Abdomen Flashcards
How many muscles compose the anterolateral abdominal wall? Which type of muscles are these?
5 bilaterally paired: 3 flat muscles and 2 vertical muscles
Which are the flat muscles that compose the anterolateral abdominal wall?
External oblique internal oblique, and transversus abdominis
Where is the external oblique located and what is the direction of its fibers?
- Superificial muscle
- Fibers pass inferomedially and interdigitate with slips of serratus anterior
What is the inguinal ligament and where is it?
Undercurving fibrous band of the external oblique that spans between anterior superior iliac spine and pubic tubercle, at the inferior margin of the muscle
Where is the internal oblique located and what is the direction of its fibers?
Intermediate muscle
Fibers fan out so that its upper fibers are perpendicular and its lower fibers are parallel to. those of the external oblique
Where is the transversus abdominis locared and what is the direction of its fibers?
- Innermost muscle
- Fibers (except for most inferior ones) run horizontally
Where is the rectus sheath?
Between the midclavicular line and the midline, enclosing the rectus abdominis
What is the rectus sheath mede out of?
Interlaced aponeuroses of flat abdominal muscles
What is the linea alba?
Midline raphe made of the interweave of aponeuroses of flat abdominal muscles; this extends from xiphoid process to the pubic symphysis
This interweaving doesn’t just result from the merging of right and left sides of the rectus sheath, but also between superficial, intermediate, and deep layers (flat muscles of abdominal wall)
Which are the vertical muscles that compose the anterolateral abdominal wall?
Rectus abdominis and pyramidalis
How are the muscle fibers of the rectus abdominis arranged?
Muscle fibers don’t run the length of the muscle; rather, they run between 3 or more “tendinous intersections”
Where are the tendinous intersections of the rectus abdominis located?
At the level of xiphoid process, the umbilicus, and halfway between these points
Each intersection is firmly attached to the anterior layer of the rectus sheath
Where should the pyramidalis be located?
Lies in the rectus sheath anterior to the inferior part of the rectus abdominis; arises from the pubic crest and attaches along the linea alba, when it tenses
What is the origin of the external oblique?
External surfaces of 5-12th ribs
What is the insertion of the external oblique?
Linea alba, pubic tubercle, and anterior half of iliac crest
What is the nerve supply of the external oblique?
Thoraco-abdominal and subcostal nerves (anterior rami of T7-T12 spinal nerves)