Temporal and Infratemporal Fossae Flashcards
Coronoid process
the site of insertion for the temporalis muscle
Mandibular foramen
Where Inferior Alveolar nerve and artery pass into the mandible
Mental foramen
The Inferior Alveolar nerve and artery exit the bone through the mental foramen as the Mental nerve and artery
Muscles of mastication
1) Temporalis,
2) Masseter,
3) Medial pterygoid
4) Lateral pterygoid
All are inverted by the Mandibular nerve (CN V3).
Elevation or closing the jaw
1) Temporalis,
2) Masseter,
3) Medial pterygoid
Depression or opening the jaw
1) gravity,
2) mylohyoid
3) digastric
4) geniohyoid
Protrusion or Anterior movement of the jaw
Lateral pterygoid (assisted somewhat by Medial pterygoid)
Restriction orPosterior movement of the jaw
The posterior, horizontal fibers of temporalis (assisted by digastric and geniohyoid)
Sliding and rotatory (grinding) movement of the jaw
1) Medial pterygoid
2) Lateral pterygoid
Temporalis Muscle
• Origin: Floor of the temporal fossa which includes
portions of four bones of the cranium (temporal, parietal, frontal and sphenoid) which come together at the pterion.
• Insertion: The muscle passes medial (deep) to the zygomatic arch to insert on the coronoid process of
the mandible and is covered on its external surface by the tough temporalis fascia from which it also
originates.
• Innervation: Mandibular nerve (CN V3)
Temporalis fascia
• Origin: Superior temporal line
• Insertion: Inserts on and supports the zygomatic
arch, resisting the inferior pull of the masseter muscle
Masseter muscle
- Origin: Zygomatic arch
- Insertion: lateral aspect of the ramus and angle of the mandible.
- Innervation: Mandibular nerve (CN V3)
Medial pterygoid
- Origin: Medial surface of the lateral pterygoid plate
- Insertion: Medial aspect of the ramus and angle of the mandible inferior to the mandibular foramen
- Innervation: Mandibular nerve (CN V3)
Lateral pterygoid
- Origin: Lateral surface of the lateral pterygoid plate
- Insertion: Capsule and articular disc of the Tempporomandibular joint (TMJ) and the neck of the mandible (pterygoid fovea)
- Innervation: Mandibular nerve (CN V3)
If one lateral pterygoid muscle is paralyzed, the contraction of the contralateral muscle will cause the jaw to protrude toward the side of the paralyzed
muscle.
Mandibular notch
Mandibular artery and nerve passes laterally through the mandibular notch
Buccinator muscle
Innervated by CN VII; Maxillary nerve
Parotid Duct
Pierces through the buccinator muscle to drain the oval cavity opposite the second maxillary molar tooth
Temporal Fossa
The temporal fossa is a shallow depression superior
to the zygomatic arch and contains the temporalis
muscle and its blood and nerve supply as well as the zygomaticotemporal branch of the maxillary nerve (V2).
Sphenomandibular ligament
It runs from the spine of the sphenoid to the lingula on the mandibular ramus, helps maintain the mandibular condyle in position and becomes fully taut when the jaw is half open.
Temporomandibular joint (TMJ)
The TMJ is a very complex synovial joint involving
the condyle of the mandible and both the mandibular fossa and articular tubercle of the temporal bone, as well as an articular disc made of
fibrous connective tissue with some features similar
to cartilage
Infratemporal fossa
It’s an extracranial area located just inferior to the
temporal fossa and the zygomatic arch.
Structures in the Infratemporal fossa
1) The two pterygoid muscles
2) Maxillary artery
3) Mandibular nerve (V3)
4) Chorda tympani nerve
5) Pterygoid venous plexus
6) The parasympathetic otic ganglion
Major branches of the Maxillary artery
1) Middle meningeal artery
2) Inferior alveolar artery
Middle meningeal artery
Pathway:Passes between the two roots of the auriculotemporal nerve (a branch of V3) and ascends to and through the foramen spinosum to enter the cranial cavity
Supplies: Major supplier of the dura mater.
