Study the following and identify the incorrect statements
(i) Muscles of iris and ciliary body are smooth muscles of mesodermal origin
(ii) Slow and sustained involuntary contraction of smooth muscles are called spasms
(iii) Quiescent mononucleate myogenic cells of skeletal muscles are called pericytes
(iv) Skeletal muscles fibre is multinucleate and is a syncytium

Options

A. I, ii
B. ii, iv
C. iii, iv
D. I, iii.

Answer

To identify the incorrect statements from the given options, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement (i): Muscles of iris and ciliary body are smooth muscles of mesodermal origin.**
- **Analysis:** The muscles of the iris and ciliary body are indeed smooth muscles, but they originate from neuroectoderm, not mesoderm. Therefore, this statement is incorrect.

2. **Statement (ii): Slow and sustained involuntary contraction of smooth muscles are called spasms.**
- **Analysis:** This statement is also incorrect. Spasms refer to short-lived, involuntary contractions of muscles, not sustained contractions. Sustained contractions are typically referred to as "tonic contractions" or "tension."

3. **Statement (iii): Quiescent mononucleate myogenic cells of skeletal muscles are called pericytes.**
- **Analysis:** This statement is correct. Pericytes are indeed quiescent mononucleate cells associated with blood vessels and can differentiate into myogenic cells.

4. **Statement (iv): Skeletal muscle fiber is multinucleate and is a syncytium.**
- **Analysis:** This statement is also correct. Skeletal muscle fibers are multinucleated and are formed by the fusion of myoblasts, making them a syncytium.

### Conclusion:
The incorrect statements are:
- (i) Muscles of iris and ciliary body are smooth muscles of mesodermal origin.
- (ii) Slow and sustained involuntary contraction of smooth muscles are called spasms.

Thus, the answer is that statements (i) and (ii) are incorrect.

### Final Answer:
The incorrect statements are (i) and (ii).

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