliocostalis cervicisIliocostalisLongissimus Fig. 2.51 Deep group of back muscles—transversospinales and segmental muscles.	Anatomy_Gray. Fig. 2.45 Rhomboid muscles and levator scapulae. Fig. 2.46 Innervation and blood supply of the rhomboid muscles. Dorsal scapular nerveTrapeziusLatissimus dorsiRhomboid minorRhomboid majorLevator scapulaeSuperficial branch of transverse cervical arteryDeep branch of transverse cervical artery Fig. 2.47 Intermediate group of back muscles—serratus posterior muscles. Fig. 2.48 Thoracolumbar fascia and the deep back muscles (transverse section). Fig. 2.49 Deep group of back muscles—spinotransversales muscles (splenius capitis and splenius cervicis). Fig. 2.50 Deep group of back muscles—erector spinae muscles. Spinous process of CVIIIliac crestSplenius capitisLongissimus capitis Ligamentum nuchaeLongissimus thoracisLongissimus cervicisSpinalis thoracisSpinalisIliocostalis lumborum Iliocostalis thoracisIliocostalis cervicisIliocostalisLongissimus Fig. 2.51 Deep group of back muscles—transversospinales and segmental muscles.
Anatomy_Gray_223	Anatomy_Gray	Fig. 2.51 Deep group of back muscles—transversospinales and segmental muscles. Spinous process of CVIIObliquus capitis inferiorObliquus capitis superiorRectus capitis posterior minorRectus capitis posterior majorSemispinalis thoracisIntertransversariusErector spinaeRotatores thoracis(short, long)Levatores costarum(short, long)Semispinalis capitisMultifidus Fig. 2.52 Deep group of back muscles—suboccipital muscles. This also shows the borders of the suboccipital triangle. Spinous process of CIIPosterior ramus of C1Obliquus capitis superior Rectus capitis posterior minorObliquus capitis inferiorRectus capitis posterior majorSplenius capitisSplenius capitisLongissimus capitisSemispinalis cervicisSemispinalis capitisSemispinalis capitisVertebral artery Fig. 2.53 Spinal cord.	Anatomy_Gray. Fig. 2.51 Deep group of back muscles—transversospinales and segmental muscles. Spinous process of CVIIObliquus capitis inferiorObliquus capitis superiorRectus capitis posterior minorRectus capitis posterior majorSemispinalis thoracisIntertransversariusErector spinaeRotatores thoracis(short, long)Levatores costarum(short, long)Semispinalis capitisMultifidus Fig. 2.52 Deep group of back muscles—suboccipital muscles. This also shows the borders of the suboccipital triangle. Spinous process of CIIPosterior ramus of C1Obliquus capitis superior Rectus capitis posterior minorObliquus capitis inferiorRectus capitis posterior majorSplenius capitisSplenius capitisLongissimus capitisSemispinalis cervicisSemispinalis capitisSemispinalis capitisVertebral artery Fig. 2.53 Spinal cord.
Anatomy_Gray_224	Anatomy_Gray	Fig. 2.53 Spinal cord. End of spinalcord LI–LIIConus medullarisInferior part ofarachnoid materEnd of subarachnoidspace SIICervicalenlargement(of spinal cord)Lumbosacralenlargement(of spinal cord)FilumterminalePial partDural partPedicles ofvertebrae Fig. 2.54 Features of the spinal cord. Fig. 2.55 Arteries that supply the spinal cord. A. Anterior view of spinal cord (not all segmental spinal arteries are shown). B. Segmental supply of spinal cord. Posterior spinal arteryADeep cervical arteryCostocervical trunkThyrocervical trunkSubclavian arteryPosterior intercostalarterySegmentalspinal arteryArtery of Adamkiewicz(branch fromsegmentalspinal artery)Ascending cervicalarteryVertebral arterySegmental medullaryarteriesAnterior spinal arterySegmental medullaryarteries (branch fromsegmental spinalartery)Lateral sacral arterySegmentalspinal artery Fig. 2.56 Veins that drain the spinal cord.	Anatomy_Gray. Fig. 2.53 Spinal cord. End of spinalcord LI–LIIConus medullarisInferior part ofarachnoid materEnd of subarachnoidspace SIICervicalenlargement(of spinal cord)Lumbosacralenlargement(of spinal cord)FilumterminalePial partDural partPedicles ofvertebrae Fig. 2.54 Features of the spinal cord. Fig. 2.55 Arteries that supply the spinal cord. A. Anterior view of spinal cord (not all segmental spinal arteries are shown). B. Segmental supply of spinal cord. Posterior spinal arteryADeep cervical arteryCostocervical trunkThyrocervical trunkSubclavian arteryPosterior intercostalarterySegmentalspinal arteryArtery of Adamkiewicz(branch fromsegmentalspinal artery)Ascending cervicalarteryVertebral arterySegmental medullaryarteriesAnterior spinal arterySegmental medullaryarteries (branch fromsegmental spinalartery)Lateral sacral arterySegmentalspinal artery Fig. 2.56 Veins that drain the spinal cord.
