W1: Cranial Nerves Flashcards
List the cranial nerves derived from pharyngeal arches
nerves providing motor supply to the pharyngeal arches
V3, VII, IX, X
Arches 1, 2, 3 and 4/6 respectively
The nerves are called branchiomotor efferents.
List the 12 cranial nerves in order
List the cranial nerves derived from rostral somites, (pre-otic)
III, IV, VI
Extraocular muscles
List the cranial nerves classfied as somatic
III, IV, VI, XII
List the cranial nerves derived from caudal somites, (post-otic)
XI, XII
innervate the tongue and sternocleidomastoid & trapezius
Describe the cranial nerves involved in special senses
I, II, VIII, IX, Chorda Tympani
How are the cranial nerve nuclei grouped?
Based on…
Grouped by embryological origin
Do the extraocular rectus muscles insert anterior of posterior to the midline?
Rectus insert anterior to the midline. Oblique insert posterior to the midline
Name the action of the extraocular muscle, superior rectus
Elevation and Adduction
Name the action of the extraocular muscle, superior oblique
Abduction and Depression
List the nerves that supply each extraocular muscle
What nerve lesion might explain this pathology? Link this to the symptoms seen
Test
3rd Nerve Palsy
What nerve lesion might explain this pathology?
Test
VI nerve palsy
Which nerves exit the skull through the superior orbital fissure
V1, III, IV, VI
Which nerve carries proprioceptive fibres (positioning and movement of the eyes) from the extraocular muscles centrally
III (Oculomotor) sensory component carries proprioceptive fibres from the extraocular muscles - fibres then join the opthalmic divison of the trigeminal nerve (hitches ride)
Describe the differences between the Autonomic nervous system and Somatic nervous system
Past Exam Q
ANS: unconcious control, SNS: concious control
Describe the sympathetic innervation of the head and the neck - specifically referring to the pre- and post- ganglionic fibre locations.
Three gnaglia in the neck divided into superior, middle and inferior cervical ganglia
The post-ganglionic sympathetic nerves that innervate the head and neck arise from the superior cervical ganglion. These fibres travel with arteries and form the cephalic periarterial nerves.
What are cephalic periarterial nerves.?
post-ganglionic sympathetic nerves that leave the superior cervical ganglion forming the cephalic periarterial nerves - the fibres wrap around and follow the arteries (ex. carotid) to innervate visceral effectors associated with the skin of the face (sweat glands, blood vessels ect.) & visceral structures of the head (lacrimal gland, eye, nasal mucosa, salivary glands)
Describe the parasympathetic innervation of the head and the neck - specifically referring to the pre- ganglionic fibre locations.
Cell bodies of pre-ganglionic parasympathetic nerves are in nuclei of four of the cranial nerves (3rd, 7th, 9th, 10th) & 2nd-4th sacral segments of spinal cord
‘cranio-caudal divison of the ANS’
The pre-ganglionic parasympathetic nerves - travelling with the cranial nerves (3rd, 7th, 9th, 10th) correspond to which ganglia?
3rd: Ciliary ganglion
7th: Pterygopalatine ganglion
7th: Submandibular ganglion
9th: Otic ganglion
Where is the ciliary ganglion located? What role do the post-ganglionic fibres (that have synapsed in the ciliary ganglion) have?
Posterior to the eye
Fibres from ciliary ganglion supply parasympathetic innervation responsible for lens accommodation, pupilary light reflex
What other types of fibres travel through the ciliary ganglion/nerve
Describe the autonomic innervation to the eye (including the muscles and reflex)
Regulate diameter of the pupil of the eye by S.M
Constrictor muscles - circumferential/circular muscles (sphincter pupillae) - innervated by parasympathetic nerves. contraction = pupil constriction
Dilator muscles - radial muscles (dilator pupillae) - innervated by sympathetic nerves. contraction = pupil dilation
Pupillary reflex - constriction of the pupil in response to bright light - mediated by oculomotor nucleus (parasympathetic)
Lens accommodation - parasympathetic innvervating ciliary muscles
Where is the pterygopalatine ganglion located? What fibres enter the ganglion (what nerve is associated with this ganglion) and exit? What do they innervate?
