Cutaneous sensations from face (pain, temp., touch): Trigeminal (V)

1. FACEWhich cranial nerves supply sensory and motor functions of the face and associated structures (e.g. hard palate, teeth and gums)?

2. Sensory from face (Think of a face with teeth bared, and eyes and nares open flared): Trigeminal nerve (V) • Cutaneous sensations from face (pain, temp., touch): Trigeminal (V) • Proprioception from face: Facial (VII) • Touch from cornea of eye and nasal mucosa (V, ophthalmic branch) • Teeth and gums: Trigeminal (V) • Maxillary branch: upper teeth and gums, plus hard palate • Mandibular branch: lower teeth and gums, plus lower jaw and inside of cheek • Skin of external ear and external auditory canal: Vagus (X), with some assistance by V, for tragus V V It is branches of V that are numbed by the dentist when you have dental work

3. Branching of V • V (Trigeminal): 3 branches • Ophthalmic: Sensory • Maxillary: Sensory • Mandibular: Sensory (+motor of mastication, which we’ll study later) V V

4. Testing Sensory of V in face • Sensory of V (trigeminal): With eyes closed, stroke… • above eyebrows (tests ophthalmic branch) • upper lip (tests maxillary branch) • between lower lip and chin (tests mandibular branch) • If you touch the pinna or ear canal you’re testing X (vagus). V innervates only the tragus It is branches of V that are numbed by the dentist when you have dental work

5. Motor innervation to muscles of facial expression: VII (facial) Fibers cross Fibers don’t cross • Remember: • Bilateral UMN innervation to the upper face • Unilateral UMN innervation (contralateral) to the lower face • LMNs (facial nerve VII and its branches) innervate the whole face on the same side as the cranial nerve Upper face: Mostly contralateral, some ipsilateral Lower face: Contralateral only

6. Motor innervation to muscles of face: VII (facial) • Notice how cranial nerve VII (facial) exits the cranium at the internal acoustic meatus (one of the foramina in the cranium), which is intimately close to the inner ear. It exits here with VIII.

7. Branching of VII • VII (Facial) branches • SVE to muscles of facial expression (including muscles for tight closure of eye) in yellow • GVE to lacrimal glands, nasal mucosa and some salivary glands (red) Note that VII also mediates proprioception from face receptors (embedded in muscles)

8. Motor innervation to certain glands near/around face/mouth • Facial nerve (VII) also mediates • Visceral innervation (in red) to • lacrimal glands, • nasal mucosa and • some salivary glands: Submandibular and sublingual (#2 and #3 below) VII

9. Note that VII also innervates stapedius muscle • VII: Dampens vibrations of the ossicles associated with loud noises (stapedius muscle) • V: Dampens vibrations of the ossicles associated with the noise of chewing (tensor tympani)

10. FACEClinical Applications

11. Pathology of motor of face (VII) • Motor of VII • Upper motor neuron lesion, e.g. cerebral stroke • Complete involvement below eye, some involvement around eye, little difficulty with forehead and frontalis muscle. (Note: Only applies to voluntary movement, not emotionally initiated movements.) • Lower motor neuron lesion: Moebius syndrome, biilateral congenital atrophy of VII • LMN lesion: Bell’s palsy, unilateral compression, viral infect. • Paralysis of entire side of face ipsilateral to the site of the compression or infection • Problems with eyelid closing • Drooping corner mouth • (Taste on anterior 2/3 of tongue affected) • Poor production of tears, reduced salivation

12. Testing motor of VII in face • Motor (voluntary) of VII (See pg. 156 of W&A) • Face at rest (look for asymetry) • Wrinkle forehead and look up • Close eyes as tightly as possible • Smile, pucker, pout • Whole side of face affected = _______ lesion on ipsilateral side, associated with _____________ dysarthria • Lower face affected, with some weakness of upper face = _________ lesion on contralateral side, associated with ___________________ dysarthria

13. TONGUEWhich cranial nerves supply sensory and motor functions of the tongue?

14. Tongue has sensation of two types (touch and taste) and is also able to move. Each of these functions is filled by different cranial nerves.

15. General sensory: Touch on tongue • V (Trigeminal), mandibular branch • General sensory for anterior 2/3 of tongue • IX (Glossopharyngeal) • General sensory for posterior 1/3 of tongue. Do you remember the other sensory functions of V? (think of face, gums, teeth, hard palate, jaw). When the mandibular branch of V is damaged or anesthetized, what sensory functions would be affected?

16. Special sensory: Taste on tongue • VII (Facial) • Special sensory for anterior 2/3 of tongue, in green on diagram to right. • IX (Glossopharyngeal) • Special sensory for posterior 1/3 of tongue. Remember these women who have VII (facial nerve) involvement? They’ll also have problems with taste on the ____________________ of tongue. Do you remember the cranial nerve of smell (I)? It works with VII and IX (taste).

