The appendix 2

The appendix 2

Lower intercontinental nerves

Course :The ventral rami of T7-T11 pass forwards in the intercontinental spaces below respective intercontinental vessels. At the back of chest they lie between the pleura and posterior intercontinental membrane but in most of their course they lie between internal intercontinental and in-tercostalis Timi. As they reach the anterior ends of their respective spaces,the 7th and 8th nerves curve upwards and medially across the deep surface of coastal margin, passing between digitization of transverses abdominal then piercing the posterior layer of internal oblique, to enter the rectos sheath, and continue to run upwards and medially parallel to the costal margin. After supplying rectos abdominal, they pierce the anterior wall of the rectos sheath to reach the skin. 7th nerve supplies skin of epigastrium and 8th below it. At the anterior ends of the 9th, 10th and 11th intercontinental spaces, the 9th, 10th and 11th intercontinental nerves pass between digitization of transverses abdominal to lie between it and the internal oblique and run in this plane. 9th nerve runs horizontally, but 10th and 11th run downwards and medially. When they reach the lateral margin of rectos sheath, enter it, pierce the muscle and its anterior sheath to supply the skin.The 10th nerve supplies the band of skin which includes the umbilicus. The ventral ramus of T12 is larger then Te others. It accompanies the subcostal artery along the lower border of 12th rib and passes behind the kidney, anterior to quadratures lumborum, pierces the aponeurosis of transverses abdominal and runs in the interval transverses and internal oblique.

Branches

Muscular : The intercostal and subcostal nerves and their collateral branches supply intercostal muscles and muscles of anterolateral abdominal wall . T 12 supplies pyramidalis also, if present.Cutaneous : The terminal parts of  T7-T12 nerves are called as the anterior cutaneous branches. These supply the skin to the anterior medain line. T10 supplying the skin arround umbilicus; T7 the skin of epigastrium and T8, T9 the intervening skin between epigastrium and the embilicus. T11, T12 and iliohypogastric (L1) supply the skin between umbilicus and pubic symphysis. The lateral cutaneous branches of the T7-T11 intercostal nerves divide into anterior and posterior branches to supply the skin of lateral side of abdomen and back. The lateral cutaneous branch of T 12 supplies the skin of anterior part of the gluteal region.

Pudendal nerve : Pudendal nerve supplies the skin,external genital organs and muscles of perineum. It is concerned with micturition defaecation, erection, ejaculation and in females, with parturition. It is accompanied by internal pudendal vessels. It arises from the sacral plexus in the pelvis. Its root value is ventral rami of S2,S3,S4 nerves.It starts in the pelvis, enters the gluteal region through greater sciatic notch, lies on the sacrospinous ligament, leaves the gluteal region through lesser sciatic notch.It just peeps into the    
gluteal region to enter the pudendal canal in the lateral wall of the ischiorectal fossa.

Collateral or prevertebral ganglla and plexuses
Coeliac plexus : It is the largest of the three autonomic plexuses, e.g coeliac, superior mesenteric and inferior mesenteric plexuses.It is a dense network of nerve fibres which unite the two coeliac ganglia. The ganglia receive the greater splanchnic nerves of both sides including some filaments of vagi and phrenic nerves.Coeliac ganglion are two irregularly shaped ganglia.Each ganglion receives greater splanchnic nerve. The lower part of the ganglion receives  lesser splanchnic nerve and is also called as aorticorenal ganglion.
The aorticorenal ganglion gives off the renal plexus which accompanies the renal vessels. Secondary plexuses arising from coeliac and aorticorenal plexus are distributed along the branches of the aorta, namely phrenic, splenic, left gastric, hepatic, intermesenteric, suprarenal, renal, gonadal, superior and inferior mesenteric plexuses, and abdominal aortic plexus. Thus inferior hypogastric plexus contains both sympathetic and parasympathetic nerves. These are for the supply of the pelvic viscera along the branches of
the arteries. The plexuses supply gastrointestinal tract and genitourinary tract. The autonomic nerves supply of various organs and their effects are described.

Gastrointestinal tract               
Oesophagus : It receives its nerve supply from vagus and sympathetic.Cervical part of oesophagus receives branches from recurrent laryngeal nerve of vagus and middle cervical ganglion of sympathetic trunk. Thoracic part gets branches from vagal trunks and oesophageal plexus as well as from sympathetic trunks and greater splanchnic nerves. Abdominal part receives fibres from vagal trunk thoracic part of sympathetic trunks, greater splanchnic nerves and plexus left gastric artery. The nerves from a plexus called myenteric plexus between two layers of the muscularis externa and another one in the submucous layer.

