Lecture 6 - Cranial Nerves Flashcards
Where does the neural plate develop?
In the ectoderm
Lateral margins of the neural plate grow upward to form what?
The neural folds/neural groove
The neural folds meet at the midline, fuse, and form what?
The neural tube
What is a notochord?
Defines the axis of the embryo, basis for the axial skeleton and future site of the vertebrae
Neural crest cells give rise to what?
The peripheral nervous system
From where does the spinal cord develop?
The caudal end of the neural tube
The neural tube differentiates into what 3 encephalons?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Based on the embryology of the cranial nerves, where do the nerves fall in the different ‘encephalons’ of the brain?
Tel - i
Die - ii
Mes - iii, iv
Met – v, vi, vii, viii
Mye – ix, x, xi, xii
Pharyngeal arch 1 gives rise to which cranial nerve? This serves what function?
CN V - trigeminal
Muscles of mastication
Pharyngeal arch 2 gives rise to which cranial nerve? This serves what function?
CN VII - facial
Facial expression
CN IX (glossopharyngeal) is derived from which pharyngeal arch?
3
Pharyngeal arch 4 gives rise to what cranial nerve branch? What is its function?
Superior laryngeal branch of vagus nerve
- Muscles of soft palate & pharynx
Pharyngeal arch 5 gives rise to which cranial nerve branch? What is its function?
Recurrent laryngeal branch of vagus nerve
- Intrinsic laryngeal muscles & skeleton muscles of esophagus
List the cranial nerves and their function (S, M, B)
CN I - Olfactory (S)
CN II - Optic (S)
CN III - Oculomotor (M)
CN IV - Trochlear (M)
CN V - Trigeminal (B)
CN VI - Abducens (M)
CN VII - Facial (B)
CN VIII - Vestibulocochlear (S)
CN IX - Glossopharyngeal (B)
CN X - Vagus (B)
CN XI - Accessory (M)
CN XII - Hypoglossal (M)
Which of the cranial nerves have somatic efferent functions?
III oculomotor
IV trochlear
VI abducens
XI accessory
XII hypoglossal
Which of the cranial nerves have somatic afferent functions?
V trigeminal
IX glossopharyngeal
Which of the cranial nerves have autonomic efferent parasympathetic functions?
III oculomotor
VII facial
IX glossopharyngeal
X vagus
Which of the cranial nerves have autonomic afferent parasympathetic functions?
X vagus
Which of the cranial nerves are derived from brachial/pharyngeal archs and have special efferent function?
V trigeminal
VII facial
IX glossopharyngeal
X vagus
Which of the cranial nerves have a special afferent function?
I olfactory
II optic
VII facial
VIII hypoglossal
IX glossopharyngeal
X vagus
CN I - olfactory deals with what? Afferent or efferent?
Afferent smell
CN II - optic deals with what? Afferent or efferent?
Afferent vision
CN IV trochlear deals with what? Somatic or autonomic? Afferent or efferent?
Somatic efferent eye muscle
CN VI abducens deals with what? Somatic or autonomic? Afferent or efferent?
Somatic efferent eye muscle
CN VIII vestibulocochlear deals with what? Afferent or efferent?
Afferent hearing/balance
CN XI accessory deals with what? Afferent or efferent?
Efferent neck muscle
XII hypoglossal deals with what? Afferent or efferent?
Somatic efferent tongue muscle
CN III oculomotor has how many different functions? What are they?
1) somatic efferent eye muscle
2) autonomic efferent (parasympathetic) ciliary body/iris muscles
CN V trigeminal has how many different functions? What are they?
1) somatic afferent sensation of face
2) special efferent ear and jaw muscles
CN VII facial has how many different functions? What are they?
1) autonomic efferent (parasympathetic) salivary, lacrimal glands
2) special afferent taste anterior ⅔ tongue
3) special efferent muscles of face and ear
CN IX glossopharyngeal has how many different functions? What are they?
1) somatic afferent face, ear, palate, tongue sensation
2) autonomic efferent (parasympathetic) salivary and mucosal glands
3) special efferent stylopharyngeus muscle
4) special afferent taste posterior ⅓ tongue
CN X vagus has how many different functions? What are they?
1) autonomic afferent pharynx, larynx, thorax, abdomen
2) autonomic efferent (parasympathetic) heart, vessels, trachea, esophagus, stomach & intestine
3) special efferent laryngeal, soft palate, pharyngeal muscles
4) special afferent taste pharynx
Neuroepithelial olfactory cells send axons through the ______ of the ______ bone to synapse in the _______ ______ to the ________ ______
Cribiform plate, ethmoid, olfactory bulb, olfactory tract
Damage to the optic nerve symptoms & their definitions (3)
Blurry vision
Monocular loss (prechiasm) - one eye
Homonymous hemianopia (postchiasm) - contralateral visual field
Scotoma - blind spot
Damage to CN I symptoms & their definition (2)
Anosmia - loss of smell
Ageusia - loss of taste
CN II has special receptors cells located where?