17. Clinical testing of sensory functions of tongue • Swab dipped in flavored solution • Tests taste (function of special sensory branch of VII) • Tests touch (function of mandibular branch, general sensory, of V)

18. Motor functions of tongue, Hypoglossal (XII) • Motor input to muscles that • Change the tongue’s shape • Shorten, narrow, elongate, flatten and make concave • Move the tongue through space • Protrude, draw tongue up and back, retract and depress

19. Testing tongue movement (looking for injury of c.n. XII, i.e., LMN) • Protrude tongue (deviation to side of injured cranial nerve (LMN); protrusion of stronger side overcomes weaker) • Freely and against resistance • Lateralize tongue to corners of mouth or to internal cheek (inability to lateralize on side of injured cranial nerve, e.g. XII damaged on R  can’t lateralize to R) • Freely and against resistance • Elevate tongue while you hold chin down • Look for involuntary movements (facsiculations, fibrillation) and wasting away (atrophy) of the tongue • Fasciculations are small muscle twitches, which look like little, moving dimpling of tongue; moving corrugations • Fibrillation looks like a fast tremor

20. Clinical presentation of tongue in different dysarthrias • Flaccid dysarthria: Look for atrophy, changes in functional ability and involuntary movement of tongue as described on previous slide • Spastic dysarthria: Articulation is imprecise and distorted because muscles are too tight • Ataxic dysarthria: Articulation is sometimes precise, sometimes not, due to discoordination • Hyperkinetic dysarthria: Tongue may move involuntarily

21. LOWER JAWWhich cranial nerves supply muscles used for movements of mandible (for speaking and eating?)

22. You have to be able to move mandible (lower jaw) for chewing (mastication) and speaking, and sense how jaw is positioned

23. Jaw movement, V (Trigeminal, mandibular branch) • Motor input to muscles that • Close and open the jaw • Move the jaw laterally (grinding and lateral movements)

24. Pathology of motor V • Motor of V (trigeminal): Lower motor neuron lesion of mandibular branch • Flaccid paresis or paralysis of the ipsilateral muscles of mastication • Slight deviation of jaw to the same side as the damaged LMN • Unilateral upper motor neuron disease unlikely to affect function, because of bilateral innervation • Transitory or mild paresis (i.e., slight or partial paralysis)

25. Testing motor of V (LMN damage) • Motor of V (trigeminal): Mandibular branch • Palpate area of masseter as patients bites down as hard as possible, then relaxes • Feel for bulk of the muscle • Look for atrophy of the temporal muscle: Shrunken area at the temple of the face? • Jaw closing while you hold chin down and forehead in place • Ask patient to bite down hard against resistance of your hand • Jaw opening with resistance under chin • Ask patient to move jaw side to side • Ask client to articulate phonemes that require jaw movement (e.g. bilabials)

26. SOFT PALATEWhich cranial nerves supply muscles used for movements of soft palate, used for controlling nasality, and for keeping food out of nasal passages when swallowing?

27. Soft palate has sensation, and is also able to move. Each of these functions is filled by different cranial nerves.

28. Sensory innervation of soft palate • Glossopharyngeal (IX) Mediates sensation from • Soft palate • Posterior 1/3 of tongue • Tonsils and faucial pillars • Pharynx (which we’ll see in upcoming slides) • IX also mediates sensation from the middle ear (tympanic cavity and Eustachian tube)

29. Motor innervation of soft palate • Vagus (X) • Provides primary innervation to soft palate • V (Trigeminal) • Partially responsible for flattening and tensing of soft palate • Opens Eustachian tube • (Remember that it also innervates jaw muscles)

30. Clinical testing of movement of soft palate • Motor (V & X): Soft palate should • raise symmetrically on repeated production of /a/. • Raise sufficiently so that no nasality is heard on oral sounds • Raise completely and symmetrically as part of gag reflex • Do this test only if speech is hypernasal and no movement is seen on repeated /a/

31. Clinical presentation for dysarthria of soft palate • Flaccid dysarthria: Consistently hypernasal, because soft palate cannot lift at all, or lifts only on one side (see previous slide) • Spastic dysarthria: Consistently hypernasal, muscles can’t reach posterior pharynx • Ataxic dysarthria: Occasional, inconsistent hypernasality; can’t coordinate timing of palate lifting

32. PHARYNXWhich cranial nerves supply muscles used for sensation in, and movements of, pharynx, important for swallowing and gag reflex?

