HNS32 Parotid And Infratemporal Regions Flashcards
Temporal fossa and Infratemporal fossa
Temporal fossa:
- narrow fan-shaped space
- mastication muscles —> Temporalis
Infratemporal fossa
- highway centre —> connect with a lot of space (orbit, nasal, cranial cavity, mediastinum (pericardial infection) etc.)
—> anterior: Inferior orbital fissure —> **Orbit
—> roof: Foramen rotundum, Pterygoid canal —> **Middle cranial fossa (brain)
—> medial: Sphenopalatine foramen —> ***Nasal cavity
- below zygomatic arch
- below Temporal fossa
- interconnect with Temporal fossa on lateral side of head
- below skull base
- Temporomandibular joint (TMJ)
- mastication muscles —> Temporalis
Bony framework and landmarks of Infratemporal fossa
- Medial: Lateral pterygoid plate, Lateral wall of pharynx, Tensor (CNV3) / Levator veli palatini (Pharyngeal plexus)
- contains ***Pterygomaxillary fissure —> leads to Pterygopalatine fossa - Lateral: Mandibular ramus (medial surface)
- contains ***Mandibular foramen - Roof: Infratemporal crest of greater wing of Sphenoid / Temporal bone / Temporal fossa
- contains **Foramen ovale, **Foramen spinosum, ***Petrotympanic fissure - Anterior: Posterior surface of Maxilla (Maxillary tuberosity) / Maxillary process of Zygomatic bone
- contains **Alveolar foramina
- upper part opens as **Inferior orbital fissure - Posterior: Styloid process of Temporal bone
—> Open to neck posteroinferiorly (infection spread)
***Foramen ovale, Foramen spinosum, Petrotympanic fissure
Foramen ovale (OVALE acronym):
- ***Otic ganglion (from CN9)
- ***CNV3
- Accessory meningeal artery
- ***Lesser petrosal nerve
- Emissary veins
Foramen spinosum:
- ***Middle meningeal artery
- Middle meningeal vein
- ***Recurrent meningeal branch of CNV3 (every branch of CN5 have meningeal branch)
Petrotympanic fissure:
1. ***Chorda tympani (CN7)
Inferior orbital fissure
- Zygomatic branch (CNV2)
- Infraorbital nerve (CNV2)
- Infraorbital A+V (Maxillary)
- Ascending fibres from Pterygopalatine ganglion
***Infratemporal fossa communications
- Cranial cavity
- Foramen ovale
- Foramen spinosum - Orbit
- Inferior orbital fissure - Pterygopalatine fossa
- Pterygomaxillary fissure (connect with nasal, oral cavity, orbit)
- Sphenopalatine foramen
Attachment of styloid process
Ligaments:
- Stylohyoid ligament
- Stylomandibular ligament
- **Muscles:
1. Stylohyoid (CN7)
2. Styloglossus (CN12)
4. Stylopharyngeus (CN9)
***Infratemporal fossa contents
Ligament:
1. Sphenomandibular ligament
- **Muscles of mastication:
1. Medial pterygoid muscle
2. Lateral pterygoid muscle
3. Masseter
4. Temporalis
Nerve:
- ***Mandibular nerve (CNV3)
- motor + sensory
- sensory: from Trigeminal ganglion through Foramen ovale
- motor: motor root bypass medially to Trigeminal ganglion —> enter Foramen ovale —> fuse with sensory —> Mandibular nerve
Blood vessels:
- ***Maxillary artery
- ***Pterygoid venous plexus
Temporomandibular joint (TMJ)
- Only pair of synovial joint in skull (movable)
- Opening / closing, Chewing, Side-to-side movement of lower jaw
- Formed between Mandible head + Mandibular fossa / Articular tubercle
- Divided completely by articular disc —> upper / lower part
- 3 Extracapular ligaments of TMJ:
1. Sphenomandibular ligament (spine of sphenoid to lingula of mandible) (Maxillary artery, inferior alveolar nerve)
2. Lateral ligament
3. Stylomandibular ligament (division of infratemporal region / parotid region)
4 Mastication muscles
- Medial pterygoid
- Lateral pterygoid
- Masseter (strongest muscle: elevate jaw / 開合口)
- Temporalis
ALL supplied by **Maxillary artery + **CNV3
Medial pterygoid muscle
- Quadrangular
- 2 heads: Deep + Superficial heads (夾住Lateral pterygoid plate)
Deep head:
- attached to ***medial surface of Lateral pterygoid plate + associated surface of pyramidal surface of Palatine bone
Superficial head:
- smaller
- from Maxillary tuberosity + adjacent pyramidal process of Palatine bone
Insertion:
- Medial angle of mandible
Action:
- **Elevate mandible, **Protrusion of lower jaw, ***Move mandible medially
Lateral pterygoid muscle
