Sacral Plexus & Nerves

ANSMajor arteries

Accessory arteriesMajor veins

Accessory veinsCavity lymphatics

Perineum lymphatics Gross AnatomyFrom School

1.1. Location:Location: lies ant to& covered with pelvic fascia w/ nerves exiting in greater sciatic

foramen

2. Comp:2. Comp: Ventral rami of:

a) a) lumbosacral trunklumbosacral trunk – –

1. 1. Sciatic n.Sciatic n. – – largest; major n. of LL a) comp: b) exits:

c) splits into: 1. 1. Tibial n.Tibial n. – –

2. 2. Common fibular n.Common fibular n. – – superficial & deep fibular nerves

2. 2. Pudendal n.Pudendal n. – –

a) comp:

b) Exits: inf to piriformis m., crosses over lig, & re-enters in

lesser sciatic f.

c) Enters Pudendal canalPudendal canal – medial border of neurovascular

bundle

d) Pudendal n. in canal divides into: 1. 1. Inf rectal n.Inf rectal n. – – near entrance of

pudendal canal a) motor:a) motor: ext. anal sphincter &

levator ani b) sensory:b) sensory: skin of anal triangle

2. 2. Dorsal n of penis (clitoris) Dorsal n of penis (clitoris) – – descends in pudendal canal & in

F =F = primary

3. 3. Perineal n.Perineal n. – – descends in canal & & divides into:

a) a) Deep perineal n.Deep perineal n. – – enters

motor:motor: muscles of deep & sup perineal pouches

sensory:sensory: vestibule & inf. vagina

b) b) Superficial perineal n.Superficial perineal n. – – becomes

posterior scrotal or labial nposterior scrotal or labial n. -. - sensory

3. Other branches of sacral plexus:3. Other branches of sacral plexus: Name Spinal Seg

Function

Sup glutealInf gluteal

N. to obturator internusN. to quadratus femoris

Post femoral cutaneous nPerforating cutaneous n.

N. to piriformisN. to levator ani, coccygeus, ext anal sphincter

1. 1. Sacral paravertebral trunk (2)Sacral paravertebral trunk (2) – – ganglia of the sympathetic trunk in pelvic cavity; a) courses over ala & descends medial

to ant. sacral foramina b) b) Ganglion imparGanglion impar – –

2. 2. Sacral prevertebal trunkSacral prevertebal trunk – – carries sympathetic, parasymp, & visceral afferent

fibers for pelvic organs &

3. 3. Superior hypogastric plexusSuperior hypogastric plexus – –distributes sacral prevertebal fibers to

4. 4. Rt & lt hypogastric nervesRt & lt hypogastric nerves – – descend into pelvic cavity and connect with

5. 5. Rt & Lt inf hypogastric plexus (2) Rt & Lt inf hypogastric plexus (2) – – composed of:

Pelvic splanchnic n.Pelvic splanchnic n. - -

6. Subsidiary plexuses –6. Subsidiary plexuses – inn by inf. hypogastric plx:

a) a) Rectal plexusRectal plexus b) b) Vesicle plexusVesicle plexus

c) c) Uterovaginal (Prostatic) plexusUterovaginal (Prostatic) plexus – – 1. 1. Cavernous n.Cavernous n. – – from prostatic plexus

erectile tissues of penis

1. Def: major artery of the perineum1. Def: major artery of the perineum2. Origin:2. Origin: bifurcation of common iliac a. @

lumbosacral joint3. bifurcates3. bifurcates at pelvic brim into: ant. and

post trunks

a) a) Anterior trunkAnterior trunk – – pelvic viscera, perineum, gluteal region, medial thigh, placenta

b) b) Posterior trunkPosterior trunk - - post abdominal & pelvic walls + gluteal region of hip

4. Posterior Trunk (Prox 4. Posterior Trunk (Prox dist): dist): a) a) iliolumbar a.iliolumbar a. – ascends – ascends above pelvic

brim along lumbosacral trunk: 1. 1. iliac branchiliac branch – – serves iliac fossa

2. 2. lumbar branchlumbar branch – – lower post abdominal wall

b) b) Lateral sacral a (2)Lateral sacral a (2) – – ant. sacral foramina to serve sacrum & skin

c) c) Sup. gluteal a.Sup. gluteal a. – – greater sciatic notch, above piriformis to serve gluteal region

5. Anterior Trunk (prox 5. Anterior Trunk (prox dist): dist): a) a) Umbilical aUmbilical a –adjacent to pelvic inlet –adjacent to pelvic inlet

ascends in ant. abdominal wall to umbilicus; one branch:

