Abdominal Wall

Landmarks: bony & soft costal arch: formed by #7-10 costal cartilages a. infrasternal angle - sharp upward angle at midline, xiphoid process at the apex b. epigastric fossa - depression just inferior to xiphoid

Coxal bones Three bones fused together ilium: anterior superior iliac spine; iliac crest ischium pubis: pubic symphysis, inguinal ligament (below): indicated at surface by depression separating leg from abdomen

Abdominal wall Linea alba: midline from xiphoid to pubic bone, umbilicus - at level of L4 Linea semilunaris: parallels linea alba on each side; marks lateral border of rectus abdominis Tendinous intersections: 3 horizontal divisions of rectus abdominis between linea semilunaris

Regions

Superficial vessels thoracoepigastric veins: drain laterally from umbilical level up anterior perforating veins: closer to midline umbilical venous plexus (caput medusae may seen in portal hypertension) superficial epigastric artery, vein superficial circumflex iliac artery vein

Nerves Thoracoabdominal nerve: continuations of intercostals 7-11 & subcostal from thorax to abdomen, between internal oblique & transverse abdominis Anterior, lateral cutaneous nerve: terminal branches of thoracoabdominal nerve to the surface T7-9 to skin superior to umbilicus T10 to skin surrounding umbilicus T11-12, L1 to skin inferior to umbilicus Iliohypogastric nerve: to skin over inguinal region Ilioinguinal nerve: just inferior to iliohypogastric to skin of superior, medial thigh

Muscles External oblique muscle Internal oblique muscle Transversus abdominis Rectus abdominis

EXTERNAL ABDOMINAL OBLIQUE Origin Anterior fibers: external surfaces of ribs five through eight interdigitating with serratus anterior lateral fibers: external surface of ninth rib, interdigitating with serratus anterior; and external surfaces of 10th, 11 th ans 12th ribs, interdigitating with latissnus dorsi Insertion Anterior fibers: into a board, flat aponeurosis, terminating in the linea alba, which is a tendinous rephe which extends from the xiphoid Lateral fibers: as the inguinal ligament, into anterior superior spine and public tubercle, and into the external lip of anterior one half of iliac crest.

EXTERNAL ABDOMINAL OBLIQUE Action Anterior fibers: acting bilaterally, the anterior fibers flex the vertebral column approximating the thorax and pelvis anteriorly, support and compress the abdominal viscera, depress the thorax, and assist in respiration. Acting unilaterally with the anterior fibers of the Internal Oblique on the opposite site, the anterior fibers of External Oblique rotate the vertebral column, bring the thorax forward (when the pelvis is fixed), or the pelvis backward (when the thorax is fixed). For example, with the pelvis fixed, the right external oblique rotates the thorax counterclockwise, and the left external oblique rotates the thorax clockwise.

EXTERNAL ABDOMINAL OBLIQUE Action Lateral fibers: acting bilaterally, the lateral fibers of the external oblique flex the vertebral column, with major influence on the lumbar spine, titling the pelvis posteriorly. Acting unilaterally with the lateral fibers of the internal oblique on the same side, these fibers of the external oblique laterally flex the vertebral column, approximating the thorax and iliac crest. These external oblique fibers also act with the internal oblique on the opposite side to rotate the vertebral column. The external oblique, in its action on the thorax, is comparable to the sternocleidomastoid in its action on the head.

EXTERNAL ABDOMINAL OBLIQUE Nerve Anterior fibers: T5, 6, T7-T12 Lateral fibers: T5, 6, T7-T12 Direction of the fibers: Anterior fibers: the fibers extend obliquely downward and medialward with the uppermost fibers from the xiphoid Lateral fibers: fibers extend obliquely downward and medialward, more downward than the anterior fibers

INTERNAL ABDOMINAL OBLIQUE Origin Lower anterior fibers: middle one third of intermediate line of iliac crest, and thoracolumbar fascia Upper anterior fibers: anterior one third of intermediate line of iliac crest Lateral fibers: middle one third of intermediate line of iliac crest, and thoracolumbar fascia Insertion Lower anterior fibers: inferior borders of 10th, 11th, and 12th ribs and linea alba by means of aponeurosis Upper anterior fibers: linea alba by means of aponeurosis Lateral fibers: inferior borders of 10th, 11th, and 12th ribs and linea alba by means of aponeurosis

INTERNAL ABDOMINAL OBLIQUE Action Lower anterior fibers: acting bilaterally, the lateral fibers flex the veterbral column, approximating the thorax and pelvis anteriorly, and depress the thorax. Acting unilaterally with the lateral fibers of the external oblique on the same side, these fibers of the internal oblique laterally flex the vertebral column, approximating the thorax and pelvis. These fibers also act with the external oblique on the opposite side to rotate the vertebral column.

