UGS Lecture – 5(2021)

C. Muscles of the pelvisa. Muscles of the lateral walls – The obturatorinternus (fig. 27):▪ Arises from the internal surface of obturator

membrane and adjoining part of hip bone.▪ Muscle fibers converge to a tendon, which

leaves the pelvis through lesser sciaticforamen and is inserted into an impression onmedial surface of greater trochanter of femur.

Nerve supply: Nerve to obturator internus, L5and S1.Action: It is a lateral rotator of the thigh at hipjoint.

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Obturator internus muscle andfascia

Muscles of Lateral Wall of Pelvic CavityThe Obturator Internus Muscle

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b. Muscles of the posterior wall – Thepiriformis (fig. 27):▪ Arises from the lateral mass of the middle

three pieces of sacrum.▪ It extends medially between the anterior

sacral foramina; thus the emerging sacralnerves and sacral plexus lie on the muscle.

▪ It runs transversely to the greater sciaticforamen to be inserted into the upperborder of greater trochanter of femur.

Nerve supply: L5, S1 and 2.Action: It is a lateral rotator of the thigh at hipjoint. 3

Piriformis

Muscles of Lateral Wall of Pelvic CavityThe Obturator Internus Muscle

4A

Right andleft

piriformis

Muscles of Lateral Wall of Pelvic CavityThe Obturator Internus Muscle

5B

c. Muscles of the floor – Pelvic diaphragm:(1) Levator Ani:▪ Arise in continuity from inner surface ofbody of pubis to inner surface of ischialspine across the obturator fascia, along acondensation of the fascia, the tendinousarch.▪ The muscle consists of two main parts,pubococcygeus and iliococcygeus.i. The pubococcygeus part:▪ Is that part of levator ani that arises frombody of pubis and anterior half of thetendinous arch. 6

▪ The most anterior fibers that arise from thebody of pubis pass backwards alongsidethe prostate and sphincter urethrae in themale and decussate across the midlinebehind the urethra to be inserted intoperineal body and the sheath of theprostate.

▪ These fibers form a sling around theprostate and are referred to as levatorprostate (pubourethralis).

▪ In the female, these fibers sling around theposterior wall of the vagina and arereferred to as pubovaginalis. 7

▪ The rest of the posterior fibers which arise fromthe body of pubis, swing inferomedially aroundthe anorectal junction and join with fibers ofopposite side and external anal sphincter.

▪ This part of the muscle is called puborectalis,and forms a U-shaped sling that holds theanorectal junction angled forwards.

▪ The bulk of the posterior fibers arising from theanterior half of the tendinous arch are insertedinto anococcygeal raphe (a small fibrous massbetween the anal canal and the tip of thecoccyx).

▪ These fibers constitute the pubococcygeusmuscle proper.

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ii. The iliococcygeus part:▪ Arises from posterior half of tendinous

arch and the ischial spine.▪ Its fibers are inserted into side of coccyx

and anococcygeal raphe, which extendsfrom tip of coccyx to anorectal junction.

Nerve supply:▪ It is mainly supplied by a branch from S4

spinal nerve.▪ The levator prostate or pubovaginalis, and

puborectalis are supplied by the perinealbranch of S4 and the inferior rectal branchof the pudendal nerve.9

Muscles of Posterior Wall of Pelvic Cavity1. The Levator Ani Muscle

10A

Levatorani

Tendinous archof levator ani

muscleSpine ofischium

Coccygeus

Anococcygealbody Coccygeus

Ilicoccygeus

Levator prostate orsphincter vaginaePuborectali

sPubococcyge

us

Perineal body

Muscles of the Floor of Pelvic Cavity1. The Levator Ani Muscle

(2) Coccygeus:▪ Arises from the tip of ischial spine.▪ Fibers fan out to be inserted into the side

of coccyx and the lowest piece of sacrum.▪ It lies edge to edge with the lower border of

piriformis and is overlapped anteriorly byiliococcygeus.

▪ Its gluteal surface is fibrous tissue, and isindeed the sacrospinous ligament.

Nerve supply: By branches from S4 and 5spinal nerves.

