The+Temporal+and+Infratemporal+Regions

=**The Temporal and Infratemporal Regions**=


 * 1. Define the temporal fossa.**

The temporal fossa is located above the zygomatic arch. The zygomatic arch is made up by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone and forms the inferior limit of the temporal fossa.

The temporal fossa is an oval region bound by the temporal lines, and the frontal and zygomatic bones. The superior temporal line is the attachment point of the temporalis fascia and the superior border of the temporal region. The inferior temporal line is where the temporalis muscle attaches.


 * 2. What are the contents of the temporal fossa?**

The temporal fossa is mostly filled by the temporalis muscle which attaches at the inferior temporal line. Its fascia continues up to attach at the superior temporal line.


 * 3A. How do you define the infratemporal fossa?**

The infratemporal fossa is the irregular-shaped space inferior to the zygomatic arch, deep to the ramus of the mandible, and posterior to the maxilla.


 * 3B. Do the temporal and infratemporal fossa communicate?**

The temporal and infratemporal fossa communicate through the interval between (deep to) the zygomatic arch and (superficial to) the cranial bones.


 * 4A. What are the contents of the infratemporal fossa?**

The infratemporal fossa contains portions of the muscles of mastication, the branches of the maxillary artery, the pterygoid plexus of veins, and branches of the mandibular nerve (CN V3).

The muscles of mastication include the temporalis, masseter, and medial and lateral pterygoid muscles.

The important branches of the maxillary artery include the middle meningeal, accessory meningeal, inferior alveolar, deep temporalis, and posterior superior alveolar arteries.


 * 4B. What foramina are associated with the infratemporal fossa?**

There are several foramina associated with the infratemporal fossa in the mandible and the sphenoid bones.

__Mandible__ The mandibular formaen is the entrance for the mandibular canal which runs through the mandible, providing a path the inferior alveolar nerve, artery, and vein to enter and supply the mandible and teeth. The inferior alveolar nerve and vessels exit of the mandibular canal at the mental foramen where they become the mental nerve, artery and vein.

__Sphenoid__ The superior orbital fissure is a foramen lying between the lesser and greater wings of the sphenoid bone. Several important anatomical structures pass through the superior orbital fissure: the superior and inferior divisions of the oculomotor nerve (CN III), trochlear nerve (CN IV), lacrimal, frontal, and nasociliary branches of the ophthalmic nerve (CN V1), abducens nerve (CN VI), superior ophthalmic vein, and sympathetic fibers from the cavernous plexus.

As is medical school tradition, there is a dirty mnemonic to help remember these structures:


 * Structure || Mnemonic ||
 * Lacrimal branch of ophthalmic nerve (CN V1) || Lazy ||
 * Frontal branch of ophthalmic nerve (CN V1) || French ||
 * Trochlear nerve (CN IV) || Tarts ||
 * Superior division of oculomotor nerve (CN III) || Sit ||
 * Nasociliary branch of ophthalmic nerve (CN V1) || Naked ||
 * Inferior division of oculomotor nerve (CN III) || In ||
 * Abducens nerve (CN VI) || Anticipation ||
 * (Superior) Ophthalmic vein || Of ||
 * Sympathetic fibers from cavernous sinus || Sex ||

The greater wing of the sphenoid also includes the foramen rotundum, foramen ovale, and foramen spinosum, arranged anterior to posterior, and medial to lateral. The foramen rotundum transmits the maxillary nerve (CN V2). The foramen ovale transmits the mandibular nerve (CN V3) and the accessory meningeal artery (branch of the maxillary artery). The foramen spinosum transmits the middle meningeal artery, a branch of the maxillary artery from the external carotid.


 * 4C. What are the muscles of the fossa?**

__Some Basic Anatomy of the Mandible__ //Mandibular notch//: at the superior portion of the ramus over which the masseteric artery, vein, and nerve pass over. //Coronoid process//: Pointy anteriosuperior part of the mandible. //Head or Condylar process//: the only articular surface of the mandibule; articulates with the temporal bone at the temporal-mandibular joint (TMJ). //Angle:// The corner of the mandible. //Lingula//: attachment point on the inside surface of the mandible for the sphenomandibular ligament which is the primary ligament holding the mandibule to the skull. //Mylohyoid grove//: a groove alone the inside surface of the mandible for nerve to mylohyoid muscle. //Mylohyoid line//: Attachemnt point along the inside surface of the mandible for the mylohyoid muscle.

