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Petrous part of the temporal bone

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Petrous part of temporal bone

Dr Craig Hacking and Dr Henry Knipe et al.

The petrous part of the temporal bone (or more simply petrous temporal bone) forms the part of skull base  between the sphenoid  and occipital bones .

On this page:


  • Gross anatomy
  • Variant anatomy
  • Related pathology
  • Related articles
  • References


  • Cases and figures

Gross anatomy

The petrous temporal bone has a pyramidal shape with an apex and a base as well as three surfaces and angles: 

  • apex

    • direct medially; articulates with the posterior aspect of the greater wing of the sphenoid and basilar occiput
    • forms internal border of the carotid canal and the posterolateral boundary of the foramen lacerum
  • base

    • directed laterally and fuses with the internal surface of squama temporalis and mastoid

The petrous temporal bone has three surfaces – anterior, posterior and inferior:

The anterior surface forms the posterior part of the middle cranial fossa . It is continuous with the inner surface of the squamous part united by the petrosquamous suture. Near its centre lies the arcuate eminence, which indicates the location of the superior semicircular canal . Lateral to the arcuate eminence is a depression which indicates the position of middle ear cavity . A shallow groove directed posterolaterally to open into the hiatus of the facial canal . Lateral to this hiatus a smaller hiatus for the lesser petrosal nerve . At the apex, the termination of the carotid canal  is present.

The posterior surface forms the anterior part of posterior cranial fossa . It fuses with the inner surface of the mastoid. Near the centre of the posterior surface is the internal acoustic meatus . Posteriorly to the internal acoustic meatus is a small slit, leading to the canal of the vestibular aqueduct .

The inferior surface forms part of the exterior of the base of the skull. There are a number of foramina including the inferior opening of the carotid canal and posteriorly the jugular foramen and in between a small inferior tympanic canaliculus, through which the tympanic branch of the glossopharyngeal nerve  passes.  The stylomastoid foramen  is situated on the inferior surface. It provides attachment to the levator veli palatini  and the cartilaginous portion of the Eustachian tube . 

The petrous temporal bone has three angles:

  • superior angle:  attachment of tentorium cerebelli , its medial arm lodges the trigeminal nerve  and the superior petrosal sinus  lodges in the groove of the angle
  • posterior angle: contains a sulcus that houses the inferior petrosal sinus  medially, and the jugular notch of the occipital bone forms the jugular foramen  laterally
  • anterior angle: medial half articulates with the spinous process of the sphenoid  and lateral half fuses with the squamous part  at the petrosquamous suture

Variant anatomy

  • pneumatisation of the petrous apex

Related pathology

  • petrous temporal bone fracture


  • 1. Temporal Bone Imaging. Thieme. ISBN:1588904016. Read it at Google Books – Find it at Amazon
  • 2. Gray H. Anatomy of the Human Body, 20th edition. (1918) ISBN:1587341026. Read it at Google Books – Find it at Amazon
Anatomy: Head and neck
  • skeleton of the head and neck
    • cranial vault

      • scalp ( mnemonic )

        • galea aponeurotica
      • sutures

        • calvarial
          • coronal suture
          • sagittal suture
          • lambdoid suture

            • accessory occipital bone sutures
          • metopic suture
          • squamosal suture
          • sphenosquamosal suture
          • squamomastoid suture
        • facial
          • frontozygomatic suture
          • frontomaxillary suture
          • frontolacrimal suture
          • frontonasal suture
          • temporozygomatic suture
          • zygomaticomaxillary suture
          • parietotemporal suture  (parietomastoid suture)
          • occipitotemporal suture (occipitomastoid suture)
          • sphenofrontal suture
          • sphenozygomatic suture
          • spheno-occipital suture
          • lacrimomaxillary suture
          • nasomaxillary suture
          • internasal suture
        • basal/internal
          • frontoethmoidal suture
          • petrosquamous suture
          • petroclival suture
          • sphenoethmoidal suture
          • sphenopetrosal suture
      • skull landmarks