- Triangular
- 2 heads: Upper + Lower heads (Lateral pterygoid plate出面)
Upper head:
- from roof of Infratemporal fossa
- lateral to Foramen ovale + Foramen spinosum
Lower head (比Medial pterygoid包住):
- larger
- attached to lateral surface of Lateral pterygoid plate
- between 2 heads of Medial pterygoid muscle
Insertion:
- Condylar process of mandible
Action:
- Major **protruder of lower jaw, assist **side-to-side movement of lower jaw
Temporalis muscle
Origin:
- bony surface superiorly to inferior temporal line
- attaching laterally to Temporal fossa
Insertion:
- Coronoid process and along anterior margin of Mandible ramus
Action:
- Anterior fibres: ***Elevate mandible —> Close jaw
- Posterior fibres: **Retract mandible (ONLY retractor) + assist **side-to-side movement of mandible
Masseter
- 2 heads: Superficial + Deep heads
Origin:
- Maxilla and Zygomatic arch
Insertion:
- Lateral surface of Mandible ramus + Coronoid process
Action:
- **Elevation, **Protrusion of mandible
***Mandibular nerve CNV3
Function: - Sensory: teeth and gingivae of mandible, ***anterior 2/3 tongue, mucosa of oral cavity floor, lower lip, skin over temple, lower face skin, part of dura mater - Motor: —> ***Mastication muscles —> ***Tensor tympani —> ***Tensor veli palatini —> ***Anterior belly of digastric —> ***Mylohyoid
- Trunk branches (origin: Medial side of CNV3)
—> ***Meningeal nerve
- enters Foramen spinosum (with middle meningeal artery)
- sensory to dura mater (in middle cranial fossa)
—> Nerve to medial pterygoid (branch to tensor tympani, tensor veli palatini) - Anterior branches (***Motor mostly)
—> Masseteric nerve (laterally over lateral pterygoid muscle through mandibular notch)
—> Deep temporal nerve (Temporalis)
—> Nerve to lateral pterygoid
—> Buccal nerve (最前) (cheek, mucosa, buccal gingiva) (Buccinator: CN7) - Posterior branches (***Sensory mostly)
—> ***Auriculotemporal nerve (包住middle meningeal artery)
- General sensory: skin over temple, external ear, external acoustic meatus, tympanic membrane, TMJ
- Visceral motor: carries postsynaptic fibre from **Otic ganglion (presynpatic fibre: **Lesser petrosal nerve from CN9) —> Parotid gland
—> Inferior alveolar nerve
- Sensory: lower teeth and associated gingivae, mucosa, skin of lower lips, skin of chin
- Motor: ***Mylohyoid + Anterior belly of digastric
- Incisive nerve —> ***Mental nerve (exit in mental foramen)
—> ***Lingual nerve
- General sensory: anterior 2/3 tongue, mucosa of oral cavity floor, lingual gingivae
- Visceral motor: joined by **Chorda tympani (Taste + Parasympathetic presynaptic fibres from CN7 within middle ear) —> **Submandibular ganglion —> Sublingual gland + Submandibular gland (ALL salivary glands below level of oral fissure)
Chorda tympani
- Branch of CN7
- Origin: inside temple bone, passes through medial end of petrotympanic fissure
- Joins Lingual nerve medial to lateral pterygoid muscle
- Special sensory: taste fibres from anterior 2/3 tongue
- Visceral motor: Presynaptic parasympathetic fibres —> Submandibular ganglion —> Sublingual gland + Submandibular gland + Blood vessels of tongue
Submandibular ganglion
- Hangs from Lingual nerve at lateral surface of ***Hyoglossus muscle
- Secondary cell bodies for Presynpatic fibres in Chorda tympani
- Postsynaptic fibres travel along Lingual nerve to Submandibular gland + Sublingual gland
Lesser petrosal nerve
- Branch of Tympanic plexus
- Carries presynpatic fibres from CN9
- Passes medially and descend with CNV3 through Foramen ovale
- Presynpatic fibres —> Otic ganglion (medial side of CNV3) —> Auriculotemporal nerve
***Maxillary artery
- Largest branch of External carotid artery
- Origin: deep substance of parotid gland —> between mandibular neck and sphenomandibular ligament —> Infratemporal fossa —> Pterygomaxillary fissure —> Pterygopalatine fossa
- nasal cavity, lateral wall + roof of oral cavity, dura mater, infratemporal fossa
- 1st part: Between neck of mandible and sphenomandibular ligament (Posterior to Lateral Pterygoid)
—> **Middle meningeal artery
—> **Inferior alveolar artery
