Temporal bone

Temporal bone: Anatomy & FunctionKey facts about the anatomy of the temporal bone.
~ 3 min

In this pdf-note, we will learn about the structure of the temporal bone (os temporale). It contains the organs of hearing and balance, and many blood vessels and nerves pass through it.

Temporal bone (os temporale)
Temporal bone (os temporale)

There are several parts of the temporal bone:

  • Petrous part (pars petrosa)

Petrous part (pars petrosa)
Petrous part (pars petrosa)
  • Tympanic part (pars tympanica)

    Tympanic part (pars tympanica)
    Tympanic part (pars tympanica)
  • Squamous part (pars squamosa)

    Squamous part (pars squamosa)
    Squamous part (pars squamosa)
  • Mastoid process (processus mastoideus)

    Mastoid process (processus mastoideus)
    Mastoid process (processus mastoideus)

    The petrous part of the temporal bone has an apex (apex partis petrosae).

    Apex of the petrous part (apex partis petrosae)
    Apex of the petrous part (apex partis petrosae)

    It also has three surfaces:

  • Anterior surface (facies anterior)

    Anterior surface (facies anterior)
    Anterior surface (facies anterior)
  • Posterior surface (facies posterior)

    Posterior surface (facies posterior)
    Posterior surface (facies posterior)
  • Inferior surface (facies inferior)

    Inferior surface (facies inferior)
    Inferior surface (facies inferior)

    And three margins:

  • Superior margin (margo superior)

    Superior margin (margo superior)
    Superior margin (margo superior)
  • Anterior margin (margo anterior)

  • Posterior margin (margo posterior)

    Posterior margin (margo posterior)
    Posterior margin (margo posterior)

    On the anterior surface of the petrous part, near the apex, there is a trigeminal impression (impressio trigeminalis), which is formed due to the adherence of the trigeminal ganglion.

    Trigeminal impression (impressio trigeminalis)
    Trigeminal impression (impressio trigeminalis)

    There are two small foramina in this impression:

  • Hiatus for the greater petrosal nerve (hiatus canalis nervi petrosi majoris). It continues into the groove for the greater petrosal nerve (sulcus nervi petrosi majoris).

    Hiatus for the greater petrosal nerve (hiatus canalis nervi petrosi majoris)
    Hiatus for the greater petrosal nerve (hiatus canalis nervi petrosi majoris)
    Groove for the greater petrosal nerve (sulcus nervi petrosi majoris)
    Groove for the greater petrosal nerve (sulcus nervi petrosi majoris)
  • Hiatus for the lesser petrosal nerve (hiatus canalis nervi petrosi minoris). It continues into the groove for the lesser petrosal nerve (sulcus nervi petrosi minoris).

    Groove for the lesser petrosal nerve (sulcus nervi petrosi minoris)
    Groove for the lesser petrosal nerve (sulcus nervi petrosi minoris)

    Also, on the anterior surface of the petrous part, there is a so-called arcuate eminence (eminentia arcuata), under which the superior semicircular canal of the bony labyrinth is located inside the petrous part.

    Arcuate eminence (eminentia arcuata)
    Arcuate eminence (eminentia arcuata)

    Tegmen tympani (tegmen tympani) is located laterally.

    Tegmen tympani (tegmen tympani)
    Tegmen tympani (tegmen tympani)

    The groove for the superior petrosal sinus (sulcus sinus petrosi superioris) passes along the superior margin of the petrous part.

    Groove for the superior petrosal sinus (sulcus sinus petrosi superioris)
    Groove for the superior petrosal sinus (sulcus sinus petrosi superioris)

    On the posterior surface of the petrous part, there is an internal acoustic opening (porus acusticus internus), which continues into the internal acoustic meatus (meatus acusticus internus). This is where the facial, vestibular, and cochlear nerves, as well as labyrinthine arteries and veins pass.

    Internal acoustic opening (porus acusticus internus)
    Internal acoustic opening (porus acusticus internus)
    Internal acoustic meatus (meatus acusticus internus)
    Internal acoustic meatus (meatus acusticus internus)

    The subarcuate fossa (fossa subarcuata) is located laterally to the internal acoustic meatus.

    Subarcuate fossa (fossa subarcuata)
    Subarcuate fossa (fossa subarcuata)

    Under this fossa, the external aperture of the vestibular aqueduct (apertura externa aqueductus vestibuli) is located.

    The groove for the inferior petrosal sinus (sulcus sinus petrosi inferioris) passes along the posterior margin of the petrous part.