        • nasion
        • glabella
        • bregma
        • vertex
        • lambda
        • inion
        • pterion
        • asterion
        • basion
        • opisthion
        • obelion
      • frontal bone

        • supratrochlear foramen
        • supraorbital foramen
      • temporal bone

        • squamous part

          • MacEwen triangle
          • mandibular fossa
          • sigmoid plate
        • petrous part

          • Fallopian canal
          • jugular fossa
          • otic capsule
          • petrous ridge

            • Dorello canal
          • petromastoid canal
        • mastoid part

          • mastoid antrum
          • mastoid air cells

            • Koerner’s septum
          • mastoid foramen
        • tympanic part
        • styloid process

          • stylomastoid foramen
          • styloid apparatus
          • stylohyoid ligament
      • parietal bone

        • parietal foramen
      • occipital bone

        • clivus

          • inferior median clival canal

            • foveola pharyngica recess
        • occipital condyle

          • third condyle
    • skull base ( foramina )

      • anterior cranial fossa

        • anterior ethmoidal foramen
        • posterior ethmoidal foramen
        • foramen caecum
        • cribriform plate
      • middle cranial fossa ( mnemonic )

        • foramen rotundum
        • foramen ovale ( mnemonic )
        • foramen spinosum
        • foramen Vesalii
        • foramen lacerum
        • carotid canal
        • pterygoid canal
      • posterior cranial fossa

        • condylar canal
        • jugular foramen

          • jugular spine
        • hypoglossal canal
        • foramen magnum
    • facial bones

      • midline single bones
        • sphenoid bone

          • body

            • pituitary fossa

              • sella turcica
              • dorsum sellae

                • pneumatised dorsum sellae
              • tuberculum sellae
            • persistent hypophyseal canal
          • lesser wing
          • greater wing
          • pterygoid processes

            • palatovaginal canal
        • ethmoid bone

          • labyrinth of ethmoid
          • cribriform plate

            • crista galli
            • olfactory fossa

              • Keros classification
        • vomer
        • mandible

          • temporomandibular joint

            • articular disc
            • retrodiscal zone
          • pterygoid fovea
          • lingula
          • mandibular foramen
          • mandibular canal
          • mental foramen
        • maxilla
        • incisive canal

          • incisive foramen
      • paired bilateral bones
        • palatine bone

          • sphenopalatine foramen
          • greater palatine foramen (canal)
          • lesser palatine foramina (canal)
        • nasal bone
        • lacrimal bone
        • zygoma (zygomatic bone)

          • zygomaticofacial foramen
          • zygomaticotemporal foramen
          • zygomatic arch
    • cervical spine
    • hyoid bone
    • laryngeal cartilages

      • arytenoid cartilage
      • corniculate cartilage
      • cuneiform cartilage
      • cricoid cartilage
      • thyroid cartilage
  • muscles of the head and neck
    • muscles of the tongue (mnemonic)

      • extrinsic muscles of the tongue

        • genioglossus muscle
        • hyoglossus muscle
        • styloglossus muscle
        • palatoglossus muscle
      • intrinsic muscles of the tongue

        • superior longitudinal muscle of the tongue
        • inferior longitudinal muscle of the tongue
        • transverse muscle of the tongue
        • vertical muscle of the tongue
    • muscles of mastication

      • temporalis muscle
      • masseter muscle
      • medial pterygoid muscle
      • lateral pterygoid muscle
    • facial muscles

      • occipitalis
      • orbicularis oculi
      • corrugator supercilii
      • procerus
    • muscles of the middle ear
      • stapedius muscle
      • tensor tympani muscle
    • orbital muscles
      • extraocular muscles

        • superior rectus
        • inferior rectus
        • lateral rectus
        • medial rectus
        • superior oblique
        • inferior oblique
      • levator palpebrae superioris
    • muscles of the soft palate

      • tensor veli palatini
      • levator veli palatini
      • ​ palatopharyngeus
      • palatoglossus
      • muscle of the uvula
    • pharyngeal muscles

