Temple Bone
Os Temporale
location_on Lateral and inferior aspects of the cranium, forming the temple region
The temporal bone is one of the most complex bones in the body, housing the organs of hearing and balance within the petrous part. It contributes to the middle cranial fossa, the mandibular fossa for the jaw joint, and the external acoustic meatus. The bone consists of five distinct parts: squamous, petrous, tympanic, mastoid, and styloid process.
Key Anatomical Features
- Petrous part houses the cochlea and vestibular apparatus in the densest bone in the body
- Mastoid process contains air cells and provides attachment for the sternocleidomastoid
- External acoustic meatus is the bony ear canal leading to the tympanic membrane
- Mandibular fossa and articular eminence form the socket of the temporomandibular joint
- Styloid process provides attachment for three muscles and two ligaments
- Zygomatic process extends anteriorly to form the zygomatic arch
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Temporalis | Temporal fossa on squamous part | Elevates and retracts the mandible |
| Sternocleidomastoid | Mastoid process | Rotates and flexes the head |
| Splenius capitis | Mastoid process | Extends and rotates the head |
| Longissimus capitis | Mastoid process | Extends the head |
| Digastric (posterior belly) | Mastoid notch | Depresses the mandible and elevates the hyoid |
| Stylohyoid | Styloid process | Elevates and retracts the hyoid bone |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Temporomandibular joint | Synovial modified hinge | Mandible |
| Squamous suture | Fibrous suture | Parietal bone |
| Petro-occipital fissure | Fibrous synchondrosis | Occipital bone |
Common Pathologies
Mastoiditis
Infection of the mastoid air cells, typically as a complication of middle ear infection. Can lead to intracranial complications including sigmoid sinus thrombosis and brain abscess.
Temporal bone fracture
Classified as longitudinal or transverse. Longitudinal fractures may damage the ear canal and tympanic membrane; transverse fractures can sever the facial nerve or damage the cochlea causing sensorineural hearing loss.
Cholesteatoma
An abnormal keratinizing epithelial growth in the middle ear that can erode the temporal bone, ossicles, and potentially extend intracranially.
TMJ dysfunction
Disorder of the temporomandibular joint causing jaw pain, clicking, and limited opening. Often related to disc displacement within the mandibular fossa.
Clinical Relevance
Temporal bone fractures require assessment of facial nerve function, hearing, and CSF leak from the ear (otorrhea). Battle sign, bruising behind the ear over the mastoid, indicates a basilar skull fracture through the temporal bone. The facial nerve takes a complex course through the temporal bone and is vulnerable to injury during mastoid surgery.
Development and Ossification
The temporal bone ossifies from multiple centers. The petrous and squamous parts ossify separately and fuse before birth. The tympanic ring, styloid process, and mastoid process fuse postnatally. Mastoid air cells do not develop until after the second year of life.
Did You Know?
- The petrous part of the temporal bone is the densest bone in the human body
- The three smallest bones in the body, the auditory ossicles, are housed within the temporal bone
- The temporal bone is named from the Latin tempus because the hair over the temple is often the first to turn gray with time
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