Respiratory System: Parotid, Temporal, and Pterygopalatine Regions

Parotid Region

• Located in the posterolateral part of the facial region
• Bounded by:
  • Superior: Zygomatic arch
  • Posterior: External ear and anterior border of the sternocleidomastoid
  • Medial: Ramus of Mandible
  • Inferior: Angle and inferior border of the mandible
• Includes:
  • Parotid gland and duct
  • Parotid plexus of facial nerve (CN VII)
  • Retromandibular vein
  • External carotid artery
  • Masseter muscle

Parotid Gland

• The largest of three paired salivary glands
• Enclosed in a tough fascial capsule (parotid sheath)
• Irregular shape
• Apex: Posterior to the angle of the mandible
• Base: Zygomatic arch
• Parotid duct passes horizontally from the anterior edge of the gland and enters the oral cavity through a small orifice opposite the 2nd maxillary molar tooth

Structures within Parotid Gland

• Embedded within the parotid gland (from superficial to deep):
  • Parotid plexus of the facial nerve (CN VII) and its branches
  • Retromandibular vein
  • External carotid artery
  • Parotid lymph nodes

Innervation of Parotid Region and Related Structures

• Sensory nerve fibers:
  • Great auricular nerve (a branch of the cervical plexus)
  • Auriculotemporal nerve (a branch of CN V3)
• Parasympathetic component:
  • Glossopharyngeal nerve (CN IX) supplies presynaptic secretory fibers to the otic ganglion
  • Postsynaptic parasympathetic fibers are conveyed from the ganglion to the parotid gland by the auriculotemporal nerve
• Sympathetic fibers:
  • Derived from the cervical ganglia through the external carotid nerve plexus on the external carotid artery

Clinical Correlations: Mumps

• Highly contagious viral illness
• Affects the inside mucosa of the mouth and the parotid glands
• Symptoms:
  • Fever
  • Headache
  • Muscle pain
  • Pain when eating
  • Pain in the ears, jaw, chin
  • Swollen cheeks, jaw
• Spreads through:
  • Airborne
  • Saliva
  • Touching contaminated surfaces

Temporal Region

• Includes the lateral area of the scalp and the deeper soft tissues overlying the temporal fossa of the cranium
• Superior to the zygomatic arch
• Divided into:
  • Temporal fossa
  • Infratemporal fossa

Temporal Fossa

• Boundaries:
  • Superior and posterior: Temporal lines
  • Anterior: Frontal and zygomatic bones
  • Lateral: Zygomatic arch
  • Inferior: Infratemporal crest
  • Floor: Pterion (Frontal, temporal, parietal, and greater wing of sphenoid bones)
  • Roof: Temporal fascia
• Contents:
  • Temporalis muscle
  • Zygomaticotemporal branches of the maxillary nerve (CN V2)

Infratemporal Fossa

• Boundaries:
  • Lateral: Ramus of mandible
  • Medial: Lateral pterygoid plate
  • Anterior: Posterior aspect of maxilla
  • Posterior: Tympanic plate and mastoid and styloid processes of temporal bone
  • Superior/roof: Inferior surface of greater wing of sphenoid
  • Inferior: Where the medial pterygoid muscle attaches to the mandible near its angle
• Contents:
  • Inferior part of temporalis muscle
  • Medial and lateral pterygoid muscles
  • Maxillary artery
  • Pterygoid venous plexus
  • Mandibular nerve and its branches (Inferior alveolar, lingual, and buccal nerves, chorda tympani)
  • Otic ganglion

Temporomandibular Joint (TMJ)

• Type: Modified hinge type of synovial joint
• Movements:
  • Depression
  • Elevation
  • Protrusion (Protraction)
  • Retrusion (Retraction)
  • Lateral movements
• Supporting structures:
  • Lateral (temporomandibular) ligament
  • Stylomandibular ligament
  • Sphenomandibular ligament
• Arterial supply:
  • Branches of the external carotid artery
  • Superficial temporal branch
  • Deep auricular, ascending pharyngeal, and maxillary arteries
• Nerve supply:
  • Auriculotemporal and masseteric branches of the mandibular nerve (CN V3)

Clinical Correlations: Dislocation of TMJ

• Cause: Excessive contraction of the lateral pterygoids
• Symptoms:
  • The mandible remains depressed and the person is unable to close their mouth
  • Dislocation can occur during yawning or taking a large bite

