FUNCTIONAL ANATOMY - Cranial Nerves Flashcards
What are the twelve cranial nerves?
I Olfactory nerve
II Optic nerve
III Oculomotor nerve
IV Trochlear nerve
V Trigeminal nerve
VI Abducens nerve
VII Facial nerve
VIII Vestibulocochlear nerve
IX Glossopharyngeal nerve
X Vagus nerve
XI Accessory nerve
XII Hypoglossal nerve
What is the function of cranial nerve I (olfactory nerve)?
Olfaction
What are three clinical signs of cranial nerve I (olfactory nerve) dysfunction?
Hyposmia (partial loss of smell)
Anosmia (complete loss of smell)
Inappetence
What can be done to test the function of cranial nerve I (olfactory nerve)?
Test the animal’s response to aromatic substances while they are blindfolded
What is the function of cranial nerve II (optic nerve)?
Vision
What are the functions of cranial nerve III (oculomotor nerve)?
Motor innervation of the ipsilateral dorsal rectus, medial rectus, ventral rectus and ventral oblique extraocular muscles and parasympathetic innervation of the iris (for miosis)
What are two clinical signs of cranial nerve III (oculomotor nerve) dysfunction?
Ventrolateral strabismus of the ipsilateral eye
Absent pupillary light reflex (mydriasis)
What can be done to test the function of cranial nerve III (oculomotor nerve)?
Observe the eye position
Test pupillary light reflex (PLR)
What is the function of cranial nerve IV (trochlear nerve)?
Motor innervation of the contralateral dorsal oblique extraocular muscle
What is the clinical sign of cranial nerve IV (trochlear nerve) dysfunction?
Dorsolateral strabismus of contralateral eye
What can be done to test the function of cranial nerve IV (trochlear nerve)?
Observe the position of the eye
What are the three branches of the trigeminal nerve?
Ophthalmic branch
Maxillary branch
Mandibular branch
What are the functions of cranial nerve V (trigeminal nerve)?
Sensory innervation of the face
Motor innervation of the masticatory muscles
What are the two clinical signs of cranial nerve V (trigeminal nerve) dysfunction?
Absent facial sensation
Masticatory muscle atrophy
What can be done to test the function of cranial nerve V (trigeminal nerve)?
Observe and palpate the masticatory muscles for atrophy
Corneal reflex
Palpebral reflex
What is the function of cranial nerve VI (abducens nerve)?
Motor innervation of the ipsilater lateral rectus and retractor bulbi extraocular muscles
What are the three clinical signs of cranial nerve VI (abducens nerve) dysfunction?
Medial strabismus of the ipsilateral eye
Inability to retract the eyeball
Absent vestibulo-ocular reflex
Inability to retract eyeball = absent corneal reflex
What can be done to test the function of cranial nerve VI (abducens nerve)?
Observe the position of the eye
Corneal reflex
Test vestibulo-ocular reflex
What are the functions of cranial nerve VII (facial nerve)?
Sensory innervation to the tongue and ear pinna
Motor innervation of the facial muscles
Parasympathetic innervation of the nasal glands, lacrimal glands and mandibular and sublingual salivary glands
What are the three clinical signs of acute cranial nerve VII (facial nerve) dysfunction?
Ipsilateral ear and lip drooping
Absence of blinking
Keratoconjunctivitis sicca
What is Keratoconjunctivitis sicca?
‘Dry eye’
What is the clinical sign of chronic cranial nerve VII (facial nerve) dysfunction?
Retracted lip
What can be done to test the function of cranial nerve VII (facial nerve)?
Palpebral reflex
Menace response
Lip pinch
Schirmers tear test
What are the two branches of cranial nerve VIII (vestibulocochlear nerve)?
Cochlear branch
Vestibular branch
What are the functions of cranial nerve VIII (vestibulocochlear nerve)?
Hearing
Balance
What are the two clinical signs of cranial nerve VIII (vestibulocochlear nerve) dysfunction?
Deafness
Vestibular symptoms
What can be done to test the function of cranial nerve VIII (vestibulocochlear nerve)?
Observe for any vestibular symptoms
Test the vestibulo-ocular reflex
Brain auditory evoked response (BAER) test for hearing
What are the functions of cranial nerve IX (glossopharyngeal nerve)?
Sensory innervation of the tongue and pharynx (taste)
Motor innervation to the stylopharyngeus muscle
Parasympathetic innervation of the parotid and zygomatic salivary glands
What are the functions of cranial nerve X (vagus nerve)?
Sensory innervation of the pharynx (sensation and taste)
Motor innervation of the pharynx, larynx and oesophagus
Parasympathetic innervation of the cervical, thoracic and abdominal viscera
What are the five clinical signs of cranial nerve IX (glossopharyngeal nerve) and cranial nerve X (vagus nerve) dysfunction?
Dysphagia
Absent gag reflex
Inspiratory dyspnoea
Dysphonia
Megaoesophagus
What can be done to test the functions of cranial nerve IX (glossopharyngeal nerve) and cranial nerve X (vagus nerve)?
Test the gag reflex
What is the function of cranial nerve XI (accessory nerve)?
Motor innervation of the neck muscles (trapezius, brachiocephalic and sternocephalic muscles)
What is the clinical sign of cranial nerve XI (accessory nerve) dysfunction?
Deviation of the neck
What is the function of cranial nerve XII (hypoglossal nerve)?
Motor innervation of the tongue
What are the three clinical sign of cranial nerve XII (hypoglossal nerve) dysfunction?
Tongue atrophy
Tongue deviation
Abnormal deglutition (swallowing)
What can be done to test the function of cranial nerve XII (hypoglassal nerve)?
Observe for tongue position and atrophy
