Muscle most commonly affected by congenital absence is –
**Core Concept**
The question is testing the knowledge of congenital muscular dystrophy, a group of disorders characterized by muscle weakness and degeneration present at birth. The condition is often associated with mutations in genes encoding for proteins that provide structural support to muscle cells.
**Why the Correct Answer is Right**
The correct answer is related to the most common type of congenital muscular dystrophy, which is caused by mutations in the COL6A1 gene. This gene encodes for a component of collagen type VI, a protein that provides structural support to muscle cells and the surrounding connective tissue. The absence or mutations in this protein lead to muscle weakness and degeneration. The most commonly affected muscle in this condition is the quadriceps femoris, which is a group of muscles at the front of the thigh responsible for knee extension.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not specify a muscle group commonly affected by congenital muscular dystrophy.
* **Option B:** This option is incorrect as it does not correspond to a known muscle commonly affected by congenital muscular dystrophy.
* **Option C:** This option is incorrect as it does not accurately describe the muscle most commonly affected by congenital muscular dystrophy.
**Clinical Pearl / High-Yield Fact**
In congenital muscular dystrophy, the absence of collagen type VI protein leads to muscle weakness and degeneration, often resulting in significant muscle wasting and joint deformities.
**Correct Answer:** D. Quadriceps femoris.