Hypoglossal canal
- Synonyms
- Also referred to as the canal of the twelfth cranial nerve.
- Detailed Anatomy and Boundaries
- The hypoglossal canal is a bilateral structure located at the base of the skull. - It is situated along the lateral margin of the anterior half of the foramen magnum. - Anatomically, the canal is approximately 5 mm above the junction of the posterior and middle third of the occipital condyle. - The canal's position is significant, as it lies near critical structures at the skull base.
- Neighbouring Structures
- The hypoglossal canal is close to the jugular foramen and the nerves that pass below it.
- The canal is located medial to the jugular foramen.
- It is also near the occipital condyle and the foramen magnum, which are key landmarks in skull base anatomy.
- Contents of the Canal
- The hypoglossal nerve (Cranial Nerve XII) passes through this canal.
- The rootlets pass from the preolivary sulcus to the canal.
- The nerve is responsible for motor control of the tongue muscles. - Structures such as the styloglossus, stylopharyngeal, and stylohyoid muscles are within this canal.
- Clinical Significance
- The hypoglossal canal and nerve are crucial considerations in surgeries involving the skull base, particularly in the region of the foramen magnum. - Lesions or pathologies affecting the hypoglossal canal can lead to hypoglossal nerve palsy, characterized by tongue weakness or paralysis. - The nerve's proximity to the jugular foramen makes it susceptible to involvement in jugular foramen syndromes. - Understanding the canal's anatomy is vital for procedures like suboccipital craniectomies, where inadvertent damage to the hypoglossal nerve can have significant functional implications.
- Surgical Considerations
- Access to the hypoglossal canal requires careful navigation to avoid damaging the hypoglossal nerve. - It can be exposed extradurally for increased access to the front of the brainstem, especially in complex skull base surgeries. - Surgical approaches must account for the canal's proximity to other cranial nerves and vascular structures.