__Some Basic Anatomy of the Sphenoid Bone__ //Greater wing//: Contributes to the middle cranial fossa. //Lesser wing//: Contributes to the anterior cranial fossa. //Body//: Central part of the sphenoid between the greater and lesser wings. //Pituitary fossa//: Where the pituitary gland sits on the sella turcica on the sphenoid body. //Lateral pterygoid plate//: Where muscles of mastication attach. //Medial pterygoid plate//: where the muscles of the palate and pharynx attach.

The muscles in the infratemporal fossa are muscles of mastication, and include the temporalis, masseter, and medial and lateral pterygoid muscles. //All the muscles of mastication are innervated by the mandibular nerve (CN V3) by named nerves (e.g., nerve to temporalis, etc.).//

__Temporalis__ The temporalis fascia and muscle originates on the frontal bone and adjacent bones (parietal and occipital bones), along the superior and inferior temporal lines, respectively. It inserts on the mandibule on the coronoid process and anterior margin of the ramus. Its main action is elevation and retraction.

__Masseter__ The masseter originates on the zygmatic arch; the superficial and deep heads orginate from the superficial and deep surfaces of the zygmatic arch. It inserts on the lateral surface of the famus of the mandible from the coronary process to the angle. Its main action is elevation and protraction.

__Medial Pterygoid__ The medial pterygoid muscle originates on the medial aspect of the lateral pterygoid plate and the posterior maxilla. It inserts on the internal surface of the ramus inferior to the mandibular foramen. Its main action is elevation and protraction of the mandibule. Acting alternately, they produce a grinding motion.

The medial pterygoid and masseter muscles have fibers that run in the same direction, froming a sling for the mandible with the masseter on the outside and the medial pterygoid muscle on the inside.

__Lateral Pterygoid__ The lateral pterygoid muscle has two heads; one originates on the sphenoid bone and the other on the lateral surface of the lateral pterygoid plate. They insert on the mandibular condyle and no the articular disk of the temporal mandibular joint. Its main action is protraction and depression of the chin. Acting alternately, they produce the side-to-side movements of the mandible.


 * 4D. What are the major blood vessels of the fossa?**

The branches of the maxillary artery provide the main blood supply to the infratemporal fossa. The maxillary artery is one of the terminal branches of the external carotid artery. It passes posterior to the neck of the mandible and may pass anterior or posterior to the lateral pterygoid muscle. The maxillary artery leaves the infratemporal fossa to enter the posterior aspect of the nasal cavity through the infraorbital fossa.

The maxillary artery sometimes stays superfical to the lateral pterygoid muscle but can also dive deep to the lateral pterygoid muscle. When the maxillary dives deep, the deep tempral artery looks a lot like the maxillary artery, but it would not go through the infratemporal fossa and into the nasal cavity.

The important branches of the maxillary artery in the infratemporal fossa include the middle meningeal artery, accessory meningeal artery, inferior alveolar artery, deep temporal artery, and the posterior superior alveolar artery.

__Middle Meningeal Artery__ Dives deep into the foramen spinosum and into the cranial vault.

__Accessory Meningeal Artery__ Travels through the foramen ovale with the mandibular nerve (CN V3)

__Inferior Alveolar Artery__ Enters the mandibular canal through the mandibular foramen with the inferior alveolar vein and nerve. The inferior alveolar artery supplies the teeth. When the inferior alveolar artery, vein, and nerve exit the mandibular canal through the mental foramen, it ebcues the mental artery, vein, and nerve and goes on to supply the skin of the chin, and mucous membranes.

__Deep Temporal Artery__ Goes to supply the temporalis muscle.

__Posterior Superior Alveolar Artery__ Enters the maxillia to supply the upper posterior maxillary teeth (upper molars).

The pterygoid plexus of veins are the deep veins of the face and lies deep to the temporalis muscle to receive veins from the orbit, face, and pharynx to drain ultimately into the internal jugular vein. It also wraps around the maxillary arteries. See Vessels and Nerves of the Neck for drainage pattern.


 * 4E. What are the nerves of the fossa?**

All the nerves of the infratemporal fossa are branches of the mandibular nerve (CN V3) except for the chorda tympani. The mandibular nerve has both motor and sensory fibers and exits the middle cranial fossa into the infratemporal fossa using the foramen ovale.

