Pyramidalis muscle

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Pyramidalis muscle
Gray397.png
Muscles at the front of the abdomen, showing the pyramidalis at the bottom centre.
Details
Origin pubic symphysis and pubic crest
Insertion linea alba
Artery Inferior and superior epigastric arteries
Nerve Subcostal nerve (T12)
Actions tensing the linea alba
Identifiers
Latin musculus pyramidalis
TA A04.5.01.007
FMA 15568
Anatomical terms of muscle

The pyramidalis is a small triangular muscle, anterior to the rectus abdominis muscle, and contained in the rectus sheath.

Structure[edit]

Inferiorly, the pyramidalis attaches to the pelvis in two places: the pubic symphysis and pubic crest, arising by tendinous fibers from the anterior part of the pubis and the anterior pubic ligament.

Superiorly, the fleshy portion of the pyramidalis 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[edit]

The pyramidalis is innervated by the ventral portion of T12.

Blood supply[edit]

The inferior and superior epigastric arteries supply blood to this muscle.

Variation[edit]

The pyramidalis muscle is present in 80% of human population.[1]This muscle may be absent on one or both sides; the lower end of the rectus then becomes proportionately increased in size.

Occasionally it is double 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[edit]

The pyramidalis, when contracting, tenses the linea alba.

Clinical significance[edit]

While making the longitudinal inscision for a classical caesarean section, the pyramidalis is used to determine midline and location of the linea alba.

Additional images[edit]

References[edit]

  1. ^ "7 Vestigial Features of the Human Body". Encyclopedia Britannica. Retrieved 2017-11-09. 

External links[edit]