Osteology
|
| Bone |
Structure |
Description |
Notes |
| os coxae (TG6-06) |
|
one of three bones that form the pelvis |
paired; the os coxae forms the lateral part of the pelvis; it is formed by three fused bones: ischium, ilium & pubis; also known as the innominate bone |
|
obturator foramen |
a large foramen formed by the pubic and ischial rami |
obturator means to occlude or stop up, a reference to the fact that the obturator membrane closes the obturator foramen almost completely; a site of attachment for the obturator externus m. and the obturator internus m. |
|
obturator groove |
groove on the inferior surface of the superior pubic ramus |
marks the area of passage of the obturator vessels and n. in the obturator canal |
| ischium (N486, TG3-04, N486, N353, N503, TG3-04, TG3-28, TG6-06) |
|
the "V"- shaped bone that forms the posteroinferior part of the pelvis |
one of the three bones that form the os coxae: ilium, ischium, pubis |
| |
ischial ramus |
the limb of the ischium that passes anteriorly and superomedially toward the pubis |
it articulates with the inferior ramus of the pubis (Greek, ischion = hip joint; Latin, ramus = a branch) |
|
ischial tuberosity |
the roughened projection that protrudes posteroinferiorly from the body of the ischium |
it is the site of attachment of the sacrotuberous ligament; it is the site of origin of the inferior gemellus m., quadratus femoris m. and the hamstring mm. (semitendinosus, semimembranosus, long head of biceps femoris, ischiocondylar portion of the adductor magnus) (Greek, ischion = hip joint) |
|
lesser sciatic notch |
the notch located between the ischial tuberosity and the ischial spine |
the lesser sciatic notch is converted to the lesser sciatic foramen by the sacrospinous ligament and the sacrotuberous ligament |
|
ischial spine |
the spine that arises just superior to the lesser sciatic notch |
it is the site of attachment of the sacrospinous ligament and the site of origin of the superior gemellus m. (Greek, ischion = hip joint) |
| ilium (TG3-04) |
|
fan-shaped bone that forms the lateral prominence of the pelvis |
one of three bones that form the os coxae: ilium, ischium, pubis |
|
greater sciatic notch |
the notch on the inferior portion of ilium located posteromedial to the ischial spine |
the greater sciatic notch is converted to the greater sciatic foramen by the sacrospinous ligament and the sacrotuberous ligament |
| sacrum (N248, N365, TG5-03, TG6-06) |
|
a triangular bone that is the posterior skeletal element forming the pelvis |
it is formed by 5 fused vertebrae; the sacrum and two os coxae bones form the pelvis |
|
sacroiliac joint |
the articulation between the ala of the sacrum and the auricular surface of the ilium |
a synovial joint; the fibrous articular capsule is thickened dorsally and ventrally to form the sacroiliac ligaments; because of the interlocking nature of the joint surfaces and the strong sacroiliac ligaments, only limited movement is permitted at the sacroiliac joint (Latin, sacrum = sacred bone) |
|
anterior sacral foramina |
an opening in the anterior surface of the sacrum |
there are four pairs; each transmits the ventral primary ramus of the respective sacral spinal nerve; branches of the lateral sacral aa. Enter the sacral canal through these openings |
| coccyx (TG6-04) |
|
the most inferior portion of the vertebral column |
the coccyx results from the fusion of the four coccygeal vertebrae; it may be a single bone or the first coccygeal vertebra may be separated from the other three; it articulates with the fifth sacral segment; coccygeal vertebrae are reduced in complexity, having no pedicles, laminae or spines (Greek, coccyx = a cockoo's beak) |
Muscles
|
| Muscle |
Origin |
Insertion |
Action |
Innervation |
Artery |
Notes |
Image |
| coccygeus (TG6-15, TG6-21, TG6-23) |
