Pyramidalis innervation originates from which nerve?

Pyramidalis innervation originates from which nerve?

• A. Subcostal nerve
• B. Iliohypogastric nerve
• C. Ilioinguinal nerve
• D. Genitofemoral nerve

Answer: (A)

Pyramidalis is supplied by the subcostal nerve, which is the ventral ramus of the twelfth thoracic nerve. This nerve runs along the bottom edge of the 12th rib and provides motor innervation to the anterior abdominal wall muscles, including the pyramidalis. The other nerves listed come from L1 or serve different regions (iliohypogastric and ilioinguinal mainly to lower abdominal muscles and skin, genitofemoral to the genital area and cremaster), so they aren’t the typical source for pyramidalis innervation. Therefore, the subcostal nerve best explains the innervation of this small muscle.

Pyramidalis is supplied by the subcostal nerve, which is the ventral ramus of the twelfth thoracic nerve. This nerve runs along the bottom edge of the 12th rib and provides motor innervation to the anterior abdominal wall muscles, including the pyramidalis. The other nerves listed come from L1 or serve different regions (iliohypogastric and ilioinguinal mainly to lower abdominal muscles and skin, genitofemoral to the genital area and cremaster), so they aren’t the typical source for pyramidalis innervation. Therefore, the subcostal nerve best explains the innervation of this small muscle.