Nerves of posterior abdominal Nerves of posterior abdominal

wall(spinal nerves):wall(spinal nerves): Lumbar Lumbar PlexusPlexus Roots:

It is formed from anterior (ventral) rami of upper 4 lumbar nerves.

Site :

It is formed within the substance of psoas major muscle.

Its branches emerge from lateral & medial borders of the muscle and its anterior surface.

It is one of the main nervous supplying the lower limb.

All anterior rami receive gray rami communicantes from sympathetic trunk, and the upper 2 lumbar nerves give off white rami communicantes to symp. trunk.

White rami communicantes : the upper 2 ganglia receive a white rami communicantes from 1st & 2nd lumbar spinal nerves, they contain preganglionic N.Fs. & sensory N.Fs.Gray rami communicantes (postganglionic Fs.) to all lumbar spinal nerves. A grey ramus contains postganglionic N.Fs. These Fs.are distributed through the branches of spinal nerves to skin : 1-blood vessels (vasomotor) 2-sweat glands 3-arrector pili muscles of skin.

Branches of Sympathetic trunkBranches of Sympathetic trunk

(Abdominal part) :(Abdominal part) :

A- N.Fs. Synapse in a symp.chain ganglion at same level.

B- N.Fs. synapse in a symp.chain ganglion at a different level.

C- N.Fs. Synapse in a collaterl (aortic) ganglion as sup.mesenteric ganglion.

Branches of Lumbar plexusBranches of Lumbar plexusIliohypogastric, ilioinguinal, lateral cutaneous N. of thigh and femoral N. emerge from lateral border of psoas muscle, in order that from above downward.

Iliohypogastric & ilioinguinal nerves (L1) :

-Iliohypogastric N.supplies skin of lower part of anterior + lateral abdominal wall, while -ilioinguinal N. passes through inguinal canal to supply skin of groin (upper medial part of thigh) + scrotum or labium majus.

Lateral cut.N. of thigh (L2,3) : passes in front of iliacus muscle and enter thigh behind lateral end of inguinal ligament to supply skin of lateral surface of thigh.

Branches of Lumbar plexusBranches of Lumbar plexusFemoral N. ( dorsal division of ventral rami of L2,3,4): is the largest branch of lumbar plexus.it descends between psoas & iliacus and enters thigh behind inguinal lig. and lateral to femoral vessels & sheath. -In abdomen : It supplies iliacus +psoas major. -In lower limb : It supplies muscles of front of thigh + skin of anterior & lateral surface of thigh + skin of medial side of leg & foot through saphenous N.Obturator N. (ventral division of ventral rami of L2,3,4) : emerge from medial border of psoas muscle. it descends in front of sacroiliac joint and behind common iliac vessels in the pelvis. It enters thigh through obturator foramen.

Branches of Lumbar plexusBranches of Lumbar plexus

-Genitofemoral nerve is involved in cremateric reflex, in which stimulation of skin of thigh in male results in reflex contraction of cremaster muscle and drawing upward of testis within the scrotum,

4th lumbar root of lumbosacral trunk : -it takes part in sacral plexus formation. -it descends anterior to ala of sacrum to join 1st sacral nerve.

Genitofemoral nerve (L1,2) : -emerges from anterior surface of psoas major. -it descends in front of psoas and above inguinal ligament it divides into genital branch, which enters spermatic cord and supplies cremaster muscle + skin of scrotum, and a femoral branch, which supplies a small area of skin in the uppermost part of front of thigh.

Lymph Nodes of posterior Lymph Nodes of posterior abdominal wall: abdominal wall:They are closely related to aorta to

form a preaortic and a right & left lateral aortic (para-aortic or lumbar) chain.

Preaortic L.Ns. lie around origins of celiac, superior mesenteric,and inferior mesenteric arteries. They drain lymph from G.I.T.from lower 1/3 of esophagus to halfway down anal canal, and also from spleen, pancreas,gallbladder & liver. Efferent lymph vessels form large intestinal lymph trunk.

Lateral aortic (para-aortic or lumbar) L.Ns.: drain lymph from kidneys & suprarenals, from testes or ovaries, uterine tubes & fundus of uterus, from deep lymph vessels of abdominal walls, and from common iliac Ns. Efferent lymph vessels form right & left lumbar trunks.

Lymph vessels of posterior Lymph vessels of posterior abdominal wall:abdominal wall:

Cisterna chyli : -it is a narrow sac , opens upwards into thoracic duct. –it collects lymph from abdomen & lower limbs. -Tributaries : it receives intestinal trunk, right & left lumbar trunks and some lymph vessels from lower thorax.Thoracic duct : begins in the abdomen as an elongated lymph sac, cisterna chyli, which lies below diaphragm, in front of first 2 lumbar vertebrae and on right site of aorta.

Thoracic ductThoracic duct

(A),Tributaries of thoracic duct & right lymphatic duct.

(B), The areas of body drained into thoracic duct (clear) and right lymphatic duct (black).