      • superior pharyngeal constrictor muscle

        • Passavant cushion
      • middle pharyngeal constrictor muscle
      • inferior pharyngeal constrictor muscle
      • stylopharyngeus muscle
      • salpingopharyngeus muscle
    • suprahyoid muscles

      • digastric muscle
      • geniohyoid muscle
      • mylohyoid muscle

        • mylohyoid boutonniere
      • stylohyoid muscle
    • infrahyoid muscles

      • sternohyoid muscle
      • sternothyroid muscle
      • thyrohyoid muscle
      • omohyoid muscle
    • intrinsic muscles of the larynx
    • muscles of the neck
      • platysma
      • longus colli muscle
      • longus capitis muscle
      • scalenus anterior muscle

        • colliscalene triangle
      • scalenus medius muscle
      • scalenus posterior muscle
      • scalenus pleuralis muscle
      • sternocleidomastoid
      • suboccipital muscles

        • rectus capitis posterior major muscle
        • rectus capitis posterior minor muscle
        • obliquus capitis superior muscle
        • obliquus capitis inferior muscle
  • deep spaces of the neck

    • anterior cervical space
    • buccal space
    • carotid space

      • carotid sheath
    • danger space
    • deep cervical fascia
    • infratemporal fossa
    • masticator space
    • parapharyngeal space
    • parotid space
    • pharyngeal (superficial) mucosal space
    • ​ perivertebral space
    • posterior cervical space
    • pterygopalatine fossa

      • pterygomaxillary fissure
    • retropharyngeal space
    • suprasternal space (of Burns)
    • visceral space
  • surgical triangles of the neck

    • anterior triangle

      • digastric triangle
      • carotid triangle
      • muscular triangle
      • submental triangle
    • posterior triangle

      • occipital triangle
      • supraclavicular triangle
  • orbit

    • bony orbit

      • orbital apex

        • optic canal
        • superior orbital fissure ( mnemonic )
        • inferior orbital fissure
        • infraorbital foramen
        • tendinous ring
      • supraorbital ridge
    • orbital spaces

      • extraconal
      • myofascial cone
      • intraconal
      • globe

        • conjunctiva
        • cornea
        • sclera
        • uvea
        • iris
        • ora serrata
        • vitreous body

          • Cloquet’s canal
        • lens
      • optic nerve-sheath complex

        • fovea
    • orbital septum
    • naso-orbital ethmoid region
    • eye movements

      • ocular adductors
      • ocular abductors
      • ocular elevators
      • ocular depressors
      • ocular internal rotators
      • ocular external rotators
    • orbital blood supply

      • ophthalmic artery
      • superior ophthalmic vein
      • inferior ophthalmic vein
    • orbital nerve supply
    • lacrimal apparatus

      • lacrimal gland
      • nasolacrimal drainage apparatus

        • lacrimal canaliculi
        • lacrimal sac
        • nasolacrimal duct
  • ear

    • inner ear

      • internal acoustic meatus ( mnemonic )

        • Bill bar
        • falciform crescent
        • porus acusticus internus
      • labyrinth

        • cochlea
        • semicircular canals
        • vestibular aqueduct
        • vestibule
        • saccule
        • utricle
      • facial nerve canal
    • middle ear

      • hypotympanum

        • Eustachian tube
      • mesotympanum

        • cochlear promontory
        • fissula ante fenestram
        • ossicular chain

          • malleus
          • incus

            • lentiform nodule
          • stapes
      • epitympanum

        • anterior epitympanic recess
        • Prussak space
    • external ear

      • external auditory meatus

        • foramen tympanicum
        • porus acusticus externus
      • external auditory canal

        • scutum
      • tympanic membrane

        • pars tensa
        • pars flaccida
        • tympanic annulus
  • paranasal sinuses

    • frontal sinuses
    • maxillary sinuses
    • ethmoid air cells (sinuses)

      • ethmoidal infundibulum
      • ethmoid bulla
      • agger nasi air cells
      • infraorbital ethmoidal air cells
      • sphenoethmoidal air cells
    • sphenoid sinuses