Muscles of Mastication

• Include:
  • Masseter
  • Temporalis
  • Lateral pterygoid
  • Medial pterygoid
• All are innervated by CN V3 (Mandibular branch of the trigeminal nerve)

Neurovasculature of Infratemporal Fossa

• Maxillary artery:

  • Divided into 3 parts based on its relation to the lateral pterygoid muscle
  • Mandibular (1st part)
  • Pterygoid (2nd part)
  • Pterygopalatine (3rd part)

• Branches of the maxillary artery:

  • Deep auricular artery
  • Anterior tympanic artery
  • Middle meningeal artery
  • Accessory meningeal artery
  • Inferior alveolar artery
  • Masseteric artery
  • Deep temporal arteries
  • Pterygoid branches
  • Buccal artery
  • Posterior superior alveolar artery
  • Infra-orbital artery
  • Artery of pterygoid canal
  • Pharyngeal branch
  • Descending palatine artery
  • Sphenopalatine artery

• Pterygoid venous plexus:

  • The venous equivalent of most of the maxillary artery
  • Anastomoses anteriorly with the facial vein via the deep facial vein and superiorly with the cavernous sinus via emissary veins

• Mandibular nerve (CN V3):

  • Branches:
    • Auriculotemporal nerve
    • Inferior alveolar nerve
    • Lingual nerve
    • Nerve to mylohyoid
    • Buccal nerve### Neurovasculature of Infratemporal Fossa

• The mental nerve, a branch of the plexus, passes through the mental foramen and supplies the skin and mucous membrane of the lower lip, the skin of the chin, and the vestibular gingiva of the mandibular incisor teeth.

Lingual Nerve

• Lies anterior to the inferior alveolar nerve
• Sensory to the anterior two-thirds of the tongue, the floor of the mouth, and the lingual gingivae
• Enters the mouth between the medial pterygoid muscle and the ramus of the mandible and passes anteriorly under cover of the oral mucosa, medial and inferior to the 3rd molar tooth
• Chorda tympani nerve, a branch of CN VII carrying taste fibers from the anterior two-thirds of the tongue, joins the lingual nerve in the infratemporal fossa
• Chorda tympani also carries secretomotor fibers for the submandibular and sublingual salivary glands

Buccal Nerve

• Predominantly a sensory nerve
• May also carry motor innervation to the lateral pterygoid muscle and part of the temporalis muscle
• Passes laterally between the upper and lower heads of the lateral pterygoid and then descends around the anterior margin of the ramus of the mandible and continues to the cheek lateral to the buccinator muscle
• Supplies general sensory nerves to the adjacent skin and oral mucosa and the buccal gingivae of the lower molars

Otic Ganglion

• Located in the infratemporal fossa, just inferior to the foramen ovale, medial to CN V3 and posterior to the medial pterygoid muscle
• Presynaptic parasympathetic fibers, derived mainly from the glossopharyngeal nerve, synapse in the otic ganglion
• Post-synaptic parasympathetic fibers, which are secretory to the parotid gland, pass from the otic ganglion to this gland through the auriculo-temporal nerve

Parotid Region

• Parotid gland
• Structures within the parotid gland
• Innervation of the parotid gland and related structures
• Clinical correlations

Temporal Region

• Temporal fossa
• Infratemporal fossa
• Temporomandibular joint (TMJ)
• Muscles of mastication
• Neurovasculature of infratemporal fossa
• Clinical correlations

Pterygopalatine Fossa

• An inverted 'tear-drop' shaped space between bones on the lateral side of the skull immediately posterior to the maxilla
• Communicates via fissures and foramina in its walls with the middle cranial fossa, infratemporal fossa, floor of the orbit, lateral wall of the nasal cavity, oropharynx, and roof of the oral cavity
• Major site of distribution for the maxillary nerve (CN V2) and for the terminal part of the maxillary artery
• Parasympathetic fibers from the facial nerve (CN VII) and sympathetic fibers originating from the T1 spinal cord level join branches of the maxillary nerve (CN V2) in the pterygopalatine fossa
• All the upper teeth receive their innervation and blood supply from the maxillary nerve (CN V2) and the terminal part of the maxillary artery, respectively, that pass through the pterygopalatine fossa

Contents of Pterygopalatine Fossa

• Pterygopalatine part of the maxillary artery
• Maxillary nerve
• Pterygopalatine ganglion and nerve of the pterygoid canal
• Preganglionic parasympathetic fibers from the greater petrosal branch of the facial nerve (CN VII)
• Postganglionic sympathetic fibers from the deep petrosal branch of the carotid plexus