- Any of the muscles of the front and side walls of the abdominal cavity.Three flat layersthe external oblique, internal oblique, and transverse abdominis musclesextend from each side of the spine between the lower ribs and the hipbone. The abdominal muscles attach to aponeuroses, connective tissue sheaths that merge toward the midline, sheathing the rectus abdominis muscle on each side of the midline. The abdominal muscles support and protect the internal organs and take part in exhaling, coughing, urinating, defecating, childbirth, and motion of the trunk, groin, and lower limbs.
* * *any of the muscles of the anterolateral walls of the abdominal cavity, composed of three flat muscular sheets, from without inward: external oblique, internal oblique, and transverse abdominis, supplemented in front on each side of the midline by rectus abdominis.The first three muscle layers extend between the vertebral column behind, the lower ribs above, and the iliac crest and pubis of the hip bone below. Their fibres all merge toward the midline, where they surround the rectus abdominis in a sheath before they meet the fibres from the opposite side at the linea alba. Strength is developed in these rather thin walls by the crisscrossing of fibres. Thus, the fibres of the external oblique are directed downward and forward, those of the internal oblique upward and forward, and those of the transverse horizontally forward.Around the rectus abdominis, which extends from the pubis upward to the ribs, the above muscles are all fibrous. In the region of the groin, between the pubic bone and the anterior superior iliac spine, a specialized arrangement of these fibres permits the formation of the inguinal canal, a passage through the muscular layers. This develops at birth as the testes descend out of the abdominal cavity through its wall into the scrotum. In the female this is replaced by a fibrous cord from the uterus. This gap is a potentially weak area where inguinal hernias can occur.The muscles of the abdominal walls perform a variety of functions: (1) They provide a tonic, elastic muscular support for the viscera and, by their recoil, pull down the rib cage in expiration. (2) They contract against blows to form a rigid protective wall for the viscera. (3) When the glottis is closed and the thorax and pelvis are fixed, these muscles take part in the expulsive efforts of urination, defecation, childbirth, vomiting, and of singing and coughing. (4) When the pelvis is fixed, they initiate the movement of bending the trunk forward. Thereafter, gravity comes into play, the abdominal muscles relax, and the muscles of the back then take on the strain. (5) Conversely, the abdominal muscles come into play in preventing hyperextension. (6) When the thorax is fixed, the abdominal muscles can pull up the pelvis and lower limbs. (7) The muscles of one side can bend the vertebral column sideways and assist in its rotation.
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abdominal muscle — noun the muscles of the abdomen • Syn: ↑abdominal, ↑ab • Hypernyms: ↑skeletal muscle, ↑striated muscle • Hyponyms: ↑external oblique muscle, ↑ … Useful english dictionary
Abdominal muscle deficiency syndrome — Partial or complete absence of the abdominal muscles so that the outlines of the intestines are visible through the thin, lax, protruding abdominal wall. Also called the prune belly syndrome. The full syndrome probably occurs only in males. In… … Medical dictionary
Syndrome, abdominal muscle deficiency — Partial or complete absence of the abdominal muscles so that the outlines of the intestines are visible through the thin, lax, protruding abdominal wall. Also called the prune belly syndrome. The full syndrome probably occurs only in males. In… … Medical dictionary
transverse abdominal muscle — musculus transversus abdominis … Medical dictionary
Abdominal wall — Body cavities Diagram of sheath … Wikipedia
Abdominal internal oblique muscle — Muscles of the trunk … Wikipedia
Abdominal exercise — Abdominal exercises are those that affect the abdominal muscles (colloquially known as the stomach muscles or abs ). Contents 1 Usage 2 Breakdowns 3 Types of abdominal exercises and effectiveness 3.1 … Wikipedia
muscle — muscleless, adj. muscly, adj. /mus euhl/, n., v., muscled, muscling, adj. n. 1. a tissue composed of cells or fibers, the contraction of which produces movement in the body. 2. an organ, composed of muscle tissue, that contracts to produce a… … Universalium
abdominal — I noun the muscles of the abdomen • Syn: ↑abdominal muscle, ↑ab • Hypernyms: ↑skeletal muscle, ↑striated muscle • Hyponyms: ↑ … Useful english dictionary
abdominal external oblique muscle — noun a diagonally arranged abdominal muscle on either side of the torso • Syn: ↑external oblique muscle, ↑musculus obliquus externus abdominis, ↑oblique • Derivationally related forms: ↑oblique (for: ↑oblique) … Useful english dictionary