STUDY OF HUMAN ANATOMY

ANATOMY OF THE ABDOMEN

A region of the body bounded by the following regions:- DEFINITION OF ABDOMEN A region of the body bounded by the following regions:- Superiorly – thorax Inferiorly – pelvis/perineum Posteroinferiorly – back Inferolaterally – lower limbs

BONY LANDMARKS OF THE ABDOMEN Xiphoid process Costal margin – 7th – 11th costal cartilages Pelvic bones L1 – L5 Lumbar vertebrae

ABDOMINAL CAVITY extends btw thoracic diaphragm & pelvic diaphragm – abdominopelvic cavity upper part is under cover of the osteocartilagenous thoracic cage occupied by organs of the digestive, urogenital, endocrine & vascular structures.

CONTENTS OF THE ABDOMINAL CAVITY

CONTENTS OF THE ABDOMINAL CAVITY

ABDOMINAL WALL

PLANES OF THE ABDOMEN 4 planes divide the abdominal cavity into 9 regions 2 vertical (midclavicular), midclavicular to midinguinal 2 transverse – ( subcostal & transtubercular) Subcostal – pass through 10th costal cartilage Transtubercular – pass through iliac tubercle

REGIONS OF THE ABDOMEN

REGIONS OF THE ABDOMEN

QUADRANTS OF THE ABDOMEN 2 planes delineate the abdominal cavity into 4 quadrants 1 vertical – median 1 transverse – transumbilical

POSITIONS OF THE ABDOMINAL ORGANS

ANTEROLATERAL ABDOMINAL WALL Anterior & lateral walls extending from the thorax to pelvis Consists of the (1) Skin (2) Fascia - Subcutaneous & deep (3) Muscles (4) Transversalis fascia (5) Extraperitoenal fat (6) Peritoneum

ANTEROLATERAL ABDOMINAL WALL Anterior & lateral walls extending from the thorax to pelvis Consists of the (1) Skin (2) Fascia - Subcutaneous & deep (3) Muscles (4) Transversalis fascia (5) Extraperitoenal fat (6) Peritoneum

SKIN Loosely attaches to the superficial fascia, except at the umbilicus. Varies in texture - wrinkle, rough, smooth, scars. Thin in front and thick at the back Distribution of hair varies with sex, age and race. Natural tension lines run horizontally around the body wall.

FASCIA (L. panniculi – apron) Composed of fatty tissues and fibrous connective tissue Divided into two layers (1) Superficial (2) Deep – covers abdominal muscles (1) Same as elsewhere and varies in amount of fat. (1) Major site of fat storage. (1) Excessive fat deposition in the lower anterior abdominal wall – morbid obesity

SUPERFICILA FASCIA/TISSUE Superior to umbilicus Consistent with other regions Inferior to umbilicus Reinforced by collagen and elastic fibers Thus 2 layers – (1) Superficial fatty layer (Camper’s fascia) Same elsewhere (2) Deep membranous layer (Scarpa’s fascia) Membranous continues to the perineum – Colles’s fascia, not to the thigh.

SUPERFICIAL FASCIA

SUPERFICIAL FASCIA

MUSCLES OF THE ANTEROLATERAL ABDOMINAL WALL 5 pairs of muscles bilaterally – 3 flat, 2 vertical (1) External oblique (2) Internal oblique (3) Transversus abdominis (4) Rectus abdominis (5) Pyramidalis

EXTERNAL OBLIQUE MUSCLE O: external surfaces of 5th – 12th ribs I: linea alba, pubic tubercle, ant ½ of iliac crest N: thoracoabdominal nerves (T7-T11 spinal nerves), subcostal nerve. A: compresses the abdomen to provide support for abdominal organs.

INTERNAL OBLIQUE MUSCLE O: thoracolumbar fascia, ant 2/3 of iliac crest, lat 1/3 of inguinal ligament. I: inferior borders of 10th – 12th ribs, linea alba, pecten pubis, conjoint tendon. N: thoracoabdominal nerves (T6-T12 spinal nerves), L1 nerve A: compresses and supports abdominal viscera

TRANSVERSUS ABDOMINIS MUSCLE O: thoracolumbar fascia, internal surfaces of 7th-12th costal cartilages, iliac crest, lat 1/3 of inguinal ligament. I: linea alba, pubic crest, pecten pubis, conjoint tendon. N: thoracoabdominal nerves (T6-T12 anterior rami of spinal nerves), L1 nerve A: compresses and supports abdominal viscera

RECTUS ABDOMINIS MUSCLE O: pubic symphysis & pubic crest I: xiphoid process & 5th-7th costal cartilages N: thoracoabdominal nerves (T6-T12 spinal nerves) A: flexes trunk, compresses and supports abdominal organs, prevents pelvic tilting

ABDOMINAL MUSCLES

ABDOMINAL MUSCLES

DEEP FASCIA Dense connective tissue layer , devoid of fat, that covers the muscles and their aponeurosis. 3 layers – superficial, intermediate & deep.

DEEP FASCIA

PYRAMIDALIS MUSCLE Small, insignificant muscle. Absent in 20% of people O: pubic crest, pubic symphysis I: linea alba N: subcostal nerve (T12) A: tenses the abdomen

RECTUS SHEATH A strong incomplete fibrous compartment Formed by decussation and interweaving of the flat abdominal muscles. Internal oblique aponeurosis splits into two layers: anterior & posterior and invest the rectus abdominis muscle.

RECTUS SHEATH Anterior wall – external oblique, anterior layer of internal oblique Posterior wall – transversus abdominis and posterior layer of internal oblique. All aponeuroses fuse in the midline – linea alba. In the midline, it contains the umbilical ring. A defect where fetal umbilical vessels pass to the placenta. Splitting of internal oblique, lateral to rectus abdominis – semilunar line.

RECTUS SHEATH Posterior wall ends slightly below the umbilicus – arcuate line of Douglas. The rectus abdominis is covered by the transversalis fascia posteriorly.

CONTENTS OF THE RECTUS SHEATH Rectus abdominis muscle Pyramidalis Superior & inferior epigastric vessels Intercostal nerves (T7-T11)

RECTUS SHEATH

ENDOABDOMINAL FASCIA A membranous and areolar sheets. Named according to muscle or aponeurosis it lines. Transversalis fascia as it lines the transversus abdominis muscle. A variable amount of fat separates the fascia above from the peritoneum – extraperitoneal fat. Peritoneum – a single layer of epithelial cells and connective tissue.

NERVES OF THE ANTEROLATERAL ABDOMINAL WALL (1) thoracoabdominal nerves (T7 – T11) (2) Subcostal nerve (anterior ramus of T12) (3) Iliohypogastric (4) Ilioinguinal

VESSELS OF THE ANTEROLATERAL ABDOMINAL WALL (1) superior epigastric artery (2) musculophrenic artery (3) 10th & 11th post intercostal arteries (4) subcostal artery (5) inferior epigastric (6) deep circumflex iliac (7) superficial circumflex iliac (8) superficial epigastric

VEINS & LYMPHATICS OF THE ANTEROLATERAL ABDOMINAL WALL (1) Subcutaneous venous plexus (2) Paraumbilical veins (3) Lateral thoracic vein (4) Superficial epigastric veins (5) superficial circumflex iliac (6) superior & inferior epigastric (7) deep circumflex iliac (8) posterior interocstal (11th) & subcostal veins

FUNCTIONS OF THE ABDOMINAL MUSCLES Form a strong expandible support for the wall Support organs from injuries Compress to increase intraabdominal pressure to facilitate expulsion Move trunk to maintain posture Assists in breathing

FINIS