    External aperture of the vestibular aqueduct (sulcus sinus petrosi inferioris)
    External aperture of the vestibular aqueduct (sulcus sinus petrosi inferioris)

    Also, on this margin there is an external opening of the cochlear canaliculus (aperture externa canaliculi cochleae).

    External opening of the cochlear canaliculus (apertura externa canaliculi cochleae)
    External opening of the cochlear canaliculus (apertura externa canaliculi cochleae)

    There are many structures on the inferior surface of the petrous part.

    The jugular fossa (fossa jugularis) is located near the posterior part.

    Jugular fossa (fossa jugularis)
    Jugular fossa (fossa jugularis)

    In this fossa, there is an opening of the mastoid canaliculus (canaliculus mastoideus), in which the auricular branch of the vagus nerve passes.

    Mastoid canaliculus (canaliculus mastoideus)
    Mastoid canaliculus (canaliculus mastoideus)

    On the posterior side, the fossa is delimited by a jugular notch (incisura jugularis).

    Jugular notch (incisura jugularis)
    Jugular notch (incisura jugularis)

    Together with the jugular notch of the occipital bone, they form the jugular foramen (foramen jugulare), through which the internal jugular vein, as well as the glossopharyngeal, vagus, and accessory nerves pass.

    Jugular foramen (foramen jugulare)
    Jugular foramen (foramen jugulare)

    Intrajugular process (processus intrajugularis) separates the jugular foramen into two segments.

    Intrajugular process (processus intrajugularis)
    Intrajugular process (processus intrajugularis)

    Anteriorly to the jugular fossa, there is a small petrosal fossula (fossula petrosa).

    Petrosal fossula (fossula petrosa)
    Petrosal fossula (fossula petrosa)

    The inferior aperture of the tympanic canaliculus (apertura inferior canaliculi tympanici) is located at its bottom. The tympanic nerve and the inferior tympanic artery pass through this canaliculus.

    The external opening of the carotid canal (apertura externa canalis carotici) is located anteriorly to the petrosal fossula. And the internal opening of this canal (apertura interna canalis carotici) opens at the apex of the petrous part.

    External opening of the carotid canal (apertura externa canalis carotici)
    External opening of the carotid canal (apertura externa canalis carotici)
    Internal opening of this canal (apertura externa canalis carotici)
    Internal opening of this canal (apertura externa canalis carotici)

    Inside the carotid canal, there are two small foramina of the caroticotympanic canaliculi (canaliculi carotico-tympanici), where the caroticotympanic nerves pass.

    Laterally to the jugular fossa, a long styloid process (processus styloideus) arises from the temporal bone. The stylohyoid and stylopharyngeus muscles arise from this process.

    Styloid process (processus styloideus)
    Styloid process (processus styloideus)

    Between this process and the mastoid process, there is the stylomastoid foramen (foramen stylomastoideum), which is the foramen of the facial canal. The facial nerve proper and the stylomastoid vessels pass in this canal.

    Stylomastoid foramen (foramen stylomastoideum)
    Stylomastoid foramen (foramen stylomastoideum)

    The anterior margin of the pyramid is separated from the squamous part by the petrosquamous fissure (fissura petrosquamosa).

    Petrosquamous fissure (fissura petrosquamosa)
    Petrosquamous fissure (fissura petrosquamosa)

    Next to this fissure, there is the opening of the musculotubal canal (canalis musculotubarius), which leads to the tympanic cavity. This canal is separated into two semicanals:

  • Canal for the auditory tube (semicanalis tubae auditivae)

  • Canal for the tensor tympani muscle (semicanalis musculi tensoris tympani)

    Musculotubal canal (canalis musculotubarius)
    Musculotubal canal (canalis musculotubarius)
    Canal for the auditory tube (semicanalis tubae auditivae)
    Canal for the auditory tube (semicanalis tubae auditivae)
    Canal for the tensor tympani muscle (semicanalis musculi tensoris tympani)
    Canal for the tensor tympani muscle (semicanalis musculi tensoris tympani)

    Interiorly, the mastoid process consists of mastoid cells (cellulae mastoideae).

    Mastoid cells (cellulae mastoideae)
    Mastoid cells (cellulae mastoideae)

    The largest of them is called the mastoid antrum (antrum mastoideum) and communicates with the tympanic cavity.

