Medical Gross Anatomy
Anatomy Tables - Muscles
|
|
|
|
Medical Gross Anatomy |
|
|
Muscles of the Pelvis and Perineum - Listed Alphabetically |
|||||||
|---|---|---|---|---|---|---|---|
| Muscle | Origin | Insertion | Action | Innervation | Artery | Notes | Image |
| anal sphincter, external | perineal body or central tendinous point of the perineum | encircles the anal canal; superficial fibers attach to the coccyx | constricts the anal canal | inferior rectal nerves (from the pudendal nerve) | inferior rectal a. | skeletal (voluntary) muscle, as contrasted with sphincter ani internus, which is smooth (involuntary) muscle; the external anal sphincter is considered part of the pelvic diaphragm | ) |
| anal sphincter, internal | encircles the anal canal | encircles the anal canal | constricts the anal canal | parasympathetic fibers from S4 | middle rectal a. | smooth muscle (involuntary), as contrasted with sphincter ani externus, which is skeletal muscle (voluntary) | ) |
| bulbospongiosus, in female | perineal body and fascia of the bulb of the vestibule | perineal membrane and corpus cavernosum of the clitoris | compresses the vestibular bulb and constricts the vaginal orifice | deep branch of the perineal nerve (from pudendal nerve) | perineal a. | skeletal muscle | ) |
| bulbospongiosus, in male | central tendinous point and the midline raphe on the bulb of the penis | perineal membrane, dorsal surface of the corpus spongiosum, deep penile fascia | compresses the bulb of the penis, compresses the spongy urethra | deep branch of the perineal nerve (from pudendal nerve) | perineal a. | expels the last drops of urine from urethra; expels semen during ejaculation | ) |
| coccygeus | 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 | ) |
| deep transverse perineus | medial surface of the ischial ramus | contralateral muscle and perineal body/central tendinous point | fixes and stabilizes the perineal body/central tendinous point | deep branch of perineal nerve from pudendal nerve | internal pudendal a. | superficial and deep transverse perineus muscles are separated by the perineal membrane | ){kind=spacer} |
| detruser of bladder | smooth muscle in the wall of the urinary bladder | fascicles are arranged roughly in three layers | compresses the urinary bladder | parasympathetic nerve fibers from the pelvic splanchnic nerves (S2-S4 spinal cord levels) | superior and inferior vesical aa. | muscles in the neck of bladder must contract and cause the internal urethral orifice to open before the detruser muscle can void the bladder | ) |
| iliococcygeus | 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. | ) |
| ischiocavernosus | medial surface of the ischial tuberosity and the ischiopubic ramus | corpus cavernosum and crus of the penis/clitoris | compresses the corpus cavernosum | deep branch of the perineal nerve (from pudendal nerve) | perineal a. | ischiocavernosus m. is closely applied to the surface of the crus penis/clitoris | ) |
| levator ani | 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 | ) |
| levator prostatae | posterior aspect of the pubis | fascia of the prostate | elevates the prostate | branches of the ventral primary rami of spinal nerves S3-S4 | inferior gluteal a. | levator prostatae is part of the puborectalis m. | ) |
| obturator internus | 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 | 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 | 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 | 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 | ) |
| sphincter ani externus | perineal body or central tendinous point of the perineum | encircles the anal canal; superficial fibers attach to the coccyx | constricts the anal canal | inferior rectal nerves (from the pudendal nerve) | inferior rectal a. | skeletal (voluntary) muscle, as contrasted with sphincter ani internus, which is smooth (involuntary) muscle; the external anal sphincter is considered part of the pelvic diaphragm | |
| sphincter ani internus | encircles the anal canal | encircles the anal canal | constricts the anal canal | parasympathetic fibers from S4 | middle rectal a. | smooth muscle (involuntary), as contrasted with sphincter ani externus, which is skeletal muscle (voluntary) | |
| sphincter urethrae, in female | encircles the urethra | encircles urethra and vagina; extends superiorly along the urethra as far as the inferior surface of the bladder | compresses urethra and vagina | deep branch of perineal nerve from pudendal nerve | internal pudendal a. | skeletal muscle | ) |
| sphincter urethrae, in male | encircles the urethra | encircles urethra, reaches lateral surface of prostate and inferior bladder | compresses urethra | deep branch of perineal nerve from pudendal nerve | internal pudendal a. | skeletal muscle | ) |
| superficial transverse perineus | medial surface of the ischial ramus | contralateral muscle and the perineal body/central tendinous point | fixes and stabilizes perineal body/central tendinous point | deep branch of perineal nerve from pudendal nerve | perineal a. | superficial and deep transverse perineus muscles are separated by the perineal membrane | ){kind=spacer} |
| transverse perineus, deep | medial surface of the ischial ramus | contralateral muscle and perineal body/central tendinous point | fixes and stabilizes the perineal body/central tendinous point | deep branch of perineal nerve from pudendal nerve | internal pudendal a. | superficial and deep transverse perineus muscles are separated by the perineal membrane | |
| transverse perineus, superficial | medial surface of the ischial ramus | contralateral muscle and the perineal body/central tendinous point | fixes and stabilizes perineal body/central tendinous point | deep branch of perineal nerve from pudendal nerve | perineal a. | superficial and deep transverse perineus muscles are separated by the perineal membrane | |
| The material presented in these tables is
contained in the book: MedCharts Anatomy by Thomas R. Gest & Jaye Schlesinger Published by ILOC, Inc., New York Copyright © 1995, unauthorized use prohibited. |
The excellent editorial assistance of Dr. Pat Tank, UAMS is gratefully acknowledged. |
|
||
| Copyright© 2000 The University of Michigan. Unauthorized use prohibited. |
|
|