Located lateral to the sphenopalatine foramen - between the sphenoid and palatine bones
Recieves pre-ganglionic fibres from the facial nerve (VII)
Post-ganglionic fibres asend to maxilary nerve (V2)
= parasympathetic innervation of the nasal mucosa, palate, pharynx and lacrimal glands
What is another common name for the pterygopalatine ganglion
Hayfever ganglion
Describe the innervation and role of the lacrimal gland
lacrimal gland receives postganglionic parasympathetic fibres from the pterygopalatine ganglion (via zygomaticotemporal branch of V,)
AND
Sympathetic innvervation
Role: produces lacrimal fluid (tears) - a watery solution containing salts, mucus and lysozyme if an irritating substance comes into contact with the conjunctiva (protective mechanism)
Describe innervation to the nasal mucosa
Sympathetic and parasympathetic innvervation
Parasympathetic: innervate seromucous glands and cause dilation of B.V’s = secretion
Sympathetic : innervate B.V’s of the mucosa = vasoconstriction = decreased secretion
Decongestants mimic this effect in order to reduce mucus production
Where is the submandibular ganglion located? What fibres enter the ganglion (what nerve is associated with this ganglion) and exit?
The submandibular ganglia receive parasympathetic fibres that travel with the facial nerve (7th) and then chorda tympani (travels with lingual nerve - branch of mandibular nerve)
Post-ganglionic parasympathetic fibres pass to the submandibular, or, re-enter the lingual nerve to pass to the sublingual and buccal salivary glands.
Where is the otic ganglion located? What fibres enter the ganglion (what nerve is associated with this ganglion) and exit?
The otic ganglia are inferior to the foramen ovale
Receive pre-ganglionic fibres from the glossopharyngeal nerve and send post-ganglionic fibres to the parotid salivary glands
Describe the autonomic innvervation to the salivary glands and the result of the different types of innervation
Parasympathetic innervation of submandibular and sublingual salivary glands = facial nerve
Parotid = glossophayngeal nerve
Parasympathetic = increases secretory activity, and increases blood flow to the glands, = large volumes of a watery secretion
Sympathetic (from superior cervical ganglion via carotid plexus) travel with B.V’s = decreases secretory activity = small volume of more viscous saliva stressed = dry mouth
Describe the autonomic innvervation to the skin including the main N.T involved and the result of the different types of innervation
Sympathetic nerves to the skin of the face…
* innervate the sweat glands = increase sweat production (use acetylcholine as N.T)
* innervate vasculature = vasoconstriction
* cause contraction of arrector pili muscles - erection of hairs
What are the two types of receptors Ach binds to?
Muscarinic (metabotropic) involved in 2nd messenger pathways
Nicotinic (ionotropic) at N-M junction
What is Scapolomine?
