Where is the inferior petrosal sulcus located?
The inferior petrosal sulcus is situated on the intracranial (superior) surface of the basilar part of the occipital bone and continues onto the posterior surface of the petrous part of the temporal bone.
- On the basilar part (Pars basilaris): the basilar part is located anterior to the foramen magnum (Foramen magnum). Along the midline here is the clivus (Clivus), and lateral to it is the inferior petrosal sulcus.
- On the petrous part of the temporal bone (Pars petrosa): the sulcus continues onto the posterior surface of the petrous pyramid. The apex of the petrous part (Apex partis petrosae) is directed anteriorly and medially, while its base is directed posteriorly and laterally.
Topography and adjacent structures
On the posterior surface of the petrous part of the temporal bone, in addition to the inferior petrosal sulcus, are found:
- Internal acoustic opening (Porus acusticus internus), leading into the internal acoustic meatus (Meatus acusticus internus).
- Subarcuate fossa (Fossa subarcuata).
- Aperture of the vestibular canaliculus (Apertura canaliculi vestibuli), continuing into the vestibular canaliculus (Canaliculus vestibuli).
On the external (inferior) surface of the basilar part along the midline near the site of pharyngeal attachment lies the pharyngeal tubercle (Tuberculum pharyngeum).
Relation to the petro-occipital fissure
Between the occipital and temporal bones lies the petro-occipital fissure (Fissura petrooccipitalis). On a macerated skull, this fissure is visible at the level of the Sulcus sinus petrosi inferioris. Between the occipital and temporal bones is also the jugular foramen (Foramen jugulare).
Relation to the posterior cranial fossa
Boundaries of the posterior cranial fossa:
- Anterior boundary: laterally — superior border of the petrous part (Margo superior partis petrosae) or superior petrosal sulcus (Sulcus sinus petrosi superioris); in the midline — dorsum sellae (Dorsum sellae) of the sphenoid body.
- Posterior boundary: in the midline — cruciform eminence (Eminentia cruciformis) or internal occipital protuberance (Protuberantia occipitalis interna); laterally — transverse sinus sulcus (Sulcus sinus transversi).
Communications of the posterior cranial fossa with the external cranial base and inner ear include:
- On the occipital bone: foramen magnum (Foramen magnum), condylar canal (Canalis condylaris), hypoglossal canal (Canalis nervi hypoglossi).
- On the temporal bone: mastoid foramen (Foramen mastoideum).
- With the cavities of the inner ear: aperture of the vestibular canaliculus (Apertura canaliculi vestibuli) and aperture of the cochlear canaliculus (Apertura canaliculi cochleae).
Adjacent surfaces of the petrous part
The pyramid of the temporal bone contains the tympanic cavity (Cavitas tympani) of the middle ear.
- Anterior surface: here are the trigeminal impression (Impressio trigeminalis), arcuate eminence (Eminentia arcuata), tegmen tympani (Tegmen tympani), and superior petrosal sulcus.
- Inferior surface: here are the jugular notch (Incisura jugularis) with the intrajugular process (Processus intrajugularis), jugular fossa (Fossa jugularis), styloid process (Processus styloideus), and external aperture of the carotid canal (Apertura externa canalis carotici). Between the styloid and mastoid processes is the stylomastoid foramen (Foramen stylomastoideum).
The base of the pyramid passes into the mastoid process (Processus mastoideus), which is directed posteriorly and laterally and is bounded by the occipital margin (Margo occipitalis).
Grammatical features of the term
In Latin anatomical nomenclature, the term Sulcus sinus petrosi inferioris is classified as a complex term with a noun in the genitive case. The main noun sulcus (sulcus) is modified by a dependent construction in the genitive case (Genitivus) — sinus petrosi inferioris (of the inferior petrosal sinus).
Class and exam questions
Where is the inferior petrosal sulcus located?
It is located on the intracranial surface of the basilar part lateral to the clivus and continues onto the posterior surface of the petrous part of the temporal bone.
What anatomical fissure is visible at the level of this sulcus?
On a macerated skull at the level of the inferior petrosal sulcus between the occipital and temporal bones, the petro-occipital fissure (Fissura petrooccipitalis) is visible.
What else to study on this topic
- Basilar part of the occipital bone (Pars basilaris)
- Petrous part of the temporal bone (Pars petrosa)
- Petro-occipital fissure (Fissura petrooccipitalis)
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