Lecture 2: Cranial Nerves and Craniofacial Autonomics Flashcards
What CN’s are above pons, in the pons, in medulla, and are medial?
4 CN are above pons (I, II, III, IV)
4 CN are in pons (V, VI, VII, VIII)
4 CN are in medulla (IX, X, XI, XII)
4 CN nuclei are medial (III, IV, VI, XII) - Factors of 12, except 1 and 2
What is CN I; pathway; synapses; injury?
- Olfactory = sensory
- Pathway: cribiform plate of ethmoid bone
- Synapse in olfactory bulb –> piriform cortex
- Injury: anosmia
The afferent fibers of which CN do not go to the thalamus?
CN I
What is CN II; function; pathway; arises from where?
- Optic N = special sensory
- Sight
- Pathway: optic canal of the sphenoid bone
- Arises from the diencephalon
What are the three nerves to the Ocular muscles and which CN do they arise from?
1) Trochlear N (CN IV)
2) Abducent (CN VI)
3) Oculomotor (CN III)
How do the somatic motor efferent fibers of CN III (oculomotor) move the superior rectus m, medial rectus m, inferior rectus m, inferior oblique m., and levator palpebrae of the eyes?
- Superior rectus m. (up)
- Medial rectus m. (medial)
- Inferior rectus m. (inferior)
- Inferior oblique m. (superior rotation)
- Levator palpebrae (elevates eyelid)
What are the parasympathetic motor (visceral efferent) effects of CN III (oculomotor) on the sphincter pupillae and ciliary muscle?
- Sphincter pupillae: pupillary constriction
- Ciliary muscle - for near vision
Which CN’s innervate the motor functions of the lateral rectus m and superior oblique ms. of the eye?
Lateral rectus m = CN VI
Superior Oblique = CN IV
Mnemonic: SO4LR6
What CN is affected here?
- Right oculomotor (CN III) nerve palsy
- Downward and outward gaze, dilated pupil, eyelid manually elevated due to ptosis
- Only CN IV and VI are functioning
What CN innervates the superior oblique m. of the eye and what type of movement?
- CN IV (trochlear)
- Turns eye down/in
- Used when reading/going down stairs
What is characteristic of trochlear (CN IV) palsy?
- Eye tilted outward
- Unable to look down/in (stairs, reading)
- Tucking chin and head tilting away from affected side (to compensate)
What CN innervates the lateral rectus m. of the eye and what kind of movement?
- CN VI (abducens)
- Lateral movement of the eye
What is characterisitic of abducens nerve palsy?
- Diplopia (double vision)
- Can’t laterally move (look out) affected eye
What are the sensory and motor functions of the Trigeminal (CN V)?
Sensory (touch-pain-temp) to face
- 3 divisions: opthalmic (V1), maxillary (V2), mandibular (V3)
Motor: muscles of mastification (chewing)
- Mandibular (V3)
- Part of corneal reflex (sensory input via V1)
What is the corneal reflex and the CN involved?
- Touch eye with Q-tip
- Input sensoes by V1 of CN V
- Transmit to CN VII (bilaterally)
- CN VII (facial n.) -> blink
What provides the sensory input for each of the three colors in this image?
Orange = Opthalmic (CN V1)
Blue = Maxillary (CN V2)
Green = Mandibular (CN V3)
What are the 4 main sensory branches that arise from the Opthalmic nerve (V1)?
1) Lacrimal
2) Frontal
3) Nasociliary
4) Meningeal branch (from the tentorium cerebelli)
What are the 6 main sensory branches that arise from the Maxillary nerve (V2)?
- Zygomatic
- Infraorbital
- Superior alveolar
- Nasociliary
- Palantine
- Meningeal
What are the 5 main sensory branches that arise from the Mandibular nerve (V3)?
1) Buccal
2) Lingual
3) Inferior alveolar
4) Auriculotemporal
5) Meningeal (spinous)
What are the 5 main motor branches that arise from the Mandibular nerve (V3)?
1) Medial ptergoid
2) Lateral pterygoid
3) Masseteric
4) Deep temporal
5) Mylohyoid
What are the characteristics of Trigeminal nerve (CN V) palsy?
- Numb face (sensory)
- Weak jaw (motor) - deviates to affected side
What is characteristic of Trigeminal (CN V) neuralgia?
- Recurrent, sudden sharp pains
- Tic douloureux (painful tic)
- So intense you wince
Describe the route of the presynaptic parasympathetic fibers (secretomotor) of the facial n. (CN VII)?
Go to pterygopalantine ganglion via greater petrosal nerve and to anterior tongue and submandibular ganglion via chorda tympani
What are characteristics of Facial (CN VII) palsy?
