Infratemporal Fossa HN

• 1) the inferior part of the temporal muscle,
• 2) lateral & medial pterygoids,
• 3) maxillary artery & brs
• 4) pterygoid venous plexus,
• 5) V3 (mandibular division) & its branches including the inferior alveolar, lingual, and long buccal nerves
• 6) chorda tympani,
• 7) the otic ganglion.
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• formed by parietal, frontal, temporal & sphenoid bones
• occupied by temporalis muscle
• superior to zygomatic arch
• 

• anatomical space inferior and medial to the zygomatic arch and deep to the ramus of the mandible that is defined by bony landmarks.
• The fossa has anterior, posterior, medial, and lateral walls, a roof and floor.
• 1. Anterior Wall – posterior surface of maxilla
• 2. Posterior Wall – styloid process, mastoid process, tympanic part of temporal bone
• 3. Medial Wall – lateral surface of lateral pterygoid plate
• 4. Lateral Wall – ramus of mandible
• 5. Roof – mostly greater wing of sphenoid, (but also by temporal bone)

• a. foramen ovale – transmits V3 root and accessory meningeal a.
• b. foramen spinosum – transmits middle meningeal a. & meningeal br. of V3
• c. mandibular fossa – part of TMJ
• d. articular eminence (a.k.a. articular tubercle)
• e. infratemporal crest – ridge where the bone changes angles (90°)

medial pterygoid muscle (the floor is described differently by different sources)

• 1. Head (a.k.a. “condyle”)
• 2. Neck – with pterygoid fovea
• 3. Mandibular notch (or “incisure”) – masseteric n & vessels course through the notch
• 4. Coronoid Process – attachment site for temporalis
• 5. Ramus
• 6. Angle
• 7. Body
• 8. Alveolar Arch
• 9. Mental Foramen – transmits mental n. & vessels
• 10. Mental Protuberance – point of the chin
• 11. Mandibular Foramen – transmits inferior alveolar n. & vessels
• 12. Lingula – attachment site for sphenomandibular ligament
• 13. Mylohyoid groove – occupied by mylohyoid nerve
• 14. Mylohyoid line – attachment site for mylohyoid muscle
• 15. Submandibular Fossa – occupied by submandibular gland (deep part)
• 16. Sublingual Fossa – occupied by sublingual gland
• 17. Genial tubercles – attachment site for genial muscles (genioglossus & geniohyoid – these will be studied with the Oral Cavity)

• develop from the 1st branchial arch
• receive branchial motor (SVE) fibers from branches of V3
• Two of the muscles – temporalis and masseter – are outside the infratemporal fossa
• Two muscles – medial & later (formerly internal & external) pterygoids – are inside the infratemporal fossa.

temporalis (1), masseter (1), medial pterygoid (2)

lateral ptergyoid (1), gravity (2), digastric-ant belly (2), mylohyoid (2)

lateral pterygoid (1), medial pterygoid (2)

posterior fibers of temporalis

combination of all muscles

lateral excursion or deviation (side to side motion) – med. & lat. pterygoids

• lateral excursion or deviation (side to side motion)
• temporalis & masseter (ipsilateral excursion)

• 
• Along with the masseter, the medial pterygoid forms a “sling” around the mandible.
• Note how the temporalis, masseter, and medial pterygoid are in a position to be elevators.

• gives rise to the trigeminal nerve (CN V) and the muscles of mastication, the anterior belly of the digastric m., tensor veli palatini, and tensor tympani muscles.
• It also gives rise to inner ear bones (malleus & incus) and the mandible.

• branches of the V3 (Mandibular) Division.
• The V3 Division is sometimes referred to as the “mandibular nerve” and has branches that are sensory and/or motor branches.
• The V3 Division originates from the trigeminal nerve in the middle cranial fossa and passes through the foramen ovale into the infratemporal fossa.
• It then breaks up into its branches: lingual n., long buccal n., auriculotemporal n., inferior alveolar n., mylohyoid n., deep temporal ns., masseteric n., and pterygoid ns.
• Note: Clinically, the inferior alveolar nerve is also sometimes referred to as “the mandibular nerve.”
• So be careful! Inconsistent use of terminology is confusing, but reflects the real world situation that you will find yourself in.