—> Deep auricular, Anterior tympanic, Accessory meningeal arteries
- 2nd part: Within Lateral pterygoid muscle —> Deep temporal branch —> Masseteric branch —> Buccal branch —> Pterygoid branch
- 3rd part / Terminal branch: Pterygopalatine fossa (Anterior to Lateral Pterygoid)
—> **Infraorbital artery
—> **Sphenopalatine artery
Pterygoid venous plexus
- Network of veins between Medial + Lateral pterygoid muscle / between Lateral pterygoid + Temporalis
- Drains nasal cavity, lateral wall + roof of oral cavity, all teeth, muscles in infratemporal fossa, paranasal sinuses, nasopharynx
1. Posterior: Short maxillary vein, connects with **Retromandibular vein —> **External jugular vein
2. Anterior: Deep facial vein, connects with **Facial vein —> **Internal jugular vein
3. Inferior ophthalmic vein from orbit —> Inferior orbital fissure —> Pterygoid plexus
4. ***Cavernous sinus: through Inferior ophthalmic vein + Emissary veins (pass through skull)
***Clinical relevance of Infratemporal fossa
- Fracture of pterion (太陽穴)
- overlies **Middle meningeal vessels (anterior branch)
—> blow to lateral side of head
—> **Epidural haematoma
—> pressure on cerebral cortex - Pterygoid venous plexus
- connects to Facial vein through **Inferior ophthalmic and **Deep facial vein
—> infection in oral cavity and nasal cavity could spread through pterygoid plexus
—> Emissary veins
—> Cavernous sinus
—> **Septic thrombosis
—> **Stroke, Meningitis, Encephalitis
- Danger triangle of face —> Facial vein —> Cavernous sinus —> Cavernous sinus thrombosis —> meningitis, brain abscess - Lingual nerve injury
- proximal to where Chorda tympani joins —> loss of general sensation (anterior 2/3 tongue, oral mucosa, gingivae)
- distal to where Chorda tympani joins —> above + loss of saliva from submandibular / sublingual gland + taste from anterior 2/3 tongue
- enter oral cavity floor in a shallow groove on medial surface of mandible immediately inferior to last molar teeth —> in danger when operating on molar teeth and gingivae - Perineuronal infiltration of Inferior alveolar nerve (posterior branch of CNV3) by LA in dental procedures
—> needle placed lateral to anterior arch of fauces
—> advances along medial border around inferior 1/3 of mandible
—> possible to anaesthetise infraorbital, mental, incisive, buccal nerves
***Parotid gland
- Largest salivary gland
- Inverted pyramid shape: Superior + Superficial + Anteromedial + Posteromedial surface + Tapering blunt apex inferiorly
- CN7 divides gland into Superficial (larger) + Deep (smaller) part
- ***Structures traversing parotid gland (入—>出):
—> ECA
—> Retromandibular vein
—> CN7 + branches - Parotid fascia: from Deep investing cervical fascia splitting in face
—> enclose Parotid gland - Parotid LN:
—> lie on / within parotid fascia
—> within gland
—> ALL drain into Upper ***Deep cervical LN
Location:
- Below external acoustic meatus
- Between Mandible ramus, SCM, Mastoid process (medial to mandible ramus, anteromedial surface of gland passes forward to reach medial pterygoid muscle)
- Anterior border:
—> anterior border of condyle of mandible to a point at middle of Masseter then to a point 2cm below and behind angle of mandible
- Upper border:
—> curve traced from condyle of mandible across lobule of ear to mastoid process
- Posterior border:
—> line joining posterior ends of anterior and upper border
***Facial nerve CN7
Emerges from Stylomastoid foramen
—> winds laterally to styloid process
—> dives into posteromedial surface of Parotid gland
—> bifurcate into Upper + Lower divisions
Upper division:
- Temporal branch
- Zygomatic branch
Lower division:
- Buccal branch
- Marginal mandibular branch
- Cervical branch
ALL branches exit Parotid gland along its anterior border
Parotid duct
- 5cm
- arise from anterior border of gland
- on Masseter about 1 finger’s width below Zygomatic arch
- opens into mucosa opposite **2nd upper molar at **Parotid papilla
- can be palpated on clenched masseter
- middle 1/3 of a line drawn from lower border of tragus of ear to midpoint of philtrum
