Innervation

NERVES

Thoracoabdominal nn. T7-T11	Each of T7-T11 continuation of intercostals nn. To skin of abdomen. Runs between internal oblique m. and transversus abdominus m.
Subcostal n. T12	T12 along 12^th rib inferior border. Pass posterior to lateral arcuate ligaments into the abdomen and cross anterior surface of quadratus lumborum mm. And pass through transversus abdominus and internal oblique Supplies lower external oblique m. and skin over anterior superior iliac spine and hip
Iliohypogastric n. L1 (T12)	From lumbar plexus. Runs posterior to medial arcuate ligament and over quadratus lumborum. Pierces transverses abdominus and branches through external oblique aponurosis to supply skin of hypogastric and iliac crest and internal oblique and transversus abdominus mm.
Ilioinguinal n. L1	From lumbar plexus.Runs posterior to medial arcuate ligament and over quadratus lumborum.Runs between internal oblique and transversus abdominus mm. and through inguinal canal to anterior skin of scrotum or labium majus, mons pubis and thigh skin with internal oblique m. and transversus abdominus m.
Genitofemoral n. L1,L2	Pierces the anterior surface of the psoas major muscle and runs unferiorly on it deep to psoas fascia; it divides lateral to the common and external iliac aa. into femoral and genital branches. The genital branch supplies cremaster m.
Pudendal n. S2-S4	Perineal branch supplies posterior of scrotum
Posterior femoral cutaneous n. S2,S3	Inferior surface of scrotum
Greater splanchnic n. T5-T9 Sympathetic	Oesphagus
Lesser splanchnic n T10-T11 Sympathetic.	Oesphagus
Least splanchnic n. T12 Sympathetic
Lumber splanchnic n Sympathetic	Branches of four lumber sympathetic ganglia
Sacral splanchnic nn Sympathetic	Branches of the 2^nd and 3^rd sacral sympathetic ganglia
Pelvic splanchnic nn Parasympathetic	Ranches of the ventral rami of sacral spinal nerves S2 S3 (S4)
Right phrenic	Sensory to gall bladder
Lumbar nerves	Pass from the spinal cord through the intervertebral foramen where they divide into ventral and dorsal primary rami each with sensory and motor fibres. The ventral pass into the psoas major muscle and are connected to the sympathetic trunk by rami communicantes
LUMBAR PLEXUS
Obturator n. L2-L4	From lumbar plexus emerges from the medial border of psoas to supply adductor muscles of the thigh and parietal perineum on lateral wall of pelvis
Femoral n. L2-L4	From lumbar plexus it emerges from the lateral psoas border and innervates the iliacus and extensors of the knee
Lumbrosacral trunk L4,L5	Passes over ala of sacrum and descends into pelvis to take part in the sacral plexus along with ventral rami of S1-S4
Lateral femoral cutaneous nerve L2,L3	Runs inferolaterally on the iliacuus muscle and enters the thigh posterior to the inguinal ligament, just medial to the iliac spine to supply the skin on the anterolateral surface of the thigh

SACRAL PLEXUS NERVES	Piriformis muscle provides a bed for the sacral and coccygeal nerve plexuses with the ventral rami of S2 and S3 emerging between the digitations of these muscles. The descending part of L4 which unites with the ventral ramus of L5 forms the thick cord-like lumbrosacral trunk
Sciatic L4,L5,S1,S2,S3	Articular branches to hip joint and muscular branches to flexors in thigh and all muscles in leg and foot
Superior gluteal L4,L5,S1	Gluteus medius and gluteus minimus mm.
Inferior gluteal L5 S1 S2	Gluteus maximus m.
Nerve to piriformis S1,S2	Piriformis m.
Nerve to quadratus femoris and inferior gemellus L4,L5,S1	Quadratus femoris and inferior gemellus mm
Nerve to obturator internus and superior gemellus L5,S1,S2	Obturator internus and superior gemellus mm.
Pudendal S2,S3,S4	Structures in perineum : sensory to genitalia, muscular branches to sphincter urethrae and external anal sphincter
Inferior rectal from pudendal	Innervates the voluntary external anal sphincter
Dorsal nerve of penis/clitoris from pudendal	Skin on posterior scrotum or labia majora
Perineal nerve from pudendal	Muscles of urogenital triangle (ant) of perineaum
Nerve to Levator ani and coccygeus S3,S4	Levator ani and coccygeus mm.
Posterior femoral cutaneous S2,S3	Cutaneous branches to buttock and posterior surface of thigh
Perforating cutaneous S2,S3	Cutaneous branches on medial part of buttock
Pelvic splanchnic S2,S3,S4	Pelvic viscera via hypogastric plexus

ORGANS

OESOPHAGUS

Vagal trunks via ant and post gastric nerves, thoracic sympathetic trunks and greater and lesser splanchnic nerves, the plexus of nerves around the left gastric and inferior phrenic arteries

