Hypoglossal canal

Location of the Hypoglossal Canal

1. The hypoglossal canal is a component of the skull structure.
2. It is situated in the posterior fossa in the superior border of the petrous part of the temporal bone.
3. It is situated above the condylar region and adjacent to the condylar canal and the stylomastoid foramen.

1. It can be accessed after removing the jugular tubercle and applying retraction at the midportion of the cerebellar hemisphere.
2. It should be preserved if it is not affected by any lesions.
3. Structures such as the styloglossus, stylopharyngeal, and stylohyoid muscles are within this canal.

Title: Comprehensive Details on the Hypoglossal Canal

1. The internal orifice of the canal is posterolateral to that of the posterior condylar canal.
2. It is situated just posterolateral to the small condylar canal.
3. There is no communication between the condylar canal and this canal.
4. The supracondylar vein and a meningeal branch of the occipital artery are found in the posterior condylar canal.
5. It is a canal that is supplied by meningeal branches.

Title: "Detailed Information on the Hypoglossal Canal and Nerve"

1. This canal is crucial for the passage of the hypoglossal nerve.
2. The nerve is a purely somatic efferent nerve that supplies the musculature of the tongue.
3. The rootlets pass from the preolivary sulcus to the canal.
4. The nerve arises in front of the olive in the brainstem.
5. The canal provides a passage for the nerve from the brain to the tongue.
6. The nerve travels through the canal.
7. The canal is a pathway for the nerve's rootlets.
8. The distance between the upper surface of the nerve and the roof of the canal is typically measured in millimeters.
9. The nerve is responsible for the movement of the tongue.
10. The nerve is responsible for innervating the muscles of the tongue.
11. The nerve descends between the carotid artery and the jugular vein.
12. The nerve is located below the level of the digastric muscle.
13. One of the rootlets of the nerve loops around the origin of the pica.
14. The canal also contains the digastric nerve.
15. The nerve descends vertically in the neck after leaving the canal.
16. The nerve turns anteriorly across the lateral wall of the artery.
17. The nerve descends lateral to the vagus nerve after leaving the cranial cavity.
18. The nerve passes adjacent to the vagus nerve.
19. The right canal specifically houses the hypoglossal nerve.
20. The nerve reaches a level just below the angle of the mandible.
21. After traversing the canal, the two bundles of rootlets unite.
22. The somatic efferent fibers of the nerve emerge from the medulla oblongata.
23. The nerve also innervates all intrinsic muscles of the tongue.
24. The nerve's rootlets originate ventral to the inferior olive.
25. Dysfunction of the nerve can result in difficulty with speaking and swallowing.
26. The nerve innervates the hyoglossus, genioglossus, and styloglossus muscles.

Title: Anatomy and Relationships of the Hypoglossal Canal

1. The bone of the jugular tubercle is situated above the canal.
2. The canal is located below the jugular tubercle on the upper surface of the jugular process of the occipital bone.
3. The canal is a part of the jugular foramen.
4. The canal is connected to the jugular process of the occipital bone.
5. The inferior boundary of the jugular tubercle is the canal.
6. The canal is located medial to the jugular foramen.
7. The jugular tubercle is located just above and anterior to the canal.
8. The canal is involved in the venous drainage of the jugular bulb and adjacent part of the internal jugular vein.
9. The jugular process is a component of the wall of the jugular foramen, alongside the canal.
10. The canal is located deep to the jugular vein.
11. The canal is involved in the removal of all or part of the jugular tubercle.
12. The hypoglossal nerve joins the nerves exiting the jugular foramen on the medial side of the internal jugular vein.
13. The glossopharyngeal, vagus, and accessory nerves pass through a shallow furrow on the surface of the jugular tubercle, which is located above the canal.
14. The jugular tubercle forms the roof of the canal.
15. The bone of the jugular tubercle can be removed extradurally to gain additional exposure of the canal.
16. The canal is closely related to the jugular foramen.
17. The canal is located between the internal carotid artery and internal jugular vein.
18. The canal is a passageway for nerves below the jugular foramen.
19. The canal can be reached when accessing the jugular foramen, internal acoustic meatus, and inferior surface of the tentorium.
20. Tumors can also spread through the canal from the jugular foramen to the cerebellopontine angle.
21. The jugular tubercle serves a dual role, providing structure to both the canal and the jugular foramen.
22. The jugular tubercle is an oval prominence found above the canal.
23. The canal is exposed after resecting a segment of the internal jugular vein and jugular bulb.
24. The canal descends with the nerves exiting the jugular foramen.
25. The canal shares a relationship with the internal acoustic meatus and jugular foramen.
26. The canal opens laterally into the interval between the jugular foramen and carotid canal.
27. The canal is located laterally to a large irregular jugular foramen.
28. The canal is usually connected to the sigmoid sinus or jugular bulb.
29. It is located approximately mm below the jugular tubercle.

