Learning Objective: By the end of this lesson, the student should be able to describe the boundaries, contents, and clinical relevance of the infratemporal fossa, and identify key foramina and structures passing through it.
The infratemporal fossa is a deep, wedge-shaped space at the base of the skull, lying beneath the zygomatic arch and deep to the masseter muscle. It acts as a conduit between the cranial cavity, temporal fossa, and pterygopalatine fossa, transmitting important neurovascular and muscular structures.
Borders
| Boundary | Structure |
|---|---|
| Lateral | Ramus and condylar process of the mandible |
| Medial | Lateral pterygoid plate; tensor and levator veli palatini, superior constrictor |
| Anterior | Posterior wall of the maxillary sinus |
| Posterior | Carotid sheath |
| Roof | Greater wing of the sphenoid bone (transmits foramen ovale and spinosum) |
| Floor | Medial pterygoid muscle |
Note: The roof allows passage of the mandibular nerve (CN V3) and middle meningeal artery through the foramina.
Contents
Muscles
- The medial pterygoid and lateral pterygoid lie within the fossa.
- Masseter and temporalis are associated with its borders and mastication.
Nerves
- Mandibular nerve (CN V3) – motor and sensory branches enter via foramen ovale.
- Branches: auriculotemporal, buccal, lingual, and inferior alveolar nerves.
- Chorda tympani (CN VII): joins the lingual nerve → taste to the anterior 2/3 tongue.
- Otic ganglion: parasympathetic relay → parotid gland.
Vasculature
- Maxillary artery – terminal branch of the external carotid artery.
- Gives off the middle meningeal artery (through foramen spinosum).
- Venous drainage: via the pterygoid venous plexus, which connects to the cavernous sinus, creating a potential route for intracranial infection.
Clinical Relevance
Fracture of the Pterion
- The pterion marks the junction of the frontal, parietal, temporal, and sphenoid bones.
- Deep to it lies the middle meningeal artery (MMA) → rupture causes epidural (extradural) hematoma.
- Rapid increase in intracranial pressure → herniation, ischemia, coma, or death.
- Management: urgent neurosurgical decompression (burr holes).
Key Points
- The infratemporal fossa is deep to the masseter, below the temporal fossa, and posterior to the maxilla.
- It transmits CN V3, the maxillary artery, and the pterygoid muscles.
- The pterygoid venous plexus provides a dangerous route for facial infection to → cavernous sinus.
- Middle meningeal artery injury = epidural hematoma (high-yield clinical).
