The infratemporal fossa is an irregular space at the lateral aspect of the skull. As its name suggests, it is situated just inferior to the temporal fossa and deep to the ramus of the mandible. The temporal and infratemporal fossae communicate with each other through the opening deep to the zygomatic arch. In addition, the infratemporal fossa communicates medially with the pterygopalatine fossa through the pterygomaxillary fissure and anteriorly with the orbit through the inferior orbital fissure.
The infratemporal fossa has four well-defined walls which are as follows: anterior, lateral, medial, and superior (roof). It's important to note that the fossa has no anatomical floor, thus it is open to the neck region. The fossa contains a number of structures, mainly neurovascular structures and muscles of mastication.
The main function of the infratemporal fossa is to serve as the passageway for numerous neurovascular structures and to protect them from external factors.
This article will discuss the anatomy and function of the infratemporal fossa.
|Definition||The infratemporal fossa is an irregular space at the lateral aspect of the skull, situated inferior to the temporal fossa and deep to the ramus of the mandible.|
Anterior wall: Posterior and infratemporal surface of the maxilla
Posterior wall: Tympanic plate, mastoid and styloid processes of the temporal bone.
Medial wall: Lateral pterygoid plate of the pterygoid process of sphenoid bone, pharynx, and tensor veli palatini muscle
Lateral wall: Ramus of mandible
Superior wall (roof): Greater wing of the sphenoid bone, infratemporal surface of the temporal bone
Muscles: Lateral pterygoid muscle, medial pterygoid muscle, temporalis muscle
Vessels: Maxillary artery and its branches, pterygoid venous plexus
Nerves: Mandibular nerve and its branches, chorda tympani, lesser petrosal nerves; otic ganglion
|Connections||Temporal fossa, pterygopalatine fossa, orbit|
The walls of the infratemporal fossa include:
- The superior wall (roof) of the infratemporal fossa is mostly formed by the infratemporal surface of the greater wing of the sphenoid bone. The small part of the roof is formed by the infratemporal surface of the temporal bone. The roof of the infratemporal fossa contains the foramen spinosum and foramen ovale.
- The anterior wall is formed by the infratemporal surface of the maxilla. The upper margin of the anterior wall is at the inferior orbital fissure, while the inferior end is at the maxillary tuberosity.
- The medial wall is formed anteriorly by the lateral pterygoid plate of the pterygoid process of the sphenoid bone. Posteriorly, the medial wall is formed by the pharynx and tensor veli palatini muscle. It is separated from the anterior surface by the pterygomaxillary fissure.
- The lateral wall is formed by the ramus of the mandible.
- The posterior wall is not well defined as other walls. This wall is partly formed by the tympanic plate, along with the mastoid and styloid processes of the temporal bone.
- The 'floor' is open towards the neck region and it extends up to the level of the base of the mandible.
Try out our free labeling diagrams about the bones of the skull to enhance your learning process.
The major structures present in the infratemporal fossa can be divided into three types:
- Muscular structures
- Nervous structures
- Vascular structures
The infratemporal fossa is associated with the muscles of mastication. The medial pterygoid and lateral pterygoid muscles are located fully within the fossa itself and occupy most of the space in the infratemporal fossa. In addition, the inferior part of the temporalis muscle is also associated with the infratemporal fossa.
Most of the nervous structures in the infratemporal fossa come from the mandibular nerve (CN V3) which exits the skull through the foramen ovale. Upon exiting the skull the mandibular nerve gives off its meningeal branch called the spinous nerve, which re-enters the skull through the foramen spinosum. The otic ganglion is attached to the mandibular nerve at this level.
The mandibular nerve then terminates by splitting its anterior and posterior divisions. The anterior division gives off the deep temporal, masseteric, and buccal nerves. The posterior division gives off three branches including inferior alveolar, lingual and auriculotemporal nerves. The chorda typani, a branch of the facial nerve (CN VII), also appears in the infratemporal fossa to unite with the lingual nerve.
The main arterial vessel located in the infratemporal fossa is the maxillary artery, the terminal branch of the external carotid artery. The maxillary artery runs superficially, and within the fossa, it gives rise to several branches including the middle meningeal artery, inferior alveolar artery, masseteric artery, buccal artery, anterior and posterior deep temporal arteries. The middle meningeal artery is one of the larger branches that courses superiorly and passes through the superior wall of the fossa via the foramen spinosum. The inferior alveolar artery follows the course of the inferior alveolar nerve.
The small venous vessels of the infratemporal fossa form the venous network known as the pterygoid venous plexus. This plexus accompanies the maxillary artery, and lies around and within the lateral pterygoid muscle. Around the neck of the mandible, the pterygoid venous plexus gives rise to the maxillary vein which then unites with the superficial temporal vein to form the retromandibular vein. The venous system of the infratemporal fossa is important in the spread of potential infection in this area.
The infratemporal fossa can be a significant area for clinicians because it is an area where infectious and neoplastic processes can either arise from or spread to. Pathology found in this region tends to spread posteriorly or inferiorly, due to well-defined anterior, medial, and lateral bony barriers present in the infratemporal fossa. The symptoms that can occur from pathology present in this region, include restriction of the range of motion of the jaws (trismus) and any manifestation of mandibular nerve compression (e.g. paresis of mastication muscles, numbness or loss of taste sensation from the tongue, anesthesia of the gums, or speech articulation difficulties).
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