Cranial Nerves Flashcards
Number 1, name?
Olfactory
Number 2, name?
Optic
Number 3, name?
Oculomotor
Number 4, name?
Trochlear
Number 5, name?
Trigeminal
Number 6, name?
Abducens
Number 7, name
Facial
Number 8 name?
Vestibulocochlear
Number 9 name
Glossopharyngeal
Number 10 name
Vagus
Number 11 name
Accessory
Number 12, name
Hypoglossal
Segment 1
Pharyngeal arch-> none
Ventral root Nerve-> Oculomotor
Somite SE ->Most orbital muscles
Dorsal root nerve->Trigeminal (Ophthalmic)
Ectoderm SA-Skin of top of head
Endoderm AA-None
Glands AE-None
Lateral plate mesoderm-None
Pouches-None
Segment 2
Segment 2:
Pharyngeal arch-> 1
Ventral root Nerve-> Trochlear
Somite SE ->Dorsal oblique
Dorsal root nerve->Trigeminal (Maxillary and Mandibular)
Ectoderm SA-Skin of face, rostral ⅔ of tongue
Endoderm AA-None
Glands AE-None
Lateral plate mesoderm-Chewing muscles (malleus and incus)
Pouches-Middle ear, eustachian tube
Segment 3
Pharyngeal arch-> 2
Ventral root Nerve-> Abducens
Somite SE ->Lateral rectus and retractor bulbi/ oculi
Dorsal root nerve->Facial
Ectoderm SA-Negligible
Endoderm AA-Thyroid gland
Glands AE-Mandibular/Sublingual Salivary, Nasal, Lacrimal Glands
Lateral plate mesoderm-Facial muscles/stapes and hyoid
Pouches-Tonsil
Segment 4
Pharyngeal arch-> 3
Ventral root Nerve-> None
Dorsal root nerve->Glosso-pharyngeal
Ectoderm SA-Negligible
Endoderm AA-Pharynx, caudal ⅓ of tongue, carotid body/sinus
Glands AE-Parotid Salivary Gland
Lateral plate mesoderm-Stylo-pharyngeal muscle/hyoid
Pouches-Thymus, parathyroid
Segment 5
Pharyngeal arch-> 4
Ventral root Nerve-> None
Dorsal root nerve->Vagal-accessory complex
Ectoderm SA-Negligible
Endoderm AA-Rostral larynx, common larynx
Glands AE-GI Tract Glands
Lateral plate mesoderm-Pharyngeal muscles and cricothyroid muscle/laryngeal cartilages
Pouches-Thymus, parathyroid, ultimobranchial body
Segment 6
Pharyngeal arch-> 5
Ventral root Nerve-> Hypoglossal
Somite SE ->Somites migrate to form tongue muscle
Dorsal root nerve->None
Segment 7
Pharyngeal arch-> 6
Ventral root Nerve-> hypoglossal
Dorsal root nerve->Vagus-Accessory complex
Ectoderm SA-none
Endoderm AA-caudal larynx, oesophagus, respiratory
Glands AE- GI tract Glands
Lateral plate mesoderm-Laryngeal muscles/laryngeal cartilages
Pouches-none
Ophthalmic division of V
l Ectoderm only therefore
SA only
l SA
-skin of forehead & upper eyelid (zygomaticaotemporal n. & frontal n.)
-Cornea (long ciliary nn.)
-Medial eyelid / canthus (infratrochlear n.)
-Dorsal turbinates (ethmoidal n.)
-Base of horn in ox (cornual n.)
Maxillary Division of V
l Ectoderm only therefore SA only
l Skin of lower eyelid (zygomatic n.)
l Mucosa of nasal cavity (caudal nasal n.)
l Mucosa of hard palate (major palatine n.)
l Mucosa of soft palate (minor palatine n.)
l Cheek & incisor teeth of upper jaw (maxillary alveolar nn.)
l Upper lips, vibrissae, muzzle (cutaneous branches)
l Vestibule of nostril (rostral nasal n.)
Mandibular division of V
l Ectoderm = SA
l Lining of cheeks (buccinator n.)
l Lower teeth & lower lip (mandibular alveolar and mental nn.)
l Auricular & temporal regions (auricular & temporal branches)
l Rostral 2/3 of tongue (lingual n.)
l Muscles of Chewing = SVE
l Jaw closers
l Masseter m.
l Pterygoid m.
l Temporalis m.
l Jaw opener
l Rostral belly of Digastricus m (mylohyoid n.)
l Other muscles
l Tensor tympani m.
l Tensor veli palatini m.
Nasal cavity
l Dorsal turbinates from ectoderm of segment 1
l Ethmoidal n. from Opthalmic V
l Rest of nasal cavity from ectoderm of segment 2
l Caudal nasal n. & rostral nasal n. from Maxillary V
Rostral oral cavity
Presence of mouth separates trigeminal into maxillary & mandibular
l Maxillary V
l Palate (palatine n.)
l Upper teeth (max. alveolar n.)
l Mandibular V
l Lower teeth (mand. alveolar n.)
l Cheek lining (buccinator n.)
l Tongue (lingual n.)
