Which is not a feature of Skeletal muscle ?
**Core Concept**
Skeletal muscle is one of the three main types of muscle tissue in the human body, characterized by its striated appearance under a microscope and its ability to contract voluntarily. It is composed of multinucleated muscle fibers that are attached to bones via tendons, allowing for movement and locomotion.
**Why the Correct Answer is Right**
Skeletal muscle is striated due to the presence of sarcomeres, which are repeating units of actin and myosin filaments that slide past each other to produce contraction. This type of muscle is voluntary, meaning it can be controlled by the nervous system, and is innervated by motor neurons that transmit electrical signals to the muscle fibers. Skeletal muscle also has a rich blood supply, which is essential for delivering oxygen and nutrients to the muscle fibers.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a feature of skeletal muscle. Epithelial muscle, on the other hand, is a type of smooth muscle found in the walls of hollow organs such as the digestive tract.
**Option B:** This option is incorrect because it is a feature of skeletal muscle. Skeletal muscle is striated, which is due to the arrangement of actin and myosin filaments in the sarcomeres.
**Option C:** This option is incorrect because it is partially true, but not entirely specific to skeletal muscle. While it is true that skeletal muscle is multinucleated, this characteristic is also shared with cardiac muscle.
**Clinical Pearl / High-Yield Fact**
It's worth noting that skeletal muscle can be broadly classified into two types: extrafusal and intrafusal. Extrafusal fibers are the main contractile units of skeletal muscle, while intrafusal fibers are smaller and are found within the muscle spindle, a sensory organ that detects changes in muscle length and tension.
**Correct Answer: A. Epithelial muscle.**