• sensory root and motor root which pass through foramen ovale to enter the infratemporal fossa.
• These roots combine into a single trunk which then divides into anterior and posterior divisions.
• Branches of V3 arise from the trunk and the anterior and posterior divisions.
• Some of the V3 branches are sensory (SA), some are both sensory (SA) and branchial motor.
• (Note: For this course, you do not need to know which branches come off the trunk, anterior, & posterior divisions; but that information is in the INDEX of the “Infratemp Fossa & TMJ – Hyperlinked” file and presented here in case you need it for board review).

• meningeal branch (nervus spinosus) – passes through foramen spinosum & follows the middle meningeal a. to innervate the dura mater (SA)
• medial pterygoid n. – supplies the medial pterygoid m. & sends brs to the tensor tympani and tensor veli palatine. (SA/branchial motor)

• masseteric nerve – innervates the masseter m. (SA/branchial motor)
• deep temporal nerves – innervate temporalis (SA/branchial motor)
• lateral pterygoid nerve – innervates lat. pterygoid (SA/branchial motor)
• long buccal nerve – innervates skin and mucosa of cheek region (SA)

• V3 Posterior Division
• innervates the skin of the temporal region (SA).
• It has hitchhiking VE-para/post fibers from the otic ganglion that are going to the parotid gland.
• These fibers are left with the gland, and auriculotemporal nerve continues on its way to the temporal region.

• 
• V3 Posterior Division
• originates from V3 as a sensory nerve (SA).
• Along its way, it is joined by the chorda tympani which carries VE-para/pre and SS (taste) fibers from the facial nerve (CN VII).
• The taste fibers supply the anterior 2/3rd of the tongue.
• The VE-para/pre fibers travel on the lingual nerve to the submandibular ganglion.
• VE-para/post fibers from the ganglion rejoin the lingual nerve and travel anteriorly to the sublingual gland.

• V3 Posterior Division
• originates from V3 as a sensory (SA) and motor (branchial motor) nerve.
• Just before it enters the mandibular foramen it gives rise to the mylohyoid nerve.
• All of the branchial motor fibers follow the mylohyoid nerve.
• So, once the inferior alveolar nerve enters the mandibular foramen, it is a purely sensory nerve (SA) which innervates the mandibular teeth It has two terminal branches: the mental nerve and incisive nerve.
• a. mylohyoid nerve – innervates the mylohyoid & anterior belly of the digastric muscle. (SA/branchial motor).
• b. mental nerve – emerges through the mental foramen and innervates the skin of the chin, lower lip, labial alveolar mucosa, & vestibular gingival of the mandibular incisor teeth. (SA)
• c. incisive nerve – innervates the anterior mandibular teeth. (SA)
• 
• 

• located below foramen ovale, just on the medial side of the V3 trunk.
• It is comprised of VE-para/post cells whose fibers hitchhike along the auriculotemporal nerve to the parotid gland.
• These fibers are secretomotor and cause the parotid gland to secrete saliva.
• The para/pre fibers outflow in CN IX and follow the tympanic nerve to the tympanic plexus in the middle ear.
• From this plexus, the lesser petrosal nerve forms.
• This nerve brings the fibers to the otic ganglion.

CN IX → tympanic br → tympanic plexus (middle ear) → lesser petrosal nerve (passes from middle cranial fossa throughforamen ovale) → otic ganglion (synapses on para/post cells).

inferior salivatory nucleus in brain stem

otic ganglion → auriculotemporal n. → parotid gland

• can result from dental implant procedures, mandibular third molar extractions, certain endodontic procedures (root canals), mandibular fractures, etc.
• 1. Note the position and proximity of the mandibular canal to the roots of the teeth (particularly the molar roots). There can be variation in the distance between the canal and the roots.
• This may be due to individual variation and/or age-related changes in the mandible.