INTERNAL ABDOMINAL OBLIQUE Action Upper anterior fibers: acting bilaterally, the upper anterior fibers flex the vertebral column, approximating the thorax and pelvis anteriorly, support and compress the abdominal viscera, depress the thorax, and assist in respiration. Acting unilaterally, in conjuction with the anterior fibers of the external oblique on te oppisite side, the ipper anterior fibers of the internal oblique rotate the vertebral column, bringing the thorax backward (when the pelvis is fixed), or the pelvis forward (when the thorax is fixed). For example, the right internal oblique rotates the thorax clockwise and the left internal oblique rotates the thorax couinterclockwise on a fixed pelvis.

INTERNAL ABDOMINAL OBLIQUE Action Lateral fibers: acting bilaterally, the lateral fibers flex the veterbral column, approximating the thorax and pelvis anteriorly, and depress the thorax. Acting unilaterally with the lateral fibers of the external oblique on the same side, these fibers of the internal oblique laterally flex the vertebral column, approximating the thorax and pelvis. These fibers also act with the external oblique on the opposite side to rotate the vertebral column.

INTERNAL ABDOMINAL OBLIQUE Nerve Lower anterior fibers: T7-11, T12, iliohypogastric and ilioinguinal, ventral rami Upper anterior fibers: T7-11, T12, iliohypogastric and ilioinguinal, ventral Lateral fibers: T7-11, T12, iliohypogastric and ilioinguinal, ventral rami Direction of fibers: Lower anterior fibers: fibers extend obliquely upward and medialward, more upward than the anterior fibers Upper anterior fibers: fibers extend obliquely medialward and upward Lateral fibers: fibers extend obliquely upward and medialward, more upward than the anterior fibers  

TRANSVERSUS ABDOMINIS Origin inner surfaces of cartilages of lower six ribs, interdigitating with the diaphragm; thoracolumbar fascia; anterior three fourths of internal lip of iliac crest; and lateral one third of inguinal ligament Action Acts likes a girdle to flatten the abdominal wall and compress the abdominal viscera; upper portion helps to decrease the infrasternal angle of the ribs as in expiration. This muscle has no action in lateral trunk flexion except that it acts to compress the viscera and stabilize the linea alba, thereby permiting better action by anteriolateral trunk muscles Insertion linea alba by means of a board aponeurosis, pubic crest and pectin publis Nerve T7-T12, iliohypogastric, ilioinguinal, ventral divisions Direction of fibers: transverse (horizontal)

RECTUS ABDOMINIS Origin Action Insertion Nerve pubic crest and symphysis Action flexes the vertebral column by approximating the thorax and pelvis anteriorly. With the pelvis fixed, the thorax will move toward the pelvis; with the thorax fixed, the pelvis will move toward the thorax. Insertion costal cartilages of fifth, sixth, and seventh ribs, and xiphiod process of sternum Nerve T5-T12, ventral rami

Inguinal triangle bounded by lateral border of rectus abdominis muscle medially inguinal ligament inferiorly inferior epigastric artery laterally

Inguinal canal roof: posterior wall: Floor: Anterior wall: internal oblique & transversus abdominis muscle posterior wall: transveralis fascia, reinforced medially by conjoint tendon (internal oblique & transversus abdomilis muscle) Floor: Superior surface of inguinal ligament Anterior wall: aponeurosis of the external oblique muscle Superficial & deep ring

Graham “Mr Europe" Black had his hernia repaired at the Centre on Friday and on Monday he was ‘working-out' at the gym!  (not always recommended for the rest of us!)