Anatomy_Gray_225	Anatomy_Gray	Fig. 2.56 Veins that drain the spinal cord. Fig. 2.57 MRI of the spine. There is discitis of the T10-T11 intervertebral disc with destruction of the adjacent endplates. There is also a prevertebral abscess and an epidural abscess, which impinges the cord. Fig. 2.58 CT at the level of CI demonstrates two breaks in the closed ring of the atlas following an axial-loading injury. Fig. 2.59 Meninges. Fig. 2.60 Arrangement of structures in the vertebral canal and the back (lumbar region). Crura of diaphragmAortaPsoasDuraQuadratus lumborumInternal vertebral plexus of veinsin extradural spaceErector spinae musclesLigamenta flavaSupraspinous ligamentInterspinous ligamentLumbar arteryVeinCauda equinaSkinVertebraIntervertebral discIntervertebral foramenLaminaPediclePosterior longitudinal ligament Fig. 2.61 Basic organization of a spinal nerve. Fig. 2.62 Course of spinal nerves in the vertebral canal.	Anatomy_Gray. Fig. 2.56 Veins that drain the spinal cord. Fig. 2.57 MRI of the spine. There is discitis of the T10-T11 intervertebral disc with destruction of the adjacent endplates. There is also a prevertebral abscess and an epidural abscess, which impinges the cord. Fig. 2.58 CT at the level of CI demonstrates two breaks in the closed ring of the atlas following an axial-loading injury. Fig. 2.59 Meninges. Fig. 2.60 Arrangement of structures in the vertebral canal and the back (lumbar region). Crura of diaphragmAortaPsoasDuraQuadratus lumborumInternal vertebral plexus of veinsin extradural spaceErector spinae musclesLigamenta flavaSupraspinous ligamentInterspinous ligamentLumbar arteryVeinCauda equinaSkinVertebraIntervertebral discIntervertebral foramenLaminaPediclePosterior longitudinal ligament Fig. 2.61 Basic organization of a spinal nerve. Fig. 2.62 Course of spinal nerves in the vertebral canal.