• can result in anesthesia (numb tongue), paresthesia (tingling), or dysesthesia ( pain and burning ) in the tongue and inner mucosa of the mouth.
• This can be due to complication of tooth extraction of the mandibular wisdom teeth ( third molar ) or dental anesthetic injection (nerve block) for fillings, crowns.
• It results in a chronic pain syndrome or neuropathy.
• If the inferior alveolar nerve is involved, numbness of the lip may result.
• 1. Variation in the course of the lingual nerve puts it at risk during mandibular 3rd molar extractions.
• If the nerve is damaged, general sensation (SA) and taste (SS) to the anterior 2/3rd of the tongue may be affected as well as reduced salivation (possibly).

• one of the most commonly employed techniques in mandibular regional anesthesia.
• It is extremely useful when multiple teeth in one quadrant require treatment.
• The target for this technique is the inferior alveolar nerve as it travels on the medial aspect of the ramus, prior to its entry into the mandibular foramen.
• The lingual, mental, and incisive nerves are also anesthetized.
• Note the proximity of the inferior attachment to the mandibular foramen through which the inferior alveolar nerve and vessels run.
• Thus, in administering an IAN block, there is a danger of injuring the sphenomandibular ligament.

• (otherwise known as the long buccal or buccinator block)
• a useful adjunct to the inferior alveolar nerve block when manipulation of the buccal soft tissue in the mandibular molar region is indicated.
• The target for this technique is the buccal nerve as it passes over the anterior aspect of the ramus.

indicated for procedures where manipulation of buccal soft tissue anterior to the mental foramen is necessary.

• 
• is a clinically-defined space within the infratemporal fossa between the medial pterygoid muscle (medially), the medial aspect of the mandible (laterally), & lat.pterygoid (superiorly).
• This space contains the inferior alveolar nerve and lingual nerve (also the mylohyoid nerve) – nerves of primary importance to the dentist.

• The main vessels of the infratemporal fossa include the pterygoid venous plexus and the maxillary artery and its branches.
• The pterygoid venous plexus has connections with the facial vein, cavernous sinus, and retromandibular vein.
• The maxillary artery is organized into 3 parts and has 15 branches.
• It terminates as the sphenopalatine artery.

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• 

• occupies most of the infratemporal fossa.
• It is located between the temporalis and pterygoid muscles.
• It has connections to the cavernous sinus, facial vein (via the deep fascia vein) and retromandibular vein (via the maxillary veins).

• one of the 2 terminal branches of the external carotid a.
• It passes posterior to the neck of the mandible to enter the infratemporal fossa.
• Here, it gives rise to 15 branches.
• The artery is organized into 3 parts: 1st (retromandibular) Part, 2nd (pterygoid) Part, and 3rd (pterygopalatine)part.

• 
• 1. deep auricular a. – supplies the external auditory meatus & TMJ
• 2. anterior tympanic a. – supplies the tympanic membrane & TMJ
• 3. middle meningeal a. – supplies the dura mater (passes through foramen spinosum)
• 4. accessory meningeal a - .supplies the dura mater & trigeminal ganglion (passes through foramen ovale)
• 5. inferior alveolar a. – supplies the mandibular teeth (passes through the mandibular foramen); terminates as the incisive a (to anterior mandibular teeth) and mental a. (passes through mental foramen with mental n.)

• 
• (may be superficial or deep to lateral pterygoid m.)
• 6. deep temporal as. – supply the temporalis
• 7. masseteric a. – supplies the masseter (passes through mandibular notch with nerve)
• 8. pterygoid a. – supplies pterygoid muscles
• 9. buccal a. – supplies cheek region, travels with long buccal nerve.

