Infratemporal Fossa

The infratemporal fossa is a space that exists below the temporal fossa. When seen on the skull without the soft tissues, these two anatomical landmarks can be seen to communicate with one another. 

The fossa is shaped irregularly and is situated below and medial to the zygomatic arch. It is not fully enclosed by bone. The infratemporal fossa serves as the passageway for many neurovascular structures. In addition to this, it contains superficial muscles like the inferior portion of the temporalis muscle, the lateral pterygoid muscle and the medial pterygoid muscle.

This article will discuss the anatomy and content of the infratemporal fossa.

Borders

The fossa is bordered superiorly by the greater wing of the sphenoid bone at the level of the foramina ovale and spinosum. Inferiorly, there is no bony anatomical structure to limit it, but there is the medial pterygoid muscle that runs anteriorly to attach to the mandible. The maxilla forms the anterior border of the cavity and the styloid and condylar processes make up the posterior barricade. Medially, the sphenoid and the palatine bones form a vertical bony rest and laterally the ramus and coronoid process cover the fossa's opening.

Contents

The following anatomical structures pass through the infratemporal fossa:

• the temporalis muscle
• the lateral pterygoid muscle
• the medial pterygoid muscle 
• the maxillary artery 
• the pterygoid venous plexus 
• the mandibular nerve 
• the posterior superior alveolar nerve 
• the chorda tympani 
• the otic ganglion
• the lesser petrosal nerve

Blood Supply

The vascular supply of the infratemporal fossa comes singularly from the maxillary artery. The branches have been divided into three sections for clarity and are categorized according to the anatomical structure closest to them, including the:

• mandibular part
• the pterygoid part
• the pterygopalatine part

The first part, which is the mandibular part, contains several arterial branches, such as the deep auricular, the anterior tympanic, the middle and accessory meningeal arteries and the inferior alveolar artery. The branches pass between the mandible and the sphenomandibular ligament.

The second part, otherwise known as the pterygoid part, contains vessels that pass obliquely and anterosuperiorly between the mandibular ramus and the temporalis muscle. The list of vascular constituents includes the anterior and posterior deep temporal artery, the masseteric artery, the pterygoid artery and the buccal artery.

Lastly, the pteryogopalatine, or third, part is that which holds the posterior superior alveolar artery that runs from the infratemporal fossa to the pterygopalatine fossa via the pterygomaxillary fissure.

Venous drainage is managed solely by the pterygoid plexus which is most dense in and around the infratemporal fossa.

Innervation

The infratemporal fossa is densely innervated due to the large amount of musculature and vessels that pass through it and that are situated adjacently. The maxillary nerve and the mandibular nerve contribute their branches, with the mandibular nerve providing nerves from both its anterior and posterior divisions. The anterior division contains the masseteric nerve, the anterior and posterior deep temporal, the medial and lateral pterygoid nerves and the buccal nerve. Meanwhile, the posterior division includes the auriculotemporal nerve, the lingual nerve, the inferior alveolar nerve and the mylohyoid nerve.

The maxillary nerve gives a single branch known as the posterior superior alveolar nerve. Other nervous structures are mentioned above in the contents of the fossa save the parasympathetics of the parotid gland, which can be found deep in the most medial part of the fossa.