12A

Muscles of the Floor of Pelvic Cavity2. The Coccygeus Muscle

12B

Actions of the Pelvic Diaphragm1. Support and maintains the pelvic viscera inposition.2. In both sex, puborectalis part of levator ani hassphincter action on anorectal junction.3. In the female, the pubovaginalis has sphincteraction on the vagina.4. The pelvic diaphragm contracts during coughingand sneezing to resist the rise in intra-pelvicpressure, and relaxes in micturition, defaecationand partitution.5. The coccygeus pulls the coccyx forwards after ithas been pushed backwards during defaecation.

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Spermatic Cord● The testis descends from abdominal wall

into scrotum and pulls with it vas deferens,nerves and vessels.

● These structures meet at deep inguinalring and together form spermatic cord,which suspends the testis in scrotum, andextends from deep inguinal ring toposterior border of testis.

● The left spermatic cord is a little longerthan right.

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Constituent of Spermatic Cord(1) Vas deferens.

(2) Testicular artery: Branch of abdominalaorta.

(3) Artery to vas deferens: Branch of superioror inferior vesicle artery.

(4) Cremasteric artery: Branch of inferiorepigastric artery.

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(5) Testicular vein (pampiniform plexus):● The pampiniform plexus ascends from

posterior border of testis and entersinguinal canal.

● At about level of deep inguinal ring, asingle testicular vein is formed, whichdrains into left renal vein, on left side andinto inferior vena cava, on right side.

(6) Genital branch of genitofemoral nerve L1and 2: Supplies cremaster muscle.

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(7) Testicular sympathetic plexus:● These fibers are derived from the renal or

aortic plexus of nerves.

They follow the testicular artery.

(8) Testicular lymph vessels: Follow thetesticular artery and drain into para-aorticlymph nodes.

(9) Fibrous remains of processus vaginalis.17

Spermatic

cord

Testicularartery

Ductusdeferens

Pampinifoirmvenous plexus

Genitalbranch of

genitofemoralnerve

Spermatic cord18

Covering of Spermatic Cord (SpermaticFascia)

● The spermatic cord enters inguinal canal bypassing through deep inguinal ring.

● Within canal it acquires three fascialcovering from fibers of muscles betweenwhich it lies.

● This facial covering continues downwardsinto scrotum:

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(1) Internal spermatic fascia: Acquired fromfascia transversalis at deep inguinal ring.

(2) Cremasteric fascia: Acquired from internaloblique muscle within inguinal canal.

(3) External spermatic fascia: Acquired fromaponeurosis of external oblique muscle atsuperficial inguinal ring.

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External

Spermatic

FasciaCremastermuscle and

fascia

Spermatic Fascia21

Scrotum● The scrotum is a cutaneous fibromuscular sac

that contains testis, epididymis, and lower part ofspermatic cord.

● It is situated below root of penis.● It is divided by a median fibrous septum into right

and left halves.● The septum is indicated on under surface of the

scrotum by a median longitudinal raphe, thescrotal raphe, which is continuous with theperineal raphe that extends to anus.

● The scrotal skin is very thin, of a brownish color,and often thrown into folds or rugae.

● It is covered with thinly scattered, curly hairs. 22

A 23

B 24

● The scrotal skin is provided with sebaceousglands, the secretion of which has a peculiar odor.It also contains numerous sweat glands, pigmentcells, and nerve endings responding tomechanical stimulation of hairs and skin, and tovariations in circumambient temperature.

● The tunica vaginalis (lower expanded part ofprocessus vaginalis) lies within spermatic fasciaeand covers anterior, medial, and lateral surfacesof testis.

● Normally, just before birth, it becomes shut offfrom upper part of processus and peritonealcavity. 25

● The tunica vaginalis is thus a closed sac,invaginated from behind by testis.

● It constitutes two layers:

a. Visceral layer:It is closely applied to the testis, epididymis, and

inferior part of vas deferens.

b. Parietal layer:● Lies adjacent to spermatic fascia.

● It extends superiorly for a short distance into thedistal part of spermatic cord.

