Week 8: Cranial Nerves Flashcards
Cranial Nerve #1 Olfactory Nerve
- Conducts information to the olfactory bub to interpret smell
- Is often damaged by a traumatic brain injury
Cranial Nerve #2 Optic Nerve
Conveys visual information
- Pupillary accommodation reflex
Cranial Nerve #3 Oculomotor Nerve
Innervates muscles that move the eye, open the eyelid, constrict the pupil, and modulate the curvature of the lens in the eye
- Vestibulo-ocular reflex
- Pupillary and accommodation reflexes
Cranial Nerve #4 Trochlear Nerve
Innervates one muscle: the superior oblique muscle
- Vestibulo-ocular reflex
Cranial Nerve #5 Trigeminal Nerve
Sensory and motor
- 3 branches: mandibular, maxillary, and opthalmic
- Responsible for chewing and adjusting the tension of the eardrum in response to loud noises
- Corneal reflex
Cranial Nerve #6 Abducens Nerve
Innervates one muscle: The lateral rectus muscle
- Vestibulo-ocular reflex
Cranial Nerve #7 Facial Nerve
Sensory, motor, and parasympathetic
- Corneal reflex
- Controls facial expressions
- Sensory innervation of the anterior two-thirds of the tounge
Cranial Nerve #8 Vestibulocochlear
Hearing
- Balance, spatial sensation, and posture
- Vestibulo-ocular reflex
Cranial Nerve #9 Glossopharyngeal Nerve
Motor control of pharynx and larynx to allow for swallowing
- Gag and swallowing reflexes
- Sensation of posterior third of the tongue
Cranial Nerve #10 Vagus Nerve
Motor, sensory, parasympathetic autonomic nerve
- Sensory information from the pahrynx, larynx, and some of the external ear
- Innervates muscles of the pharynx and larynx
- Many functions of the throat, organs
Can lower hear rate, constrict bronchi, and effect speech and digestion
Cranial Nerve #11 Spinal Accessory Nerve
- Innervates the trapezius and sternoclidomastoid muscles
- Controls some neck movements
Cranial Nerve #12 Hypoglossal Nerve
Innervates muscles of the tongue
Cranial nerve
Specialized nerves originating in the brain stem which provide afferent and efferent innervation to the head and neck
Intorsion
Superior aspect of the eye twists medially
Extorsion
Superior aspect of the eye twists laterally
Pupillary Reflex
Autonomic adjustment of the size of the pupil based upon the amount of light that reaches the retina (CN 2 and 3)
Vestibulo-Ocular Reflex
Stabilization of gaze during head movement (CN 3, 4, 6, 8)
Congugate eye movement
Eyes moving in the same directions (also called conjunctive)
Disconjugate eye movement
Each eye moving in a different direction (also called disjunctive)
Accommodation Reflex
Modulation of vergence/convergence, lens shape and pupil size in response to looking quickly at near then far objects (or vice versa) (CN 2, 3)
Corneal Reflex
Also known as the blink reflex, in response to a real or perceived external stimulus (CN 5, 7)
Gag Reflex
Attempted elimination of unwanted objects from the oral cavity through muscle contraction at the base of the tongue and the pharyngeal wall (CN 9)
Swallowing Reflex
Closure of the glottis, larynx elevation, cease of respiration (CN 9)
Pupillary constriction
. Place pt. in a seated position
2. Darken the room to enlarge the pt. pupils. Instruct the pt. to look straight ahead.
3. Shine a penlight directly into the pupil of the eye being screened. Note whether the pupil constricts quickly or sluggishly.
4. Repeat the procedure for the other eye
5. Shine the light into both eyes at the same time so the same amount of light reaches both eyes
Oculomotor damage
Consensual light reflex
- Place the pt. in a seated position
- Darken the room
- Place 1 hand on the pt. nose between the eyes straight vertically
- Shine a penlight into 1 eye and observe the pupillary reflex in the other eyes (both eyes should constrict)
- Document whether the pupil of the unstimulated eye constricts at the same time as the pupil of the other eyes
Screening convergence
- Place the pt. in a seated position
- Hold a pencil in front of the pt.
- Instruct the pt. to visually fixate on the pencil
- Begin to move the pencil in a straight line toward the pt. nose
- Instruct the pt. to keep looking at the pencil as it is moved closer to his or her nose
- Observe for symmetrical medial eye movement
- Record the distance the convergence was broken or pt. could no longer medially invert both eyes
- Note whether the pupils constricted as both eyes converged. In normally functioning eyes, the pupils constrict as they converge. Convergence is normally broken at approximately 3-4 inches from the pt. nose
Screening the functions of the eye muscles
- Screen 1 eye at a time
- Occlude the eye not being screened
- Instruct the pt. to maintain his or her head in a fixed position while visually scanning a moving stimulus
- Move the visual stimulus in the shape of an H and an X allowing you to determine whether the eye-ball muscles are functioning adequately
- Oculomotor moves up downward and laterally
- Trochlear moves downward and laterally
- Abducens moves laterally - Each time, note the smoothness of the movement and the distance the eye moves as it follows the visual stimulus. Document any abnormality in the smoothness or distance of movement
- Repeat using both eyes
Screening of the motor half of the trigeminal nerve
- Place the pt. in a seated position
- Occlude vision
- Ask the pt. to open his or her mouth. Check for deviation of the jaw to the involved side
- Check for asymmetry of the size of the mouth opening. If the trigeminal nerve is impaired the pt. will likely exhibit a decreased ability to open the mouth on the involved side
- Ask the pt. to move his or her jaw from side to side. Check for asymmetry of jaw movements
Motor portion of the facial nerve
- Sit facing the pt., who is also seated
- Ask the pt. to elevate his or her eyebrows and forehead
- Ask the pt. to smile, frown, and pucker the lips
- Check for asymmetry on the right and left sides of the face
- Ask the pt. to blow his or her cheeks up with air. Gently push on the pt. cheeks while asking him or her to resist
- Check for asymmetry of facial muscle strength
Bell’s Palsy is caused by impairment to which cranial nerve?
Facial Nerve #7
The vagus nerve (CN #10) makes significant contributions to the _____ nervous system
Parasympathetic
Which two cranial nerves provide sensation to the tongue
Facial (CN #7) & Glossopharyngeal (CN #9)
____ is crucial for stabilization of gaze during head movement
Vestibulo-ocular reflex
How Many cranial nerves are involved with the movement of the eyeball (i.e., not reflexes or vision itself)?
3 - Oculomotor, trochlear, and abducens
Match the cranial nerve to how it is assessed
Olfactory - Client is presented with scents
Optic - Client is given a visual acuity (eye chart) test
Trigeminal - OT assesses light touch, hot/cold, and sharp/dull, on client’s face
Accessory - OT places fingers over the client’s adams apple to check to rise and fall of the larynx
An OT student on fieldwork sees their fieldwork instructor shining a pen light into the clients eyes while they look straight ahead
Pupillary Constriction
An OTR screens the function of the eye muscles. During the assessment, the OTR notes the client has difficulty moving the eye up and medially. Which of the following cranial nerves are most likely impaired?
Oculomotor
An OTR in acute care enters a clients room. While conversing with the client, the OTR notes asymmetry on the left side of the face during expressions like smiling. Which of the following facial nerves is most likely impaired?
Cranial nerve #7 facial nerve
During the chart review, the OTR notes that the client has an impairment to cranial nerves 9 and 10. Which of the following daily living activities is the client most likely to have difficulty doing?
Safely eating and swallowing
