The infratemporal fossa is a complex anatomical area located at the base of the skull, deep to the masseter muscle. It is closely associated with both the temporal and pterygopalatine fossae, which are themselves located at the base of the skull, and further functions as a conduit for many neurovascular structures entering and leaving the cranial cavity. This article will outline the borders and content of the fossa before examining its clinical relevance.
The infratemporal fossa can be said to have a wedge-like shape. It is located deep to the masseter muscle and zygomatic arch – to which the masseter muscle attaches. The fossa is closely associated with both the pterygopalatine fossa, via the pterygomaxillary fissure, and with the temporal fossa, which lies superiorly (figure 1.0).
The boundaries of this complex structure consist of both bone and muscle:
The roof of the infratemporal fossa, formed by the greater wing of the sphenoid bone, provides an important passage for a number of neurovascular structures that are transmitted through the foramen ovale and spinosum. These structures include the mandibular branch of the trigeminal nerve and the middle meningeal artery.
The infratemporal fossa acts as a pathway for a range of neurovascular structures passing to and from the cranial cavity, the pterygopalatine fossa and the temporal fossa. It also contains some of the muscles of mastication; in fact, the lateral pterygoid muscle divides the fossa contents in two. The branches of the mandibular nerve lie deep to the muscle, while the maxillary artery lies superficial to it.
The infratemporal fossa is associated with the muscles of mastication. The medial and lateral pterygoid muscles are located within the fossa itself; whilst the masseter and temporalis muscles insert and originate into the borders of the fossa.
The infratemporal fossa forms an important passage for a number of nerves originating in the cranial cavity (figure 1.2):
The infratemporal fossa contains several important vascular structures:
The pterion is an important structure in cranial anatomy – it is the point where the temporal, parietal, frontal and sphenoid bones meet and serves as a point of potential weakness in the skull. The infratemporal fossa is therefore an area of particular clinical relevance for fractures of the pterion.
In order to understand the significance of the infratemporal fossa, it is important to recognize its anatomical composition and contents. The fossa is closely associated with many muscles of mastication, providing a passage for vital neurovascular structures – including the mandibular branch of the trigeminal nerve, the maxillary artery and the middle meningeal artery – to the face and head, and further offers the potential for infections of the face to spread intracranially. As such, fractures of the pterion – due to its immediate proximity – may have significant implications for the long-term health and function of the facial structures.
The pterion is an important structure in cranial anatomy. It is located at the junction of the four bones that make up the skull - temporal, parietal, frontal and sphenoid - and is considered to be the weakest point of the skull. Trauma in this region can lead to an extradural haematoma, which is the accumulation of blood outside of the dura mater. This is due to the fact that the middle meningeal artery (MMA) lies deep to the pterion.
An extradural haematoma causes a dangerous increase in intra-cranial pressure due to the accumulation of blood in the space. This can lead to herniation of brain tissue and ischemia, and has a variety of symptoms including nausea, vomiting, seizures, bradycardia and limb weakness. Treatment for minor cases can involve the use of diuretics, while more extreme haemorrhages can necessitate surgical intervention in the form of drilling burr holes into the skull.
The boundaries of the infratemporal fossa, which is associated with the pterion, is made up of both bone and muscle. Laterally, it is made up of the condylar process and ramus of the mandible bone, while medially there is the lateral pterygoid plate, the tensor veli palatine, the levator veli palatine and the superior constrictor muscles. Anteriorly, the fossa is bounded by the posterior border of the maxillary sinus, while posteriorly it is demarcated by the carotid sheath. The greatest wing of the sphenoid bone forms the roof, and the medial pterygoid muscle forms the floor.
The infratemporal fossa also acts as a pathway for a number of neurovascular structures that pass to and from the cranial cavity, the pterygopalatine fossa and the temporal fossa. It also holds several of the muscles of mastication, with the lateral pterygoid splitting the fossa content in half. Branches of the mandibular nerve are located deep to the lateral pterygoid muscle, while the maxillary artery is situated superficially. It is also associated with the muscles of mastication, with the medial and lateral pterygoids found within the fossa, and the masseter and temporalis muscles originating and inserting into it.
The infratemporal fossa also serves as an important passage for a range of nerves that arise from the cranial cavity. These include the mandibular nerve, which is a branch of V, the trigeminal nerve; the auriculotemporal, buccal, lingual and inferior alveolar nerves, which are the sensory branches of the trigeminal nerve; the chorda tympani, which is a branch of the facial nerve (VII); and the otic ganglion, which is a parasympathetic collection of neuron cells that connect to the auriculotemporal nerve in order to reach the parotid gland.
The infratemporal fossa also contains several important vascular structures. These include the maxillary artery, which is the terminal branch of the external carotid artery, and gives rise to the middle meningeal artery which passes through the superior border via the foramen spinosum. There is also the pterygoid venous plexus, which serves to drain the blood from the eyes and is directly connected to the cavernous sinus, providing a potential route for infection to travel into the cranial cavity.
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