    Mastoid antrum (antrum mastoideum)
    Mastoid antrum (antrum mastoideum)

    Superiorly, the mastoid process is separated from the squamous part of the temporal bone by the parietal notch (incisura parietalis).

    Parietal notch (incisura parietalis)
    Parietal notch (incisura parietalis)

    And on the medial side, this process is delimited by the mastoid notch (incisura mastoidea).

    Mastoid notch (incisura mastoidea)
    Mastoid notch (incisura mastoidea)

    Medially to this notch, there is the groove of the occipital artery (sulcus arteriae occipitalis).

    Groove of the occipital artery (sulcus arteriae occipitalis)
    Groove of the occipital artery (sulcus arteriae occipitalis)

    Sometimes there is a mastoid foramen (foramen mastoideum) in the mastoid process, in which the mastoid branches of the occipital artery and the mastoid emissary vein pass. This foramen, however, is not always the case.

    Mastoid foramen (foramen mastoideum)
    Mastoid foramen (foramen mastoideum)

    Near the mastoid angle, there is a groove for the sigmoid sinus (sulcus sinus sigmoidei).

    Groove for the sigmoid sinus (sulcus sinus sigmoidei)
    Groove for the sigmoid sinus (sulcus sinus sigmoidei)

    In the superior segment of the tympanic part, there is a large external acoustic opening (porus acusticus externus).

    External acoustic opening (porus acusticus externus)
    External acoustic opening (porus acusticus externus)

    This opening continues into the external acoustic meatus (meatus acusticus externus). From the inside, the passage is limited by the tympanic membrane, which separates it from the tympanic cavity.

    External acoustic meatus (meatus acusticus externus)
    External acoustic meatus (meatus acusticus externus)

    Tympanosquamous fissure (fissura tympanosquamosa) is located anteriorly from the external acoustic opening.

    Tympanosquamous fissure (fissura tympanosquamosa)
    Tympanosquamous fissure (fissura tympanosquamosa)

    The small lamina tympani (lamina tympani) divides this fissure into two others:

  • Petrosquamous fissure (fissura petrosquamosa)

  • Petrotympanic fissure / fissura Glaseri (fissura petro– tympanica), where the nerve called chorda tympani passes

    Petrosquamous fissure (fissura petrosquamosa)
    Petrosquamous fissure (fissura petrosquamosa)
    Petrotympanic fissure / fissura Glaseri (fissura petrotympanica)
    Petrotympanic fissure / fissura Glaseri (fissura petrotympanica)

    The tympanic part is separated from the mastoid process by the tympanomastoid fissure (fissura tympanomastoidea), where the auricular branch of the vagus nerve passes.

    Tympanomastoid fissure (fissura tympanomastoidea)
    Tympanomastoid fissure (fissura tympanomastoidea)

    The squamous part of the temporal bone has two edges:

  • Parietal margin (margo parietalis)

    Parietal margin (margo parietalis)
    Parietal margin (margo parietalis)
  • Sphenoidal margin (margo sphenoidalis)

    Sphenoidal margin (margo sphenoidalis)
    Sphenoidal margin (margo sphenoidalis)

    The squamous part also has two surfaces:

  • External/temporal surface (facies temporalis), which participates in the formation of the temporal fossa. It

    External/temporal surface (facies temporalis)
    External/temporal surface (facies temporalis)

    contains the groove for the middle temporal artery (sulcus arteriae temporalis mediae).

    Groove for the middle temporal artery (sulcus arteriae temporalis mediae)
    Groove for the middle temporal artery (sulcus arteriae temporalis mediae)
  • Internal/cerebral surface (facies cerebralis), which has traces of the adherence of cerebral and vascular structures.

    Internal/cerebral surface (facies cerebralis)
    Internal/cerebral surface (facies cerebralis)

    These traces are the impressions of the cerebral gyri (impressiones digitatae, juga cerebralia) and the arterial grooves (sulci arteriosi).

    The squamous part is separated from the petrous part by the supramastoid crest (crista supramastoidea).

    Supramastoid crest (crista supramastoidea)
    Supramastoid crest (crista supramastoidea)

    The zygomatic process (processus zygomaticus) arises from the squamous part anteriorly

    Zygomatic process (processus zygomaticus)
    Zygomatic process (processus zygomaticus)

    It connects to the zygomatic bone, forming the zygomatic arch (arcus zygomaticus).

    Zygomatic arch (arcus zygomaticus)
    Zygomatic arch (arcus zygomaticus)

    At the base of the zygomatic process, there is a large mandibular fossa (fossa mandibularis), which serves as the articular surface for the mandible.

