Abdominal muscles

The anterior and lateral walls of the abdominal cavity are formed by three pairs of broad abdominal muscles, their tendon stretches and rectus abdominal muscles with their fascia. Muscles and fasciae of the abdominal walls form the abdominal press, which protects the internal organs from external influences, exerts pressure on them and holds them in a certain position, and also participates in the movements of the spine and ribs. The structure of the back wall of the abdominal cavity includes the lumbar spine, as well as paired large lumbar and square muscles of the waist. The lower wall is formed by ileal bones, muscles and fascia of the pelvic floor - the pelvic diaphragm and urogenital diaphragm.

The abdominal muscles and the fascia covering them form the muscular basis of the lateral, anterior and posterior walls of the abdominal cavity. Accordingly, the topography and the place of the beginning and attachment of the abdominal muscles can be subdivided into the lateral, front and rear.

Muscles of the side walls of the abdominal cavity

The side walls of the abdominal cavity form three paired, broad muscles: the external oblique abdominal muscle, the internal oblique abdominal muscle and the transverse abdominal muscle. Being located layer by layer, the bundles of these muscles pass in different directions. In the outer and inner oblique muscles of the abdomen, the muscle bundles cross each other at an angle of approximately 90 °, and the transverse abdominal muscle bundles are oriented horizontally. 

The external oblique abdominal muscle (m. Obliquus extemus abdominis) is the most superficial and extensive of the abdominal muscles. It begins with large teeth on the outer surface of the eight lower ribs. The upper five muscle teeth enter between the teeth of the anterior dentate muscle, and the lower three - between the teeth of the latissimus muscle of the back.

  Outer oblique abdominal muscle

The internal oblique abdominal muscle (m. Obhquus internus abdominis) is located inside of the outer oblique abdominal muscle, forming the second layer of abdominal wall muscles. The muscle begins on the intermediate line of the iliac crest, the lumbosacral fascia and the lateral half of the inguinal ligament.

 Inner oblique abdominal muscle

The transverse muscle of the abdomen (m. Transversus abdominis) forms the deepest, third layer in the lateral parts of the abdominal wall. The bunches of the transverse abdominal muscle are arranged horizontally, passing forward and medially.

 Transverse abdominal muscle

Muscles of the anterior wall of the abdominal cavity

The rectus abdominis (rectus abdominis) is a flat, long muscle of the ribbon-like shape, located on the side of the median line. Separated from the same muscle of the opposite side with a white belly line. The muscle begins with two tendon parts - on the pubic bone (between the pubic symphysis and the pubic tubercle) and pubic ligaments.

 Straight abdominal muscle

The pyramidal muscle (m. Pyramidalis) is triangular in shape, located in front of the lower part of the rectus abdominis muscle. The muscle begins on the pubic symphysis. The muscle fibers are guided from the bottom up and intertwined into the white line of the abdomen. (Sometimes the muscle is absent.)

 Pyramidal muscle

Muscles of the back wall of the abdominal cavity

The square muscle of the waist (m. Quadratus lumborum) is located at the side of the transverse processes of the lumbar vertebrae. It begins on the iliac crest, ilio-lumbar ligament and on the transverse processes of the lower lumbar vertebrae. It is attached to the lower edge of the XII rib and to the transverse processes of the upper lumbar vertebrae.

Square lumbar muscle

[1], [2], [3], [4], [5], [6]