STOMACH

Parasympathetic from ant and post vagal trunks. Sympathetic nerve supply from T6 – T9 pass to celiac plexus and distributed around the gastric and gastroomental arteries

DUODENUM

Vagus and sympathetic nerves by way of plexusus on the pancreaticoduodenal arteries

JEJUNUM AND ILEUM

Sympathetic nerves originate in T5-T9 and reach the celiac plexus through the sympathetic trunks and the greater splanchnic nn. The preganglionic sympathetic fibres synapse in the celiac and superior mesenteric ganglia. Parasympathetic nerves are derived from the posterior vagal trunks ( mainly right vagus) Sensory fibres only detect distension as colic (cramps)

CECUM and APPENDIX

Sympathetic and parasympathetic nerves from the superior mesenteric pexus. The sympathetic originate in the lower thoracic spinal cord and the parasympathetics come from the vagus. Afferent nerves from the appendix (pain) accompany the sympathetic nerves to the T10 segment of the spinal cord

COLON

Transverse and ascending supplied by nerves from the superior mesenteric plexus and the descending colon is supplied by the hypogastric plexus around the inferior mesenteric artery -as is the sigmoid – the parasympathetics come from the pelvic splanchnic nerves and the sympathetics from the lumber section of the sympathetic trunk.

SPLEEN

Derived from the celiac plexus and are vasomotor and enter the spleen on the splenic artery

PANCREAS

Derived from the vagus and thoracic splanchnic nerves. The parasympathetic and sympathetic fibres pass from the celiac and superior mesenteric plexusus along the arteries

LIVER

Nerves are derived from the hepatic plexus, the largest derivative of the celiac plexus. Sympathetics from celiac plexus and parasympathetics from anterior and posterior vagal trunks – the left vagus gives off a large hepatic branch which passes directly to the liver.

GALL BLADDER

Pass along cystic artery from the celiac plexus (sympathetic) and the vagus nerve. The right phrenic nerve provides sensory supply

KIDNEYS, URETERS AND SUPRARENAL GLANDS

Arise from renal plexus and have sympathetic and parasympathetic parts. The plexus is supplied by fibres from the thoracic splanchnic nerves. The suprarenal glands have a rich nerve supply from the celiac plexus and thoracic splanchnic nerves

ABDOMINAL AUTONOMIC NERVES

These are distributed via a series of plexusus along the anterior of the abdominal aorta.

Sympathetics come from the Thoracic splanchnic nerves from the thoracic sympathetic trunk and lumbar splanchnic nerves.

Parasympathetics come from anterior and posterior vagal trunks and the pelvic splanchnic nerves S2,S3,S4

Sympathetic Nerves: - outflow only T1-L2 (rest = just grey rami)

Thoracic splanchnic are the main source – Greater T5-T9, Lesser T10,T11 and the Least T12. Thoracic splanchnic nerves are composed or preganglionic fibres from white rami communicantes and pass through the ganglia without synapsing. They pierce the corresponding crus of the diaphragm to synapse in the celiac and aorticorenal ganglia that convey both sympathetic and parasympathetic fibres, branches from the first and sometimes second lumbar splanchnic nerves, renal branches from intermesenteric nerves and contributions from the superior hypogastric plexus. The postganglionic fibres are relayed through autonomic plexusus to the viscera.

The lumbar splanchnic nerves arise from the abdominal portion of the sympathetic trunk. This enters the abdomen by passing posterior to the medial arcuate ligament. It is usually composed of four lumbar sympathetic ganglia with interconnecting ganglia. The sympathetic trunks usually lie in a groove along the medial border of the psoas major muscle. The trunks receive white rami communicantes from L1,L2. Medially the lumbar sympathetic trunk gives off three to four splanchnic nerves to end in the intermesenteric, inferior mesenteric and superior hypogastric plexusus. Postganglionic fibres of the inferior mesenteric supply the distal part of the large intestine.

Although sympathetic fibres are motor they also carry sensory fibres from sense organs in the viscera. These fibres pass toward the spinal cord in the splanchnic nerves as far as the sympathetic trunk. They then leave the sympathetic trunk in white rami communicantes and enter a spinal nerve to reach the spinal cord through its ventral root.

Parasympathetics – III, VII, IX & X S2-S4

Abdominal branches arise from the anterior and posterior vagal trunks and are conveyed by the abdominal autonomic plexuses where they synapse with ganglion cells in the walls of viscera. The postganglionic fibres supply smooth muscle of the digestive tract as far as the left colic flexure. The pelvic splanchnic nerves from S2-S4 accompany the inferior hypogastric plexus to supply the descending and sigmoid colon and pelvic organs.