Stomach : Sympathetic supply reaches from coeliac plexus along gastric and gastroepiploic arteries. A few branches also reach from thoracic and lumbar sympathetic trunks. Parasympathetic supply is derived from vagus nerves. The left vagus forms anterior gastric, while right vagus comprises posterior gastric nerve. The anterior gastric nerve supplies cardiac orifice, anterior surface of body as well as fundus pf stomach,pylorus and liver.Posterior gastric nerve supplies posterior surface of body and fundus till pyloric antrum. It gives a number of coeliac plexus. Vagus is secretomotor to stomach. Its stimulation causes secretion which is rich in
pepsin. Sympathetic inhibits peristalsis and is motor to the pyloric sphincter. It also carries pain fibres from stomach. Spasm ischaemia and distension causes pain.

Small intestine : The nerves of is part of the gut are derived from coeliac ganglia formed by posterior gastric nerve (parasympathetic) and the plexus around superior mesenteric artery. These nerves from myenteric plexus and submucous plexus. Parasympathetic fibres relay in the ganglion cells prasent in these plexuses. Sympathetic inhibits but stimulates the sphincters. Large intestine : Large intestine except the lower half of anal canal is supplied by both components of autonomic nervous system. The derivatives of midgut,i.e. caecum, vermiform appendix, ascending colon  and right two thirds of transverse colon receive their
sympathetic nerve supply from coeliac and superior mesenteric ganglia and parasympathetic from vagus nerve.Left one-third of transverse colon, descending colon, sigmoid colon, rectum and upper half of anal canal (developed from hindgut and anorectal canal) receive their sympathetic nerve supply from lumbar part of sympathetic trunk and superior hypogastric plexus through the plexuses on the branches of inferior mesenteric artery. Its effect is chiefly vasomotor. Parasympathetic supply of colon is received from pelvic
splanchnic nerves. Pelvic splanchnic nerve give fibres to inferior hypogastric plexuses to supply rectum and upper half of anal canal. Some fibres of inferior hypogastric plexus pass up through superior hypogastric plexus and get distributed along the branches of inferior mesenteric artery to the left one-third of transverse colon, descending and sigmoid colon.

Clinical anatomy    
In some diseases affecting the nerve trunks near their origins, the pain is referred to their peripheral terminations. In tuberculosis of thoracic vertebrae, the pain when one nerve is involved or general diffuse pain when more nerves are involved. The muscle and skin of the anterolateral abdominal wall is supplied by thoracic 7-12 spinal nerves. These muscles protect the underlying viscera effectively. Any blow to the abdominal wall will do no harm to the viscera if the muscles are caught unawares, blow can do a lot of damage to viscera. Mostly there is reflex contraction of muscles if there is any attack to the skin. The lower intercostal nerves are connected to sympathetic ganglia via the rami communicans. From these ganglia arise greater splanchnic nerves which supply abdominal viscera. In injury to the viscera or peritonitis, the muscles of abdominal wall firmly contract, giving rise to ''board-like rigidity'' to prevent any further insult to the viscera. If the lateral cutaneous nerve of thigh gets compressed as it pierces the inguinal ligament, there is
pain tingline, numbness and anaesthesia ovar the anterolateral aspect of thigh. This is called ''meralgia paraesthetica''.

Male and female reproductive organs
Testicular plexus accompanies the testicular artery to reach the testis. It is formed by renal and aortic plexus, and also from superior and inferior hypogastric plexuses.This plexus is derived from renal,aortic plexuses and also superior and inferior hypogastric plexuses. This plexus supplies the epididymis and ductus deferens. Prostatic plexus is formed from inferior hypogastric plexus.and branches are distributed to prostate, seminal vesicle, prostatic urethra, ejaculatory ducts, erectile tissue of penis, penila part of urethra and bulbourethral glands.Sympathetic nerves cause vasoconstriction, parasympathetic nerves cause vasodilatation.Ovary
and uterine tube receive their nerve supply from plexus around the overian vessels. This plexus is derived from renal, aortic plexuses, and also superior and inferior hypogastric plexuses. Sympathetic fibres derived from T10 and T11 segments of spinal cord are vasomotor in nature whereas parasympathetic fibres are probably vasodillator in function.