- Loss of corneal reflex (motor output)
- Loss of taste anterior 2/3 of tongue
- Hyperacusis (stapedius paralysis): pt cannot tolerate sounds
What is Bell’s Palsy; how is it brought on; characteristics; how does it resolve?
- Idiopathic mononeuropathy of CN VII
- Sudden onset of facial paralysis
- Usually resolves in weeks to months
What is the function of CN VIII (vestibulocochlear); describe both portions and what occur with lesions to each of the regions?
- Special sensory
- Hearing, balance, equilibrium
Cochlear portion: hearing
- Lesions = loss of hearing, tinnitus
Vestibular portion: equilirum –> compensatory eye movement
- Lesions = vertigo, nystagmus, vomiting, nausea
What type of innervation from CN IX and the important functions?
- Motor, sensory
- Taste/sensation posterior 1/3 of tongue
- Salivation (parotid gland)
- Carotid body and sinus (chemo- and baroreceptor)
- Stylopharyngeus: elevates pharynx for swallowing/gagging
What does damage to the Glossopharyngeal (CN IX) lead to?
Glossopharyngeal palsy
- Loss of gag reflex
- Loss of taste posterior 1/3 tongue
- Loss sensation upper pharynx
Hemodynamic effects
- Trick body into thinking low BP
- Increase BP and vasoconstriction
What are the important function of the Vagus (CN X) in the head and neck?
- Taste, supra-epiglottic region
- Swallowing (dysphagia = vagus)
- Palate elevation
- Midline uvula
- Talking
- Coughing
What chemo/baroreceptors does the Vagus n vs. Glossopharyngeal n. play a role in?
Vagus (CN X) = Aortic arch
Glossopharyngeal (CN IX) = Carotid body and sinus
The nucleus solitarius is involved with what CN’s and functions?
- Visceral Sensory information (i.e., taste, baroreceptors, gut distention)
- VII, IX, X
The nucleus ambigous is involved with what CN’s and functions?
- Motor innervation of pharynx, larynx, upper esophagus (i.e., swallowing, palate elevation)
- IX, X, XI (cranial portion)
The dorsal motor nucleus is involved with what CN’s and what functions?
- Sends autonomic (parasympathetic) fibers to heart, lungs, upper GI
- CN X
What is seen in Vagus (X) nerve palsy; what specifically with the Uvula?
- Hoarsness, dysphagia, dysarthria
- Loss of gag reflex
- Loss of sensation pharynx and larynx
- Weak side of palate collapse (lower)
- Uvula deviates AWAY from affected side (U go away)
What are the hemodynamic effects of Vagus n. palsy?
- Unopposed sympathetic stimulation of heart
- Increased HR
What is the most common cause of syncope (fainting); characteristics and triggers?
- Vasovagal syncope
- Trigger to vagus nerve: increase parasympathetic outflow via vagus
- Decrease HR, decrease BP –> fainting
- Many triggers = hot weather, prolonged standing, pain, sight of blood
What kind of innervation from spinal accessory (CN XI) and functions?
- Motor (branchial type)
- Turning head
- Shoulder shrugging: SCM and Trapezius
What is seen with Spinal Accessory (CN XI) palsy?
- Difficulty turning head toward normal side (SCM)
- Shoulder droop (affected side)
What kind of innervation from Hypoglossal (CN XII), what are the functions?
- Motor
- Tongue movement
What is seen with Hypoglossal (CN XII) palsy?
- Protrusion of tongue TOWARD the affected side
- Opposite side pushes tongue away unopposed
What are the 4 superficial cervical nerves and what spinal segments does each come from?
1) Lesser Occipital (C2-C3)
2) Great Auricular (C3-C4)
3) Transverse Cervical (C3-C4)
4) Supraclavicular (C3-C4)
What is the ansa cervicalis; where is it found; what are its divisions; what does it innervate?
- Formed by a loop of nerve fibers from the anterior rami of C1-C3
- Embedded in the fascia of carotid sheath
- Superior root (C1-C2) leaves hypoglossal nerve
- Inferior root (C2-C3) crosses lateral to IJV
- Directly innervates all the infrahyoid muscles
*Travel with CN XII, but not a functional component of
General somatic afferent fibers innervate structures of what embryologic origin and what type of sensory info is relayed; primarily conveyed by what nerve?
- Ectodermal origin
- Pain, temperature, tactile, pressure and proprioception (highly localized)
- Primarily conveyed by Trigeminal n. (CN V)
General visceal afferent fibers innervate structures of what embryologic origin, what type of sensory info is relayed; what nerve has huge distribtution of these fibers?