It runs upward to enter thorax through aortic opening of diaphragm, then into root of neck to end in left brachiocephalic vein.

It conveys all lymph from lower limbs, pelvic cavity, abdominal cavity, left side of thorax + left side of head,neck & left upper limb to blood of left brachio-cephalic vein.

The right side of head ,neck & right uper limb are drained by right lymph trunk into right brachio-cephalic vein.

Structures of pelvic walls Structures of pelvic walls Anterior pelvic wall : it is a shortest wall, it is formed by : -posterior surface of pubic bodies bones. -symphysis pubis.

posterior pelvic wall : It is formed by : –sacrum & coccyx. -Piriformis muscle. -Parietal pelvic fascia which covers bones & piriformis muscles.

Piriformis muscle Piriformis muscle Origin : front of middle 3 pieces (S2,3,4) of sacrum.

Insertion : it leaves pelvis to enter gluteal region by passing through greater sciatic foramen to be inserted into top (upper border) of of greater trochanter of femur.

N.suply : branches from sacral plexus (S1,2).

Action : lateral rotator of femur at hi joint.

Structures of Pelvic wallsStructures of Pelvic wallsLateral pelvic wall : it consists of : -Part of hip bone below pelvic inlet. -Obturator membrane. -Obturator internus & its covering fascia. -Sacrotuberous & sacrospinous ligaments.

Inferior pelvic wall (Pelvic floor ) or (pelvic diaphragm) : -it supports pelvic viscera, it divides pelvis into : -upper part : it is the main pelvic cavity. -lower part : it is the perineum (structures that fill outlet of true pelvis) -pelvic floor is formed of : 1-levator ani muscles. 2-coccygeus muscles. 3-fascia covering these muscles. -the pelvic floor is incompletle anteriorly to allow passage of urethra in male + urethra & vagina in female.

Pelvic wallsPelvic wallsSacrotuberous ligament : is strong. –its medial upper end is attched to : 1-posterior inferior iliac sine. 2-lateral surface of sacrum & coccyx. -its lateral lower end : is attached to : 1-medial margin of ischial tuberosity. Sacrospinous ligament : is a strong triangular ligament. -its apex : ischial spine. -its base : last piece of sacrum + first piece of coccyx.

The function of 2 ligaments : 1-they convert greater & lesser sciatic notches into foramina, greater & lesser sciatic foramina. 2- they prevent lower end of sacrum & coccyx from being rotated upwards at sacroiliac joint by the weight of body.

Obturator membrane, Canal Obturator membrane, Canal & muscle :& muscle : obturator membrane : is

completely closes the obturator foramen except at the upper part where it leaves a small gap called obturator canal.

Obturator N. & vessels leave the pelvis to enter thigh by passing through obturator canal.

Obturator internus muscle : -origin : pelvic surface of obturator membrane + adjoining part of hip bone. -insertion : its tendon leaves pelvis through lesser sciatic foramen to be inserted into upper border of greater trochanter of femur. -N.supply : N.to obturator internus (sacral plexus). -action : lateral rotation of thigh at hip joint.

Obturator FasciaObturator Fascia

It is a part of parietal pelvic fascia.

It covers pelvic surface of obturator internus muscle.

A tendinous arch is formed by thickening of pelvic fascia (obturator fascia) covering the obturator internus, and gives a linear origin for levator ani muscle.

Levator ani muscleLevator ani muscleIt is a wide thin sheet that has linear origin from : 1-back of body of pubis. 2-obturator fascia (tendinous arch). 3-ischial spine.

Insertion : by 3 fibres.

1-anterior fibres : (levator prostatae or sphincter vaginae). : form a sling around prostate or vagina and inserted into perineal body (a mass of fibrous tissue) in front of anal canal. -its function is to support the prostate or to constrict the vagina + to stabilize the perineal body.

Levator ani muscleLevator ani muscle

2-Intermediate fibres : a-(puborectalis) : it forms a sling around the junction of rectum & anal canal to meet other fibres. b-(Pubococcygeus) : passes posteriorly to be inserted into ano-coccygeal body, (a small fibrous mass) between tip of coccyx & anal canal.

3-Posterior fibres : ( iliococcygeus) : passes posteriorly to be inserted into ano-coccygeal body & coccyx.

Levator ani muscleLevator ani muscleAction : 1-They support pelvic viscera in position. 2-They support head of child during labour. 3-They resist any rise in intra-pelvic pressure during straining and intra-abdominal pressure as in coughing. 4-They have sphincter action by its pubo-rectalis fibres on anorectal junction. 5-They have sphincter action on vagina by its anterior sphincter vaginae fibres.

N.supply : 1-perineal branch of 4th sacral N. 2-perineal branch of pudendal N.

Coccygeus muscleCoccygeus muscle

Origin : ischial spine.

Insertion : lower end of sacrum + upper end of coccyx.

N.supply : S4,5 nerves.

