Sacrospinous ligament
Encyclopedia
The sacrospinous ligament (small or anterior sacrosciatic ligament) is thin, triangular ligament
attached by its apex to the ischial spine
, and medially, by its broad base, to the lateral margins of the sacrum
and coccyx
, in front of the sacrotuberous ligament
with which its fibers are intermingled.
into the greater sciatic foramen
and the lesser sciatic notch
into the lesser sciatic foramen
.
The lateral part of its upper border forms the lower boundary of the greater foramen, while the lateral part of its lower border forms the upper part of the lesser foramen.
Its posterior half is covered by the sacrotuberous ligament, and in its entire length it covers the equally triangular coccygeus muscle
, to which its closely connected.
The pudendal vessels
and nerve
pass behind the sacrospinous ligament directly medially and inferiorly to the ischial spine. The inferior gluteal artery
, from a branch of the internal iliac artery
, pass behind the sciatic nerve
and the sacrospinous ligament and is left uncovered in a small opening above the top of the sacrospinous ligament. The coccygeal branch of the inferior gluteal artery passes behind the mid-portion of the sacrospinous ligament and pierces the sacrotuberous ligament at multiple locations. The main body of the inferior gluteal artery leaves the pelvis posteriorly to the upper border of the sacrospinous ligament, to follow the inferior portion of the sciatic nerve out of the greater sciatic foramen.
When pelvic ligaments and connective tissue supports are severally attenuated or absent in women, the sacrospinous ligament provides a consistently strong site for fixation of the vaginal apex, so called sacrospinous ligament suspension, in which the vaginal apex is suspended posteriorly and laterally to the ligament on either side or both sides.
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
attached by its apex to the ischial spine
Ischial spine
From the posterior border of the body of the Ischium there extends backward a thin and pointed triangular eminence, the ischial spine, more or less elongated in different subjects.It can serve as a landmark in pudendal anesthesia.-Surfaces:...
, and medially, by its broad base, to the lateral margins of the sacrum
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
and coccyx
Coccyx
The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
, in front of the sacrotuberous ligament
Sacrotuberous ligament
The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends....
with which its fibers are intermingled.
Relations
Together with the sacrotuberous ligament, it converts the greater sciatic notchGreater sciatic notch
Above the ischial spine is a large notch, the greater sciatic notch, converted into a foramen by the sacrospinous ligament.It transmits the Piriformis, the superior and inferior gluteal vessels and nerves, the sciatic and posterior femoral cutaneous nerves, the internal pudendal vessels, and the...
into the greater sciatic foramen
Greater sciatic foramen
-Boundaries:It is bounded as follows:* anterolaterally by the greater sciatic notch of the illium* posteromedially by the sacrotuberous ligament* inferiorly by the sacrospinous ligament and the ischial spine* superiorly by the anterior sacroilliac ligament...
and the lesser sciatic notch
Lesser sciatic notch
Below the ischial spine is a smaller notch, the lesser sciatic notch; it is smooth, coated in the recent state with cartilage, the surface of which presents two or three ridges corresponding to the subdivisions of the tendon of the Obturator internus, which winds over it.It is converted into a...
into the lesser sciatic foramen
Lesser sciatic foramen
An opening between the pelvis and the posterior thigh, the foramen is formed by the sacrotuberous ligament which runs between the sacrum and the ischial tuberosity and the sacrospinous ligament which runs between the sacrum and the ischial spine.-Boundaries:...
.
The lateral part of its upper border forms the lower boundary of the greater foramen, while the lateral part of its lower border forms the upper part of the lesser foramen.
Its posterior half is covered by the sacrotuberous ligament, and in its entire length it covers the equally triangular coccygeus muscle
Coccygeus muscle
The Coccygeus is a muscle of the pelvic wall , located posterior to levator ani and anterior to the sacrospinous ligament....
, to which its closely connected.
The pudendal vessels
Pudendal vessels
Pudendal vessels can refer to:* Internal pudendal artery* Deep external pudendal artery...
and nerve
Pudendal nerve
The pudendal nerve is a sensory and somatic nerve in the pelvic region which is a large branch of the sacral plexus that innervates the external genitalia of both sexes, as well as sphincters for the bladder and the rectum...
pass behind the sacrospinous ligament directly medially and inferiorly to the ischial spine. The inferior gluteal artery
Inferior gluteal artery
The inferior gluteal artery , the larger of the two terminal branches of the anterior trunk of the internal iliac artery, is distributed chiefly to the buttock and back of the thigh....
, from a branch of the internal iliac artery
Internal iliac artery
The internal iliac artery is the main artery of the pelvis.-Structure:The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compartment of the thigh...
, pass behind the sciatic nerve
Sciatic nerve
The sciatic nerve is a large nerve fiber in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb...
and the sacrospinous ligament and is left uncovered in a small opening above the top of the sacrospinous ligament. The coccygeal branch of the inferior gluteal artery passes behind the mid-portion of the sacrospinous ligament and pierces the sacrotuberous ligament at multiple locations. The main body of the inferior gluteal artery leaves the pelvis posteriorly to the upper border of the sacrospinous ligament, to follow the inferior portion of the sciatic nerve out of the greater sciatic foramen.
Function
Its main function is to prevent posterior rotation of the ilium with respect to the sacrum. Laxity of this ligament along with the sacrotuberous ligament allows for this posterior rotation to occur. Stresses to these ligaments occur most often when leaning forward or getting out of a chair.When pelvic ligaments and connective tissue supports are severally attenuated or absent in women, the sacrospinous ligament provides a consistently strong site for fixation of the vaginal apex, so called sacrospinous ligament suspension, in which the vaginal apex is suspended posteriorly and laterally to the ligament on either side or both sides.