Which of the following correlations are incorrect?

Options

A. There are seven free cervical vertebrae and seven pairs of cervical spinal nerves
B. There are twelve free thoracic vertebrae and twelve pairs of thoracic spinal nerves
C. There are five free lumber vertebrae and five pairs of lumbar spinal nerves
D. There are five fused sacral vertebrae and five pairs of sacral spinal nerves

Answer

To determine which of the correlations regarding vertebrae and spinal nerves are incorrect, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Cervical Vertebrae and Spinal Nerves**:
- The cervical vertebrae are numbered from C1 to C7, which gives us a total of **7 cervical vertebrae**.
- However, there are **8 pairs of cervical spinal nerves** (C1 to C8). This means that the statement claiming there are 7 pairs of pre-cervical spinal nerves is **incorrect**.

2. **Analyzing Thoracic Vertebrae and Spinal Nerves**:
- There are **12 thoracic vertebrae** (T1 to T12).
- Correspondingly, there are **12 pairs of thoracic spinal nerves**. Therefore, this statement is **correct**.

3. **Examining Lumbar Vertebrae and Spinal Nerves**:
- There are **5 lumbar vertebrae** (L1 to L5).
- There are also **5 pairs of lumbar spinal nerves**. Thus, this statement is **correct**.

4. **Reviewing Sacral Vertebrae and Spinal Nerves**:
- There are **5 sacral vertebrae** (S1 to S5).
- There are **5 pairs of sacral spinal nerves**. Hence, this statement is also **correct**.

5. **Conclusion**:
- The only incorrect correlation identified is the one regarding the cervical vertebrae and spinal nerves, where it states there are 7 pairs of pre-cervical spinal nerves. The correct number is 8 pairs.

### Final Answer:
The incorrect correlation is: **There are 7 pairs of pre-cervical spinal nerves.**