Sacral canal contains all EXCEPT
**Core Concept**
The sacral canal, also known as the dural sac, is a continuation of the spinal canal that traverses the sacrum and contains the cauda equina, a bundle of spinal nerves that arise from the lower end of the spinal cord.
**Why the Correct Answer is Right**
The sacral canal is a narrow, cylindrical space that houses the cauda equina, which includes the spinal nerves that emerge from the lower end of the spinal cord. These nerves, including the S1-S5 nerve roots, are responsible for controlling various functions such as bladder and bowel control, as well as sensation in the lower extremities. The sacral canal is surrounded by the dura mater, a thick, fibrous membrane that protects the spinal cord and its contents.
**Why Each Wrong Option is Incorrect**
**Option A:** The film terminale is actually a small, fibrous structure that connects the end of the spinal cord to the coccyx, and is not contained within the sacral canal.
**Option B:** The cauda equina is indeed contained within the sacral canal, making this option incorrect.
**Option C:** The meninges, including the dura mater, arachnoid mater, and pia mater, surround the spinal cord and its contents, including the cauda equina, within the sacral canal.
**Clinical Pearl / High-Yield Fact**
The sacral canal is an important anatomical structure that is relevant to various medical conditions, including cauda equina syndrome, a condition that occurs when the nerves in the cauda equina are compressed or irritated, leading to symptoms such as numbness, weakness, and bladder and bowel dysfunction.
**Correct Answer: A. The film terminale is actually a small, fibrous structure that connects the end of the spinal cord to the coccyx, and is not contained within the sacral canal.**