3 - Clinical anatomy - innervation, bones of facial skeleton, Masticatory muscles Flashcards
Maxillary Nerve (V2) Path
Exclusively a sensory nerve
Arises from trigeminal ganglion then through wall of cavernous sinus
passes through foramen rotundum - pterygopalatine fossa - infraorbital foramen - lesser + greater palatine foramen
Gives rise to 14 branches
Branches of maxillary nerve - On the face
Superior labial nerve - innervates upper lip
Inferior palpebral nerve - innervates lower eyelid
Lateral nasal nerve - innervated anterior part of lateral wall of nasal cavity
Infraorbital Branches of Maxillary nerve
From infraorbital canal is infraorbital nerve
divides into:
Anterior superior alveolar nerve - innervates incisors + canines + anterior portion of superior dental plexus
Middle superior alveolar nerve - Innervates premolars + medial + lateral aspects of mamillary sinus/ may also innervate mesiobuccal root of 1st molar
Branches via pterygopalatine fossa
Posterior superior alveolar nerve - innervates maxillary molars + posterior aspect of maxillary sinus - this with all other superior alveolar nerves forms dental plexus
zygomatic nerve passes through infraorbital fissure + divides into:
zygomaticofacial - innervates skin of cheek
zygomaticotemporal - innervates skin of forehead
Greater palatine nerve - innervates hard palate via greater palatine foramen
Lesser palatine nerve - innervates soft palate via lesser palatine foramen
Nasopalatine - innervates hard palate + mucosa of nasal septum via incisive fossa
Pharyngeal Nerve - mucous membrane of nasopharynx
Mandibular Nerve (V3)
Has sensory + motor function
contains sensory + motor axons which arise from 3 sensory nuclei:
mesencephalic, principle sensory + spinal nuclei of CN V
Nerve passes through foramen ovale
Gives rise to 4 branches in infratemporal fossa:
Auriculotemporal Nerve
Superior root - sensory fibres
Inferior secretory root - motor parasympathetic fibres to parotid gland
These roots innervate:
anterior part of auricle
lateral part of temple
anterior external meatus
anterior tympanic membrane
Buccal Nerve
sensory fibres
provides sensory innervation to the cheek, 2nd + 3rd molar teeth
passes through 2 heads of lateral pterygoid muscle
Lingual Nerve
Sensory nerve
acts as a conduit for sensory + autonomic nerve fibres belonging to chorda tympani
Special sensory - taste for anterior 2/3rd of tongue
parasympathetic - innervates submandibular + sublingual glands after synapse in submandibular ganglion
General sensory innervates anterior 2/3rd of tongue
Inferior Alveolar Nerve
Both sensory + motor axons
gives rise to mylohyoid nerve
Enters mandibular canal + branches to mandibular teeth to from inferior dental plexus
Nerve emerges through mental foramen as mental nerve
provides sensory innervation to lower lip + chin
Motor functions - motor axons at level of mandibular tubercle
distributes axons to muscles of mastication:
Masseter
Medial + lateral pterygoid
Temporalis
Facial Nerve - extracranial path
- The first extracranial branch is the posterior auricular nerve - motor innervation to intrinsic + extrinsic muscles of outer ear
- supplies occipital part of occipitalis muscle
- distal to this, motor branches are sent to posterior belly of digastric muscle - raises hyoid bone
- branches also sent to stylohyoid muscle - raises hyoid bone
- Motor root continues anteriorly + inferiorly into the parotid gland
- within the gland the nerve terminates by splitting into 5 branches: innervates muscles of facial expression
- temporal branch - innervates frontalis, orbicularis oculi + corrugator supercili
- zygomatic branch - innervates orbicularis oculi
- buccal branch - innervates orbicularis oris, buccinator + zygomaticus muscles
- marginal mandibular branch - innervates mentalis muscle
- cervical branch - innervates platysma
Facial Bones - Overview
- There are 14 facial bones:
- Nasal bones x2
- Lacrimal bones x2
- inferior nasal concha x2
- Maxilla x2
- Mandible
- Vomer
- Zygomatic bones x2
- Palatine bones x2
Nasal Bone
- paired structure
- situated superiorly
Lacrimal Bones
- paired bones
- smallest bones on face
- form part of the medial wall of the orbit
Inferior Nasal Conchae
- 2 of these
- located in nasal cavity
- increase surface area of cavity - increasing amount of inspired air that can come into contact w/cavity walls
Vomer
- Forms posterior aspect of nasal septum
Palatine Bones
- paired bones
- situated at rear of oral cavity + forms part of the hard palate
Maxilla
- paired bone
- comprises of upper jaw and hard palate
Mandible
- Articulates w/base of cranium at temporomandibular joint
Masticatory Muscles - Overview
- These muscles are associated w/movements of the jaw (TMJ)
- there are 4 masticatory muscles:
- Masseter
- Temporalis
- Medial Pterygoid
- Lateral Pterygoid
- innervated by mandibular branch of trigeminal nerve - inferior alveolar nerve
Masseter
Most powerful muscle of mastication - quadrangular in shape - elevates mandible to close mouth
Has deep + superficial parts - lies superficially to pterygoids + temporalis, covering them
Attachments
- superficial part originates from maxillary process of zygomatic bone
- deep part from zygomatic arch of temporal vone
- both parts attach to ramus of mandible
Innervation - Mandibular nerve
Temporalis
- Originates from inferior temporal line of temporal fossa - elevates mandible to close mouth + retracts mandible to pull jaw posteriorly
- attachments - condenses into a tendon that inserts onto coronoid process of mandible
Medial Pterygoid
- Quadrangular shape w superficial head + deep head - located inferiorly to lateral pterygoid
Attachments
- Superficial head - originates from maxillary tuberosity + pyramidal process of palatine bone
- Deep head - originated from medial aspect of lateral pterygoid of sphenoid bone
- Both heads attach to ramus of mandible
Lateral Pterygoid
- Triangular shape w/ superior + inferior heads
- Horizontally oriented muscle fibres
- Protracts mandible to push jaw forwards + Unilateral action = side-side movement of jaw
Attachments
- Superior head originates from greater wing of sphenoid bone
- Inferior from lateral pterygoid plate of sphenoid bone
- 2 heads converge into a tendon that attaches to neck of mandible