      • sphenoethmoidal recess
    • extramural air cell
    • ostiomeatal complex

      • ostiomeatal narrowing due to variant anatomy
  • nose

    • external nose

      • columella
      • nasal sill
      • nasal ala
    • nasal septum
    • nasal cavity
    • pyriform aperture
    • nasal concha

      • inferior
      • middle

        • concha bullosa
        • paradoxical middle turbinate
        • hiatus semilunaris
        • uncinate process
      • superior
    • Kiesselbach plexus
    • Schneiderian epithelium
  • oral cavity

    • palate

      • hard palate
      • soft palate
    • floor of mouth
    • retromolar trigone
    • sublingual space
    • submandibular space
    • submental space
    • tongue

      • root of tongue
    • ​ teeth  ( dental terminology )
      • supernumerary teeth

        • mesiodens
      • hypodontia
  • pharynx

    • nasopharynx

      • Rosenmüller fossa
      • torus tubarius
    • oropharynx

      • pharyngeal tonsils
    • hypopharynx
  • larynx

    • supraglottic space

      • epiglottis

        • omega epiglottis
      • false vocal cords
      • aryepiglottic folds
    • glottis

      • true vocal cords

        • anterior commissure of the larynx

      subglottic space

  • viscera of the neck
    • deep cervical fascia
    • Waldeyer ring

      • adenoid tonsils
      • palatine tonsils
      • lingual tonsils
    • thyroid gland

      • ectopic thyroid
      • Zuckerkandl tubercle
      • thyroglossal duct
      • variant anatomy
        • pyramidal lobe of thyroid
    • parathyroid gland
    • salivary glands and ducts

      • major salivary glands

        • parotid gland

          • parotid duct
          • accessory parotid gland
        • submandibular gland

          • submandibular (Wharton) duct
        • sublingual gland

          • duct of Rivinus
      • minor salivary glands
    • oesophagus
    • trachea
  • blood supply of the head and neck
    • arterial supply

      • common carotid artery

        • carotid body
        • carotid bifurcation

          • internal carotid artery ( segments )

            • caroticotympanic artery

              • persistent stapedial artery
            • ophthalmic artery

              • supraorbital artery
              • lacrimal artery
              • central artery of the retina
              • supratrochlear artery
              • dorsal nasal artery
          • external carotid artery ( mnemonic )

            • superior thyroid artery

              • superior laryngeal artery
            • ascending pharyngeal artery
            • lingual artery
            • facial artery

              • inferior labial artery
              • superior labial artery
            • occipital artery
            • posterior auricular artery
            • (internal) maxillary artery ( mnemonic )

              • deep auricular artery
              • middle meningeal artery
              • greater (descending) palatine artery
              • inferior alveolar artery

                • mental artery
              • sphenopalatine artery
              • anterior ethmoidal artery
              • posterior ethmoidal artery
              • infraorbital artery
              • masseteric artery
              • buccinator artery
              • deep temporal branches
              • Vidian artery
            • superficial temporal artery
        • subclavian artery

          • vertebral artery
          • internal thoracic artery
          • thyrocervical trunk

            • inferior thyroid artery
            • suprascapular artery
            • ascending cervical artery
            • transverse cervical artery

              • dorsal scapular artery
          • costocervical trunk
        • variants
          • thyroidea ima artery
    • venous drainage

      • internal jugular vein ( mnemonic )

        • jugular bulb
          • asymmetrically large jugular bulb
        • pharyngeal vein
        • common facial vein

          • angular vein

            • supraorbital vein
            • supratrochlear vein
        • lingual vein
        • superior thyroid vein
        • middle thyroid vein
      • external jugular vein ( mnemonic )

        • posterior auricular vein
        • retromandibular vein

          • superficial temporal vein
          • (deep/internal) maxillary vein
            • pterygoid venous plexus
        • facial vein
        • anterior jugular vein
        • posterior external jugular vein
        • suprascapular vein
        • transverse cervical vein
      • cavernous sinus
      • facial-cavernous anastomoses
  • innervation of the head and neck
    • cranial nerves

