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Arteries of the Abdomen

  1. Anterior abdominal wall is divided into 9 regions with the help of two vertical and two horizontal planes. The horizontal planes include: -
    1. Transpyloric plane (of Adison):- It lies midway between the suprasternal notch and pubic symphysis. It passes anteriorly through tips of 9th costal cartilage and posteriorly through lower border of L, vertebra. Organs present at this level are hilum of kidney, pylorus of stomach, beginning of duodenum, neck of pancreas, fundus of gall bladder and origin of SMA.
    2. Transtubercular plane: - It connects the tubercles of iliac crests and passes through upper border of L5 vertebra.
  2. The two vertical planes are right and left lateral planes passing through midinguinal point (also called as midinguinal plane or midclavicular plane).
  3. The nine regions from above downwards are -
    1. In middle:Epigastrium, umbilical, hypogastrium.
    2. On right side:- Right hypochondrium, right lumbar, and right inguinal (iliac) regions.
    3. Left side:- Left hypochondrium, left lumbar and left inguinal (iliac) regions.

Important landmarks

  1. Xiphoid process lies at the level of T9 vertebra. Pubic symphysis lies at the level of coccyx. Line joining the xiphoid process and pubic symphysis is anterior median plane.
  2. Costal margins are formed by 7th, 8th, 9th and 10thcostal cartilage. The transverse plane passing through lowest part of costal margin (10th costal cartilage in midaxillary line) is called subcostal plane, which passes through L1 vertebra.
  3. Highest point of iliac crest lies at L4 vertebra.
  4. Umblicus lies between L3 and L4 vertebrae.
  5. The angle between the last rib and outer border of erector spinae is known as renal angle

Superficial fascia

  1. The superficial fascia of anterior abdominal wall (below the level of umblicus) is divided into: Superficial fatty layer (fascia of camper or camper's fascia), and deep membranous layer (fascia of scarpa or scarpa's fascia).
  2. The fatty layer (fascia of camper) is continuous with the superficial fascia of adjoining part of the body. However, in the penis it is devoid of fat and in scrotum it is replaced by dartos muscle, i.e., in scrotum dartos muscle is present instead of fatty layer of superficial fascia.
  3. The membranous part (fascia of scarpa) is continuous with membranous part of superficial fascia of perineum (colle's fascia). The attachments of Scarps's fascia of abdomen and colle's fascia of perineum are such that they prevent the passage of extravagated urine due to rupture of urethra backward into ischiorectal fossa and downward into the thigh. Crossing the inguinal ligament it is attached to fascia lata of thigh along the Holden's line, below and parallel to inguinal ligament. In the median plane, the membranous layer (Scarpa's fascia) is thickened to form the suspensory ligament of the penis or of the clitoris.

Deep fascia

  1. It is present in the form of a thin layer covering the muscles and their aponeurosis and large neurovascular structures. At superficial inguinal ring it continues over the spermatic cord as external spermatic fascia into scrotum and continues over the penis as deep fascia of penis (Buck's fascia).

Nerve supply

  1. The skin of anterior abdominal wall is innervated by ventral rami of T7 to T12 spinal nerves (lower 5 intercostal and subcostal nerve) and ventral rami of L1 (iliohypogastric nerve). Lateral cutaneous branches of T7 - T u supply lateral part of skin of anterior abdominal wall. Anterior cutaneous branches of lower 5 intercostal (T7- T 11), subcostal (T12) and iliohypogastric (L1) supply paramedian region emerging through anterior wall of rectus sheath. The dermatomal pattern is arranged in serial order; T7 near xiphoid process (epigastric pit), T10 at umblicus level, the iliohypogastric (L1) 2.5 cm above the superficial ring and others at proportionate distance between them.

Superficial lymphatics

  1. The umblicus is a watershed; above the level of umblicus lymph flows upwards to drain into axillary lymph nodes. Below the level of umblicus lymph flows downwards to drain into superficial inguinal lymph nodes.

Rectus sheath

  1. It is an aponeurotic sheath enclosing rectus abdominis muscle formed by aponeurosis of the three flat abdominal muscles. Rectus sheath has two walls - (i) anterior and (ii) posterior.
  2. Anterior wall is complete and its composition is variable as follows –
    1. Above costal margin: - Formed by external oblique aponeurosis.
    2. Between costal margin and Arcuateline: - Formed by external oblique aponeurosis and anterior lamina of aponeurosis of internal oblique.
    3. Below arcuate line: - Aponeurosis of all three muscles (external oblique, internal oblique, transverses abdominis). The aponeurosis of internal oblique and transversus abdominis fuse, but the external oblique neurosis remains separate.
  3. Posterior wall is incomplete and is deficient above the costal margin and below arcuate line :-
    1. Above costal margin: - Deficient and rectus abdominis rests directly on 5th, 6th and 7th costal cartilages.
    2. Between costal margin and arcuateline: - Formed by posterior lamina of aponeurosis of internal oblique and aponeurosis of transversus abdominis.
    3. Below arcuate line :- Deficient and the rectus muscles rests on the fascia transversal

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  1. Contents of rectus sheath
    1. Muscles :- Rectus abdominis, pyramidalis
    2. Arteries :- Superior epigastricartery (a branch of internal thoracic) which anastomoses with inferior epigastric artery (a branch of external iliac).
    3. Veins :- Superior epigastric and inferior epigastric veins.
    4. Nerves: - Terminal parts of lower six thoracic nerves (lower 5 intercostal and subcostal nerves.
  2. Three aponeurotic layers forming rectus sheath of both sides interlace with each other to form a tendinous raphe, Linea Alba. It extends from xiphoid process to pubic symphysis. Linea Alba is narrow and indistinct below the umbilicus as two recti lie in close contact. Linea alba broadens out above the level of umblicus.