Anatomy_Gray_226	Anatomy_Gray	Fig. 2.61 Basic organization of a spinal nerve. Fig. 2.62 Course of spinal nerves in the vertebral canal. 1121110112233445595678412345678123C8T1T2T3T4T5T6T7T8T9T10T11T12L1L2L3L4L5S1S2S3S4S5CoC7C6C5C4Cervical enlargement(of spinal cord)C2C3C1Lumbosacral enlargement(of spinal cord)Cauda equinaPedicles of vertebraeSpinal ganglion Fig. 2.63 Nomenclature of the spinal nerves. Nerve C1 emerges betweenskull and CI vertebraNerve C8 emerges inferior topedicle of CVII vertebraNerves C2 to C7 emergesuperior to pediclesNerves T1 to Co emergeinferior to pedicles oftheir respective vertebraeC2C1C3C4C5C6C7C8T1CICVIITIPedicleTransition innomenclatureof nervesT2 Fig. 2.64 Normal appearance of the back. A. In women. B. In men. Fig. 2.65 Normal curvatures of the vertebral column. Fig. 2.66 Back of a woman with major palpable bony landmarks indicated.	Anatomy_Gray. Fig. 2.61 Basic organization of a spinal nerve. Fig. 2.62 Course of spinal nerves in the vertebral canal. 1121110112233445595678412345678123C8T1T2T3T4T5T6T7T8T9T10T11T12L1L2L3L4L5S1S2S3S4S5CoC7C6C5C4Cervical enlargement(of spinal cord)C2C3C1Lumbosacral enlargement(of spinal cord)Cauda equinaPedicles of vertebraeSpinal ganglion Fig. 2.63 Nomenclature of the spinal nerves. Nerve C1 emerges betweenskull and CI vertebraNerve C8 emerges inferior topedicle of CVII vertebraNerves C2 to C7 emergesuperior to pediclesNerves T1 to Co emergeinferior to pedicles oftheir respective vertebraeC2C1C3C4C5C6C7C8T1CICVIITIPedicleTransition innomenclatureof nervesT2 Fig. 2.64 Normal appearance of the back. A. In women. B. In men. Fig. 2.65 Normal curvatures of the vertebral column. Fig. 2.66 Back of a woman with major palpable bony landmarks indicated.
Anatomy_Gray_227	Anatomy_Gray	Fig. 2.64 Normal appearance of the back. A. In women. B. In men. Fig. 2.65 Normal curvatures of the vertebral column. Fig. 2.66 Back of a woman with major palpable bony landmarks indicated. Spine of scapulaInferior angle of scapulaMedial border of scapulaPosition of externaloccipital protuberancePosterior superior iliac spineIliac crest Fig. 2.67 The back with the positions of vertebral spinous processes and associated structures indicated. A. In a man. B. In a woman with neck flexed. The prominent CVII and TI vertebral spinous processes are labeled. C. In a woman with neck flexed to accentuate the ligamentum nuchae.	Anatomy_Gray. Fig. 2.64 Normal appearance of the back. A. In women. B. In men. Fig. 2.65 Normal curvatures of the vertebral column. Fig. 2.66 Back of a woman with major palpable bony landmarks indicated. Spine of scapulaInferior angle of scapulaMedial border of scapulaPosition of externaloccipital protuberancePosterior superior iliac spineIliac crest Fig. 2.67 The back with the positions of vertebral spinous processes and associated structures indicated. A. In a man. B. In a woman with neck flexed. The prominent CVII and TI vertebral spinous processes are labeled. C. In a woman with neck flexed to accentuate the ligamentum nuchae.
Anatomy_Gray_228	Anatomy_Gray	Tip of coccyxSII vertebral spinous processTXII vertebral spinous processTVII vertebral spinous processTIII vertebral spinous processTI vertebral spinous processRoot of spine of scapulaInferior angle of scapulaHighest point of iliac crestIliac crestSacral dimpleCVII vertebral spinous processCII vertebral spinous processPosition of externaloccipital protuberanceLIV vertebral spinous processA Fig. 2.68 Back with the ends of the spinal cord and subarachnoid space indicated. A. In a man. Back with the ends of the spinal cord and subarachnoid space indicated. B. In a woman lying on her side in a fetal position, which accentuates the lumbar vertebral spinous processes and opens the spaces between adjacent vertebral arches. Cerebrospinal fluid can be withdrawn from the subarachnoid space in lower lumbar regions without endangering the spinal cord.	Anatomy_Gray. Tip of coccyxSII vertebral spinous processTXII vertebral spinous processTVII vertebral spinous processTIII vertebral spinous processTI vertebral spinous processRoot of spine of scapulaInferior angle of scapulaHighest point of iliac crestIliac crestSacral dimpleCVII vertebral spinous processCII vertebral spinous processPosition of externaloccipital protuberanceLIV vertebral spinous processA Fig. 2.68 Back with the ends of the spinal cord and subarachnoid space indicated. A. In a man. Back with the ends of the spinal cord and subarachnoid space indicated. B. In a woman lying on her side in a fetal position, which accentuates the lumbar vertebral spinous processes and opens the spaces between adjacent vertebral arches. Cerebrospinal fluid can be withdrawn from the subarachnoid space in lower lumbar regions without endangering the spinal cord.
