+Actions of the spinal nerves Level Motor Function C1–C6 Neck flexors C1–T1 Neck extensors C3, C4, C5 Supply diaphragm (mostly C4) C5, C6 Move shoulder, raise arm (deltoid); flex elbow (biceps) C6 externally rotate (supinate) the arm C6, C7 Extend elbow and wrist (triceps and wrist extensors); pronate wrist C7, T1 Flex wrist; supply small muscles of the hand T1–T6 Intercostals and trunk above the waist T7–L1 Abdominal muscles L1–L4 Flex thigh L2, L3, L4 Adduct thigh; Extend leg at the knee (quadriceps femoris) L4, L5, S1 abduct thigh; Flex leg at the knee (hamstrings); Dorsiflex foot (tibialis anterior); Extend toes L5, S1, S2 Extend leg at the hip (gluteus maximus); Plantar flex foot and flex toes Signs (observed by a clinician) and symptoms (experienced by a patient) vary depending on where the spine is<unk> d and the extent of the<unk> . A section of skin innervated through a specific part of the spine is called a dermatome, and<unk>  to that part of the spine can cause pain, numbness, or a loss of sensation in the related areas. Paraesthesia, a tingling or burning sensation in affected areas of the skin, is another symptom. A person with a lowered level of consciousness may show a response to a painful stimulus above a certain point but not below it. A group of muscles innervated through a specific part of the spine is called a myotome, and<unk>  to that part of the spinal<unk>  can cause problems with movements that involve those muscles. The muscles may contract uncontrollably (spasticity), become weak, or be completely paralysed. Spinal shock, loss of neural activity including reflexes below the level of<unk> , occurs shortly after the<unk>  and usually goes away within a day. Priapism, an erection of the penis may be a sign of acute<unk> . The specific parts of the body affected by loss of function are determined by the level of<unk> . Some signs, such as bowel and bladder dysfunction can occur at any level. Neurogenic bladder involves a compromised ability to empty the bladder and is a common symptom of<unk> . This can lead to high pressures in the bladder that can damage the kidneys. Lumbosacral The effects of<unk> es at or above the lumbar or sacral regions of the spinal<unk>  (lower back and pelvis) include decreased control of the legs and hips, genitourinary system, and anus. People<unk> d below level L2 may still have use of their hip flexor and knee extensor muscles. Bowel and bladder function are regulated by the sacral region. It is common to experience sexual dysfunction after<unk> , as well as dysfunction of the bowel and bladder, including fecal and urinary incontinence. Thoracic In addition to the problems found in lower-level<unk> es, thoracic (chest height) spinal lesions can affect the muscles in the trunk.<unk> es at the level of T1 to T8 result in inability to control the abdominal muscles. Trunk stability may be affected; even more so in higher level<unk> es. The lower the level of<unk> , the less extensive its effects.<unk> es from T9 to T12 result in partial loss of trunk and abdominal muscle control. Thoracic spinal<unk> es result in paraplegia, but function of the hands, arms, and neck are not affected. One condition that occurs typically in lesions above the T6 level is autonomic dysreflexia (AD), in which the blood pressure increases to dangerous levels, high enough to cause potentially deadly stroke. It results from an overreaction of the system to a stimulus such as pain below the level of<unk> , because inhibitory signals from the brain cannot pass the lesion to dampen the excitatory sympathetic nervous system response. Signs and symptoms of AD include anxiety, headache, nausea, ringing in the ears, blurred vision, flushed skin, and nasal congestion. It can occur shortly after the<unk>  or not until years later. Other autonomic functions may also be disrupted. For example, problems with body temperature regulation mostly occur in<unk> es at T8 and above. Another serious complication that can result from lesions above T6 is neurogenic shock, which results from an interruption in output from the sympathetic nervous system responsible for maintaining muscle tone in the blood vessels. Without the sympathetic input, the vessels relax and dilate. Neurogenic shock presents with dangerously low blood pressure, low heart rate, and blood pooling in the limbs—which results in insufficient blood flow to the spinal<unk>  and potentially further damage to it. Cervical<unk> es at the cervical (neck) level result in full or partial tetraplegia (also called quadriplegia). Depending on the specific location and severity of trauma, limited function may be retained. Additional symptoms of cervical<unk> es