Mastoid foramen: Definition from Answers.com

Bone: Mastoid foramen

Left temporal bone. Inner surface. (Mastoid foramen labeled at bottom left.)

Base of the skull. Upper surface. (Temporal bone is pink, and label for mastoid foramen is at left, second from the bottom.)
Latin	foramen mastoideum
Gray's	subject #34 141

The outer surface of the temporal bone is perforated by numerous foramina; one of these, of large size, situated near the posterior border, is termed the mastoid foramen

It transmits a vein to the transverse sinus and a small branch of the occipital artery to the dura mater.

Variations

The position and size of this foramen are very variable; it is not always present; sometimes it is situated in the occipital bone, or in the suture between the temporal and the occipital.

It transmits (1) an emissary vein connecting the sigmoid sinus with the posterior auricular vein and (2) a meningeal branch of the occipital artery

Additional images

Base of skull. Inferior surface.

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated.

Bones of head and neck: the cranium of the skull

Occipital

Squama	external (Inion/External occipital protuberance, Nuchal lines) · planes (Occipital, Nuchal) · internal (Cruciform eminence, Internal occipital protuberance, Sagittal sulcus, Internal occipital crest)

Lateral parts	Condyle (Condyloid fossa, Condylar canal) · Hypoglossal canal · jugular (Jugular process, Jugular tubercle)

Basilar part	Pharyngeal tubercle

Other	Foramen magnum

Parietal

Parietal eminence · Temporal line · Parietal foramen

Frontal

Squama	Frontal suture · Frontal eminence · external (Superciliary arches, Glabella) · foramina (Supraorbital, Cecum) · Zygomatic process · internal (Sagittal sulcus, Frontal crest)

Orbital part	Ethmoidal notch · Lacrimal fossa · Trochlear fovea · Frontal sinus · Frontonasal duct

Temporal

Squama	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 (Entrance)

Petrous part	Carotid canal · Facial canal (Hiatus) · Internal auditory meatus · Aqueduct of cochlea · 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 Superior nasal concha · Superior meatus · Middle nasal concha · Middle meatus

Labyrinth	Ethmoid sinus · ethmoidal foramina (Posterior, Anterior)

v • d • e Foramina of the skull (and canals, fissures, meati, and hiati)

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

Pterygopalatine fossa	to Nasal cavity: sphenopalatine foramen to Oral cavity: greater palatine canal/greater palatine foramen · lesser palatine canals/lesser palatine foramina to Infratemporal fossa: pterygomaxillary fissure to Nasopharynx: palatovaginal canal

Nasal cavity	to Oral cavity: incisive canals · incisive foramen

Other	external acoustic meatus · mandibular foramen · mental foramen · parietal foramen · petrotympanic fissure · semilunar hiatus

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