Superior vesical a.Superior vesical a.–– serves distal ureter, superior surface of bladder, ductus deferens

b) b) Obturator aObturator a – – below margin of pelvic brim, descends through obturator foramen

w/ n. (above) & v. (below); serves medial thigh compartment

c) c) Inf. vesical (vaginal) a.Inf. vesical (vaginal) a. – – inf. bladder, ureter, seminal vesicle, & prostate

(vagina), part of rectum)

d) d) Middle rectal aMiddle rectal a – – serves rectum; anastomoses w/:

1. 1. Superior rectal aSuperior rectal a – – from inf. mesenteric

2. 2. Inferior rectal aInferior rectal a - - from internal pudendal

e) e) Internal pudendal a.Internal pudendal a. – – main artery of perineum

1. greater sciatic foramen - inf to piriformis

2. re-enters in lesser sciatic f. thru pudendal canal

3. Branches of int. pudendal a.: a) a) Inf. rectal a.Inf. rectal a. – – ischioanal fossa middle rect. a.

b) b) Perineal a.Perineal a. – – pudendal canal sup. pouch

w/ branches:

1. 1. Post. scrotal (labial) a.Post. scrotal (labial) a. – – in superficial pouch

2. 2. Dorsal artery of penis (clitoris)Dorsal artery of penis (clitoris) – – through supplies superficial

penis / clitoris & has two branches:

3. 3. Deep artery of penis (clitoris)Deep artery of penis (clitoris) –terminal –terminal branch of perineal arterybranch of perineal artery = serves the crus &

corpora cavernosum

a) a) Artery of bulb of penis (vestibular Artery of bulb of penis (vestibular bulb)bulb) – – in deep pouch to serve corpus

spongiusum b) b) Urethral a.Urethral a. – – in deep pouch serves

urethra

f) Additional anterior trunk branches in women:

1. 1. Uterine aUterine a –through broad ligament –through broad ligamenta) ascends lat. to uterine wall to

uterine tubes anastomizes w/ ovarian a.

b) descends lat to vaginal wall

2. 2. vaginal avaginal a–– to vagina & anastomizes w/ uterine artery

g) g) Inferior gluteal aInferior gluteal a – – terminal branch of anterior trunk

exits in gr sciatic f., inf to piriformis

1. 1. Median sacral aMedian sacral a – – @ bifurcation of abdominal aorta, descends in midline ant to

sacrum, anastomizes w/ iliolumbar and lat.

Sacral arteries

2. 2. Ovarian a.Ovarian a. – – in suspensory lig, anast. With ant branch of int. iliac

3. 3. Ext. pudendal aExt. pudendal a. –. – from femoral artery courses medially to serve anterior

perineum skin

1. Most veins follow arteries 1. Most veins follow arteries internal iliac internal iliac v.v.

2. 2. Pelvic plexuses of veinsPelvic plexuses of veins – – networks of veins on surfaces of most pelvic viscera: a) a) Dorsum vein of penis (clitoris)Dorsum vein of penis (clitoris) – –

parallels dorsal artery of penis/clitoris

b) b) Prostatic (vesical) venous plexusProstatic (vesical) venous plexus – – prostate & bladder

c) c) External rectal plexusExternal rectal plexus – – subcutaneous subcutaneous around perianal skinaround perianal skin

inf rectal v. (external anal sphincter) middle rectal v

internal iliac v.

1. 1. Internal rectal plexusInternal rectal plexus – – in submucsa of in submucsa of anal canalanal canal drains

into superior rectum v. inf mesenteric hepatic portal system

2. 2. Gonadal Gonadal (testicular or (testicular or ovarian) vovarian) v - -

a) left b) right

3. Median sacral 3. Median sacral v.v.

1. Visceral lymphatics:1. Visceral lymphatics: a) int. & ext. iliac nodes a) int. & ext. iliac nodes b) common iliac nodes

c) lateral aortic & preaortic nodes d) lumbar trunks e) e) thoracic ductthoracic duct – –

2. Perineum lymphatics:2. Perineum lymphatics: a) superficial penis & scrotum (clitoris & labium major) Superficial inguinal Superficial inguinal

nodes nodes ext. iliac nodes

b) glans penis, glans clitoris, labia minora, inferior vagina deep inguinal nodesdeep inguinal nodes

external iliac nodes external iliac nodes

c) testes: spermatic cord post abdominal wall lateral aorticlateral aortic & prearotic nodesprearotic nodes

d) ovaries, uterus, uterine tubes: suspensory ligament post abdominal wall

lateral aortic & preaortic nodeslateral aortic & preaortic nodes

e) deep perineum internal iliac nodesinternal iliac nodes CI nodes