Facial VII + Glosso-pharyngeal IX Nerves Flashcards
What does the Facial Nerve VII contain
Segment 3
Pharyngeal arch 2 therefore has dorsal root nerve = CN VII
Supplies some autonomic nerves to segments 1 + 2 because Trigeminal (CN V) has lost all its autonomic components
- travel through middle ear cavity (in facial canal of petrous temporal bone). Vulnerable to injury is middle ear becomes infected
Some major branches of subcutaneous- vulnerable to injury
What types of neuron’s does the facial nerve contain
SA - skin of external ear (int. auricular)
AA - taste from rostral 2/3 of tongue (chorda tympani) taste from palate (major petrosal)
AE - mandibular / sublingual salivary glands (chorda tympani). Nasal glands / lacriminal glands (major petrosal)
SVE - facial muscles (buccal nn. Nerves to individual muscles), caudal belly of digastricus
What is invading the territory of CN V (1)
Major petrosal nerve (VII) to pterygopalatine ganglion
AE - to lacrimal gland via opthalmic V
AE - to nasal glands via caudal nasal n (maxillary V)
AA - (SVA) to taste from palate via palatine n. (Maxillary V)
What is invading the territory of CN V (2)
Chorda tympani (VII)
Lingual n. (Mandibular)
AA - (SVA) taste from rostral 2/3rds of tongue
AE - to mandibular / sublingual salivary glands
What are the SVE’s to the facial muscles
Caudal auricular - caudal muscles of external ear along with C1/C2
Auriculopalpebral - rostral muscles of external ear. (Auricular). Muscles of eyelid/face (palpebral)
Dorsal / ventral buccal- facial muscles
Branch to caudal belly of digastricus
Branch to stylohyoid muscle
Branch to stapedius muscle
What are the functional groups of facial muscles
Nostril muscles - dilation of nostril in breathing important in racing horses
Cheek muscles - buccinator muscles like a diaphragm keeping the cheek taught
What are the muscles in the lip and eyelid function group
Lip and eyelid muscles - oval slit with flaps above and below
3 essential muscles
Closer = orbicularis oris / oculae
Lift upper flap = levator labii / palpebrae superioris
Depress lower flap = depressor labii / palpebrae inferioris
What are more specific muscles of the eyelid
An extra lifter medially - levator anguli oculis
Retractor laterally - retractor anguli oculis
Bundles of smooth muscle - lift upper lid / depress lower lid
What can the ear muscles do
Pull ear forward
Pull ear backward
Adduct ear
Abduct ear
What can the cervicoauricularis muscle do
Pulls ear back
Attaches laterally on cartilage
Therefore also rotates the ear outwards
What nerves supply the nostril lip and cheek muscles
Dorsal / ventral buccal branches of the facial (VII)
What nerves supply the eyelid muscles
Mainly facial VII
Except
Levator palpebrae superioris - occulomotor III
Smooth muscle - sympathetic from cranial cervical ganglion
Damage can cause drooping of eyelid
What nerves supply the ear muscle
Rostral (forward and abductors) = auricular (branch of auriculopalpebral)
Caudal (backwards and adductors) = caudal auricular
Also supplied by C1 and C2 via great auricular
What nerves are prone to damage and what can this cause
Buccal and auriculopalpebral are subcutaneous and prone to damage
Can cause
Loss of muscle tone in lips and nostrils
Can’t retain food bolus in mouth - food stuck in cheek
Slight ptosis (dropping of upper eyelid) innervation by CN III and sympathetic prevent total ptosis
Weak palpebral / corneal reflex - paralysis of orbicularis oculi
Ears rotated outward and caudally - supply by C1 and 2 to cervicoauricularis muscle intact
What does the Glosso-pharyngeal nerve (IX) contain
Pharyngeal arch 3
SA - external ear (tympanic nerve)
AA - taste (SVA) and sensation to caudal 1/3 of tongue (lingual branch) and pharynx (pharyngeal branch), chemo/baro receptors (carotid sinus nerve)
AE - parotid salivary gland (minor petrosal nerve)
SVE - stylopharyngeus muscle (only pharyngeal dilator)
