ABDOMINAL MUSCLES ABDOMINAL MUSCLES Abdominal muscles have been
ABDOMINAL MUSCLES
ABDOMINAL MUSCLES • Abdominal muscles have been divided into 2 main parts. 1 - anterior abdominal wall muscles. 2 - posterior abdominal wall muscles.
ANTERIOR ABDOMINAL WALL MUSCLES The muscles of anterior abdominal wall consists of three broad thin sheets that are APONUEROTIC. - IN FRONT= from exterior to interior they are external oblique, internal oblique and transversus. - On either side of midline anteriorly there is a muscle known as rectus abdominis. They are enclosed by thin sheath which is called as rectus sheath. - The lower part of rectus sheath there is a small muscle beneath rectus abdominis and is known as PYRAMIDALIS. - Muscles= external oblique, internal oblique, transversus abdominus, rectus abdominus and pyramidalis.
EXTERNAL OBLIQUE • This muscle is a broad, thin, muscular sheath that rises from lower right ribs and inserted into linea alba, pubic crest and anterior half of iliac crest. • Blood supply: • its main blood supply is from one or two branches of deep circumflex artery and iliolumbar artery. Nerve supply: • Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L 1) Action: • Supports abdominal contents; compresses abdominal contents; assists in flexing and rotation of trunk; assists in forced expiration, micturition, defecation and vomiting.
INTERNAL OBLIQUE • This Is also a broad, thin, muscular sheath type of muscle that lies just deep to external oblique. It rises from lumbar fascia, iliac crest and inserted into lower three ribs and costal cartilages, xiphoid process and linea alba and symphysis pubis(pectineal line). • Blood supply: • Blood supply is mainly from Subcostal arteries. Nerve supply: • Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L 1) Action: • Supports abdominal contents; compresses abdominal contents; assists in flexing and rotation of trunk; assists in forced expiration, micturition, defecation and vomiting.
TRANSVERSES ABDOMINIS • The transversus muscle is a thin sheet of muscle that lies deep to internal oblique and its fibers run horizontally forward. • It rises from lower six costal cartilages, the lumbar fascia, iliac crest and inguinal ligament. It then inserted into xiphoid process, linea alba and symphysis pubis. • Blood supply: • Its blood supply is from many branches that includes posterior intercostal and subcostal arteries, superior and inferior epigastric arteries, superficial and deep circumflex arteries. • Nerve supply: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L 1) Action: • Compresses abdominal contents
RECTUS ABDOMINIS • This muscle is a long strap that extends along whole anterior abdominal wall. • It rises by two heads from front of symphysis pubis and from pubic crest and it is inserted into 5 th, 6 th and 7 th costal cartilages and xiphoid process. • Rectus abdominis is divided into segments by three tendinous intersections; one at level of xiphoid process, one at level of umbilicus and one halfway between these two. • Blood supply: It is supplied by inferior epigastric artery. • Nerve supply: Lower six thoracic nerves • Action: Compresses abdominal contents and flexes vertebral column; accessory muscle of expiration
PYRAMIDALIS • The pyramidalis muscle is often absent. It rises from anterior surface of pubis and inserted into linea alba. • Blood supply: • Supplied by inferior epigastric artery. • Nerve supply 12 th thoracic nerve • Action: Tenses the linea alba
POSTERIOR ABDOMINAL WALL • The main muscles of posterior abdominal wall are 3 in number. • 1 - PSOAS MAJOR • 2 - QUADRATUS LABORUM • 3 - ILIACUS.
PSOAS MAJOR • The psoas major rises from root of transverse processes and intervertebral disks and it is inserted into lesser trochanter of femur. The psoas major is enclosed in a fibrous sheath derived from lumber fascia. • Blood supply: This muscle has a complex arterial supply. Its main blood supply is from lumbar, iliolumbar, obturator, external iliac and common femoral. Nerve supply: This muscle is supplied by the lumbar plexus. Action: The psoas flexes the thigh at the hip joint on the trunk, or if the thigh is fixed, it flexes the trunk on the thigh, as in sitting up from a lying position.
QUADRATUS LUMBORUM • Quadratus lumborum is a flat, quadrilateral shape muscle. • It rises from iliolumbar ligament, iliac crest, tips of transverse processes of lower lumber vertebrae and it inserted into the lower border of 12 th rib and transverse process of upper four lumbar vertebrae. • Blood supply: • This muscle is supplied by branches of lumbar arteries and lumbar branch of iliolumbar artery. • Nerve supply: This muscle is supplied by the lumbar plexus. Action: It fixes or depresses the 12 th rib during respiration and laterally flexes the vertebral column to the same side.
ILIACUS • The iliacus muscle is fan shaped and rises from upper part of iliac fossa and its fibers then join the lateral side of psoas tendon inserted into lesser trochanter of femur. • Those combined muscles are often referred to as Iliopsoas. • Blood supply: • It is supplied by medial femoral circumflex artery, iliac branch of iliolumbar artery. • Nerve supply: This muscle is supplied by the femoral nerve, a branch of the lumbar plexus. Action: The iliopsoas flexes the thigh on the trunk at the hip joint, or if the thigh is fixed, it flexes the trunk on the thigh.
- Slides: 12