Title: Anatomical Positioning and Characteristics of the Hypoglossal Canal

1. The intracranial end of this canal is situated inferomedial to the petrosal part of the jugular foramen.
2. It is positioned medial to the lower half of the intracranial end of the jugular foramen.
3. This canal is located above the occipital condyle.
4. It is one of the structures present on the intracranial surface.
5. It can be found at the posterior border of the intracranial end.
6. A sinus that crosses the intracranial surface communicates with the veins within this canal.
7. It is located within the skull.
8. It is positioned above the condyle.
9. This canal is found at the lateral aspect of the intracranial end.
10. It serves as the intracranial entrance of a structure.
11. It is one of the structures, along with the jugular foramen and internal acoustic meatus, that penetrate the intracranial surface.
12. The extracranial end of the canal is positioned medially.
13. It is located inferior to Meckel's cave and the cochlea.
14. The canal is positioned several millimeters below the lower part of the petroclival fissure.
15. It is a small oval opening located at the intracranial end.

Title: "Anatomical Insights and Surgical Considerations of the Hypoglossal Canal"

1. The canal is situated above the condyle and is part of the skull near the occipital condyle and jugular tubercle.
2. It is located within the occipital bone.
3. The canal can be exposed by drilling the cancellous bone above the posterior third of the condyle.
4. It allows for the removal of the lateral part of the posterior two-thirds of the condyle.
5. It is approximately mm above the junction of the posterior and middle third of the occipital condyle.
6. The average distance between the posterior edge of the occipital condyle and the posterior border of the canal is within the range of mm to mm.
7. The crosshatched area indicates the portion of the occipital condyle that can be removed without exposing the nerve in the canal.
8. The supracondylar exposure can be directed above the occipital condyle to the canal.
9. The posterior condylar vein passes above both the occipital condyle and the canal.
10. The canal is overlaid by an oval jugular tubercle on the superior surface of the occipital condyle.
11. It extends laterally from the area above the posterior half of the occipital condyle.
12. Access to the canal does not require removing the posterior third of the occipital condyle.
13. The cancellous body of the condyle contributes to the formation of the canal.
14. The maximum extent that the upper portion of the occipital condyle can be drilled without exposing the canal is limited to its posterior third of the long axis.
15. The central third of the occipital condyle can be removed to expose the nerve.
16. The canal is reached by removing approximately the posterior third of the occipital condyle.
17. The cortical bone of the condyle and the articular surface can be preserved during the drilling process.
18. The canal is an important consideration when studying the relationship of the occipital condyle to the foramen magnum.
19. The clivus and adjacent part of the occipital and temporal bones can be removed to expose the canal.
20. The canal is located anterior and superior to each condyle and crosses the occipital bone.
21. It is on the extracranial surface behind and above each occipital condyle.
22. Understanding the relationship between the canal and the occipital condyle is essential for the condyle drilling technique.
23. The extent of occipital condyle removal is determined by examining the canal.
24. Further drilling of the occipital condyle can be done without entering the canal.
25. The canal can be accessed by drilling into the occipital condyle from a far lateral perspective.
26. The lateral clivus can also be exposed while drilling the occipital condyle.
27. Removing less than half of the occipital condyle does not pose a risk to spinal stability.

Title: Detailed Information on the Hypoglossal Canal and Its Surgical Approaches

1. The canal is located in the lower lateral part of the clivus.
2. It can be exposed in the far lateral approach to the skull.
3. The presence of the jugular tubercle can affect the far lateral approach to the canal.
4. Drilling in the supracondylar location above the canal accesses the jugular tubercle.
5. It is located in the supracondylar area.
6. The canal is an important aspect of the approach.
7. The lateral side of the clivus can be reached by going above and below the canal.
8. The supracondylar approach allows access to the medial side of the canal.
9. The canal is located in the region accessed by the supracondylar approach.
10. The supracondylar approach involves removing the jugular tubercle to expose the canal.
11. The canal is located in the supracondylar and paracondylar areas.
12. Accessing the lateral edge of the clivus can be achieved by drilling in a supracondylar location below the canal.
13. The occipital transcondylar variant is a pathway that passes through the canal.
14. The location of the canal can be inferred by identifying the supracondylar groove.
15. The transcondylar approach can be used to access the canal.
16. The transcondylar, retrocondylar, and supracondylar modifications of the canal are described in the chapter on the far lateral approach.
17. The canal is involved in the transcondylar extension of the far lateral approach.
18. The canal is a structure that can be exposed during the transcondylar approach.
19. The transcondylar approach also provides access to the jugular tubercle along with the canal.
20. The canal is located in the lateral medullary segments.
21. The occipital transcondylar variant allows access to the lower clivus and the area in front of the medulla.
22. Drilling can be done in a supracondylar location below the canal.
23. The canal is directed from medial to lateral.
24. The canal serves as a route for the occipital transcondylar variant to reach its destination.
25. The large arrow indicates the direction of the transcondylar approach.
26. The occipital transcondylar variant is directed above the atlantooccipital joint.