● The small amount of fluid in cavity of tunicavaginalis separates visceral and parietal layers,allowing testis to move freely within its side ofscrotum. 26

Visceral layer oftunica vaginalis

covering thetestis

Parietallayer oftunica

vaginalis

Tunica vaginalis 27

Testes● These are two ovoid, firm and mobile

organs that produce spermatozoa andhormones, principally testosteronehormone.

● Each testis is suspended withincorresponding half of scrotum.

● The left testis usually lies at a lower levelthan right.

● The testis is surrounded by a tough fibrouscapsule called the tunica albuginea, whichis thickened on the posterior surface of thetestis to form the mediastinum of the testis.

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Testis

Scrotum

● Numerous incomplete fibrous septa arisefrom the mediastinum testis pass inwardthrough the substance of the testis,dividing it into about 250 pyramidal-shapedlobules.

● Because septa are incomplete, inter-communications between lobules areexpected.

● Each lobe is occupied by 1 – 3seminiferous tubules.

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The testis

Intratesticular DuctsA. Straight tubules: Connect seminiferous

tubules with rete testis.

B. Rete testis: Is a highly anastomotic networkof channels, contained within mediastinumof testis.

C. Efferent Ducts:● From rete testis extends 15 – 20 efferent

ducts.

● These tubules carry sperm from rete testis tohead of epididymis. 32

Straighttubule

Efferent duct

Rete testis

Intratesticular ducts

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Excretory Genital DuctsA. Ductus Epididymis:● It is a firm coma-shaped structure, closely

applied to posterior margin of testis, withvas deferens lying on its medial side.

● It is formed by minute convolution of ductof the epididymis (4 – 6 m long), so highlycompact that appear solid.

● It has an expanded upper end, head, amiddle portion, body, and a pointed lowerportion, tail. 34

● Laterally, a distinct groove, sinus ofepididymis lies between testis andepididymis, which is lined with viscerallayer of tunica vaginalis.

● The major function of epididymis is storageand maturation of spermatozoa; inepididymis spermatozoa develop motility.

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Head ofepididymis

Body ofepididymis

Tail ofepididymis

Ductusepididymis

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The Epididymis

Epididymalsinus

body ofepididymis

tail ofepididymis

lower pole oftestis

anterior border oftestis

lateral surfaceof testis

superior pole oftestis

head ofepididymis

spermaticcord

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The Epididymis

B. Ductus (Vas) Deferens:● Is a cordlike structure that can be palpated

between finger and thumb in upper part ofthe scrotum.

● It is a thick walled muscular tube about 45cm long that conveys mature sperm fromepididymis to ejaculatory duct.

● It is at first very tortuous, but, becominggradually straighter.

● It merges from tail of epididymis andascends over posterior border of testis,along the medial side of epididymis, to reachupper pole of testis.38

● It leaves the canal at deep ingunal ring andturns round lateral side of inferior epigastricartery and pass medially behind this arteryand across external iliac vessels.

● Next it descends to pelvic brim, where itcontinue downward along lateral wall of lesserpelvis deep to parietal layer of peritoneum,crossing ureter.

● About level of ischial spine, it bends at anacute angle and runs downwards, medially,and slightly forwards between posteriorsurface of bladder and rectum, along medialside of corresponding seminal vesicle andcome to lie alongside vas deferens of otherside. 39

● Its terminal part is dilated, the ampulla ofvas deferens.

● The inferior end of ampulla joins duct ofseminal vesicle to form ejaculatory duct.

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Ductus (vas)deferens

The Vas deferens

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Ductus (vas)deferens

42The Vas deferens

Urinary bladder

Ureter

Ductus(vas)

deferens

Ampulla of(vas) deferens

Seminalvesicle

Ejaculatoryduct

Seminal vesicleduct

The Vas deferens43

C. Ejaculatory Ducts:● About 2.5 cm long and are formed by union

of terminal end of vas deferens with duct ofseminal vesicle.

● They pierce posterior surface of prostateand open into upper part of prostaticurethra close to margins of opening ofutricle.

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Prostate

Prostaticurethra

Ejaculatoryduct

The Ejaculatory duct 45