A Haversian canal with its surrounding lamellae
and osteocytes contitutes a cylindrical unit of bone called

Options

A. periosteum
B. endosteum
C. osteon
D. haversian

Answer

To solve the question regarding the cylindrical unit of bone formed by a Haversian canal, surrounding lamellae, and osteocytes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components**:
- Identify the components mentioned in the question: Haversian canal, lamellae, and osteocytes.
- The Haversian canal is a central channel that contains blood vessels and nerves.
- Lamellae are concentric rings of bone matrix surrounding the Haversian canal.
- Osteocytes are mature bone cells located within small spaces called lacunae, which are found between the lamellae.

2. **Identify the Structure**:
- The combination of the Haversian canal, the surrounding lamellae, and osteocytes forms a specific structural unit in bone.
- This structure is essential for the organization and function of bone tissue.

3. **Recall the Terminology**:
- The specific term for the cylindrical unit that includes the Haversian canal, lamellae, and osteocytes is known as an "osteon."
- An osteon is also referred to as a Haversian system, but since the question specifically asks for the term that includes all components, "osteon" is the correct answer.

4. **Evaluate the Options**:
- Review the provided options:
- **Option A**: Periosteum - Incorrect, as it is the outer layer of bone.
- **Option B**: Endosteum - Incorrect, as it is the inner layer lining the bone marrow cavity.
- **Option C**: Osteon - Correct, as it describes the unit formed by the Haversian canal, lamellae, and osteocytes.
- **Option D**: Haversian - Incorrect, as it does not fully describe the structure.

5. **Conclusion**:
- The correct answer to the question is **Option C: Osteon**.