ischial spine |
side of the coccyx and lower sacrum |
elevates the pelvic floor |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
coccygeus and levator ani combined form the pelvic diaphragm |
 |
| iliococcygeus (TG6-15, TG6-21, TG6-23) |
arcus tendineus levator ani and the ischial spine |
anococcygeal raphe and the coccyx |
elevates the pelvic floor |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
the combination of puborectalis, pubococcygeus and iliococcygeus is called the levator ani m. |
 |
| levator ani (TG6-15, TG6-21, TG6-23) |
posterior surface of the body of the pubis, fascia of the obturator internus m. (arcus tendineus levator ani), ischial spine |
anococcygeal raphe and coccyx |
elevates the pelvic floor |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
the combination of puborectalis, pubococcygeus & iliococcygeus is the levator ani m.; coccygeus and levator ani combined form the pelvic diaphragm (Latin, levator = to lift) |
 |
| obturator internus (TG3-13, TG5-07, TG6-14) |
the internal surface of the obturator membrane and margin of the obturator foramen |
greater trochanter on its medial surface above the trochanteric fossa |
laterally rotates and abducts the thigh |
nerve to the obturator internus m. |
obturator a. |
the obturator internus m. leaves the pelvis by passing through the lesser sciatic foramen; the superior and inferior gemellus mm. insert on the obturator internus tendon |
 |
| piriformis (TG3-12, TG6-21, TG6-23) |
anterior surface of sacrum |
upper border of greater trochanter of femur |
laterally rotates and abducts thigh |
ventral rami of S1-S2 |
|
piriformis leaves the pelvis by passing through the greater sciatic foramen |
 |
| pubococcygeus (TG6-15, TG6-21, TG6-22, TG6-23, (TG6-35, TG6-36) |
posterior aspect of the superior pubic ramis |
coccyx |
elevates the pelvic floor |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
the combination of puborectalis, pubococcygeus and iliococcygeus is called the levator ani m. |
 |
| puborectalis (TG6-15, TG6-21, TG6-22, TG6-23, (TG6-35, TG6-36) |
posterior aspect of the body of the pubis |
unites with the puborectalis m. of other side posterior to the rectum |
draws the distal rectum forward and superiorly; aids in voluntary retention of feces |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
the combination of puborectalis, pubococcygeus and iliococcygeus is called the levator ani m. |
 |
| pubovaginalis |
posterior aspect of the body of the pubis |
fascia of the vagina and perineal body |
draws the vagina forward and superiorly |
branches of the ventral primary rami of spinal nerves S3-S4 |
inferior gluteal a. |
pubovaginalis is part of the levator ani muscle |
 |
Nerves
|
| Nerve |
Source |
Branches |
Motor |
Sensory |
Notes |
| hypogastric plexus, inferior (N409, TG5-39) |
hypogastric nn. and sacral splanchnic nn. (postganglionic sympathetic axons); pelvic splanchnic nn. (preganglionic parasympathetic axons from the ventral primary rami of spinal nerves S2-S4) |
contributes branches to: uterine/vaginal plexus, vesical plexus, prostatic plexus |
sympathetic: supplies vascular smooth muscle of vessels supplying the pelvic viscera; parasympathetic: supplies smooth muscle of the pelvic viscera |
pain from the pelvic viscera; general visceral afferent from the pelvic viscera |
inferior hypogastric plexus lies between the pelvic viscera and the pelvic wall (Latin, hypogastric = below the stomach + plexus = a braid, a network of nerves, blood vessels or lymphatic vessels) |
| lumbosacral trunk |
part of the ventral primary ramus of L4 united with the ventral primary ramus of L5 |
no named branches; it contributes to the formation of the sacral plexus |
muscles of the hip and posterior thigh |
see sacral plexus |
the lumbosacral trunk is not considered to be part of the lumbar plexus |