      • olfactory nerve (CN I)
      • optic nerve (CN II)
      • oculomotor nerve (CN III)
      • trochlear nerve (CN IV)
      • trigeminal nerve (mnemonic) (CN V)

        • ophthalmic division
          • tentorial nerve
          • frontal nerve

            • supra-orbital nerve
            • supratrochlear nerve
          • lacrimal nerve
          • nasociliary nerve

            • small communicating branch to the ciliary ganglion
            • short ciliary nerves
            • long ciliary nerves
            • infratrochlear nerve
            • posterior ethmoidal nerve
            • anterior ethmoidal nerve
        • maxillary division
          • middle meningeal nerve
          • zygomatic nerve

            • zygomaticotemporal nerve
            • zygomaticofacial nerve
          • infra-orbital nerve

            • posterior superior alveolar nerve
            • middle superior alveolar nerve
            • anterior superior alveolar nerve
          • nasopalatine nerve
          • posterior superior nasal nerves
          • greater palatine nerve

            • lateral posterior inferior nasal nerve
          • lesser palatine nerves
          • pharyngeal nerve
        • mandibular division
          • nervus spinosus
          • nerve to medial pterygoid
          • anterior division

            • deep temporal nerves
            • lateral pterygoid nerves
            • masseteric nerve
            • buccal nerve
          • posterior division

            • auriculotemporal nerve
            • lingual nerve
            • inferior alveolar nerve

              • nerve to mylohyoid
              • incisive nerve
              • mental nerve
      • abducens nerve (CN VI)
      • facial nerve (CN VII)

        • chorda tympani
        • nerve to stapedius
      • vestibulocochlear nerve (CN VIII)
      • glossopharyngeal nerve (CN IX)

        • Jacobson nerve
      • vagus nerve (CN X)

        • recurrent laryngeal nerve
      • (spinal) accessory nerve (CN XI)
      • hypoglossal nerve (CN XII)
    • parasympathetic ganglia  of the head and neck

      • ciliary ganglion
      • pterygopalatine ganglion
      • otic ganglion ​
      • submandibular ganglion
    • greater occipital nerve
    • cervical plexus

      • muscular branches
        • longus capitis
        • longus colli
        • scalenes
          • scalenus anterior
          • scalenus medius
          • scalenus posterior
        • geniohyoid
        • thyrohyoid
        • ansa cervicalis

          • omohyoid (superior and inferior bellies separately)
          • sternothyroid
          • sternohyoid
        • phrenic nerve
        • contribution to the accessory nerve (CN XI)
      • cutaneous branches
        • less occipital nerve
        • greater auricular nerve
        • transverse cervical nerve
        • supraclavicular nerve
    • brachial plexus
    • pharyngeal plexus
  • lymphatic drainage of the head and neck
    • cervical lymph node groups

      • Delphian node
    • cervical lymph node levels
    • supraclavicular lymph nodes

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Article information

rID: 28369
System: Head & Neck , Musculoskeletal
Section: Anatomy
Tag: anatomy rewrite , refs
Synonyms or Alternate Spellings:

  • Petrous part of the temporal bone
  • Petrous temporal bone

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    Figure 1: temporal bone divisions (CT anatomy) Figure 1: temporal bone divisions (CT anatomy)
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    Case 1: normal CT Case 1: normal CT
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    Case 2: HRCT of petrous temporal bones Case 2: HRCT of petrous temporal bones
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      Petrous part of the temporal bone

      From Wikipedia, the free encyclopedia

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      Petrous part of the temporal bone

      Left temporal bone . Outer surface.
      Temporal bone3.jpg

      Petrous part of the temporal bone
      Latin Pars petrosa ossis temporalis
      MeSH D010579
      TA A02.1.06.002
      FMA 52871
      Anatomical terms of bone

      [ edit on Wikidata ]

      The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones . Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three angles, and houses in its interior, the components of the inner ear . The petrous portion is among the most basal elements of the skull and forms part of the endocranium . Petrous comes from the Latin word petrosus, meaning “stone-like, hard”. It is one of the densest bones in the body.

