The<unk>  region of the trunk is the lower part of the trunk, between the abdomen and the thighs. It includes several structures: the bony<unk> , the<unk>  cavity, the<unk>  floor, and the perineum. The bony<unk>  <unk>  skeleton) is the part of the skeleton embedded in the<unk>  region of the trunk. It is subdivided into the<unk>  girdle and the<unk>  spine. The<unk>  girdle is composed of the appendicular hip bones (ilium, ischium, and pubis) oriented in a ring, and connects the<unk>  region of the spine to the lower limbs. The<unk>  spine consists of the sacrum and coccyx. * the<unk>  cavity, typically defined as a small part of the space enclosed by the bony<unk> , delimited by the<unk>  brim above and the<unk>  floor below; alternatively, the<unk>  cavity is sometimes also defined as the whole space enclosed by the<unk>  skeleton, subdivided into: * the greater (or false)<unk> , above the<unk>  brim * the lesser (or true)<unk> , below the<unk>  brim * the<unk>  floor (or<unk>  diaphragm), below the<unk>  cavity * the perineum, below the<unk>  floor<unk>  bone The<unk>  skeleton is formed posteriorly (in the area of the back), by the sacrum and the coccyx and laterally and anteriorly (forward and to the sides), by a pair of hip bones. Each hip bone consists of 3 sections, ilium, ischium, and pubis. During childhood, these sections are separate bones, joined by the triradiate cartilage. During puberty, they fuse together to form a single bone.<unk>  cavity 180px 180px 180px The<unk>  cavity is a body cavity that is bounded by the bones of the<unk>  and which primarily contains reproductive organs and the rectum. A distinction is made between the lesser or true<unk>  inferior to the terminal line, and the greater or false<unk>  above it. The<unk>  inlet or superior<unk>  aperture, which leads into the lesser<unk> , is bordered by the promontory, the arcuate line of ilium, the iliopubic eminence, the pecten of the pubis, and the upper part of the pubic symphysis. The<unk>  outlet or inferior<unk>  aperture is the region between the subpubic angle or pubic arch, the ischial tuberosities and the coccyx. * Ligaments: obturator membrane, inguinal ligament (lacunar ligament, iliopectineal arch) Alternatively, the<unk>  is divided into three planes: the inlet, midplane, and outlet.<unk>  floor Female perineum The<unk>  floor has two inherently conflicting functions: One is to close the<unk>  and abdominal cavities and bear the load of the visceral organs; the other is to control the openings of the rectum and urogenital organs that pierce the<unk>  floor and make it weaker. To achieve both these tasks, the<unk>  floor is composed of several overlapping sheets of muscles and connective tissues. The<unk>  diaphragm is composed of the levator ani and the coccygeus muscle. These arise between the symphysis and the ischial spine and converge on the coccyx and the anococcygeal ligament which spans between the tip of the coccyx and the anal hiatus. This leaves a slit for the anal and urogenital openings. Because of the width of the genital aperture, which is wider in females, a second closing mechanism is required. The urogenital diaphragm consists mainly of the deep transverse perineal which arises from the inferior ischial and pubic rami and extends to the urogenital hiatus. The urogenital diaphragm is reinforced posteriorly by the superficial transverse perineal. The external anal and urethral sphincters close the anus and the urethra. The former is surrounded by the bulbospongiosus which narrows the vaginal introitus in females and surrounds the corpus spongiosum in males. Ischiocavernosus squeezes blood into the corpus cavernosum penis and clitoridis. Variation Modern humans are to a large extent characterized by bipedal locomotion and large brains. Because the<unk>  is vital to both locomotion and childbirth, natural selection has been confronted by two conflicting demands: a wide birth canal and locomotion efficiency, a conflict referred to as the "obstetrical dilemma". The female<unk> , or gynecoid<unk> , has evolved to its maximum width for childbirth—a wider<unk>  would make women unable to walk. In contrast, human male<unk> es are not constrained by the need to give birth and therefore are more optimized for bipedal locomotion. The principal differences between male and female true and false<unk>  include: * The female<unk>  is larger and broader than the male<unk>  which is taller, narrower, and more compact. * The female inlet is larger and oval in shape, while the male sacral promontory projects further (i.e. the male inlet is more heart-shaped). * The sides of the male<unk>  converge from the inlet to the outlet, whereas the sides of the female<unk>  are wider apart. * The angle between the inferior pubic rami is acute (70 degrees) in men, but obtuse (90–100 degrees) in women. Accordingly, the angle is called subpubic angle in men and pubic arch in women. Additionally, the bones forming the angle/arch are more concave in females but straight in males. * The distance between the ischia bones is small in males, making the outlet narrow, but large in females, who have a relatively large outlet. The ischial spines and tuberosities are heavier and project farther into the<unk>  cavity in males. The greater sciatic notch is wider in females. * The iliac crests are higher and more pronounced in males, making the male false<unk>  deeper and more narrow than in females. * The male sacrum is long, narrow, more straight, and has a pronounced sacral promontory. The female sacrum is shorter, wider, more curved posteriorly, and has a less pronounced promontory. * The acetabula are wider apart in females than in males. In males, the acetabulum faces more laterally, while it faces more anteriorly in females. Consequently, when males walk the leg can move forwards and backwards in a single plane. In females, the leg must swing forward and inward, from where the pivoting head of the femur moves the leg back in another plane. This change in the angle of the femoral head gives the female gait its characteristic (i.e. swinging of hips).
Pelvis
Ovary
Testicle
Breast
Callus
Shine 
Collyrium
Skull