Horn of ruminants and nerves
Variation in individuals
l 5 nerves involved
l Trigeminal branches
l Cornual n.
l Cornual br. Of infratrochlear n.
l Frontal n.
l Nerve to frontal sinus (never superficial)
l Cutaneous from C1 / C2
Muscles of chewing
l Arch 1 (segment 2) gives rise to muscles of chewing:
l Jaw closers
l Masseter m.
l Medial & Lateral Pterygoid mm.
l Temporalis m.
l Jaw opener
l Digastricus
l 2 bellies, cranial from Arch 1 therefore innervated by V, caudal from Arch 2 therefore innervated by VII
l All innervated by mandibular V (SVE)
Damage to trigeminal nerve
l Loss of sensation (SA)
l Inability to chew (SVE)
l Sometimes seen in dogs
l Dropped lower jaw
l Ridged appearance to crown of head due to wasting of temporalis muscle
Local anaesthesia of lower lip
l Can be torn
l Mental foramen (mental n. supplying SA to lower lip) palpable on
outer mandible
Vagal-Accessory Complex components
l Vagus (X)
l SA, AA, AE to head
l Also major AA (& AE) to thoracic / abdominal viscera
l Cranial division of Accessory (XI)
l SVE to head
l [Spinal divison of XI is SE to some neck
muscles]
VAGAL-Accessory complex pharyngeal arch
Pharyngeal arch 4 & 6
l SA
l External ear (auricular nerve)
l AA
l Epithelium of cervical oesophagus, caudal larynx, trachea (rec. laryngeal n.), cranial larynx (cr. laryngeal n.), lungs (pulmonary branches)
l Chemo / baro-receptors in aorta (aortic n.)
l Taste in pharyngeal mucosa surrounding larynx (cr. laryngeal n.)
l Epithelium of GI tract to transverse colon
l AE
l GI tract to transverse colon
l SVE
l Muscles of pharynx / larynx (pharyngeal / rec. laryngeal n.)
l Cricothyroideus (cr. laryngeal n.)
l MASSIVE AA/AE COMPONENT, SVE VIA CRANIAL DIVISON OF XI
Facial Nerve Segment
Segment 3
l Pharyngeal arch 2 therefore has dorsal root nerve (= CN VII)
l Supplies some autonomic nerves to segments 1 & 2 because Trigeminal (CN V) has lost all its autonomic components
l Travels through middle ear cavity (in facial canal of petrous temporal bone)
l Vulnerable to injury if middle ear becomes infected
l Some major branches subcutaneous
l Vulnerable to injury
Facial nerve 4 types of neuron
l SA
l Skin of external ear (int. auricular n.)
l AA
l Taste from rostral 2/3rds of tongue (chorda tympani)
l Taste from palate (major petrosal n.)
l AE
l Mandibular / sublingual salivary glands (chorda tympani)
l Nasal glands / lacrimal glands (major petrosal n.)
l SVE
l Facial muscles (buccal nn., nerves to individual muscles)
l Caudal belly of digastricus
Major petrosal nerve (VII) to pterygopalatine ganglion
l AE to lacrimal gland via opthalmic V
l AE to to nasal glands via caudal nasal n. (maxillary V)
l AA (SVA) to taste from palate via palatine n. (maxillary V)
l Chorda tympani (VII)
Lingual n. (mandibular V)
l AA (SVA) Taste from rostral 2/3rds of tongue
l AE to mandibular / sublingual salivary glands
SVE to facial muscles
l Caudal auricular nn.
l Caudal muscles of external ear (along with C1/C2)
l Auriculopalpebral n.
l Rostral muscles of external ear (auricular n.)
l Muscles of eyelid / face (palpebral n.)
l Dorsal / Ventral Buccal nn.
l Facial muscles
l Branch to caudal belly of digastricus
l Branch to stylohyoid muscle
l Branch to stapedius muscle
Nostril muscles role
-dilation of nostrils in breathing
-very important in racing horse
Cheek muscles role
-buccinator muscles
-like a diaphragm keeping cheek taught
Lip and eyelid muscles
Oval slit with flaps above and below
3 types of lip and eyelid muscles
-Closer, orbicularis oris/oculae
-lift upper flap, levator labii/palpebrae superioris
-depress lower flap, depressor labii/ palpebrae inferioris
Eyelid facial muscles
-an extra lifter medially
->levator anguli oculis
-a refractor laterally
->refractor anguli oculis
-bundles of smooth muscle
-> lift upper lip/depress lower lid
Ear muscles
l Pull ear forwards
l Pull ear backwards
l Adduct ear (towards mid-line)
l Abduct ear (away from mid-
line)
Cervicoauricularis muscle
l Pulls ear back
l Attaches laterally on cartilage
l Therefore also rotates ear
outwards
Nerve supply of nostril lip and cheek muscles
Dorsal/ventral buccal branches of Facial VII
Nerve supply eyelid muscles
-mainly by Facial VII
-Except-> levator palpebrae superioris-Occulomotor III
->Smooth muscle-sympathetic from cranial cervical ganglion
-important in neurological diagnosis as damage of these can cause ptosis (drooping of upper eyelid)
Drooping of upper eyelid
Ptosis
Ear muscles
-rostral (forward+abductors)= auricular n. (Branch of auriculopalpebral n.)
-caudal (backwards+adductors)= caudal auricular
-> also supplied by C1/C2 via great auricular
Paralysis of Facial Nerve
Buccal nn. & auriculopalpebral nn. subcutaneous therefore prone to damage
l Loss of tone in muscles of lips & nostrils
l Loss of ability to retain bolus in mouth (buccinator muscle)
l Food accumulates in cheek causing bulging
l Slight ptosis (drooping of upper eyelid)
l Innervation by CN III & sympathetic prevent total ptosis
l Weak palpebral / corneal reflex
l Due to paralysis of orbicularis oculi
l Ear rotated outwards & caudally (aggressive horse)
l Supply by C1/C2 to cervicoauricularis muscle intact
Glosso-pharyngeal nerve
-pharyngeal Arch 3
-SA: external ear (tympanic nerve)
-AA: taste (SVA) & sensation to caudal 1/3 of tongue and pharynx /// chemo/baro-receptors(carotid sinus nerve)
-AE: Parotid salivary gland ( minor petrosal nerve)
-SVE: stylopharyngeus muscle