      The petrous bone is important for studies of ancient DNA from skeletal remains, as it tends to have extremely high DNA preservation.


      • 1 Base
      • 2 Apex
      • 3 Surfaces
        • 3.1 Anterior surface
        • 3.2 Posterior surface
        • 3.3 Inferior surface
      • 4 Angles
      • 5 The petrous bone in ancient DNA studies
      • 6 Additional images
      • 7 References

      Base[ edit ]

      The base is fused with the internal surfaces of the squamous and mastoid parts .

      Apex[ edit ]

      The apex, rough and uneven, is received into the angular interval between the posterior border of the great wing of the sphenoid bone and the basilar part of the occipital bone ; it presents the anterior or internal opening of the carotid canal , and forms the postero-lateral boundary of the foramen lacerum .

      Surfaces[ edit ]

      Anterior surface[ edit ]

      The anterior surface forms the posterior part of the middle cranial fossa of the base of the skull, and is continuous with the inner surface of the squamous portion, to which it is united by the petrosquamous suture , remains of which are distinct even at a late period of life. It is marked by depressions for the convolutions of the brain, and presents six notable points:

      1. near the center, the arcuate eminence (eminentia arcuata), which indicates the location of the superior semicircular canal .
      2. in front of and a little lateral to this eminence, a depression indicating the position of the tympanic cavity : Here, the layer of bone that separates the tympanic from the cranial cavity is extremely thin, and is known as the tegmen tympani
      3. a shallow groove, sometimes double, leading lateralward and backward to an oblique opening, the hiatus for greater petrosal nerve , for the passage of the greater petrosal nerve and for the petrosal branch of the middle meningeal artery
      4. lateral to the hiatus, a smaller opening, occasionally seen, for the passage of the lesser superficial petrosal nerve
      5. near the apex of the bone, the termination of the carotid canal , the wall of which in this situation is deficient in front
      6. above this canal the shallow trigeminal impression for the reception of the trigeminal ganglion .

      Posterior surface[ edit ]

      The posterior surface forms the anterior part of the posterior cranial fossa of the base of the skull, and is continuous with the inner surface of the mastoid portion.

      Near the center is a large orifice, the internal acoustic opening , the size of which varies considerably; its margins are smooth and rounded, and it leads into the internal auditory meatus a short canal, about 1 cm. in length, which runs lateralward. It transmits the facial and acoustic nerves and the internal auditory branch of the basilar artery .

      The lateral end of the canal is closed by a vertical plate, which is divided by a horizontal crest, the falciform crest , into two unequal portions.

      Each portion is further subdivided by a vertical ridge into an anterior and a posterior part.

      • In the portion beneath the falciform crest are three sets of foramina; these openings together with this central canal transmit the nerves to the cochlea .
        • one group, just below the posterior part of the crest, situated in the area cribrosa media , consists of several small openings for the nerves to the saccule ;
        • below and behind this area is the foramen singulare , or opening for the nerve to the posterior semicircular duct ;
        • in front of and below the first is the tractus spiralis foraminosus , consisting of a number of small spirally arranged openings, which encircle the canalis centralis cochleæ .
      • The portion above the crista falciformis presents behind, the area cribrosa superior, pierced by a series of small openings, for the passage of the nerves to the utricle and the superior and lateral semicircular ducts, and, in front, the area facians, with one large opening, the commencement of the canal for the facial nerve (aquæductus Fallopii).

      Behind the internal acoustic meatus is a small slit almost hidden by a thin plate of bone, leading to a canal, the aquæductus vestibuli, which transmits the ductus endolymphaticus together with a small artery and vein.

      Above and between these two openings is an irregular depression that lodges a process of the dura mater and transmits a small vein; in the infant, this depression is represented by a large fossa, the subarcuate fossa , which extends backward as a blind tunnel under the superior semicircular canal .