• 
• (deep to lateral pterygoid; all branches arise from maxillary artery within the pterygopalatine fossa).
• 10. posterior superior alveolar a. - travels with the posterior superior aveolar n. (V2 branch) and supplies the maxillary molar and premolar teeth, buccal gingiva, and lining of the maxillary sinus.
• 11. descending palatine a. – descends in greater palatine canal; supplies the mucous membrane and glands of the palate (roof of mouth) and palatine gingiva.
• 12. infraorbital a. - supplies the inferior eyelid, lacrimal sac, infraorbital region of the face, side of the nose, and upper lip; occupies the infraobital groove and canal & emerges unto face through the infraorbital foramen.
• 13. artery of the pterygoid canal – occupies the pterygoid (Vidian’s) canal along with nerve to the pterygoid canal; supplies pharynx, auditory tube, sphenoidal sinus
• 14. pharyngeal br. – very small branch; supplies pharynx, auditory tube, sphenoidal sinus
• 15. sphenopalatine a. – is the continuation of the maxillary artery which changes names when it passes through the sphenopalatine foramen to enter the nasal cavity. It supplies the lateral nasal wall, nasal septum, and adjacent paranasal sinuses.

• a synovial joint (subtype: modified hinge joint).
• The articular surfaces involve the head of the mandible, the articular tubercle of the temporal bone, and the mandibular fossa.
• The articular surfaces of the TMJ are covered by fibrocartilage (rather than hyaline cartilage as in a typical synovial joint).
• An articular disc divides the joint into two separate joint cavities.
• A thickening of the joint capsule forms the lateral ligament (temporomandibular ligament) which strengthens the TMJ and, with the postglenoid tubercle, acts to prevent posterior displacement of the joint.

• is a thickening of the fibrous joint capsule of the TMJ.
• It helps to provide lateral stability to the joint.

The TMJ has a single joint capsule, but is divided into two synovial joint spaces by an articular disc.

• To open the mouth wider than just separating the upper and lower teeth, the head of the mandible and articular disc must move anteriorly on the articular tubercle (aka “articular eminence”).
• In dentistry, this movement is referred to as “translation.”
• Note the relative position of the articular tubercle and mandibular head in the “mouth open” and “mouth closed” positions.

• 1. Elevation
• 2. Depression
• 3. Protrusion
• 4. Retrusion
• 5. Lateral Excursion (or Lateral Deviation)
• Note: The reference point for these movements is the chin.

• origin: temporal fossa & deep surface of temporal fascia
• insert: coronoid process & anterior border of mandibular ramus
• nerve: deep temporal ns.
• action: elevates mandible; posterior fibers retract (retrude) mandible; ipsilateral excursion

• (has superficial and deep parts)
• origin: superficial head – ant 2/3rds of zygomatic arch;
• deep head – post. 1/3rd of zygomatic arch
• insert: superficial head – angle & lat. surface of mandible;
• deep head – superolateral ramus and coronoid process
• nerve: n. to masseter
• action: elevates mandible; superficial fibers help protrude mandible; ipsilateral excursion

• origin: deep head - lateral pterygoid plate (med surf).
• superficial head –pyramidal process of palatine bone & tuberosity of maxilla
• insert: ramus of mandible (med surf) inferior to mandibular foramen
• nerve: n. to medial pterygoid
• action: acts with masseter to elevate mandible; assists in protrusion; contralateral excursion

• origin: superior head - greater wing of sphenoid (infratemp surf & crest);
• inferior head - lateral surf of lat. pterygoid plate
• insert: superior head - joint capsule & articular disc of TMJ;
• inferior head - pterygoid fovea of mandible
• nerve: ns. to lateral pterygoid
• action: bilaterally – protracts (protrudes) mandible; translates mandibular condyle during depression; contralateral excursion

• 
• These ligaments help provide the axis of movement for the mandible which is not at the TMJ but at a point near the mandibular foramen.
• In performing its various movements, the mandible actually “rotates” about a horizontal axis at this point (near the mandibular foramen).
• Remember, the head is not fixed, but slides anterior and posterior (translates) from the mandibular fossa to the anterior tubercle and back during depression and elevation.
• The attachment of the sphenomandibular ligament is the spine of the sphenoid superiorly and the lingula of the mandible inferiorly.
• Note the proximity of the inferior attachment to the mandibular foramen through which the inferior alveolar nerve and vessels run.
• Thus, in administering an IAN block, there is a danger of injuring the sphenomandibular ligament.