Action : the 2 muscles assist levatores ani in supporting pelvic viscera.

Pelvic floorPelvic floorIt is a gutter-shaped sheet of muscle that slopes downward and forward and formed by levatores ani + coccygeus muscles + their covering fasciae.

The gutter shape of pelvic floor plays an important function during second stage of labor and helps baby’s head to rotate and to pass through lower part of birth canal.

Injury to pelvic floor during a difficult childbirth can result in loss of support of pelvic viscera leading to : 1-uterine and vaginal prolapse. 2-herniation of bladder (cystocele). 3-change in position of bladder neck and urethra (stress incontinence) =dribbling of urine during coughing or any intra-abdominal stress. 4-prolapse of rectum may occur.

Pelvic FasciaPelvic FasciaIt is a layer of loose C.T. that is continous above with fascia of abomen and below with fascia of perineum.

It is divided into 2 layers :

Parietal layer of pelvic fascia : -it lines walls of pelvis and is nammed according to muscle it covers. -it is formed of : a-Obturator internus fascia. b-Piriformis fascia. c-Levator ani & coccygeus fascia, It divides into : 1-Superior fascial layer of pelvic diaphragm. 2-Inferior fascial layer of pelvic diaphragm, on the inferior perineal surface of levator ani -when the parietal pelvic fascia comes into contact with bone, it fuses with periosteum.

Coronal section of pelvis

Below in the perineum : -- Parietal pelvic fascia covers sphincter urethrae muscle & perineal membrane, to become superior fascial layer of of urogenital diaphragm. -parietal pelvic fascia is also continous with the visceral pelvic fascia.

b-inferior fascia of pelvic diaphragm : it covers inferior perineal surface of levator ani and is continous with the obturator fascia.

Pelvic FasciaPelvic FasciaVisceral layer of pelvic fascia -it is a layer of loose C.T.that covers and support all pelvic viscera. -it is continuous with the parietal layer at the pelvic wall. -in certain locations, thickening of visceral pelvic fascia leads to formation of fascial ligaments as pubovesical & sacrocervical ligaments.

Joints of pelvisJoints of pelvis 1- Sacroiliac joint 1- Sacroiliac joint

Type : strong plane synovial joint.

Articular surfaces : between auricular surfaces of sacrum & ilium.

Ligaments : 1-strong posterior & interosseous ligaments. 2-thin anterior sacroiliac ligament.

Movements : limited movement during flexion and extension of trunk. its primary action is to transmit weight of body from vertebral column to bony pelvis.

In older people, the synovial cavity disappears and the joint becomes fibrosed.

Joints of pelvisJoints of pelvis 1- Sacroiliac joint 1- Sacroiliac joint

The weight of trunk tends to push base of sacrum downwards and turns the apex of coccyx upwards.

This rotatory movement is prevented by : 1-strong ligaments of the joint. 2-strong sacrotuberous & sacrospinous ligaments.

The iliolumbar ligament connects tip of 5th lumbar transverse process to iliac crest.

N.supply : branches of sacral spinal nerves.

2- Symphysis pubis2- Symphysis pubis

Type : secondary cartilaginous joint.

Articular surfaces : medial surfaces of the 2 pubic bones which are connected together by a fibrocartilaginous disc.

Ligaments : surrounded by anterior .,posterior, superior & inferior ligaments.

Movement : no movement.

3- Sacrococcygeal joint3- Sacrococcygeal jointType : cartilaginous joint.

Articular surfaces : between bodies of last sacral and first coccygeal vertebra.

The cornua of sacrum & coccyx are joined by intercornual ligaments.

Movement : a great amount of movement is possible.

Lateral veiw of sacrum & coccyx

4-lumbosacral joint4-lumbosacral joint

It is a cartilaginous intervertebral joint.

It is between 5th lumbar vertebra & 1st piece of sacrum.

It is supported by iliolumbar & lumbosacral ligaments.

Bony pelvisThe bony pelvis consists of 4 bones : - 2 hip bones : form lateral & anterior walls. - Sacrum & coccyx : form posterior wall.

Pelvic brim : is formed by - Sacral promontory : posteriorly. - Ilio-pectineal lines : laterally. - Symphysis pubis : anteriorly.

Parts of pelvis : 1-False (greater) pelvis : above pelvic brim, it forms part of abdominal cavity, it consists mainly of right & left iliac fossae. 2-True (lesser) pelvis : below pelvic brim, it is a curved canal which has an inlet, outlet & a cavity.

Sacral promontory : is the projecting forwards of the anterior margin of body of S1 vertebra.

Bony pelvisBony pelvis

Pelvic inlet : is formed by boundaries of pelvic brim.

Pelvic outlet : -coccyx : posteriorly. -ischial tuberosities + sacrotuberous ligament : laterally. -pubic arch + symphysis ppubis : anteriorly.

Pelvic cavity : it is a curved canal, lies between inlet & outlet, and has a short anterior wall and longer posterior wall.