Which of the following is an example of multiunit smooth muscles ?

Options

A. Smooth muscle in uterine wall
B. Smooth muscle with the intestine
C. Masseter muscle of the jaw
D. Arrector pili muscle of skin

Answer

To determine which of the following is an example of multiunit smooth muscles, we can follow these steps:

### Step 1: Understand the Types of Smooth Muscles
Smooth muscles are classified into two main types based on their functional characteristics:
- **Single-unit smooth muscles**: These muscles work together as a single unit. The cells are connected by gap junctions, allowing them to contract in unison. An example of single-unit smooth muscle is found in the gastrointestinal tract.
- **Multi-unit smooth muscles**: These muscles consist of individual muscle fibers that operate independently. They do not have the same level of interconnection as single-unit smooth muscles.

### Step 2: Identify Examples of Multiunit Smooth Muscles
Multi-unit smooth muscles are typically found in structures where fine control is necessary. Common examples include:
- Muscles of the eye (such as the ciliary muscle)
- Muscles of the hair follicles
- The muscles of the jaw, specifically the masseter muscle

### Step 3: Analyze the Options
If given options, we would look for one that corresponds to the multi-unit smooth muscle examples mentioned above. In this case, the masseter muscle of the jaw is a prime example of multi-unit smooth muscle.

### Step 4: Conclusion
Based on the classification and examples discussed, the correct answer to the question is:
- **The masseter muscle of the jaw (Option C)**.