| pelvic splanchnic n. (N410, N412, TG6-18, TG6-19) |
ventral primary rami of spinal nerves S2-S4 (cell bodies are located in the lateral horn gray of the sacral spinal cord) |
unnamed branches contribute to the pelvic plexus (inferior hypogastric) plexus |
smooth muscle and glands of the gut distal to the left colic flexure; smooth muscle and glands of all pelvic viscera |
none |
parasympathetic nerves; these contain preganglionic parasympathetic axons (Greek, splanchnic = viscera) |
| plexus, sacral (N410, N412, TG6-18, TG6-19) |
lumbosacral trunk (ventral primary rami of spinal nerves L4-L5), ventral primary rami of spinal nerves S1-S4 |
superior & inferior gluteal nn., n. to obturator internus m., n. to quadratus femoris m., sciatic n., n. to piriformis, posterior femoral cutaneous n., pudendal n., n. to pelvic diaphragm, pelvic splanchnic nn. |
muscles of the pelvic diaphragm; muscles of the urogenital diaphragm; muscles of the posterior hip, posterior thigh, leg and foot |
skin of the perineum, posterior thigh, leg and foot (excluding the medial side of the leg and foot) |
the sacral plexus is often grouped with the lumbar plexus as the "lumbosacral plexus" (Latin, plexus = a braid, a network of nerves, blood vessels or lymphatic vessels) |
| sacral splanchnic n. (N410, N412, TG6-18, TG6-19) |
sacral sympathetic ganglia |
unnamed branches contribute to the pelvic plexus (inferior hypogastric) plexus |
vascular smooth muscle of the pelvic viscera |
pain from the pelvic viscera |
sacral splanchnic nn. contain both preganglionic and postganglionic sympathetic nerve fibers with postganglionic fibers predominating in number (Greek, splanchnic = viscera) |
Arteries
|
| Artery |
Source |
Branches |
Supply to |
Notes |
| gluteal, inferior (N402, N403, TG6-17A, TG6-17B) |
internal iliac a., anterior division |
unnamed muscular branches |
gluteus maximus m., hip joint |
inferior gluteal a. participates in the formation of the cruciate anastomoses of the hip |
| gluteal, superior (N502, N402, N403, TG3-26, TG3-27, TG6-17A, TG6-17B) |
internal iliac, posterior division |
superficial br., deep br. |
gluteus maximus m., gluteus medius m., gluteus minimus m., hip joint |
superior gluteal a. participates in the formation of the cruciate anastomoses of the hip |
| iliac, common (N264, TG5-34) |
abdominal aorta |
external iliac a., internal iliac a. |
pelvis, lower limb |
abdominal aorta bifurcates at the level of the L4 vertebral body to form the right and left common iliac aa.; the common iliac artery bifurcates anterior to the sacroiliac articulation into its terminal brs. (external iliac a. and internal iliac a.) |
| iliac, external (N264, TG5-34) |
common iliac a. |
inferior epigastric a., deep circumflex iliac a., femoral a. |
lower limb |
external iliac a. is continuous with the femoral a., the name change occurs at the inguinal ligament; the common iliac artery bifurcates anterior to the sacroiliac articulation |
| iliolumbar (N264,
N402,
N403, TG5-34, TG6-17A, TG6-17B) |
internal iliac a., posterior division |
iliac br., lumbar br. |
iliacus m., psoas major m., quadratus lumborum m. |
lumbar br. of the iliolumbar a. sends a small spinal br. into the vertebral canal |
| internal iliac (TG3-18, TG3-20, TG5-30 |
common iliac a. |
anterior division gives rise to the : umbilical a., obturator a., uterine a., vaginal a., inferior vesical a., middle rectal a., internal pudendal a., inferior gluteal a.; posterior division gives rise to the: iliolumbar a., lateral sacral a., superior gluteal a. |
pelvic viscera, gluteal region, hip, medial thigh |
common iliac artery bifurcates anterior to the sacroiliac articulation to form the internal iliac a. and the external iliac a. |
| internal pudendal (N402, N403, N404, N405, TG6-17A, TG6-17B, TG6-29) |