include low heart rate, low blood pressure, problems regulating body temperature, and breathing dysfunction. If the<unk>  is high enough in the neck to impair the muscles involved in breathing, the person may not be able to breathe without the help of an endotracheal tube and mechanical ventilator. + Function after complete cervical<unk>  Level Motor Function Respiratory function C1–C4 Full paralysis of the limbs Cannot breathe without mechanical ventilation C5 Paralysis of the wrists, hands, and triceps Difficulty coughing, may need help clearing secretions C6 Paralysis of the wrist flexors, triceps, and hands C7–C8 Some hand muscle weakness, difficulty grasping and releasing Complications Complications of<unk> es include pulmonary edema, respiratory failure, neurogenic shock, and paralysis below the<unk>  site. In the long term, the loss of muscle function can have additional effects from disuse, including atrophy of the muscle. Immobility can lead to pressure sores, particularly in bony areas, requiring precautions such as extra cushioning and turning in bed every two hours (in the acute setting) to relieve pressure. In the long term, people in wheelchairs must shift periodically to relieve pressure. Another complication is pain, including nociceptive pain (indication of potential or actual tissue damage) and neuropathic pain, when nerves affected by damage convey erroneous pain signals in the absence of noxious stimuli. Spasticity, the uncontrollable tensing of muscles below the level of<unk> , occurs in 65–78% of chronic<unk> . It results from lack of input from the brain that quells muscle responses to stretch reflexes. It can be treated with drugs and physical therapy. Spasticity increases the risk of contractures (shortening of muscles, tendons, or ligaments that result from lack of use of a limb); this problem can be prevented by moving the limb through its full range of motion multiple times a day. Another problem lack of mobility can cause is loss of bone density and changes in bone structure. Loss of bone density (bone demineralization), thought to be due to lack of input from weakened or paralysed muscles, can increase the risk of fractures. Conversely, a poorly understood phenomenon is the overgrowth of bone tissue in soft tissue areas, called heterotopic ossification. It occurs below the level of<unk> , possibly as a result of inflammation, and happens to a clinically significant extent in 27% of people. Muscle mass is reduced as muscles atrophy with disuse. People with<unk>  are at especially high risk for respiratory and cardiovascular problems, so hospital staff must be watchful to avoid them. Respiratory problems (especially pneumonia) are the leading cause of death in people with<unk> , followed by infections, usually of pressure sores, urinary tract infections and respiratory infections. Pneumonia can be accompanied by shortness of breath, fever, and anxiety. Another potentially deadly threat to respiration is deep venous thrombosis (DVT), in which blood forms a clot in immobile limbs; the clot can break off and form a pulmonary embolism, lodging in the lung and cutting off blood supply to it. DVT is an especially high risk in<unk> , particularly within 10 days of<unk> , occurring in over 13% in the acute care setting. Preventative measures include anticoagulants, pressure hose, and moving the patient's limbs. The usual signs and symptoms of DVT and pulmonary embolism may be masked in<unk>  cases due to effects such as alterations in pain perception and nervous system functioning. Urinary tract infection (UTI) is another risk that may not display the usual symptoms (pain, urgency, and frequency); it may instead be associated with worsened spasticity. The risk of UTI, likely the most common complication in the long term, is heightened by use of indwelling urinary catheters. Catheterization may be necessary because<unk>  interferes with the bladder's ability to empty when it gets too full, which could trigger autonomic dysreflexia or damage the bladder permanently. The use of intermittent catheterization to empty the bladder at regular intervals throughout the day has decreased the mortality due to kidney failure from UTI in the first world, but it is still a serious problem in developing countries. An estimated 24–45% of people with<unk>  suffer disorders of depression, and the suicide rate is as much as six times that of the rest of the population. The risk of suicide is worst in the first five years after<unk> . In young people with<unk> , suicide is the leading
Spinal cord injury
Spinal tumor
Vascular myelopathy
Posterior cord syndrome
Basal ganglia disease
Spinal disease
Syringomyelia
Central cord syndrome