Anatomy_Gray_229	Anatomy_Gray	Tip of coccyxSII vertebral spinous processTXII vertebral spinous processInferior end of spinal cord(normally betweenLI and LII vertebra)Inferior end ofsubarachnoid spaceALIV vertebral spinous process LIV vertebral spinous processNeedleLV vertebral spinous processTip of coccyxB Fig. 2.69 Back muscles. A. In a man with latissimus dorsi, trapezius, and erector spinae muscles outlined. Back muscles. B. In a man with arms abducted to accentuate the lateral margins of the latissimus dorsi muscles. C. In a woman with scapulae externally rotated and forcibly retracted to accentuate the rhomboid muscles. Fig. 2.70 MRI of the lumbar spine reveals posterior herniation of the L2-3 disc resulting in compression of the cauda equina filaments. Table 2.1 Superficial (appendicular) group of back muscles Table 2.2 Intermediate (respiratory) group of back muscles Table 2.3 Spinotransversales muscles Table 2.4 Erector spinae group of back muscles	Anatomy_Gray. Tip of coccyxSII vertebral spinous processTXII vertebral spinous processInferior end of spinal cord(normally betweenLI and LII vertebra)Inferior end ofsubarachnoid spaceALIV vertebral spinous process LIV vertebral spinous processNeedleLV vertebral spinous processTip of coccyxB Fig. 2.69 Back muscles. A. In a man with latissimus dorsi, trapezius, and erector spinae muscles outlined. Back muscles. B. In a man with arms abducted to accentuate the lateral margins of the latissimus dorsi muscles. C. In a woman with scapulae externally rotated and forcibly retracted to accentuate the rhomboid muscles. Fig. 2.70 MRI of the lumbar spine reveals posterior herniation of the L2-3 disc resulting in compression of the cauda equina filaments. Table 2.1 Superficial (appendicular) group of back muscles Table 2.2 Intermediate (respiratory) group of back muscles Table 2.3 Spinotransversales muscles Table 2.4 Erector spinae group of back muscles
Anatomy_Gray_230	Anatomy_Gray	Table 2.2 Intermediate (respiratory) group of back muscles Table 2.3 Spinotransversales muscles Table 2.4 Erector spinae group of back muscles Table 2.5 Transversospinales group of back muscles Table 2.6 Segmental back muscles Table 2.7 Suboccipital group of back muscles In the clinic Spina bifida is a disorder in which the two sides of vertebral arches, usually in lower vertebrae, fail to fuse during development, resulting in an “open” vertebral canal (Fig. 2.24). There are two types of spina bifida. The commonest type is spina bifida occulta, in which there is a defect in the vertebral arch of LV or SI. This defect occurs in as many as 10% of individuals and results in failure of the posterior arch to fuse in the midline. Clinically, the patient is asymptomatic, although physical examination may reveal a tuft of hair over the spinous processes.	Anatomy_Gray. Table 2.2 Intermediate (respiratory) group of back muscles Table 2.3 Spinotransversales muscles Table 2.4 Erector spinae group of back muscles Table 2.5 Transversospinales group of back muscles Table 2.6 Segmental back muscles Table 2.7 Suboccipital group of back muscles In the clinic Spina bifida is a disorder in which the two sides of vertebral arches, usually in lower vertebrae, fail to fuse during development, resulting in an “open” vertebral canal (Fig. 2.24). There are two types of spina bifida. The commonest type is spina bifida occulta, in which there is a defect in the vertebral arch of LV or SI. This defect occurs in as many as 10% of individuals and results in failure of the posterior arch to fuse in the midline. Clinically, the patient is asymptomatic, although physical examination may reveal a tuft of hair over the spinous processes.