Title: Comprehensive Overview of the Hypoglossal Canal and its Associations

1. The dura in the posterior fossa is supplied by the meningeal branches of the occipital artery, one of which enters the skull through this canal.
2. The occipital artery is found in this canal.
3. The medullary branch of the vertebral artery can be found in this canal.
4. The posterior ascending artery is present in this canal.
5. The ascending branch of this canal anastomoses with the branches of the dorsal meningeal artery.
6. The petrous carotid artery is located near this canal.
7. A collateral artery passes rostral to the anterior arch of the atlas in this canal.
8. The left vertebral artery is also present in this canal.
9. The ascending pharyngeal artery ascends medial to the carotid artery and gives branches that pass through this canal.
10. This canal serves as an entry point for a branch from the ascending pharyngeal artery into the posterior cranial fossa.
11. The ascending pharyngeal artery, which is connected to this canal, gives rise to the inferior tympanic artery.
12. It is a passageway through which meningeal branches of the ascending pharyngeal artery pass.
13. It is located behind the vertebral artery.
14. It is a route through which occasional small branches of the ascending pharyngeal artery enter the skull.
15. It contains the key meningeal artery.
16. The dorsal meningeal and tentorial arteries, originating from the meningohypophysial trunk, enter the skull through this canal.
17. In most cases, the rootlets pass posterior to the vertebral artery.
18. It serves as an entrance for some branches of the ascending pharyngeal artery into the skull.
19. It runs downward between the carotid artery and the jugular vein.
20. It contains a meningeal branch of the ascending pharyngeal artery.
21. Carotid and vertebral arteries can be found near this canal.
22. The arcade above the odontoid process is formed by the anterior meningeal arteries.
23. Occasionally, the rootlets can pass anterior to the vertebral artery, although this is rare.
24. The branch passing through this canal divides into an ascending branch.
25. It contains precentral and postcentral arteries that supply the typical cervical vertebral body.
26. During surgery, the carotid arteries need to be avoided laterally as well as the canals inferiorly.
27. This ascending branch passes upward in the dura covering the clivus.

Title: Comprehensive Information about the Hypoglossal Canal

1. It is located in the lateral view of the skull.
2. It is one of the foramina of the skull, located at the level of the foramen magnum.
3. It exists as an opening in the skull and is one of the boundaries of the exposed area.
4. It plays a crucial role in the movement of the tongue.
5. It is part of the anatomical features of the occipital bone and is found on the squamous part of the same bone.
6. The apical arcade of the odontoid process is located within it.
7. It serves as a landmark to identify the jugular process during dissection.
8. It contains meningeal branches that supply the associated dura mater and adjoining bone.
9. It is responsible for the passage of nerves in the enlargement view and is not located in the orbit.
10. It is situated at the base of the skull and just superior to the scaphoid fossa at the root of the medial plate of the pterygoid process.
11. It provides access to the front of the medulla and the pontomedullary junction.
12. It is traversed by the posterior condylar vein and is located in the floor of the middle fossa.
13. It is found on both sides of the skull and is located close to the foramen magnum.
14. It contains meningeal branches that pass through the foramen lacerum to distribute to the dura lining the middle fossa.
15. It is essential for the proper functioning of the tongue and other associated muscles.
16. It is a passageway through which the rootlets enter and is a part of the backsection with vertebral veins, occipital and sigmoid sinuses.
17. It is directed from posterior to anterior and passes forward from near the anterior margin of the foramen lacerum.
18. It is involved in motor control of the tongue muscles and is directed anteriorly and laterally.
19. It marks the transition from cancellous to cortical bone and is a landmark that is examined during the extradural dissection stage.
20. It is a pathway for transmitting an emissary vein when present and is located extracranially.
21. It is a key landmark for inferring the location before starting the inferior clivectomy.
22. In some cases, it is divided by a bony septum and its development is a significant marker for age determination during the subadult years.
23. It is where the glossopharyngeal, vagus, and accessory nerves join and also receives blood from the verse medullary veins.
24. It is an additional feature for reliable age determination throughout the subadult years.
25. It is measured in millimeters and is surrounded by various muscles, such as the sternocleidomastoid and splenius capitis.
26. At each level, it contains radicular prelaminar and meningeal branches, and abnormalities or damage to it can lead to various neurological disorders.
27. It completes development by year and its completion at a certain age is a valuable tool for age estimation.
28. It also has a descending branch and follows an anterolateral trajectory.
29. It is used to design a customized craniectomy and is a concern for avoidance during surgery with intraoperative imaging guidance.
30. The nerve then continues its path towards the tongue and these bundles perforate the dura mater separately.