PLEXUSUS

ABDOMINAL AUTONOMIC:

These surround the abdominal aorta and its major branches. The celiac, superior mesenteric and inferior mesenteric plexuses are interconnected. The sympathetic ganglia are scattered among the celiac and mesenteric plexuses. The parasympathetic ganglia are located in the walls of the viscera.

Intermesenteric

Located between the superior and inferior mesenteric arteries and gives rise to RENAL, TESTICULAR or OVARIAN and URETERIC plexuses.

Superior hypogastric plexus

Continuous with the intermesenteric plexus and the inferior mesenteric plexus and lies anterior to the inferior part of the aorta at its bifurcation. Right and left hypogastric nerves join the superior hypogastric plexus to the inferior hypogastric plexus. The superior hypogastric plexus supplies the URETERIC and TESTICULAR or OVARIAN plexus on each common iliac artery.

Inferior hypogastric plexus

Formed on each side by the hypogastric nerve from the superior hypogastric plexus. They are on either side of the rectum, uterine cervix and urinary bladder. The plexuses receive small branches from the superior sacral sympathetic ganglia and sacral parasympathetic outflow via the pelvic splanchnic nerves. This plexus sends fibres along blood vessels to form plexuses on the walls of PELVIC VISCERA

Celiac

T6 – T9 sympathetics pass to this and go on to the stomach on the gastroomental and gastric arteries

SOMATIC

Lumbar

This is a nerve network within the psoas major muscle that is formed by the ventral primary rami of spinal nerves L1-L4. All ventral rami receive grey rami communicantes from the sympathetic trunk and the superior two send white rami communicantes to the sympathetic trunk. Branches from it (largest first) are :

Obturator L2-L4

Femoral L2-L4

Lumbosacral tunk L4,L5

Ilioinguinal L1

Iliohypogastric L1

Genitofemoral L1,L2

Lateral femoral cutaneous L2,L3

Testicular plexus

Autonomic nerves to testes via vagal parasympathetic and sympathetic fibres from the T7 spinal cord segment .

PELVIS AND PERINEUM

SACRAL PLEXUS

This is located on the posterior wall of the pelvis minor where it is closely related to the anterior surface of the piriformis muscle. The two main nerves of it are the sciatic and pudendal. The major branches leave the pelvis through the greater sciatic foreman.

Sciatic nerve

The larger nerve to the lower limb is formed by the ventral rami of L4-S3 that converge on the anterior surface of the piriformis . The sciatic nerve passes through the greater sciatic foreman inferior to the piriformis to enter the gluteal region.

Pudendal nerve

Arising from the ventral rami of S2-S4 it accompanies the internal pudendal artery and leaves the pelvis through the greater sciatic foreman between the piriformis and coccygeus muscles. The pudendal nerve then hooks around the sacrospinous ligament and enters the perineum via the lesser sciatic foreman. It supplies the muscles of the perineum and ends up as the dorsal nerve of the penis or clitoris. It is also sensory to the external genitalia.

Obturator nerve.

This arises in the abdomen from the lumbar plexus via the ventral rami of L2-L4 and enters the pelvis on the deep medial aspect of the psoas major muscle. It runs in extraperitoneal fat along the lateral pelvis walls to the obturator foramen where it divides into anterior and posterior parts that leave the pelvis through this foreman to supply adductors of the thigh (medial muscles).

COCCYGEAL PLEXUS

This is a small network of nerves that is formed by the ventral rami of S4 and S5 nerves and coccygeal nerves. It lies on the pelvic surface of the coccygeus and supplies this muscle, part of levator ani and the sacrococcygeal joint. The anococcygeal nerves arising from this plexus pierce the sacrotuberous ligament and supply a small area of skin in the region of the coccyx.

PELVIC AUTONOMIC NERVES

Each sacral trunk is smaller than the lumbar trunks and usually has four ganglia. They descend just medial to the sacral foramina and converge to form a small median ganglion impar anterior to the coccyx. The sympathetic trunks descend posterior to the rectum in the extraperitoneal fat and send grey rami communicantes t each ventral ramus of the sacral and coccygeal nerves. They also send branches to the median sacral artery and the inferior hypogastric plexus.

Branches from the superior hypogastric plexus enter the pelvis and descend anterior to the sacrum as right and lef hypogastric nerves – lateral to the rectum prostate/cervix of uterus seminal vesicles/ lateral fornices and against the inferolateral surface of the bladder.

The pelvic splanchnic nerves, containing parasympathetic and visceral afferent fibres are derived from S2-S4 spinal cord segments. Hence, the inferior hypogastric plexus contains sympathetic and parasympathetic fibres and these pass along branches of the internal iliac artery to the pelvic viscera.

BLADDER

Innervated by pelvic plexus

Sympathetics from L1 and L2 via hypogastric

Parasympathetic from pelvic splanchnics

Afferents via both but mainly S2,S3,S4

Urethral sphincter relaxes via pudendal nerve