used when undergoing surgery, muscarinic antagonist = dry mouth
Describe the type of nerve modality carried by the olfactory nerve
special visceral afferent
associated with sense of smell
Describe the type of nerve modality carried by the optic nerve
special somatic afferent
associated with sense of sight
What is the only cranial nerve that can be affected by multiple sclerosis
The optic nerve as
Unlike other sensory nerves, where there is no “processing” of sensory information, before the signals get to the CNS, the processing of visual information starts in the periphery… the myelin sheath of the optic nerve is produced by oligodendrocytes rather than by Schwann cells, as in other cranial nerves
Describe the types of nerve modality carried by the trigeminal nerve
Ophthalmic nerve (V1)
Maxillary nerve (V2)
= sensory nerve fibres (general somatic afferent)
Mandibular nerve (V3)
= general somatic afferent fibres, general proprioceptive fibres (from the muscles of mastication), and special visceral efferent fibres
Name the structures innervated by the trigeminal nerve
Generally
it innervates much of the face, the teeth and their supporting structures, most of the anterior portion of the oral cavity, and the mucous membranes of the head
The Ophthalmic nerve (V1) supplies sensory innervation to the…
- Eyeball and conjunctiva of the eye
- Lacrimal gland
- Skin of the forehead and nose
- Mucous membranes of the paranasal sinuses
Describe the three divisions of the ophthalmic nerve (once it enters the orbit)
The lacrimal (lateral conjunctiva and upper eyelid)
The frontal (medial conjunctiva and upper eyelid; skin of forehead and frontal sinus)
Nasociliary nerve (ethmoidal, sphenoidal and frontal sinuses; mucous membranes of nose)
The Maxillary nerve (V2) supplies sensory innervation to the…
- Skin on the side of the nose
- Cheek
- Lower eyelids
- Mid-face
- Nasopharynx, tonsils and palate
- Maxillary sinus
- Upper lip
- Teeth, gingiva and associated structures of the upper jaw
- Dura mater (<- gives rise to the middle meningeal nerve)
The Mandibular nerve (V3) is the largest division of the trigeminal nerve. It contains motor components in addition to its general sensory components. The sensory nerves innervate…
- Skin of the lower face
- Cheek and lower lip
- Ear and external acoustic meatus (auditory canal)
- Temporomandibular joint
- Skin of the temporal region
- The mucous membranes of the cheek
- The mucosa of the anterior two-thirds of the tongue
- The mandibular teeth, gingiva and supporting tissues
- Mandible
- Mastoid air cells
- Parts of the dura mater
The abducens nerve innervates…
extraocular muscle of the eye –lateral rectus
Describe the types of nerve modality carried by the facial nerve
sensory and motor fibres
General sensory, visceral sensory, and special sensory components
The Facial nerve supplies sensory innervation to the…
- External acoustic meatus (GSA)
- Soft palate and some of the pharynx (VSA) (greaterpetrosal nerve– joins V2)
- Involved in sense of taste (SVA), through its innervation ofthe anterior two-thirds of the tongue (chorda tympani nerve –joins V3)
What are the two components of the Vestibulocochlear Nerve?
Nerve that provides us with our senses of hearing and balance
* Cochlear nerve – innervates the organ of Corti within the cochlea – provides us with our sense of hearing
* Vestibular nerve – innervates the vestibular apparatus of the inner ear, providing us with our sense of balance
Describe the types of nerve modality carried by the glossopharyngeal nerve
Both sensory and motor fibres
General sensory, visceral sensory, and special sensory components
The Glossopharyngeal Nerve nerve supplies sensory innervation to the…
- Taste buds on the posterior one-third of the tongue, as well circumvallate papillae (lingual branches of the pharyngeal branches)
- General visceral afferents supply the posterior one-third of the tongue (lingual branches), the fauces, the palatine tonsils and the pharynx (tonsilar branches)
- vagus, it also innervates the baroreceptors (carotid sinus), and the chemoreceptors (carotid body)
- General somatic afferents provide cutaneous sensation of the ear*
- The tympanic nerve (together with the greaterpetrosal branch of VII) innervates the mucous membranes of the eardrum, and structures of the middle ear
Describe the types of nerve modality carried by the vagus nerve
Both sensory and motor fibres
General and special visceral components, and somatic sensory sensation
The meningeal branch of the vagus nerve innervates…
dura mater in posterior cranial fossa
The auricular branch of the vagus nerve innervates…
skin of the posterior aspect of the ear and auditory canal
Describe the branches of the vagus nerve that arise in the neck and the structures they innervate
- Pharyngeal branches: mucous membranes ofthe pharynx
- Superior laryngeal nerve: sensory innervation to the mucous membranes from the base of the tongue to the epiglottis, and larynx as far as the vocal folds. sense of taste from the base of tongue to larynx
- Superior cardiac branches
Describe the pathway for the pupillary light reflex
Inputs through optic nerve (II) into pons/midbrain
Output travelling with the III nerve into ciliary ganglion = change in lens (constriction)
What nerve excluding the ariculotemporal supplies the dermatome posterior to the auricle
The auricular branch innervates the skin of theposterior aspect of the ear and auditory canal