Arcuate line (linea semicircularis or fold Douglas) is the lower end of posterior wall of rectus sheath where it ends; it is midway between umblicus and pubic symphysis.



  1. Inguinal ligament (Poupart's ligament) is the folded lower border of external oblique aponeurosis, attached medially to pubic tubercle and laterally to anterior superior iliac spine. Its grooved upper surface forms floor of inguinal canal. It is 12-14 cm long in adults. Structures passing behind inguinal ligaments are psoas major, pectineus, iliacus, femoral nerve, femoral vessels, lateral cutaneous nerve of thigh, and femoral branch of genitofemoral nerve and lymphatics.
  2. Lacunar ligament (Gimbernat's ligament) is the crescent shaped expansion from the medial end of inguinal ligament attached to pectineal line of pubis. Its sharp concave base forms the medial boundary of femoral ring; its upper surface forms the floor of inguinal canal: It is extension of inguinal ligament, thus is made of external oblique aponeurosis.
  3. Pectineal ligament (Cooper's ligament) is strong fibrous band extending laterally from the lacunar ligament along pectineal line of pubis. Similar to lacunar ligament, it is made of external oblique aponeurosis.
  4. Reflected part of inguinal ligament extends from the lateral crus of superficial inguinal ring formed by inguinal ligament upwards to linea alba. It forms the posterior wall of inguinal canal.
  5. Conjoint tendon (falx inguinalis) is formed by the aponeurosis of internal oblique and transversus abdominis muscle and is attached to pubic crest. Strengthen medial half of posterior wall of inguinal canal opposite the level of superficial inguinal ring. It forms one of the covering of the medial direct hernia.



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  1. Abdominal muscles (especially internal oblique) support abdominal viscera. Oblique muscles along with transversus compress the abdomen thus help in expulsive acts like micturition, cough, vomiting and defecation.
  2. Lateral flexion of trunk is done by one sided contraction of the oblique muscles. Flexion of trunk (lumbar spine) is caused by rectus abdominis. Rotation of trunk is produced by a combined action of the external oblique with the opposite internal oblique.
  3. Majority of strength of abdominal wall is due to aponeurosis of abdominal muscles (obliques and transversus)
  4. In cremasteric reflex afferent fibers are through femoral branch of genitofemoral nerve and efferent through genital branch of genitofemoral nerve (L1, L2). Upon stroking the skin of the upper part of the medial side of thigh there is reflex contraction of the cremasteric muscle with retraction of testis.

Inguinal canal


It is 4 cm (1.5 inches) long intermuscular passage above and parallel to medial half of inguinal ligament, slanting downward and medially. It is made up of -

  1. Anterior wall: - Skin, two layers of superficial fascia (Camper's and Scarp's fasciae), external oblique aponeurosis in entire extent and muscular fibers of internal oblique in its lateral one third.
  2. Posterior wall: - Transversalis fascia, extraperitoneal fat and parietal peritoneum in whole extent. It is reinforced by conjoint tendon (falx inguinalis) and reflected part of inguinal ligament in its medial two-third.
  3. Roof: - Arched fibers of internal oblique and transversus abdominis.
  4. Floor: - Upper grooved surface of inguinal ligament and at the medial end by lacunar ligament.



Deep inguinal ring is oval or circular orifice in Transversalisfascia (posterior wall of inguinal canal) 1.25 cm above mid inguinal point. It is larger in male. Inferior epigastric vessels run upward and medially along the medial margin of deep inguinal ring. Indirect inguinal hernia enters inguinal canal through it.




Superficial inguinal ring is a triangular aperture in the external oblique aponeurosis. Base is formed by pubic crests margins are known as crura. Lateral crus is stronger and is formed by medial end of inguinal ligament. Center of the ring is above and medial to pubic tubercle. It is larger in males.



  • The spermatic cord in males and round ligament of uterus in females, enter the inguinal canal through the deep inguinal ring and pass out through superficial inguinal ring. Thus constituents of spermatic cord are also components of inguinal canal; these are ductus deferens (vas deferens), testicular artery, and cremastericartery, artery to ductus deference, pampiniform plexus, lymphatics, sympathetic plexus, and remains of process vaginalis.

Inguinal triangle of Hesselbach


It is a peritoneal triangle in the posterior wall of the inguinal canal, bounded laterally by inferior epigastric artery, medially by lateral border of rectus abdominis, and below by inguinal ligament. Direct inguinal hernia enters the inguinal canal through this triangle, which is divided by the obliterated umbilical artery into a medial part (supravesical fossa) and a lateral part (medial inguinal fossa).


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