Anatomy of the infratemporal fossa

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Introduction0:00–0:23

The infratemporal fossa, or IT fossa for short, is one of the most important spaces in the head, which acts as a conduit for neurovascular structures entering and exiting the cranial cavity.
It contains vital structures such as the maxillary artery and mandibular nerve. The infratemporal fossa is an irregularly shaped space located deep and inferior to the zygomatic arch, deep to the ramus of the mandible, and posterior to the maxilla.

Position0:23–1:10

More specifically, the fossa is bounded laterally by the the ramus of the mandible; medially by the lateral pterygoid plate; anteriorly by the posterior surface of the maxilla; posteriorly by the tympanic plate and the temporal bone’s mastoid and styloid processes; superiorly by the inferior surface of the greater wing of the sphenoid, and inferiorly by the attachment of the medial pterygoid muscle close to the angle of the mandible.
Now, the important structures within the infratemporal fossa include muscles, vessels and nerves. The muscles of the infratemporal fossa include the inferior portion of the temporalis muscle, the medial pterygoid and lateral pterygoid muscles.

Muscles1:10–2:13

Lying either superficial or deep to the lateral pterygoid muscle, there’s the pterygoid venous plexus and the maxillary artery.
Deep to the lateral pterygoid, the otic ganglion and mandibular nerve or cranial nerve V3 are located inferior to the foramen ovale.
The mandibular nerve splits within the infratemporal fossa into branches that include the inferior alveolar, auriculotemporal, lingual, buccal, masseteric, and deep temporal nerves.
Within the infratemporal fossa we also see the chorda tympani nerve, which is actually a branch or cranial nerve seven.Now let’s take a more in depth look at the different structures within the infratemporal fossa, starting with the vessels.

Vessels2:13–5:54

First up, the maxillary artery! This artery branches off from the external carotid artery, posterior to the neck of the mandible.
Then, it courses either deep to or on the superficial surface of the lateral pterygoid muscle, until it reaches the pterygomaxillary fissure.
From here onward, the maxillary artery continues as the sphenopalatine artery.Simple, right? Well, actually, this artery gives off no less than 15 branches along its course of the infratemporal fossa.
Let’s quickly run through six of the most important ones. First, the artery originates within the mass of the lateral pterygoid muscle, moves laterally and passes through the mandibular notch to enter the deep surface of the masseter muscle, which it supplies.Second, the deep temporal artery arises between the temporalis and pericranium, then pierces the deep surface of the temporalis muscle, which is supplies.Third, the buccal artery passes anteriorly and inferiorly alongside the buccal nerve, to supply the buccal fat pat, buccal oral mucosa, and the buccinator muscle.
Fourth, there’s the posterior superior alveolar artery, just anterior to the lateral pterygoid. This artery branches off the maxillary artery as it enters the pterygomaxillary fissure, and enters the infratemporal surface of the maxilla via the alveolar foramen.
It supplies the maxillary sinus and the upper premolar and molar teeth with their adjacent gingivae.Fifth, there’s the middle meningeal artery, deep to the lateral pterygoid muscle.
It arises medial to the neck of the mandible, and then moves upwards, passing through a split in the auriculotemporal nerve.
From this point, the middle meningeal artery traverses the foramen spinosum and enters the middle cranial fossa, to supply the dura mater of the lateral wall and calvaria of the neurocranium.Finally, there’s the inferior alveolar artery which begins its descent through the infratemporal fossa alongside the inferior alveolar nerve to enter the mandibular canal to supply the mandibular teeth, the mandible, mylohyoid muscle and the skin in the chin region.The last vascular structure within the infratemporal fossa is the pterygoid venous plexus.
This venous plexus is located between the temporalis and pterygoid muscles and it surrounds the maxillary artery. This way, the tributaries of the venous plexus parallel the branches of the maxillary artery.
Something to keep in mind about this plexus is its multiple routes of drainage. The plexus drains anteriorly into the facial vein through the deep facial vein, while also draining superiorly into the cavernous sinus via emissary veins.
This is important to understand because infections of the infratemporal fossa can spread to the cranial cavity this way.Time for a quick break!
Can you recall six important branches of the maxillary artery?Great! Now let’s switch gears and take a closer look at the nerves in the infratemporal fossa.
The main nerve of the infratemporal fossa is the mandibular nerve which is also known as the mandibular division of the trigeminal nerve, or cranial nerve V3.