- Endodermal origin
- Dull, aching, burning, poorly localized sensations
- Vagus nerve has a huge distribution of GVA fibers to the mucosa of posterior 1/3 tongue to the mid-portion of transverse colon
General somatic efferent fibers innervate structures of what embryologic origin; what structures specifically in the head?
- Myotomic origin
- Most muscles in the body/neck are of myotomic origin
- Only myotomic groups in head are intrinsic muscles of tongue and extraocular muscles
General visceral efferent fibers are components of what; innervate what structures?
- Components of the ANS, may be parasympathetic or sympathetic
- GVE fibers are associated w/ the parasympathetic fibers coursing in the III, VII, IX, and X cranial nerves
Special Visceral Efferent fibers innervate?
Muscles of branchiomeric origin, such as:
- Muscles of mastication (V)
- Facial expression (VII)
- Larynx and pharynx (X, except stylopharyngeus—IX)
- SCM and trapezius (XI)
What is the sensory nucleus for all sensation from the face?
- Trigeminal sensory nuclei
- ALL GSA fibers from CN’s V, VII, IX, and X terminate in some part of this nucleus
What are the 3 nuclei of the trigeminal sensory nucleus and what information does each receive?
1) Mesencephalic nucleus of V receives proprioception info from facial muscles
2) Main sensory nucleus of V receives precise tactile discriminaton info from the face
3) Descending nucleus of V received crude tactile pain, temperature info from the face
What is the sensory nucleus for general sensations from the posterior 1/3 of the tongue to the mid-portion of the transverse colon; what type of fibers?
- Solitary nucleus (nucleus tractus solitarius, NTS)
- ALL GVA and SVA (taste) fibers
What is the sensory nucleus for the salivary, lacrimation, gag, and cough reflexes?
Solitary nucleus (nucleus tractus solitarius)
What are the 4 nucleus that make up the GSE column?
1) Oculomotor nucleus: innervates the superior, inferior, and medial recti, inferior oblique, and the levator palpebrae superioris ms.
2) Trochlear nucleus: innervates the superior oblique muscle
3) Abducens nucleus innervates the lateral rectus m.
4) Hypoglossal nucleus innervates all the muscles associated w/ the tongue, except palatoglossus
What is the Edinger-Westphal nucleus?
- Part of the GVE parasympathetic column
- Sends preganglionic fibers to ciliary ganglion via branches of oculomotor nerve
- The ciliary ganglion sends postganglionic fibers to the ciliary muscles of the lens and the pupillary constrictor muscles
What is the Superior Salivatory nucleus (VII)?
- Sends preganglionic fibers to the sphenopalantine and submandibular ganglia.
- Sphenopalantine ganglion sends postganglionic fibers to the lacrimal gland, and oral and nasal cavities
- Submandibular ganglion sends postganglionic fibers to the submandibular and sublingual salivary glands
What is the Inferior Salivatory nucleus (IX)?
- Sends preganglionic fibers to the otic ganglion
- The otic ganglion sends postganglionic fibers to the parotid salivary gland
What is the Dorsal Motor nucleus (X)?
- Sends preganglionic fibers to the scattered ganglia in the larynx, pharynx, thorax, and abdomen
- These ganglia send postganglionic fibers to various glands and smooth muscle in these regions
What’s Vernet’s Syndrome; what sign do you look for?
- A basilar skull fracture due to trauma may involve the jugular foramen and result in ipsilateral IX, X, and XI paralysis
- Look for Battle’s sign (bruising behind the pinna and/or over the mastoid process)
- May be accompanied with “raccoon” eye
- Fractures of the base of skull require a lot of force, therefore, always examine for possible brain/spine injury
Outside the cervical sympathetic trunk, there are no preganglionic sympathetic fibers in the ________.
Head
From the SVE column, fibers from the nucleus ambiguus exit the brainstem w/ cranial portion of ______, and anastomose with ________ at jugular foramen.
Fibers from the nucleus ambiguus exit the brainstem with cranial portion of XI, and anastomose with vagus nerve at jugular foramen
Where do the preganglionic sympathetic fibers to the head and neck originate and how do these fibers exit the spinal cord?
- Originate in preganglionic sympathetic cells bodies located in the intermediolateral cell column of the 1st and 2nd thoracic levels of spinal cord
- Exit the spinal cord via the ventral root, travel through the white ramus to the sympathetic trunk, where they ascend for a vairable distance before terminating in one of the cervical sympathetic ganglia
Where do the postganglionic sympathetic fibers to the head and neck form plexuses and what do these fibers innervate?
