Infratemporal fossa

The infratemporal fossa is an irregularly shaped cavity in the face that is touted as being one of the most anatomically complex regions in the head and neck. The location of the infratemporal fossa makes it an area of interest for pathology treated by many surgical subspecialties including otolaryngology, neurosurgery, and maxillofacial surgery. The anatomic space defined as the infratemporal fossa contains a variety of nerves, arteries, veins, and muscles.

The infratemporal fossa is an anatomic space located below the temporal fossa. The boundaries include the greater sphenoid wing, floor of the temporal fossa, pterygoid plates, masseter muscle, mandible, posterior wall of the maxilla, glenoid fossa, tensor veli palatini, styloid process, and mastoid.

The infratemporal fossa (ITF) is a continuation of the temporal fossa between the internal surface of the zygoma and the external surface of the temporal bone and greater wing of the sphenoid bone. It is sitting deep to the ramus of the mandible. The principal structure to enable understanding of these relationships is the lateral pterygoid muscle. Other important structures include the medial pterygoid muscle, the maxillary artery, the pterygoid venous plexus, the otic ganglion, the chorda tympani nerve, and the mandibular nerve ^{1) 2) 3) 4)}

A clinically significant feature of the infratemporal fossa involves potentially life-threatening spread of infection from the infratemporal fossa through the pterygoid plexus to the cavernous sinus ⁵⁾.

Its boundaries may be defined by:

anteriorly, by the infratemporal surface of the maxilla and the ridge which descends from its zygomatic process

posteriorly, by the articular tubercle of the temporal and the spina angularis of the sphenoid

superiorly, by the greater wing of the sphenoid below the infratemporal crest, and by the under surface of the temporal squama, containing the foramen ovale, which transmits the mandibular branch of the trigeminal nerve, and the foramen spinosum, which transmits the middle meningeal artery

inferiorly, by the medial pterygoid muscle attaching to the mandible

medially, by the lateral pterygoid plate

laterally, by the ramus of mandible, which contains the mandibular foramen, leading to the mandibular canal through which the inferior alveolar nerve passes. This also contains the lingula, a triangular piece of bone that overlies the mandibular foramen antero-medially. Finally, the mylohyoid groove descends obliquely transmitting the mylohyoid nerve the only motor branch of the posterior division of the trigeminal nerve.

Lower part of the Temporalis and masseter muscles (origin of masseter muscle:lower margin of the inner surface of zygomatic bone insertion : outer surface of the ramus of the mandible )

Lateral and medial pterygoid muscles

The internal maxillary vessels, consisting of the maxillary artery originating from the external carotid artery and its branches.

Internal maxillary branches found within the infratemporal fossa including the

middle meningeal artery

inferior alveolar artery

deep temporal artery

buccal artery

pterygoid venous plexus

retromandibular vein

Mandibular nerve, inferior alveolar nerve, lingual nerve, buccal nerve, chorda tympani nerve, and otic ganglion.

Mandibular nerve which is the third branch of the trigeminal nerve (CN V3), also known as the “inferior maxillary nerve” or nervus mandibularis, enters infratemporal fossa from middle cranial fossa through foramen ovale.

Motor branches:

masseteric nerve

deep temporal nerve

lateral pterygoid nerve and medial pterygoid nerve

Its motor fibers innervate all the muscles of mastication plus the mylohyoid, anterior belly of the digastric, and the tensores veli palati and tympani

Sensory innervation:

meningeal nerve

buccal nerve

auriculotemporal nerve

lingual nerve

inferior alveolar nerve

auricle

external acoustic meatus

tympanic membrane

temporal region

cheek

skin overlying the mandible (except at the angle of the mandible)

floor of mouth

lower teeth

gingiva

see Infratemporal fossa approach.