      1. Falciform crest
      2. Area facialis, with (2’) internal opening of the facial canal
      3. Ridge separating the area facialis from the area cribrosa superior
      4. Area cribrosa superior, with (4’) openings for nerve filaments
      5. Anterior inferior cribriform area, with (5’) the tractus spiralis foraminosus, and (5’’) the canalis centralis of the cochlea.
      6. Ridge separating the tractus spiralis foraminosus from the area cribrosa media
      7. Area cribrosa media, with (7’) orifices for nerves to saccule
      8. Foramen singulare.

      Inferior surface[ edit ]

      The inferior surface is rough and irregular, and forms part of the exterior of the base of the skull. It presents eleven points for examination:

      1. near the apex is a rough surface, quadrilateral in form, which serves partly for the attachment of the Levator veli palatini and the cartilaginous portion of the auditory tube , and partly for connection with the basilar part of the occipital bone through the intervention of some dense fibrous tissue
      2. behind this is the large circular aperture of the carotid canal , which ascends at first vertically, and then, making a bend, runs horizontally forward and medially; it transmits into the cranium the internal carotid artery, and the carotid plexus of nerves
      3. medial to the opening for the carotid canal and close to its posterior border, in front of the jugular fossa , is a triangular depression; at the apex of this is a small opening, the aquæductus cochleæ , which lodges a tubular prolongation of the dura mater establishing a communication between the perilymphatic space and the subarachnoid space , and transmits a vein from the cochlea to join the internal jugular
      4. behind these openings is a deep depression, the jugular fossa , of variable depth and size in different skulls; it lodges the bulb of the internal jugular vein
      5. in the bony ridge dividing the carotid canal from the jugular fossa is the small inferior tympanic canaliculus for the passage of the tympanic branch of the glossopharyngeal nerve
      6. in the lateral part of the jugular fossa is the mastoid canaliculus for the entrance of the auricular branch of the vagus nerve
      7. behind the jugular fossa is a quadrilateral area, the jugular surface , covered with cartilage in the fresh state, and articulating with the jugular process of the occipital bone
      8. extending backward from the carotid canal is the vaginal process , a sheath-like plate of bone, which divides behind into two laminæ; the lateral lamina is continuous with the tympanic part of the bone, the medial with the lateral margin of the jugular surface
      9. between these laminæ is the styloid process , a sharp spine, about 2.5 cm. in length
      10. between the styloid and mastoid processes is the stylomastoid foramen ; it is the termination of the facial canal , and transmits the facial nerve and stylomastoid artery
      11. situated between the tympanic portion and the mastoid process is the tympanomastoid fissure , for the exit of the auricular branch of the vagus nerve .

      Angles[ edit ]

      The superior angle, the longest, is grooved for the superior petrosal sinus , and gives attachment to the tentorium cerebelli ; at its medial extremity is a notch, in which the trigeminal nerve lies.

      The posterior angle is intermediate in length between the superior and the anterior. Its medial half is marked by a sulcus, which forms, with a corresponding sulcus on the occipital bone, the channel for the inferior petrosal sinus. Its lateral half presents an excavation — the jugular fossa — which, with the jugular notch on the occipital, forms the jugular foramen; an eminence occasionally projects from the center of the fossa, and divides the foramen into two.

      The anterior angle is divided into two parts—a lateral joined to the squamous part by a suture (petrosquamous), the remains of which are more or less distinct; a medial, free, which articulates with the spinous process of the sphenoid.

      At the angle of junction of the petrous and the squamous parts are two canals, one above the other, and separated by a thin plate of bone, the septum canalis musculotubarii; both canals lead into the tympanic cavity.

      • The upper one (semicanalis m. tensoris tympani) transmits the tensor tympani .
      • the lower one (semicanalis tubae auditivae) forms the bony part of the auditory tube.