Quiz5:54–6:06

Nerves6:06–11:46

The mandibular nerve arises from the trigeminal ganglion in the middle cranial fossa, and here it receives the motor root of the trigeminal nerve.
Then, it descends through the foramen ovale in the greater wing of the sphenoid and into the infratemporal fossa deep to the lateral pterygoid muscle.
The mandibular nerve supplies motor innervation to the muscles that derive from the first pharyngeal arch, including the muscles of mastication.
It also carries sensory innervation from the lower ⅓ of the face. Now, the mandibular nerve eventually splits into 6 main branches - the inferior alveolar, auriculotemporal, lingual, buccal, masseteric, and deep temporal nerves, all of which emerge through, or at the borders of the lateral pterygoid muscle.
Let’s go through each of these branches. First, the inferior alveolar nerve travels inferiorly deep to the lateral pterygoid muscle to enter the mandibular foramen on the medial aspect of the mandible.
Just before entering the mandibular foramen the inferior alveolar nerve gives off a small branch that supplies the mylohyoid muscle called nerve to mylohyoid.
Once the inferior alveolar nerve enters the mandibular foramen it travels within the mandibular canal where it forms the inferior dental plexus, which sends branches to all mandibular teeth.
A branch of the dental plexus, called the mental nerve, passes through the mental foramen to supply the skin and mucous membrane of the lower lip, chin, and the gingivae of the mandibular incisor teeth.Second, the auriculotemporal nerve branches posteriorly, deep to the lateral pterygoid, to encircle the middle meningeal artery.
It then supplies sensory innervation to the temporomandibular joint as it courses between the head of the mandible and the external acoustic meatus.
From this point on, it crosses the zygomatic process of the temporal bone and supplies the skin of the anterior side of the ear, or the auricle, and temporal region.
The auriculotemporal nerve also carries postganglionic parasympathetic fibers from the otic ganglion to the parotid gland.
Interestingly, these stimulatory parasympathetic fibers are from the glossopharyngeal nerve. The glossopharyngeal nerve sends preganglionic fibers to the otic ganglion, which is also located in the infratemporal fossa, just inferior to the foramen ovale and medial to the mandibular nerve.
From the otic ganglion, the postganglionic parasympathetic fibers reach the parotid gland by hitching a ride along the fibers of the auriculotemporal nerve.
Talk about cranial nerve teamwork!Okay, now, third, there’s the lingual nerve, which lies just anterior to the inferior alveolar nerve.
It travels anteroinferiorly, and then enters the mouth between the medial pterygoid muscle and the ramus of the mandible.
Here, the lingual nerve carries sensory information from the anterior two thirds of the tongue, the mouth’s floor, and the lingual gingivae.Fourth, the buccal nerve emerges from the lateral pterygoid muscle.
It also travels anteroinferiorly, and it pierces the buccinator muscle to eventually carry sensory innervation from the mucosa and skin of the cheek.
The last two branches of the mandibular nerve are the masseteric and deep temporal nerves. The masseteric nerve crosses the mandibular notch posteriorly, and enters the deep surface of the masseter to supply motor innervation, and also a sensory branch to the temporomandibular joint.
The deep temporal nerves originate above the upper border of the lateral pterygoid muscle, and pierce the temporalis muscle from its deep surface to supply motor innervation.
Great! Now, besides these six mandibular nerve branches, the infratemporal fossa is also home to the chorda tympani nerve - which is actually a branch of the facial nerve or cranial nerve seven.
The chorda tympani nerve exits the skull via the petrotympanic fissure, to enter the infratemporal fossa. Then, deep to the lateral pterygoid muscle, it hitches a ride with the lingual nerve to supply the tongue.
In fact, this nerve has both special sensory and parasympathetic fibers. Special sensory, or taste, sensation of the anterior ⅔ of the tongue is relayed to the brain via the chorda tympani nerve.
Additionally, the chorda tympani nerve also carries preganglionic parasympathetic fibers to the submandibular ganglion, before innervating the submandibular and sublingual salivary glands.
Now, let’s do a “nervous breakdown” of what we just learned. Can you label the main branches of the mandibular nerve seen here?Alright, as a quick recap!
The infratemporal fossa is bounded laterally by the the ramus of the mandible; medially by the lateral pterygoid plate; anteriorly by the posterior maxillary surface; posteriorly by the tympanic plate and the temporal bone’s mastoid and styloid processes; superiorly by the inferior surface of the greater wing of the sphenoid, and inferiorly by the attachment of the medial pterygoid muscle.

Quiz11:46–12:01

Review12:01–14:10

It contains a number of important muscles, vessels and nerves. The muscles of the infratemporal fossa include the inferior portion of the temporalis muscle, and the lateral and medial pterygoid muscles.
The maxillary artery is a branch of the external carotid artery, which travels superiorly on the lateral pterygoid muscle to the pterygomaxillary fissure, from where it continues as the sphenopalatine artery.
Along the way, it gives off a number of branches including the middle meningeal, inferior alveolar, masseteric, deep temporal, buccal, and posterior superior alveolar arteries.
The pterygoid venous plexus anastomoses anteriorly with the facial vein through the deep facial vein and also superiorly with the cavernous sinus via emissary veins.
The mandibular nerve arises from the trigeminal ganglion in the middle cranial fossa and once in the infratemporal fossa, it splits into 6 main branches: the inferior alveolar nerve, the auriculotemporal nerve, the lingual nerve, the buccal nerve, the masseteric nerve and the deep temporal nerve.
Finally, the infratemporal fossa is also home to the chorda tympani nerve, which is actually a branch of cranial nerve seven.
in the infratemporal fossa, it splits into six main branches, the inferior alveolar nerve nerve. The temporal fossa is also home to the court attempt, any nerve which is actually a branch of cranial nerve 7.