Hypoglossal canal

Hypoglossal canal
Occipital bone. Inner surface.
Details
Identifiers
Latin	canalis nervi hypoglossi
Dorlands /Elsevier	c_04/12208711
TA	A02.1.04.016
FMA	75370
*Anatomical terms of bone* [edit on Wikidata]

The hypoglossal canal is a foramen in the occipital bone of the skull. It is hidden medially and superiorly to each occipital condyle. The hypoglossal nerve traverses the canal.

Structure

It transmits the hypoglossal nerve from its point of entry near the medulla oblongata to its exit from the base of the skull near the jugular foramen. It lies in the epiphyseal junction between the basiocciput and the jugular process of the occipital bone.

Function

The hypoglossal canal has recently been used to try to determine the antiquity of human speech. Researchers have found that hominids who lived as long as 2 million years ago had the same size canal as that of modern day chimpanzees; some scientists thus assume they were incapable of speech. However, archaic H. sapiens 400,000 years ago had the same size canal as that of modern humans, meaning they could have been capable of speech. Some Neanderthals also had the same size hypoglossal canal as archaic H. sapiens. However recent studies involving several primate species have failed to find conclusive evidence of a relationship between its size and speech.^[1]

Clinical significance

The hypoglossal canal is formed during the embryological stage of development in mammals, sometimes leading to the presence of more than two canals as the occipital bone is formed.^[2] Study of this area aids in the diagnosis of a variety of tumors found at the base of the skull, including: large glomus jugulare neoplasms, myelomas, and the occasional meningioma.^[3] Studies of the hypoglossal canal revolve around the development of safe drilling techniques to conduct surgery on that area of the brain.^[4]

Additional images

Hypoglossal canal
Base of the skull. Upper surface.
Median sagittal section through the occipital bone and first three cervical vertebræ.

References

↑ 02.24.99 - Graduate Students Discredit Theory that Neanderthals Could Talk
↑ Takahashi,, H.; Tanaka, H.; Fujita, N.; Tomiyama, N. (2014). "Bilateral persistent hypoglossal arteries: MRI findings". British Journal of Radiology 85 (1010): e46-48. doi:10.1259/bjr/21939976.
↑ Voyvodic, F; Whyte, A.; Slavotinek, J. (1995). "The hypoglossal canal: normal MR enhancement pattern". American Journal of Neuroradiology 16: 1707–1710.
↑ Katsuta,, T.; Matsushima, T.; Wen, H.T.; Rhoton, A.L. (2000). "Trajectory of the hypoglossal nerve in the hypoglossal canal: significance for the transcondylar approach". Neurologial Medico Chirurgica 40: 206–210. doi:10.2176/nmc.40.206.

External links

Anatomy figure: 22:5b-15 at Human Anatomy Online, SUNY Downstate Medical Center
cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (XII)
Anatomy diagram: 34257.000-1 at Roche Lexicon - illustrated navigator, Elsevier
Anatomy diagram: 34257.000-2 at Roche Lexicon - illustrated navigator, Elsevier
Image at uwo.ca

The neurocranium of the skull

Occipital

Squamous part	external Inion/External occipital protuberance External occipital crest Nuchal lines planes Occipital Nuchal internal Cruciform eminence Internal occipital protuberance Sagittal sulcus Internal occipital crest Groove for transverse sinus

Lateral parts	Condyle Condyloid fossa Condylar canal Hypoglossal canal jugular Jugular process Jugular tubercle

Basilar part	Pharyngeal tubercle Clivus

Other	Foramen magnum Basion Opisthion

Parietal

Frontal

Squamous part	Frontal suture Frontal eminence external Superciliary arches Glabella foramina Supraorbital Cecum Zygomatic process internal Sagittal sulcus Frontal crest

Orbital part	Ethmoidal notch Fossa for lacrimal gland Trochlear fovea Frontal sinus Frontonasal duct

Temporal

Squamous part	Articular tubercle Suprameatal triangle Mandibular fossa Petrotympanic fissure Zygomatic process

Mastoid part	Mastoid foramen Mastoid process (Mastoid cells) Mastoid notch Occipital groove Sigmoid sulcus Mastoid antrum (Aditus)

Petrous part	Carotid canal Facial canal Hiatus Internal auditory meatus Cochlear aqueduct Stylomastoid foramen fossae Subarcuate fossa Jugular fossa canaliculi Inferior tympanic Mastoid Styloid process Petrosquamous suture (note: ossicles in petrous part, but not part of temporal bone)

Tympanic part	Suprameatal spine

Sphenoid

Surfaces	Superior surface: Sella turcica Dorsum sellae Tuberculum sellae Hypophysial fossa Posterior clinoid processes Ethmoidal spine Chiasmatic groove Middle clinoid process Petrosal process Clivus Lateral surface: Carotid groove Sphenoidal lingula Anterior surface: Sphenoidal sinuses

Great wings	foramina Rotundum Ovale Vesalii Spinosum Spine Infratemporal crest Sulcus for auditory tube

Small wings	Superior orbital fissure Anterior clinoid process Optic canal

Pterygoid processes	fossae Pterygoid Scaphoid pterygoid plates Lateral Medial Pterygoid canal Hamulus

Other	Body Sphenoidal conchae

Ethmoid

Plates	Cribriform plate Crista galli Olfactory foramina Perpendicular plate

Surfaces	Lateral surface Orbital lamina Uncinate process Medial surface Supreme nasal concha Superior nasal concha Superior meatus Middle nasal concha Middle meatus

Labyrinth	Ethmoid sinus ethmoidal foramina Posterior Anterior

Foramina of the skull (and canals, fissures, meatus, and hiatus)

Anterior cranial fossa

to Orbit:	ethmoidal foramina anterior posterior

to Nasal cavity:	olfactory foramina (CN-I) foramen cecum

Middle cranial fossa

to Orbit:	optic canal (CN-II) superior orbital fissure (CN-III,IV,V1,VI)

to Pterygopalatine fossa:	foramen rotundum (CN-V2) pterygoid canal

to Infratemporal fossa:	foramen ovale (CN-V3) foramen spinosum/carotid canal

other:	foramen lacerum hiatus for greater petrosal nerve hiatus for lesser petrosal nerve sphenoidal emissary foramen

Posterior cranial fossa

internal auditory meatus/facial canal/stylomastoid foramen (CN-VII,VIII)
jugular foramen (CN-IX,X,XI)
foramen magnum (CN-XI)
hypoglossal canal (CN-XII)
condylar canal
mastoid foramen

Orbit

to Nasal cavity:	nasolacrimal canal

to face:	supraorbital notch foramen infraorbital foramen groove zygomatic foramen -facial -temporal

to Pterygopalatine fossa:	inferior orbital fissure

other:	Inferior orbital fissure Fossa for lacrimal sac

Pterygopalatine fossa

to Nasal cavity:	sphenopalatine foramen

to Oral cavity:	greater palatine canal foramen lesser palatine canals foramina

to Infratemporal fossa:	pterygomaxillary fissure

to Nasopharynx:	palatovaginal canal

to oral cavity:	incisive canals incisive foramen

to nasal cavity:	Foramen vomerinum Meatus vomerinus Fissura vomerina Hiatus vomerinus

Other

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