Inferior alveolar artery
Pathway: travels inferiorly to enter the mandibular foramen
Supplies: supplies the mandibular teeth and soft
tissues
It exits the mandible anteriorly through the mental
foramen as the mental artery.
Lesser branches of the Maxillary artery
First Portion
1) the deep auricular,
2) anterior tympanic
3) accessory meningeal
They contribute blood to the external acoustic meatus, middle ear and dura mater
Lesser branches of the Maxillary artery
Second Portion
1) Deep temporal - temporalis
2) Masseteric artery - masseter
3) Pterygoid artery - pterygoid
4) Buccal artery - buccinator
They supply muscles of the temporal and infratemporal fossa
Mandibular Nerve
It enters the infratemporal fossa through the foramen ovale and innervates deeper structures of
the face and oral cavity.
It is the only branch of the trigeminal nerve with
somatic efferent motor components to the 4 muscles of mastication and 4 other muscles
It also has 5 sensory nerve branches
Nerve branches of Mandibular Nerve
1) Inferior alveolar
2) Lingual
3) Auricotemporal
4) Meningeal
5) Buccal
Inferior alveolar
It enters the mandibular foramen after giving off the
motor nerve to the mylohyoid and anterior belly of
the digastric muscles; sensory to the mandibular
teeth and, as its terminal mental nerve, the lower lip
and chin.
Lingual
It provides general sensation to the anterior ⅔ of the
tongue and floor of mouth. (Accompanied for part of
its course by the chorda tympani nerve.)
Auricotemporal
It travels beside the parotid gland and ascends next
to the superficial temporal artery to the temporal region; sensory to temporal skin, ear structures, TMJ and parotid gland.
Also carries secretomotor parasympathetic postganglionic fibers from the otic ganglion to the
parotid.
Meningeal
It travels with the middle meningeal artery through
the foramen spinosum to supply the dura mater of
the middle cranial fossa mainly.
Buccal
It provides sensory to the skin, oral mucosa and gingiva in the cheek region. (The buccinator muscle
itself is innervated by the facial nerve.)
Muscles Innervated by the Mandibular Nerve
It innervates the four muscles of mastication and the following muscles:
1) Anterior belly of the digastric
2) Mylohyoid
3) Tensor veli palatini (in soft palate)
4) Tensor tympani (middle ear)
Chorda Tympani
Preganglionic parasympathetic fibers exit the brainstem with the facial nerve. In the facial canal, it branches as the Chorda Tympani. It hitchikes a ride with the Lingual nerve ans synampses in the Submandibular ganglion.
Postganglionic secretomotor fibers travel to the submandibular and sublingual
salivary glands as well as the multiple minor microscopic salivary glands in the inferior oral cavity.
Taste Fibers
Afferent special sense taste fibers from the anterior
⅔ of the tongue, originally traveling in the lingual
nerve, join the chorda tympani and travel posteriorly
to join CN VII back to the brainstem.
These taste fibers have their pseudo-‐unipolar nerve
cell bodies in the geniculate ganglion of CN VII.
Parasympathetic to Parotid
Other preganglionic parasympathetic fibers leave the glossopharyngeal nerve (CN IX) inferior to the
jugular foramen in the tympanic nerve.
They enter the middle ear and ascend on the promontory in the tympanic plexus and exit it as the lesser petrosal nerve.
After re-‐entering the cranial cavity they travel down
the petrous ridge and exit through the foramen ovale
to synapse in the ottic ganglion.
Postganglionic parasympathetc secretomotor fibers
“hitch-‐hike a ride” on the auriculotemporal nerve to
the parotid gland.
Pterygoid Venous Plexus
The pterygoid venous plexus also has direct valveless drainage into the cavernous sinus, so infections could spread there and lead to a cavernous sinus thrombosis, a potentially fatal situation.