Anatomy_Gray_231	Anatomy_Gray	The more severe form of spina bifida involves complete failure of fusion of the posterior arch at the lumbosacral junction, with a large outpouching of the meninges. This may contain cerebrospinal fluid (a meningocele) or a portion of the spinal cord (a myelomeningocele). These abnormalities may result in a variety of neurological deficits, including problems with walking and bladder function. In the clinic Vertebroplasty is a relatively new technique in which the body of a vertebra can be filled with bone cement (typically methyl methacrylate). The indications for the technique include vertebral body collapse and pain from the vertebral body, which may be secondary to tumor infiltration. The procedure is most commonly performed for osteoporotic wedge fractures, which are a considerable cause of morbidity and pain in older patients.	Anatomy_Gray. The more severe form of spina bifida involves complete failure of fusion of the posterior arch at the lumbosacral junction, with a large outpouching of the meninges. This may contain cerebrospinal fluid (a meningocele) or a portion of the spinal cord (a myelomeningocele). These abnormalities may result in a variety of neurological deficits, including problems with walking and bladder function. In the clinic Vertebroplasty is a relatively new technique in which the body of a vertebra can be filled with bone cement (typically methyl methacrylate). The indications for the technique include vertebral body collapse and pain from the vertebral body, which may be secondary to tumor infiltration. The procedure is most commonly performed for osteoporotic wedge fractures, which are a considerable cause of morbidity and pain in older patients.
Anatomy_Gray_232	Anatomy_Gray	Osteoporotic wedge fractures (Fig. 2.25) typically occur in the thoracolumbar region, and the approach to performing vertebroplasty is novel and relatively straightforward. The procedure is performed under sedation or light general anesthetic. Using X-ray guidance the pedicle is identified on the anteroposterior image. A metal cannula is placed through the pedicle into the vertebral body. Liquid bone cement is injected via the cannula into the vertebral body (Fig. 2.26). The function of the bone cement is two-fold. First, it increases the strength of the vertebral body and prevents further loss of height. Furthermore, as the bone cement sets, there is a degree of heat generated that is believed to disrupt pain nerve endings. Kyphoplasty is a similar technique that aims to restore some or all of the lost vertebral body height from the wedge fracture by injecting liquid bone cement into the vertebral body. In the clinic	Anatomy_Gray. Osteoporotic wedge fractures (Fig. 2.25) typically occur in the thoracolumbar region, and the approach to performing vertebroplasty is novel and relatively straightforward. The procedure is performed under sedation or light general anesthetic. Using X-ray guidance the pedicle is identified on the anteroposterior image. A metal cannula is placed through the pedicle into the vertebral body. Liquid bone cement is injected via the cannula into the vertebral body (Fig. 2.26). The function of the bone cement is two-fold. First, it increases the strength of the vertebral body and prevents further loss of height. Furthermore, as the bone cement sets, there is a degree of heat generated that is believed to disrupt pain nerve endings. Kyphoplasty is a similar technique that aims to restore some or all of the lost vertebral body height from the wedge fracture by injecting liquid bone cement into the vertebral body. In the clinic
Anatomy_Gray_233	Anatomy_Gray	In the clinic Scoliosis is an abnormal lateral curvature of the vertebral column (Fig. 2.27). A true scoliosis involves not only the curvature (rightor left-sided) but also a rotational element of one vertebra upon another. The commonest types of scoliosis are those for which we have little understanding about how or why they occur and are termed idiopathic scoliosis. It is thought that there is some initial axial rotation of the vertebrae, which then alters the locations of the mechanical compressive and distractive forces applied through the vertebral growth plates, leading to changes in speed of bone growth and ultimately changes to spinal curvature. These are never present at birth and tend to occur in either the infantile, juvenile, or adolescent age groups. The vertebral bodies and posterior elements (pedicles and laminae) are normal in these patients.	Anatomy_Gray. In the clinic Scoliosis is an abnormal lateral curvature of the vertebral column (Fig. 2.27). A true scoliosis involves not only the curvature (rightor left-sided) but also a rotational element of one vertebra upon another. The commonest types of scoliosis are those for which we have little understanding about how or why they occur and are termed idiopathic scoliosis. It is thought that there is some initial axial rotation of the vertebrae, which then alters the locations of the mechanical compressive and distractive forces applied through the vertebral growth plates, leading to changes in speed of bone growth and ultimately changes to spinal curvature. These are never present at birth and tend to occur in either the infantile, juvenile, or adolescent age groups. The vertebral bodies and posterior elements (pedicles and laminae) are normal in these patients.