Title: "Understanding the Hypoglossal Canal and Its Functions"

1. The jugular foramen or hypoglossal canal serves as a route for the meningeal branches to supply the surrounding dura of the posterior cranial fossa.
2. It is located at the angle and the intracranial aspect of the cranial nerves entering the jugular foramen.
3. This canal is situated in the posterior cranial fossa of the neck.
4. It is a part of the cranial nerves.
5. Ascending meningeal branches of the upper cervical nerves pass through this canal to reach the dura in the posterior cranial fossa.
6. It also supplies much of the floor of the anterior wall of the posterior cranial fossa, possibly through pathways other than that of the hypoglossal nerve.
7. The stylomastoid foramen, a passage in the posterior cranial fossa, allows the facial nerve to exit the skull.
8. It is part of the pathway for the IXth through XIIth cranial nerves.
9. It is one of the cranial nerve canals.
10. It is one of the entry points for meningeal branches from cervical nerves into the posterior cranial fossa.
11. The internal acoustic meatus, located in the posterior cranial fossa, contains the facial nerve (cranial nerve VII) and the vestibulocochlear nerve (cranial nerve VIII).
12. Meningeal branches from the cervical nerves enter the posterior cranial fossa via this canal, among other openings like the foramen magnum and jugular foramen.
13. Second and third cervical nerves enter the posterior cranial fossa through this canal to provide sensory information to the dura in that region.
14. It can serve as a pathway for glomus jugulare tumors to extend from the jugular foramen to the posterior fossa.
15. It allows the first and second cervical nerves to enter the posterior cranial fossa, providing additional innervation to the dura.
16. It is directed forward and laterally from the posterior cranial fossa.
17. Schwannomas of the cranial nerves can cause imaging findings of tongue atrophy in this canal.
18. It is a passageway for cranial nerve XII.
19. It can widen due to schwannomas of the cranial nerves.
20. Posterior fossa tumors can impact this canal.
21. It is a point of reference in cranial depth.

Title: "Comprehensive Understanding of the Hypoglossal Canal's Venous Structure and Function"

1. The canal is linked to its own veins.
2. It houses the venous plexus, contributing to the drainage system.
3. The hypoglossal nerve and venous plexus are observable within the canal, with the latter surrounding the former.
4. The anterior spinal plexus is situated within the canal.
5. The canal's venous plexus links the sigmoid sinus and the internal jugular vein.
6. Drainage from the canal to the suboccipital vertebral plexus can occur via a vein.
7. The venous plexus is revealed by drilling the cortical bone.
8. The canal houses the internal jugular vein, which receives drainage from the inferior petrosal sinus and the venous plexus.
9. The inferior petroclival vein, vertebral venous plexus, and posterior condylar emissary vein are associated with the canal.
10. Both the dura and venous plexus should be respected when working near the canal.
11. The canal wall appears dark blue due to the presence of a venous plexus.
12. The canal links the basilar venous plexus with the marginal sinus.
13. The jugular bulb and internal jugular vein drainage is contributed to by the sigmoid and inferior petrosal sinuses, vertebral venous plexus, and posterior condylar emissary vein.
14. Occasionally, the canal drains to the suboccipital vertebral plexus via a vein.
15. The inferior petrosal sinus forms a plexiform confluens with the canal's venous plexus.
16. An emissary vein from the basilar plexus is transmitted by the canal.
17. Meningiomas can develop from arachnoid granulations in the jugular bulb or venous sinuses and potentially spread through the canal.
18. The venous plexus may sometimes consist of a single vein.
19. The canal is also linked to the basilar plexus.
20. Several venous emissary foramina are located within the canal.
21. The canal contains veins that link to the marginal sinuses.

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