2-Pelvic Muscles &Sacral Plexus

8/10/2019 2-Pelvic Muscles &Sacral Plexus

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Pelvic Muscles& Sacral

Plexus

For

Medical Students

Anat 212 Prof. EL Hassan

Heidar


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mportant

Notice

These slides are only to

illustrate the lecture and are

not substitute for the

recommended textbooks.

!"#

$%&'(


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Piriformis Muscle

1- Origin

!rises from the front of the middle " sacral pieces.

Its tendon lea#es the pel#is through the greater

sciatic foramen to the gluteal region.

$- nsertion into the top of the greater trochanter.

Ner#e supply

%y branches from the sacral plexus &'() *1) $+.

"- !ction

'ateral rotation and abduction of the thigh.

,- elations in the pel#is

!nteriorly rectum) sacral plexus) branches of the

internal iliac #essels.

Posteriorly sacrum.


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Piriformis Muscle


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Obturator Internus Muscle

Origin from

Inner surface of the ilium ust belo/ the arcuate

line and obturator membrane.

nsertion

The tendon comes out from the pel#ic ca#itythrough the lesser sciatic foramen to be inserted

into the medial surface of the greater trochanter.

The tendon takes the insertion of the t/o gemelli.

Ner#e supplyarises from sacral plexus &'() *1)$+.

!ction

'ateral rotator to the thigh and assist in the

abduction of the thigh.


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Obturator Internus Muscle


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1- 'e#ator ani Muscle

Origin from the back of body of pubis.1- 0rom the inner surface of ischial spine.$- 0rom the tendinous arch of the obturator fascia.

Insertion

Inserted /ith those of the opposite side into the

perineal body. The most posterior fibers

Inserted into the side of coccyx and ano-coccygeal

body.

The intermediate fibers

0use /ith those of the opposite side ust behind the

recto-anal unction to form pubo-rectalis muscle.

Morphologically the muscle is di#ided into t/o parts

according to the origin into

Pubococcygeus and iliococcygeus


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'e#ator !ni Muscle


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$- 'e#ator !ni Muscle

Ner#e supply

Pel#ic &upper+ surface from the ,thsacral ner#e.

Perineal &lo/er+ surface from the inferior rectal branch of the

pudendal ner#e.

!ction

%oth muscles act together to increase the intra-abdominal

pressure by raising the pel#ic floor.The pubo-rectalis part acts as a sphincter to constrict the

rectum and reinforces the anal sphincter.

elations

- Pel#ic &upper+ surface

In the male related to urinary bladder) prostate) seminal #esicleand rectum.

In the female related to urinary bladder) #agina) broad ligament

and rectum.

- Perineal &lo/er+ surface

0orms the medial /all of the ischio-rectal fossa.


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'e#ator !ni muscle


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2occygeus Muscle

Origin from the tip of the

ischial spine.

nsertion into the side of

the last piece of sacrumand first piece of coccyx.

Ner#e supply from

the ,thand (thsacral ner#e.

It unite /ith its follo/ to

form /ith the le#ator ani

the pel#ic floor) /hich

sometimes called pel#ic diaphragm.


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Pel#ic 3iaphragm It forms a partition bet/een the pel#is and perineum. The pel#ic diaphragm is formed by le#ator ani and

coccygeus of both sides at the floor of the pel#is and

pierced by) urethra) rectum in the male and added #agina

in the female.

The pel#ic floor is co#ered by a layer of fascia called

parietal layer of the pel#ic fascia

The pel#ic fascia /hich co#er the pel#ic organs is called

#isceral layer or endopel#ic fascia) its loose on the

expansile organs and dense on the organ /hich does not

expand as prostate.

N.%. The fascia /hich co#ers the #iscera is loose toallo/ for distension) of the organs) /hile the fascia

/hich co#ers the muscles is tough.


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Ner#es of the Pel#is

The ner#es include the follo/ing

sacral plexus and coccygeal plexus. The obturator ner#e.

Pel#ic parts of the sympathetic trunks and)

parasympathetic ner#e supplies the pel#ic #iscera.

1- 2occygeal Plexus

It4s formed by the lo/er part of the ,thsacral /ith (thsacral and coccygeal ner#e.

It gi#es branches to the le#ator ani and coccygeus.

$- Pel#ic part of the sympathetic trunks

The sympathetic trunk in the pel#is is directed as

continuation of the sympathetic trunks of the abdomen. 5ach trunk enter the pel#is then descends medial to

anterior sacral foramina and carries , sympathetic

ganglia.

%oth trunks &right and left+ ends in one ganglion called

ganglion impar lies in front of the coccyx.


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Ner#es Of The Pel#is


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*acral Plexus

It lies on the pel#ic surface of the sacro-iliac oint andpiriformis) it4s found bet/een the muscles and its fascia.

It is formed by the anterior primary rami of ',) ( and

*1)$)"),.

The lo/er part of the ,thand (thlumbar form the lumbo-

sacral trunk /hich descends on6 the medial side of thepsoas maor) on the ala of the sacrum and on the

sacro-iliac oint to share in the formation of the sacral

plexus.

elations of the *acral Plexus to the %lood 7essels

The superior gluteal #essels pass bet/een the lumbo-sacral trunk and first sacral ner#e.

The inferior gluteal #essels pass bet/een the 1stand $nd

sacral ner#es.

The internal pudendal #essels lies in front of the sacral

ner#es.


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*acral Plexus


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elation Of %lood 7essels to The

*acral Plexus


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%ranches Of *acral Plexus

%ranches

!- 0rom the roots to

Piriformis &'() * 1)$+.

'e#ator ani &pel#ic surface *,+.

2occygeus &*,)(+.

%- 0rom the plexus1-*uperior gluteal ner#e. &',)( )*1+

$- Ner#e to 8uadratus femoris.

"- Inferior gluteal ner#e &'() *1) $+

,- Ner#e to obturator internus.

(- Posterior cutaneous ner#e of the thigh &*1)$)"+. Perineal branch of the ,thsacral ner#e.

2- T/o terminal branches of the plexus

1- *ciatic ner#e &',)( and *1)$)"+ The largest one.

$- Pudendal ner#e &*$)"),+ The smallest one.


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%ranches Of The *acral Plexus


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hankou

2-Pelvic Muscles &Sacral Plexus

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