Trisha Shetty (Editor)

Pyramidalis muscle

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Insertion
  
Actions
  
tensing the linea alba

Nerve
  
Latin
  
musculus pyramidalis

Pyramidalis muscle

Artery
  

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

Contents

Attachments and actions

Inferiorly, it 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 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.

Therefore, when contracting, it has the function of tensing the linea alba.

Variations

The pyramidalis muscle is absent in 20% of people. 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.

Innervation

The muscle is innervated by the ventral portion of T12.

Blood supply

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

Surgical landmark

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

References

Pyramidalis muscle Wikipedia


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