      The petrous bone in ancient DNA studies[ edit ]

      In ancient DNA studies, scientists extract and sequence DNA from ancient skeletal remains of humans and other species. In many cases the DNA is highly degraded, and contaminated by DNA from soil microbes. In 2015 it was found, surprisingly, that the petrous bone has remarkably high preservation of DNA. [1] A 2017 study [2] comparing DNA from different skeletal sites concluded that “The inner part of petrous bones and the cementum layer in teeth roots are currently recognized as the best substrates for (ancient DNA) research…Both substrates display significantly higher endogenous DNA content (average of 16.4% and 40.0% for teeth and petrous bones, respectively) than parietal skull bone (average of 2.2%).”

      Consequently, petrous bones are now the most widely-used skeletal site for the study of ancient DNA.

      Additional images[ edit ]

      • Base of skull. Inferior surface.

      • Base of the skull. Upper surface.

      • Dissection of the muscles of the palate from behind.

      • Temporal bone

      • Petrous part of the temporal

      • Petrous part of the temporal

      References[ edit ]

      1. ^ Pinhasi R, Fernandes D, Sirak K, Novak M, Connell S, Alpaslan-Roodenberg S, Gerritsen F, Moiseyev V, Gromov A, Raczky P, Anders A, Pietrusewsky M, Rollefson G, Jovanovic M, Trinhhoang H, Bar-Oz G, Oxenham M, Matsumura H, Hofreiter M (2015-06-18). “Optimal Ancient DNA Yields from the Inner Ear Part of the Human Petrous Bone” . PLOS One. 10 (6): e0129102. doi : 10.1371/journal.pone.0129102 . PMC   4472748 . PMID   26086078 .

      2. ^ Hansen HB, Damgaard PB, Margaryan A, Stenderup J, Lynnerup N, Willerslev E, Allentoft ME (2017-01-27). “Comparing Ancient DNA Preservation in Petrous Bone and Tooth Cementum” . PLOS One. 12 (1): e0170940. doi : 10.1371/journal.pone.0170940 . PMC   5271384 . PMID   28129388 .

      This article incorporates text in the public domain from page 142 of the 20th edition of Gray’s Anatomy (1918)

      • v
      • t
      • e
      The neurocranium of the skull
      Squamous part
      • external
        • Inion / External occipital protuberance
        • Occipital bun
        • External occipital crest
        • Nuchal lines
        • Suprainiac fossa
      • planes
        • Occipital
        • Nuchal
      • internal
        • Cruciform eminence
        • Internal occipital protuberance
        • 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
      • Foramen magnum
        • Basion
        • Opisthion
      • Parietal eminence
      • Temporal line
      • Parietal foramen
      • Sagittal sulcus
      • Sagittal keel
      • Sagittal crest
      Squamous part
      • Frontal suture
      • Frontal eminence
      • external
        • Superciliary arches
        • Glabella
      • foramina
        • Supraorbital foramen
        • Brow ridge
        • Foramen cecum
      • Zygomatic process
      • internal
        • Sagittal sulcus
        • Frontal crest
      Orbital part
      • Ethmoidal notch
      • Fossa for lacrimal gland
      • Trochlear fovea
      • Frontal sinus
      • Frontonasal duct
      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
      • 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 of auditory tube
      Small wings
      • Superior orbital fissure
      • Anterior clinoid process
      • Optic canal
      • fossae
        • Pterygoid
        • Scaphoid
      • pterygoid plates
        • Lateral
        • Medial
      • Pterygoid canal
      • Hamulus
      • Body
      • Sphenoidal conchae
      • Cribriform plate
        • Crista galli
        • Olfactory foramina
      • Perpendicular plate
      • Lateral surface Orbital lamina
      • Uncinate process
      • Medial surface Supreme nasal concha
      • Superior nasal concha
      • Superior meatus
      • Middle nasal concha
      • Middle meatus
      • Ethmoid sinus
      • ethmoidal foramina
        • Posterior
        • Anterior
      • Anatomy posture and body mechanics 08.web.jpg Anatomy portal
      Authority control Edit this at Wikidata
      • GND : 4153973-4
      • TA98 : A02.1.06.002

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