The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

. It is flat, and triangular in form; narrower in the middle than at the ends.

Structure

It runs from the

sacrum The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

(the lower transverse sacral tubercles, the inferior margins sacrum and the upper

coccyx The coccyx (: coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horse anatomy, horses. In tailless primates (e.g. hum ...

) to the

tuberosity of the ischium The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large posterior (anatomy), posterior bone, bony protuberance on the superior r ...

. It is a remnant of part of

biceps femoris The biceps femoris () is a muscle of the thigh located to the posterior, or back. As its name implies, it consists of two heads; the long head is considered part of the hamstring muscle group, while the short head is sometimes excluded from this ...

muscle. The sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments (with which it is partly blended), to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx. Its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity. It then spreads along the ischial ramus as the falciform process, whose concave edge blends with the fascial sheath of the internal pudendal vessels and pudendal nerve. The lowest fibres of

gluteus maximus The gluteus maximus is the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in ...

are attached to the posterior surface of the ligament; superficial fibres of the lower part of the ligament continue into the tendon of biceps femoris. The ligament is pierced by the coccygeal branches of the inferior gluteal artery, the perforating cutaneous nerve and filaments of the coccygeal plexus.

Variation

The membranous falciform process of the sacrotuberous ligament was found to be absent in 13% of

cadavers A cadaver, often known as a corpse, is a dead human body. Cadavers are used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a liv ...

. When present it extends towards the

ischioanal fossa The ischioanal fossa (formerly called ischiorectal fossa) is the fat-filled wedge-shaped space located lateral to the anal canal and inferior to the pelvic diaphragm. It is somewhat prismatic in shape, with its base directed to the surface of the ...

travelling along the

ischial ramus The ischium (; : is ...

and fusing with the

obturator fascia The obturator fascia, or fascia of the internal obturator muscle, covers the pelvic surface of that muscle and is attached around the margin of its origin. Above, it is loosely connected to the back part of the arcuate line, and here it is conti ...

. The lower border of the ligament was found to be directly continuous with the tendon of origin of the long head of the

in approximately 50% of subjects.Vleeming, A., R. Stoeckart, et al. (1989). "The sacrotuberous ligament: a conceptual approach to its dynamic role in stabilizing the sacroiliac joint." Clinical Biomechanics 4(4): 200–203. biceps femoris could therefore act to stabilise the sacroiliac joint via the sacrotuberous ligament.

Function

The sacrotuberous ligament contains the coccygeal branch of the

inferior gluteal artery The inferior gluteal artery (sciatic artery) is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh. Ana ...

Clinical significance

If the

pudendal nerve The pudendal nerve is the main nerve of the perineum. It is a Mixed nerve, mixed (motor and sensory) nerve and also conveys Sympathetic nervous system, sympathetic Autonomic nervous system, autonomic fibers. It carries sensation from the exter ...

becomes entrapped between this ligament and the

sacrospinous ligament The sacrospinous ligament (small or anterior sacrosciatic ligament) is a thin, triangular ligament in the human pelvis. The base of the ligament is attached to the outer edge of the sacrum and coccyx, and the tip of the ligament attaches to the i ...

causing perineal pain, the sacrotuberous ligament is surgically severed to relieve the pain.

Additional images

File:Gray319.png, Articulations of pelvis. Anterior view. File:Gray542.png, The superficial branches of the internal pudendal artery. File:Gray1077.png, The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx. File:Gray1243.png , Nélaton's line and Bryant's triangle.

References

External links

* – "Deep muscles of the gluteal region with gluteus medius and maximus muscles removed." * – "Posterior view of the bones and ligaments of the hip joint." * – "The Female Perineum" * – "The Male Perineum and the Penis: Boundaries of the

Ischioanal fossa The ischioanal fossa (formerly called ischiorectal fossa) is the fat-filled wedge-shaped space located lateral to the anal canal and inferior to the pelvic diaphragm. It is somewhat prismatic in shape, with its base directed to the surface of the ...

" * *
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Dartmouth Medical School The Geisel School of Medicine is the medical school of Dartmouth College located in Hanover, New Hampshire. The fourth oldest medical school in the United States, it was founded in 1797 by New England physician Nathan Smith. It is one of the sev ...

's Department of Anatomy {{Authority control Ligaments of the torso Ligaments