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Temporal Bone Anatomy— High-Yield Revision

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Overview of the Temporal Bone

  • Paired bone forming part of lateral walls & base of the skull.
  • Houses external, middle, and inner ear.
  • Articulates:
    • Anterior: Sphenoid bone lies between the right and left temporal bones.
    • Posterior: Occipital bone
    • Inferior: articulates with the Mandible → forms TMJ

Five Parts of Temporal Bone Mnemonic: “Some People Make Thin Structures”

  • Squamous
  • Petrous
  • Mastoid
  • Tympanic
  • Styloid

 

  1. Squamous Part
  • Largest and superior most part of the temporal bone
  • Flat, thin, translucent, shell-like plate of bone.
  • Forms lateral wall of middle cranial fossa.
  • It mainly forms the roof of the EAC and very small parts of the anterior and posterior walls of the external auditory canal (EAC).
  • Zygomatic process articulates with the temporal process of the zygomatic bone to form a zygomatic arch (palpable as ‘cheekbones’).
  • Mandibular fossa below the zygomatic process houses the temporomandibular joint.
  • Relations: It has two surfaces (lateral, medial) and two borders (superior, anteroinferior).
    • Lateral surface forms the temporal fossa and gives origin to the temporalis muscle. Supramastoid crest on the lateral surface provides attachment to temporalis fascia.
    • Medial surface is related to the temporal lobe and middle meningeal artery grooves.
    • Superior border articulates with the parietal bone.
    • Anteroinferior border articulates with the sphenoid.

  1. Petrous Part (“Rock-like”)
  • It is pyramidal shaped, dense bone and houses middle & inner ear, facial canal, cochlea, semi-circular canals.
  • It is located in the base of the skull between the sphenoid bone anteriorly and the occipital bone posteriorly.
  • Relations: It has a base, an apex, three surfaces (anterior, posterior, inferior) and three edges or margins (superior, anterior, posterior).
    • Base: Fuses with medial surfaces of squamous and mastoid part.
    • Apex: Points anteromedially; related to trigeminal (Meckel’s cave) and abducent nerves (Dorello’s canal); involved in Gradenigo’s syndrome.
    • Anterior surface: Forms posterior wall of middle cranial fossa; shows (medial to lateral) trigeminal impression, roof of internal acoustic meatus, arcuate eminence and tegmen tympani.
    • Posterior surface: Forms anterior wall of posterior cranial fossa; contains internal acoustic meatus for facial, vestibulocochlear nerves, and artery.
    • Inferior surface: Shows carotid canal, jugular fossa, and stylomastoid foramen for facial nerve exit.
    • Superior border: It is a long sharp crest between posterior and anterior cranial fossae; provides attachment for tentorium cerebelli and superior petrosal sinus.
    • Anterior border: Medially joins sphenoid; laterally fuses with squamous temporal bone via petrosquamosal suture.
    • Posterior border: Has groove for inferior petrosal sinus and contributes to jugular foramen boundary.

  1. Mastoid Part
  • It lies behind the squamous part; separated by a fused suture ~1.5 cm behind the supramastoid crest.
  • It contains mastoid antrum and air cells that communicate with the middle ear.
  • It is formed by squamous (lateral) and petrous (medial) parts, divided by Körner’s septum.
  • Relations: It has two surfaces (lateral and medial) and two borders (superior and posterior):
    • Lateral surface: Forms mastoid process; gives muscle attachments (SCM, splenius, longissimus capitis).
    • Medial surface: Features sigmoid sulcus which lodges sigmoid sinus, digastric notch, groove for occipital artery, and mastoid foramen for emissary vein and artery.
    • Superior border forms parietomastoid suture with parietal bone.
    • Posterior border joins occipital bone via occipitomastoid suture.

  1. Tympanic Part
  • It lies lateral to petrous, below squamous, and in front of mastoid part of temporal bone.
  • It forms anterior, posterior, and floor of bony EAC.
  • Sutures: Forms tympanosquamous suture (anterior) and tympanomastoid suture (posterior).
  • Petrotympanic fissure: transmits chorda tympani, anterior tympanic artery.
  • Relations: It has three borders (superior, inferior & lateral) and two surfaces (anterior & posterior):
    • Borders: superior (related to mandibular fossa), inferior (related to styloid process & petrous part), and lateral (forms bony ear canal)
    • Anterior surface relates to parotid gland and mandibular fossa.
    • Posterior surface, bears tympanic sulcus for attachment of tympanic membrane.

  1. Styloid Part (Styloid Process)
  • Thin, slender, pointed bony projection which arises from the junction of tympanic and petrous parts, in front of the jugular fossa; ~2.5 cm long.
  • Projects downward, forward, and medially; serves as an anchor for muscles and ligaments.
  • Muscles attached: Styloglossus (CN XII), Stylohyoid (CN VII), Stylopharyngeus (CN IX).
  • Ligaments attached: Stylohyoid and stylomandibular; the latter separates parotid from submandibular gland and medial pterygoid.
  • Stylomastoid foramen: Lies between styloid and mastoid; transmits facial nerve (CN VII) and stylomastoid artery.

Styloid part of Temporal Bone. Dr Rahul Bagla Online ENT Textbook

 

Important Foramina & Contents

Foramen Contents
Internal acoustic meatus CN VII, VIII, labyrinthine artery
Stylomastoid foramen Facial nerve (CN VII), stylomastoid artery
Jugular foramen CN IX, X, XI, sigmoid sinus
Carotid canal Internal carotid artery
Petrotympanic fissure Chorda tympani, anterior tympanic artery
Mastoid foramen Mastoid emissary vein

 

———— End of the chapter ————

 

Reference Textbooks.

  • Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
  • Glasscock-Shambaugh, Textbook of Surgery of the Ear.
  • P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
  • Hazarika P, Textbook of Ear Nose Throat And Head Neck Surgery Clinical Practical.
  • Mohan Bansal, Textbook of Diseases of Ear, Nose and Throat Head and Neck Surgery
  • Hans Behrbohm, Textbook of Ear, Nose, and Throat Diseases With Head and Neck Surgery.
  • Salah Mansour, Middle Ear Diseases – Advances in Diagnosis and Management.
  • Logan Turner, Textbook of Diseases of The Nose, Throat and Ear Head And Neck Surgery.
  • Rob and smith, Textbook of Operative surgery.
  • Anirban Biswas, Textbook of Clinical Audio-vestibulometry.
  • Arnold, U. Ganzer, Textbook of  Otorhinolaryngology, Head and Neck Surgery.

Author:

Dr. Rahul Bagla ENT Textbook

Dr. Rahul Bagla
MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi)
Fellow Rhinoplasty & Facial Plastic Surgery.
Renowned Teaching Faculty
Mail: msrahulbagla@gmail.com
India

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