__Motor Branches__ The motor branches of the mandibular nerve (CN V3) supply the muscles of mastication (temporalis, masseter, and medial and lateral pterygoid muscles).

It also supplies the tensor tympani (in the middle ear; used to dampen loud noises) and the tensor veli palatine (in the soft palate).

The mandibular nerve (CN V3) also gives off a motor branch to the nerve to mylohyloid, which branches off the inferior alveolar nerve and runs outside the mandibular canal on the mandibular groove on the inside surface of the mandibule. The nerve to mylohyoid supplies the mylohyoid and the anterior belly of the digastric muscle.

All the muscles innervated by the motor branch of the mandibular nerve (CN V3) (i.e., all the muscles of mastication, tensor muscles, mylohyoid muscle, and anterior belly of the digastric) are derived from the first pharyngeal arch.

__Sensory Branches__ The mandibular nerve (CN V3) gives off four sensory branches: the auriculotemporal nerve, inferior alveolar nerve, lingual nerve, and the buccal nerve (or long buccal nerve).

The auricular temporal nerve lies deep in the infratemporal fossa and encircles the middle meningeal artery. It exits the fossa laterally int eh substance of the parotid gland and travels with the superficial temporal artery on to the face. It supplies the sensory innervation to the ear, temple, and scalp.

The inferior alveolar nerve goes into the mandibular foramen to enter the mandibular canal. It exits the mental foramen and continues as the mental nerve. The inferior alveolar nerve supplies the sensory innervation to the lower teeth. The mental nerve supplies sensory innervation to the skin of the chin, lower lip, etc.

The lingual nerve lies on the medial pterygoid muscles and receives general sensation (pain, touch, and temperature) on the anterior 2/3 of the tongue.

The buccal nerve or long buccal nerve supplies sensory information to the mucous membrane of the cheek and skin on the cheek.


 * 4F. What is the otic ganglion? Where is it located? What is the significance? Are there any other ganglia in the infratemporal fossa?**

The otic ganglion is a parasympathetic ganglion located directly below the foramen ovale, medial to the mandiblar nerve and posterior to the medial pterygoid muscle. Presynaptic parasympathetic fibers derived from the glossopharyngeal nerve (CN IX) travel a branch of CN IX, the lesser petrosal nerve. The lesser petrosal nerve hitchikes (//but does not join//) along the mandibular nerve (CN V3) to reach the otic ganglion. There, the parasympathetic fibers synapse and join the auriculotemporal nerve. The parasympathetic fibers travel the auriculotemporal nerve and jump off at the parotid gland to supply secretomotor parasympathetic innervation. The auricular motor continues to supply sensory innervation to the face.


 * 4G. What is the chorda tymani? How did it acquire its name? How is it associated with the infratemporal fossa?**

The chorda tympani is a branch of the facial nerve (CN VII) that joins with the lingual nerve in the infratemporal fossa, and carries taste fibers from the anterior 2/3 of the tongue as well as preganglionic parasympathetic fibers to the submandibular and sublingual glands.

Rather than leave the skull with the facial nerve, the chorda tympani travels through the middle ear, where it runs from posterior to anterior across the tympanic membrane. The nerve continues through the petrotympanic fissure, after which it emerges from the skull into the infratemporal fossa. In the infratemporal fossa, the chorda tympani combines with the larger lingual nerve, a branch of the mandibular nerve (CN V3) with which it becomes intimate with.

The fibers of the chorda tympani travel with the lingual nerve to the submandibular ganglion. The preganglionic parasympathetic fibers of the chorda tympani synapse with postganglionic fibers which go to supply innervation to the submandibular and sublingual salivary glands. Special sensory taste fibers extend from the chorda tympani to the anterior 2/3rds of the tongue via the lingual nerve.


 * 4H. Can you differentiate between sensory and motor nerves as they related to the infratemporal region?**

The mandibular nerve (CN V3) supplies the sensory and motor nerves in the infratemporal region. The motor nerves supply the skeletal muscles derived from 1st pharyngeal arch (the 4 muscles of mastication, 2 tensor muscles, mylohyoid, and the anterior belly of the digastric muscle). The sensory nerves supply the skin of the chin, cheek, and temple as well as sensory innervation to lower teeth, gums, tongue.