ANATOMICAL BOUNDARIES OF HUMAN ABDOMEN AND IT'S CAVITY

The human Abdomen and it's cavity is the part of the trunk that is situated in-between the Thorax and the Pelvis.

 Superior border: diaphragm; the Abdominal cavity extends superiorly as far as the 4th intercostal space 

Inferior border: continues with the pelvic cavity till the pelvic diaphragm 

Anterior border: Anterior Abdominal wall  suspended from the inferior borders of the cartilages of the 7th-10th ribs and the Xiphoid process of the sternum(Skin; superficial fatty subcutaneous tissue (campers fascia); Deep membranous subcutaneous tissue (Scarpa's fascia); superficial investing fascia; External Oblique muscle; intermediate investing fascia; Internal Oblique muscle; deep investing fascia; Traversus abdominis muscle; Extraperitoneal fat; Peritoneum (parietal) 

Posterior border: Posterior Abdominal wall(lumbar vertebrae and corresponding intervertebral disc; posterior abdominal wall muscles; Diaphragm;Fascia; lumbar plexus; fat vessels and nerves)