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.

There are several parts of the temporal bone:

• Petrous part (pars petrosa)

• Tympanic part (pars tympanica)

  

• Squamous part (pars squamosa)

  

• Mastoid process (processus mastoideus)

  

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

  

  It also has three surfaces:

• Anterior surface (facies anterior)

  

• Posterior surface (facies posterior)

  

• Inferior surface (facies inferior)

  

  And three margins:

• Superior margin (margo superior)

  

• Anterior margin (margo anterior)

• 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.

  

  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 lesser petrosal nerve (hiatus canalis nervi petrosi minoris). It continues into the 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.

  

  Tegmen tympani (tegmen tympani) is located laterally.

  

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

  

  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.

  

  

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

  

  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.

  

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

  

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

  

  On the posterior side, the fossa is delimited by a 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.

  

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

  

  Anteriorly to the jugular fossa, there is a small 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.

  

  

  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.

  

  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.

  

  The anterior margin of the pyramid is separated from the squamous part by the 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)

  

  

  

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

  

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

  

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

  

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

  

  Medially to this notch, there is the 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.

  

  Near the mastoid angle, there is a 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).

  

  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.

  

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

  

  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

  

  

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

  

  The squamous part of the temporal bone has two edges:

• Parietal margin (margo parietalis)

  

• 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

  

  contains the 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.

  

  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).

  

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

  

  It connects to the zygomatic bone, forming the 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.

  

  Anteriorly, this fossa is delimited by the 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

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