Learning Objective: Describe the anatomical structure, relations, articulations, and clinical significance of the temporal bone, including its role in forming the temporomandibular joint (TMJ) and its surgical landmarks.
The temporal bone contributes to the lower lateral walls of the skull and houses the middle and inner ear. It also forms part of the TMJ and transmits several cranial nerves. It consists of five major parts: squamous, tympanic, petromastoid, zygomatic, and styloid process.
Anatomical Structure
Squamous Part
- Largest, thinnest, and plate-like superior portion.
- Forms part of the temporal fossa.
- Provides origin for the temporalis muscle.
- Articulates anteriorly with the sphenoid and superiorly with the parietal bone.
Zygomatic Process
- Projects anteriorly from the squamous part.
- Articulates with the temporal process of the zygomatic bone, forming the zygomatic arch.
- Forms the articular tubercle, the anterior boundary of the mandibular fossa (TMJ).
- The masseter muscle attaches to its lateral surface.
Tympanic Part
- Surrounds the external auditory opening, leading into the external acoustic meatus.
- Located inferior to the squamous and anterior to the petromastoid parts.
Styloid Process
- Slender projection beneath the external auditory meatus.
- Serves as an attachment point for muscles and ligaments, such as the stylomandibular ligament.
Petromastoid Part
- Posterior and pyramid-shaped.
- Divided into:
- Mastoid portion: contains mastoid air cells and the mastoid process (sternocleidomastoid attachment).
- Petrous portion: encloses the inner ear structures.
Muscular Attachments
| Muscle | Attachment Site | Function/Description |
|---|---|---|
| Temporalis | Lower part of the squamous | Elevates mandible |
| Masseter | Lateral surface of the zygomatic process | Mastication |
| Sternocleidomastoid | Mastoid process | Head rotation, neck flexion |
| Posterior belly of the digastric | Mastoid notch | Suprahyoid, swallowing |
| Splenius capitis | Mastoid process | Head extension and rotation |
Articulations
- Mandible – at the TMJ
- Parietal bone – superiorly
- Sphenoid bone – anteriorly
- Zygomatic bone – via zygomatic process
Clinical Relevance
Mastoiditis
- Infection of the mastoid air cells secondary to otitis media.
- May extend to the middle cranial fossa, risking meningitis.
- Requires surgical drainage—careful to avoid facial nerve injury.
Temporal Bone Fractures
- Result from blunt trauma.
- May cause hearing loss, vertigo, facial nerve palsy, or bleeding from the ear.
Pterion Fracture
- Weak junction of the temporal, parietal, sphenoid, and frontal bones.
- Overlies the middle meningeal artery (MMA).
- Fracture → epidural (extradural) hematoma → raised intracranial pressure.
- Symptoms: headache, vomiting, limb weakness, bradycardia.
- Requires surgical evacuation if severe.