- Form nerve plexuses on the surface of blood vessesl, or join with cervical or cranial nerves
- Innervate blood vessels, smooth muscle, and glands of the head and neck
The superior cervical ganglion is a large elliptical ganglion located where?
Posterior to the internal carotid artery, embedded in the prevertebral fascia at the level of C1-C2 and on the surface of the longus capitus muscle at the level of C1
What are the 4 major branches of the internal carotid plexus?
1) Perivascular plexuses
2) Sympathetic branch to the ciliary ganglion
3) Deep Petrosal nerve
4) Carotico-tympanic nerve
The middle cervical ganglion is located at what vertebral level and where does it send post-ganglionic fibers?
- At level of C6 above the arch of the inferior thyroid artery
- Fibers to middle cervical nerves (C4-C6) and the vertebral artery + its branches via the vertebral plexus
The vertebral ganglion is located at what spinal level and near what artery; where does it send fibers?
- Level of C7 anterior to the vertebral artery
- Send postganglionic fibers to the sixth cervical nerve and the vertebral plexus
What is Horner’s Syndrome + the signs and symptoms?
- May be caused by Interruption of the cervical sympathetic trunk; transection of spinal cord above the level of T1; hemisection of the spinal cord above level of T1 (ipsilateral Horner’s Syndrome)
- Slight ptosis of the upper lid due to paralysis of the tarsal muscle
- Mitosis or pupillary constriction due to paralysis of the dilator pupillae muscle
- Anhidrosis and blushing (vasodilation) of the skin on the face due to loss of sympathetic innervaton of the blood vessels
- Enopthalmos due to paralysis of the orbitalis muscle of Muller which has a slight protrusion function
The preganglionic parasympathetic axons course with cranial nerves ________?
III, VII, IX, or X
Describe the route of parasympathetic fibers that innervate the submandibular salivary gland?
- Superior salivatory nucleus sends preganglionic fibers, which course in the chorda tympani nerve, a branch of the facial nerve, and merge with the lingual nerve in the infratemporal fossa before reaching the submandibular ganglion
- Submandibular ganglion sends postganglionic fibers which innervate the submandibular and sublingual salivary glands
Describe the route of sympathetic innervation to the submandibular and sublingual salivary glands?
- Preganglionic sympathetic neurons are found in the intermediolateral cell column
- Facial plexus on the facial artery distributes postganglionic sympathetic fibers to the submandibular and sublingual salivary glands
Describe the route of sympathetic innervation to the parotid gland
- Preganglionic sympathetic neurons are found in the intermediolateral cell column
- Caroticotympanic nerve enters the middle ear cavity, forms part of the tympanic plexus, and exits as the lesser petrosal nerve
- Postganglionic fibers will course through the lesser petrosal nerve, foramen ovale, otic ganglion, an auricotemporal nerve before supplying postganglionic fibers to the parotid gland
Describe the route of parasympathetic innervation to the parotid gland.
- Inferior salivatory nucleus send preganglionic fibers from the lesser petrosal nerve, a branch of glossopharyngeal, to the otic ganglion
- Postganglionic fibers from the otic ganglion innervate the parotid gland via the auriculotemporal branches of the trigeminal nerve
Describe the route of sympathetic innervation to the lacrimal gland
- Preganglionic neurons are found in the interomedial cell column
- The deep petrosal nerve courses in the carotid canal, and joins with the greater petrosal nerve to from the Vidian nerve.
- Postganglionic sympathetic fibers distribute to the palate, nasal cavity, pharynx, orbit and lacrimal gland
Describe the route of parasympathetic innervation to the lacrimal gland
- Superior salivatory nucleus sends preganglionic fibers via the greater petrosal nerve, a branch of facial nerve, and then the Vidian nerve to the Sphenopalatine ganglion
- Postganglionic fibers from the ganglion will innervate the lacrimal gland, nasal cavity, nasopharynx, palate and orbit via the zygomatic nerve, a communicating branch between the maxillary/infraorbital and lacrimal nerves
Describe the route of sympathetic innervation to the eye.
- Preganglionic sympathetic neurons are found in the intermediolateral cell column of the thoracolumbar segments of the spinal cord.
- Sympathetic branch to the ciliary ganglion passes through the cavernous sinus, superior orbital fissure and the ciliary ganglion before terminating as short ciliary nerves to the eyeball
- These postganglionic fibers innervate the dilator pupillae and tarsal muscles
Describe the route of the parasympathetic innervation to the eye
- Edinger-Westphal nucleus sends preganglionic fibers via the short root of the oculomotor nerve which terminate in the ciliary ganglion
- Postganglionic fibers to the ciliary muscles of the lens and the sphincter pupillae muscles of the iris