Anatomy_Gray_234	Anatomy_Gray	When a scoliosis is present from birth (congenital scoliosis) it is usually associated with other developmental abnormalities. In these patients, there is a strong association with other abnormalities of the chest wall, genitourinary tract, and heart disease. This group of patients needs careful evaluation by many specialists. A rare but important group of scoliosis is that in which the muscle is abnormal. Muscular dystrophy is the commonest example. The abnormal muscle does not retain the normal alignment of the vertebral column, and curvature develops as a result. A muscle biopsy is needed to make the diagnosis. Other disorders that can produce scoliosis include bone tumors, spinal cord tumors, and localized disc protrusions. In the clinic	Anatomy_Gray. When a scoliosis is present from birth (congenital scoliosis) it is usually associated with other developmental abnormalities. In these patients, there is a strong association with other abnormalities of the chest wall, genitourinary tract, and heart disease. This group of patients needs careful evaluation by many specialists. A rare but important group of scoliosis is that in which the muscle is abnormal. Muscular dystrophy is the commonest example. The abnormal muscle does not retain the normal alignment of the vertebral column, and curvature develops as a result. A muscle biopsy is needed to make the diagnosis. Other disorders that can produce scoliosis include bone tumors, spinal cord tumors, and localized disc protrusions. In the clinic
Anatomy_Gray_235	Anatomy_Gray	Other disorders that can produce scoliosis include bone tumors, spinal cord tumors, and localized disc protrusions. In the clinic Kyphosis is abnormal curvature of the vertebral column in the thoracic region, producing a “hunchback” deformity. This condition occurs in certain disease states, the most dramatic of which is usually secondary to tuberculosis infection of a thoracic vertebral body, where the kyphosis becomes angulated at the site of the lesion. This produces the gibbus deformity, a deformity that was prevalent before the use of antituberculous medication (Fig. 2.28). In the clinic Lordosis is abnormal curvature of the vertebral column in the lumbar region, producing a swayback deformity. In the clinic	Anatomy_Gray. Other disorders that can produce scoliosis include bone tumors, spinal cord tumors, and localized disc protrusions. In the clinic Kyphosis is abnormal curvature of the vertebral column in the thoracic region, producing a “hunchback” deformity. This condition occurs in certain disease states, the most dramatic of which is usually secondary to tuberculosis infection of a thoracic vertebral body, where the kyphosis becomes angulated at the site of the lesion. This produces the gibbus deformity, a deformity that was prevalent before the use of antituberculous medication (Fig. 2.28). In the clinic Lordosis is abnormal curvature of the vertebral column in the lumbar region, producing a swayback deformity. In the clinic
Anatomy_Gray_236	Anatomy_Gray	In the clinic Lordosis is abnormal curvature of the vertebral column in the lumbar region, producing a swayback deformity. In the clinic There are usually seven cervical vertebrae, although in certain diseases these may be fused. Fusion of cervical vertebrae (Fig. 2.29A) can be associated with other abnormalities, for example Klippel-Feil syndrome, in which there is fusion of vertebrae CI and CII or CV and CVI, and may be associated with a high-riding abnormalities. Variations in the number of thoracic vertebrae also are well described.	Anatomy_Gray. In the clinic Lordosis is abnormal curvature of the vertebral column in the lumbar region, producing a swayback deformity. In the clinic There are usually seven cervical vertebrae, although in certain diseases these may be fused. Fusion of cervical vertebrae (Fig. 2.29A) can be associated with other abnormalities, for example Klippel-Feil syndrome, in which there is fusion of vertebrae CI and CII or CV and CVI, and may be associated with a high-riding abnormalities. Variations in the number of thoracic vertebrae also are well described.
