Infratemporal region

From IKE
Jump to: navigation, search

Infratemporal fossa

  • the region between the wall of the pharynx, medially and the ramus of the mandible, laterally
  • It is bordered behind by the styloid process and in front by the tuberosity of the maxilla
  • The base of the skull forms its roof


Muscles

Lateral pterygoid

  • originates partly from the roof of the infratemporal fossa and partly from the lateral pterygoid plate (lateral side)
  • Inserts onto the neck of the mandible and into the capsule and articular disc of the temporo-mandibular joint
  • The muscle serves to protract the mandible

Medial pterygoid

  • originates mainly from the lateral pterygoid plate (medial side) and inserts into the medial aspect of the angle of the mandible
  • serves to elevate and protract the jaw.

Innervation

Mandibular division of the trigeminal nerve.

Mandibular nerve (V3)

  • leaves the cranial cavity through the foramen ovale to enter the infratemporal fossa
  • Here, the nerve lies deep to the lateral pterygoid muscle, and gives motor branches to all the muscles derived from the first pharyngeal arch (pterygoids, masseter, temporalis, mylohyoid, anterior belly of digastric, as well as the tensor tympani and tensor palati)
  • There are also a number of sensory branches

Sensory branches

  • Buccal nerve: supplies the mucous membrane of the cheek as well as the skin over the buccinator
  • Inferior alveolar (dental) nerve
    • enters the mandible through the mandibular foramen
    • sensory to the mandibular teeth
    • Its terminal branch, the mental nerve, leaves the mandible through the mental foramen to supply the skin over the chin
    • Just before entering the mandibular foramen, the inferior alveolar nerve gives off the nerve to mylohyoid
    • The latter grooves the inside of the mandible and supplies the mylohyoid muscle and the anterior belly of digastric
  • lingual nerve
    • crosses the lateral surface of the medial pterygoid muscle, anterior to the inferior alveolar nerve
    • enters the floor of the mouth by passing under the superior constrictor muscle
    • provides general sensation to the floor of the mouth and to the anterior two-thirds of the tongue
    • Within the infratemporal fossa, the lingual nerve is joined by the chorda tympani (VII)
    • The chorda tympani enters the infratemporal fossa from the tympanic cavity
    • It tympani carries preganglionic parasympathetic fibres destined for the submandibular ganglion and taste fibres to the anterior two-thirds of the tongue
  • auriculo-temporal nerve
  • passes behind the neck of the mandible, where it becomes closely related to the parotid gland and superficial temporal vessels
  • Sensory to the parotid gland, temporomandibular joint, auricle and scalp
  • At its origin, the auriculo-temporal nerve receives postganglionic parasympathetic (secreto-motor) fibres from the otic ganglion and distributes them to the parotid gland.

Otic ganglion

Mandibular division of trifacial nerve, seen from the middle line.
  • parasympathetic
  • Allegedly lies immediately below the foramen ovale
  • in close proximity to the mandibular nerve
  • Receives preganglionic fibres from the glossopharyngeal nerve (and perhaps facial) via the lesser petrosal nerve
  • The lesser petrosal enters the infratemporal fossa through the foramen ovale
  • Post-ganglionic fibres are distributed primarily through the auriculo-temporal nerve to the parotid gland where they stimulate an increase in saliva production

Blood Supply

Branches of the internal maxillary artery.

Maxillary artery

  • a terminal branch of the external carotid artery
  • Enters the infratemporal fossa by passing deep to the neck of the mandible
  • Passes superficial or deep to the lateral pterygoid muscle, then through the pterygo-maxillary fissure, into the spheno-palatine fossa
  • Here, it divides into branches that supply the nasal cavities, air sinuses, pharynx, palate and maxillary teeth
  • Within the infratemporal fossa, the maxillary artery gives branches that accompany most of the nerves in the fossa
  • It also gives the middle meningeal artery which enters the cranial cavity through the foramen spinosum (adjacent to the foramen ovale)

Pterygoid venous plexus

  • formed around or within the lateral pterygoid muscle by several interconnecting veins that drain the areas supplied by the maxillary artery
  • A single, short maxillary vein usually arises from the plexus and joins the superficial temporal vein, to form the retromandibular vein
  • The pterygoid plexus has communications with:
    • The cavernous sinus - via an emissary vein
    • ophthalmic veins - through the pterygo-maxillary and inferior orbital fissures
    • facial vein - via the deep facial vein

Temporo-mandibular joints (TMJ)

Sagittal section of the articulation of the mandible.
  • bilateral, synovial joints
  • between the heads of the mandible and the mandibular (glenoid) fossae of the temporal bones
  • A fibrocartilaginous, articular disc divides each joint into two
    1. Lower part
      • Between the disc and the head of the mandible, to which the disc attached
      • a simple hinge movement (elevation and depression) occurs
    2. Upper part
      • Between the disc and the glenoid fossa
      • there is a sliding movement, so that the disc moves forward, out of the mandibular fossa and on to the articular eminence (tubercle) of the temporal bone, carrying the mandible with it
      • This movement is called protraction
      • The mandible is retracted when the disc slides back into the fossa
      • When the mandible is protracted, a much wider range of hinge movement (elevation and depression) is possible.

Resources