internal iliac a., anterior division |
inferior rectal a., perineal a., artery of the bulb of the clitoris/penis, urethral a., deep clitoral/penile a., dorsal clitoral/penile a. |
anus, muscles of the superficial and deep perineal spaces, clitoris/penis, posterior aspect of the scrotum/labium majus |
internal pudendal a. is the primary blood supply to the perineum (Latin, pudendus = ashamed, the term referred to "the shameful parts") |
| lateral sacral (N264, TG5-34,
N402,
N403, TG6-17A, TG6-17B) |
internal iliac a., posterior division |
spinal brs. |
sacrum, sacral nerve rootlets, meninges, adjacent muscles |
there are usually 2 lateral sacral aa. on each side, a superior one and an inferior one |
| middle rectal (N402, N403, N398, TG6-17A, TG6-17B) |
internal iliac, anterior division |
no named branches |
middle portion of the rectum |
middle rectal a. anastomoses with the inferior rectal a and the superior rectal a. |
| obturator (N402, N487, TG3-54, TG6-17) |
internal iliac a., anterior division |
pubic br., acetabular br., anterior br., posterior br. |
medial thigh and hip |
anterior and posterior brs. pass on the anterior and posterior sides of the adductor brevis m.; aberrant obturator a. arises from the inferior epigastric a. in 30% of cases |
| umbilical (N402,
N403, TG6-17A, TG6-17B) |
internal iliac a., anterior division |
superior vesical aa., a. of the ductus deferens |
superior part of the bladder; ductus deferens |
distal to the branches described at left, the lumen of the umbilical a. becomes obliterated after birth and the remnant of the vessel becomes the medial umbilical ligament |
| uterine (N402, N404, TG6-17) |
internal iliac a., anterior division |
tubal br., vaginal br. |
uterus, uterine tube |
uterine a. anastomoses with the ovarian a. and the vaginal a.; it passes superior to the ureter in the pelvis; remember the saying "water under the bridge" |
| vaginal (N402, N404, TG6-17) |
internal iliac a., anterior division; occasionally it arises from uterine a. |
numerous unnamed branches |
vagina |
anastomoses with the uterine a.; participates in the formation of the azygos arteries along the lateral surface of the vagina |
| vesical, inferior (TG6-17) |
internal iliac a., anterior division or it may arise from the middle rectal a. |
no named branches |
lower part of the urinary bladder, prostate/vagina |
inferior vesical a. anastomoses with the middle rectal a. |
| vesical, superior (TG6-17) |
umbilical a. |
no named branches |
superior aspect of the bladder |
superior vesical aa.arise from the umbilical a. proximal to where its lumen becomes obliterated |
Veins
|
| Vein |
Tributaries |
Drains Into |
Region Drained |
Notes |
| rectal venous plexus (TG5-28) |
|
superior, middle & inferior rectal vv. |
rectum & anal canal; anus |
site of portal-systemic anastomosis (Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels) |
| pudendal, internal (TG5-28, TG6-16, TG6-28) |
deep v. of clitoris/penis, v. of bulb, posterior labial/scrotal v., inferior rectal v. |
internal iliac |
crus & bulb of clitoris/penis, urogenital triangle, anal triangle |
(Latin, pudendus = ashamed, the term referred to "the shameful parts") |
| uterine venous plexus |
|
uterine vv. to internal iliac v. |
uterus & uterine tubes |
connects with ovarian v. & vaginal venous plexus (Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels) |
| vaginal plexus |
|
vaginal v. to internal iliac or uterine v. |
connects with uterine & vesical venous plexuses |
(Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels) |
| vesical plexus |
|
superior & inferior vesical vv. to internal iliac |
urinary bladder |
connects with prostatic & rectal plexus or uterine & vaginal plexus (Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels) |
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