Anatomy_Gray_237	Anatomy_Gray	Variations in the number of thoracic vertebrae also are well described. One of the commonest abnormalities in the lumbar vertebrae is a partial fusion of vertebra LV with the sacrum (sacralization of the lumbar vertebra). Partial separation of vertebra SI from the sacrum (lumbarization of first sacral vertebra) may also occur (Fig. 2.29B). The LV vertebra can usually be identified by the iliolumbar ligament, which is a band of connective tissue that runs from the tip of the transverse process of LV to the iliac crest bilaterally (Fig. 2.29C). A hemivertebra occurs when a vertebra develops only on one side (Fig. 2.29B). In the clinic The vertebrae and cancer	Anatomy_Gray. Variations in the number of thoracic vertebrae also are well described. One of the commonest abnormalities in the lumbar vertebrae is a partial fusion of vertebra LV with the sacrum (sacralization of the lumbar vertebra). Partial separation of vertebra SI from the sacrum (lumbarization of first sacral vertebra) may also occur (Fig. 2.29B). The LV vertebra can usually be identified by the iliolumbar ligament, which is a band of connective tissue that runs from the tip of the transverse process of LV to the iliac crest bilaterally (Fig. 2.29C). A hemivertebra occurs when a vertebra develops only on one side (Fig. 2.29B). In the clinic The vertebrae and cancer
Anatomy_Gray_238	Anatomy_Gray	A hemivertebra occurs when a vertebra develops only on one side (Fig. 2.29B). In the clinic The vertebrae and cancer The vertebrae are common sites for metastatic disease (secondary spread of cancer cells). When cancer cells grow within the vertebral bodies and the posterior elements, they interrupt normal bone cell turnover, leading to either bone destruction or formation and destroying the mechanical properties of the bone. A minor injury may therefore lead to vertebral collapse (Fig. 2.30A). Cancer cells have a much higher glucose metabolism compared with normal adjacent bone cells. These metastatic cancer cells can therefore be detected by administering radioisotope-labeled glucose to a patient and then tracing where the labeled glucose has been metabolized (Fig. 2.30B). Importantly, vertebrae that contain extensive metastatic disease may extrude fragments of tumor into the vertebral canal, compressing nerves and the spinal cord. In the clinic	Anatomy_Gray. A hemivertebra occurs when a vertebra develops only on one side (Fig. 2.29B). In the clinic The vertebrae and cancer The vertebrae are common sites for metastatic disease (secondary spread of cancer cells). When cancer cells grow within the vertebral bodies and the posterior elements, they interrupt normal bone cell turnover, leading to either bone destruction or formation and destroying the mechanical properties of the bone. A minor injury may therefore lead to vertebral collapse (Fig. 2.30A). Cancer cells have a much higher glucose metabolism compared with normal adjacent bone cells. These metastatic cancer cells can therefore be detected by administering radioisotope-labeled glucose to a patient and then tracing where the labeled glucose has been metabolized (Fig. 2.30B). Importantly, vertebrae that contain extensive metastatic disease may extrude fragments of tumor into the vertebral canal, compressing nerves and the spinal cord. In the clinic
Anatomy_Gray_239	Anatomy_Gray	In the clinic Osteoporosis is a pathophysiologic condition in which bone quality is normal but the quantity of bone is deficient. It is a metabolic bone disorder that commonly occurs in women in their 50s and 60s and in men in their 70s. Many factors influence the development of osteoporosis, including genetic predetermination, level of activity and nutritional status, and, in particular, estrogen levels in women. Typical complications of osteoporosis include “crush” vertebral body fractures, distal fractures of the radius, and hip fractures. With increasing age and poor-quality bone, patients are more susceptible to fracture. Healing tends to be impaired in these elderly patients, who consequently require long hospital stays and prolonged rehabilitation.	Anatomy_Gray. In the clinic Osteoporosis is a pathophysiologic condition in which bone quality is normal but the quantity of bone is deficient. It is a metabolic bone disorder that commonly occurs in women in their 50s and 60s and in men in their 70s. Many factors influence the development of osteoporosis, including genetic predetermination, level of activity and nutritional status, and, in particular, estrogen levels in women. Typical complications of osteoporosis include “crush” vertebral body fractures, distal fractures of the radius, and hip fractures. With increasing age and poor-quality bone, patients are more susceptible to fracture. Healing tends to be impaired in these elderly patients, who consequently require long hospital stays and prolonged rehabilitation.