33. Pharynx has sensation, and is also able to move. Each of these functions is filled by different cranial nerves.

34. Sensory innervation of pharynx • Glossopharyngeal (IX) Mediates sensation from • Soft palate • Posterior 1/3 of tongue • Tonsils and faucial pillars • Pharynx

35. Note: damage to the innervation of the parotid would result in EXCESSIVE salivation Motor innervation of pharynx • IX, glossopharyngeal • Lateral dilation and some elevation of pharynx via stylopharygeus muscle (#1) • Helps clear pharynx • Visceral motor innervation of parotid gland (#1 on right) • X, vagus, pharyngeal branch • Pharyngeal constrictors: moves bolus of food toward esophagus • Remember that X also innervates most muscles of soft palate

36. Phases of swallow require the use of both: • Afferent (sensory) neural pathways from pharynx • Stimulation of IX initiates the swallow • Efferent (motor) neural pathways to pharynx • X provides motor innervation to the pharyngeal constrictors, to move the bolus down Dysphagia = swallowing disorder

37. Testing sensory and motor of pharynx • Gag reflex (sensation precedes motor activity) • Sensory portion of reflex • Glossopharyngeal (IX) • Motor portion of reflex: Gag response • Glossopharyngeal (IX): Elevation and dilation of pharynx; lifting of soft palate • Vagus (X): Contraction of the pharyngeal muscles, • If no gag response, ask “Did you feel the touch/poke?” If answer is yes, then just motor portion of gag is involved (X). (Think of the last time you had a test for strep ….)

38. LARYNXWhich cranial nerves supply muscles used for sensation in, and movements of, larynx, important for voicing and for protection of airway when swallowing?

39. Larynx has sensation, and laryngeal muscles, intrinsic and extrinsic: • Both sensory and motor functions help us to protect airway • Motor functions help us to produce voicing

40. Sensory innervation of larynx • Vagus (X) Mediates sensation from larynx • Lets you know when foreign body has entered larynx • Senses pain, e.g. in cases of laryngeal cancer

41. Laryngeal INNERVATION • X (Vagus) • Sensory (lets you know when foreign body is in larynx) • motor to intrinsic muscles of larynx (changes voice) • Movements of whole larynx to protect airway: • V (trigeminal): assists with superior and anterior movement of larynx • VII (facial) assists with superior and posterior movement of larynx • IX (glossopharyngeal): assists with elevation of larynx X

42. Motor innervation of larynx • Laryngeal branches of vagus nerve (X) • Superior laryngeal • External branch • Recurrent laryngeal

43. Note X (vagus) and its branches • Pharyngeal • Laryngeal (descends) • Superior laryngeal (#1) • Internal branch • External branch • Recurrent laryngeal (#6) Note how it descends considerably below the larynx, and then re-ascends. Recurrent laryngeal nerve is vulnerable in heart and thyroid surgeries

44. Functions of each of the branches of laryngeal nerve (which itself is a branch of X vagus) • (Pharyngeal) • Laryngeal (descends) • Superior laryngeal (#1) • Internal branch: Sensory above true vocal folds, including epiglottis and base of tongue • External branch: Motor to the cricothyroid muscle (for pitch changes) • Recurrent laryngeal (#6): • Sensory of true vocal folds and below; • motor to most of the intrinsic muscles of the larynx, except cricothyroid Recurrent laryngeal nerve is vulnerable in heart and thyroid surgeries

45. Note: • Vagus also supplies afferent and efferent visceral innervation, e.g. • Heart • Respiratory system • Most of digestive system • Afferent innervation and most efferent visceral is not appreciated at conscious level

46. Pathology at laryngeal level • Silent aspiration of food into lungs when sensation is affected • internal branch of superior laryngeal • recurrent laryngeal Test with modified barium swallow • With damage to V, VII, IX, ability to move larynx up and under tongue for protection of airway may be affected • Dysphonia /aphonia when motor functions of larynx are affected (X), via damage to the • External branch of superior laryngeal, which will affect ability to change pitch • Recurrent laryngeal branch of laryngeal of X, which will affect voice quality overall Test with laryngoscopy and clinical voice evaluation

47. Clinical presentation of dysarthria at the laryngeal level • Flaccid dysarthria: Voice becomes breathy, and phrases short, ‘cause folds can’t close properly; food may be aspirated (because glottis doesn’t close) • Spastic dysarthria: Voice becomes harsh, strained-strangled, with reduced range of stress and loudness, ‘cause vocal muscles are too tight • Ataxic dysarthria: A coarse tremor of the vocal folds; pitch goes up and down. Air support is also uncoordinated, so there is occasional excessive loudness • Hypokinetic dysarthria: Monopitch because vocal muscles cannot initiate larger movements. Diaphragm does not move fully, so voice is monoloud, with low intensity • Hyperkinetic dysarthia: Voice stoppages and breaks; excessive loudness variation from involuntary diaphragm mvmt.)

48. MUSCLES OF HEAD TURNING AND SHOULDER SHRUGGINGWhich cranial nerves supply muscles used for head turning and shoulder shrugging, important for visual scanning and communication?

49. We need to turn head both to receive communication effectively and to shake our heads ‘no’ We need to shrug shoulders to communicate, and also to lift arm when communicating via pointing

50. XI: Accessory, spinal accessory Connects at the spinal cord (spinal root of XI) and medulla (cranial root of XI)