In the retina at the back of the eye
CN III has its motor nucleus where?
Upper midbrain
CN III controls most eye movements and ________ elevation
Eyelid
CN III controls _______ constriction & _____ accommodation (_______)
pupil, lens, parasympathetic
Damage to the oculomotor nerve symptoms & definitions
Strabismus – lazy eye
Diplopia– double vision
Ptosis– eye lid droop
Diminished pupillary reflex (diminished ipsi response)
CN IV has its motor nucleus where?
Midbrain
CN IV innervates which eye muscle(s)?
Superior oblique eye muscles
Damage to trochlear nerve symptoms & defintions
Diplopia - double vision
Head tilt
CN V has how many branches? What are they?
3
Ophthalmic, maxillary, mandibular
The motor nucleus of the CN V is located where?
In the pons
What are the sensory and motor functions of the trigeminal nerve?
Purpose: sensory – pain and touch from face, tongue, ear, inside of orbit, mouth and proprioception of jaw. This is the nerve the dentist numbs.
Purpose: motor – Jaw, mastication eustachian tube
Damage to the trigeminal nerve symptoms & defintions
Tic Douloureux/trigeminal neuralgia (pain spasms)
CN VI has its motor nucleus where?
Tegmentum of the pons
CN VI innervates what muscle(s)?
Lateral rectus muscles (sides of eyeball)
CN VII has a parasympathetic efferent function on what?
Salivary and lacrimal gland and mucus of nose and palate
CN VII has a special sensory function for what sense?
Taste - anterior 2/3 of the tongue
CN VII has special efferent function for what?
muscles of facial expression (frontalis, orbicularis oculi, levator labii, levator anguli oris, mentalis, orbicularis oris, buccinator, platysma, stapedius, stylohyoid, posterior belly of diagastric (not all inclusive)
Damage to facial nerve symptoms & definitions
Contralateral facial droop (Bell’s Palsy)
Dry mouth and tearing
Impairment of taste and hyperacusis (sounds seem very loud)
CN VIII has a special sensory function for what two senses? Where are their cells?
Hearing & balance
Hearing - cochlear branch - hair cells in cochlea
Balance - vestibular branch - hair cells in semicircular canals
Damage to vestibulocochlear nerve symptoms & definitions
Dizziness
Nausea
Nystagmus (involuntary rapid eye movements)
Vertigo (room spinning)
Hearing loss
CN IX has general sensory function for what structures?
ear drum, EAC, tonsil, posterior 1/3 of tongue
CN IX has special sensory function for what structure?
Taste posterior 1/3 of tongue
CN IX has a special efferent function for what muscle? What action does this correspond what?
Stylopharyngeus muscle (swallowing)
CN IX has a autonomic parasympathetic efferent function for what structure?
Parotid salivary gland
Damage to glossopharyngeal nerve symptoms & definitions
Glossopharyngeal neuralgia (pain of a nerve)
Allodynia (pain for a nonpainful stimulus)
Some loss of taste or feeling in palate/pharynx, dry/wet mouth
Difficulty swallowing
CN X has a general sensory function for what structures
Mostly pharynx and larynx
CN X has autonomic sensory function for what structures?
larynx, trachea, esophagus, guts, blood vessels
The special efferent functions of the CN X are carried out by 3 branches. What are they and what muscles to they innervate?
- Pharyngeal (muscles of resonance)
- Superior Laryngeal and
- Recurrent Laryngeal (muscles of phonation)
Innervates the palatal muscles, swallowing muscles and voicing muscles
CN X has autonomic/parasympathetic efferent motor functions for what structures?
Heart, lungs, intestines
Damage to the vagus nerve symptoms & definitions
Dysphagia is difficulty swallowing
Dysphonia refers to difficulty producing speech sounds due to issues with the voice box (larynx)
CN XI has special efferent functions for what muscles?
sternocleidomastoid and trapezius muscle
Damage to accessory nerve symptoms & definitions
Weakness in shoulder elevation Weakness in head rotation
CN XII has somatic motor function with what structures?
Most extrinsic and intrinsic muscles of the tongue
Damage to hypoglossal nerve symptoms & definitions
Tongue protrusion toward weak side
Fasciculations - small, involuntary muscle contractions or twitches
