- Pyramidalis muscle
Infobox Muscle
Name = Pyramidalis muscle
Latin = musculus pyramidalis
GraySubject = 118
GrayPage = 416
Caption = TheTransversus abdominis ,Rectus abdominis , andPyramidalis . (Pyramidalis labeled at bottom center.)
Origin =pubic symphysis andpubic crest
Insertion =linea alba
Blood =
Nerve =Subcostal nerve (T12)
Action = tensing thelinea alba
DorlandsPre = m_22
DorlandsSuf = 12550348
The pyramidalis is a small and triangular muscle, anterior to theRectus abdominis , and contained in therectus sheath .Attachments and actions
Inferiorly, it attaches to the
pubic symphysis andpubic crest , arising by tendinous fibers from the anterior part of the pubis and theanterior 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 theumbilicus and pubis.Therefore, when contracting, it has the function of tensing the
linea alba .Variations
It is absent in 20% of normal humans.
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 extend higher than the usual level.
Innervation
The muscle is innervated by the ventral portion of T12.
=AdditionalExternal links
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* - "Anterior Abdominal Wall: The Pyramidalis Muscle"
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