    Mandibular fossa (fossa mandibularis)
    Mandibular fossa (fossa mandibularis)

    Anteriorly, this fossa is delimited by the articular tubercle (tuberculum articulare).

    Articular tubercle (tuberculum articulare)
    Articular tubercle (tuberculum articulare)

    The tympanic cavity (cavitas tympani) is located inside the temporal bone. It contains the organs of hearing and balance.

    The tympanic cavity has the following walls:

  • Superior wall is the tegmen tympani

  • Inferior wall is the jugular fossa

  • Posterior wall is the mastoid process

  • Anterior wall is also the wall of the carotid canal.

  • Medial wall is also the wall of the bony labyrinth

  • Lateral wall is the tympanic membrane

Tympanic cavity (cavitas tympani)
Tympanic cavity (cavitas tympani)
Dictionary

Temporal bone

Temporal bone
os temporale
Petrous part
pars petrosa
Tympanic part
pars tympanica
Squamous part
pars squamosa
Mastoid process
processus mastoideus
Apex of the petrous part
apex partis petrosae
Anterior surface
facies anterior
Posterior surface
facies posterior
Inferior surface
facies inferior
Superior margin
margo superior
Anterior margin
margo anterior
Posterior margin
margo posterior
Trigeminal impression
impressio trigeminalis
Hiatus for the greater petrosal nerve
hiatus canalis nervi petrosi majoris
Groove for the greater petrosal nerve
sulcus nervi petrosi majoris
Hiatus for the lesser petrosal nerve
hiatus canalis nervi petrosi minoris
Groove for the lesser petrosal nerve
sulcus nervi petrosi minoris
Arcuate eminence
eminentia arcuata
Tegmen tympani
tegmen tympani
Groove for the superior petrosal sinus
sulcus sinus petrosi superioris
Internal acoustic opening
porus acusticus internus
Internal acoustic meatus
meatus acusticus internus
Subarcuate fossa
fossa subarcuata
External aperture of the vestibular aqueduct
apertura externa aqueductus vestibuli
Groove forhe inferior petrosal sinus
sulcus sinus petrosi inferioris
External aperture of the cochlear canaliculus
apertura externa canaliculi cochleae
Jugular fossa
fossa jugularis
Mastoid canaliculus
canaliculus mastoideus
Jugular notch
incisura jugularis
Jugular foramen
foramen jugulare
Intrajugular process
processus intrajugularis
Petrosal fossula
fossula petrosa
Inferior aperture of the tympanic canaliculus
apertura inferior canaliculi tympanici
External opening of the carotid canal
apertura externa canalis carotici
Internal opening of the carotid canal
apertura interna canalis carotici
Caroticotympanic canaliculi
canaliculi carotico-tympanici
Styloid process
processus styloideus
Stylomastoid foramen
foramen stylomastoideum
Petrosquamous fissure
fissura petrosquamosa
Musculotubal canal
canalis musculotubarius
Canal for the auditory tube
semicanalis tubae auditivae
Canal for the tensor tympani muscle
semicanalis musculi tensoris tympani
Mastoid cells
cellulae mastoideae
Mastoid antrum
antrum mastoideum
Parietal notch
incisura parietalis
Mastoid notch
incisura mastoidea
Groove of the occipital artery
sulcus arteriae occipitalis
Mastoid foramen
foramen mastoideum
Groove for the sigmoid sinus
sulcus sinus sigmoidei
External acoustic opening
porus acusticus externus
External acoustic meatus
meatus acusticus externus
Tympanosquamous fissure
fissura tympanosquamosa
Petrosquamous fissure
fissura petrosquamosa
Petrotympanic fissure
fissura petrotympanica
Tympanomastoid fissure
fissura tympanomastoidea
Parietal margin
margo parietalis
Sphenoidal margin
margo sphenoidalis
Temporal surface
facies temporalis
Groove for the middle temporal artery
sulcus arteriae temporalis mediae
Cerebral surface
facies cerebralis
Impressions of the cerebral gyri
impressiones digitatae
Impressions of the cerebral gyri
juga cerebralia
Arterial grooves
sulci arteriosi
Supramastoid crest
crista supramastoidea
Zygomatic process
processus zygomaticus
Zygomatic arch
arcus zygomaticus
Mandibular fossa
fossa mandibularis
Articular tubercle
tuberculum articulare
Tympanic cavity
cavitas tympani
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