The pyramidalis muscle is a small triangular
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
, anterior to the
rectus abdominis muscle, and contained in the
rectus sheath
The rectus sheath (also called the rectus fascia.) is a tough fibrous compartment formed by the aponeuroses of the transverse abdominal, transverse abdominal muscle, and the internal oblique, internal and external oblique muscles. It contains the ...
.
Structure
The pyramidalis muscle is part of the anterior abdominal wall. Inferiorly, the pyramidalis muscle attaches to the
pelvis
The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
in two places: the
pubic symphysis
The pubic symphysis (: symphyses) is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attache ...
and
pubic crest
Medial to the pubic tubercle is the pubic crest, which extends from this process to the medial end of the pubis (bone), pubic bone.
It gives attachment to the conjoint tendon, the rectus abdominis, the abdominal external oblique muscle, and the ...
, arising by tendinous fibers from the anterior part of the
pubis and the
anterior pubic ligament.
Superiorly, the fleshy portion of the pyramidalis muscle passes upward, diminishing in size as it ascends, and ends by a pointed extremity which is inserted into the
linea alba, midway between the
umbilicus and
pubis.
Nerve supply
The pyramidalis muscle is innervated by the ventral portion of
T12.
Blood supply
The
inferior and
superior epigastric arteries supply blood to the pyramidalis muscle.
Variation
The pyramidalis muscle is present in 80% of human population.
It may be absent on one or both sides; the lower end of the rectus then becomes proportionately increased in size.
Occasionally, it is doubled on one side, and the muscles of the two sides are sometimes of unequal size. It may also extend higher than the usual level.
Function
The pyramidalis muscle tenses the
linea alba when contracting.
Clinical significance
While making the longitudinal incision for a classical
caesarean section
Caesarean section, also known as C-section, cesarean, or caesarean delivery, is the Surgery, surgical procedure by which one or more babies are Childbirth, delivered through an incision in the mother's abdomen. It is often performed because va ...
, the pyramidalis muscle is used to determine midline and location of the
linea alba.
Additional images
File:Gray235.png, Right hip bone viewed from outside, showing a small line where the pyramidalis attaches
References
External links
* - "Anterior Abdominal Wall: The Pyramidalis Muscle"
*
*
{{Authority control
Muscles of the torso