Cranial Nerves Flashcards
OOOT TAFAG VAH components
- Olfactory
- Optic
- Ocularmotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Auditory and Vestibular
- Glossopharyngeal
- Vagus
- Accessory (Spinal)
- Hypoglossal
Cranial Nerve Classifications
-
Information types:
General vs. Specific -
Muscle types:
Skeletal vs. Visceral
* Fiber types:
Afferent vs. Efferent
Special Information Type Definition
- Innervation of specialized systems only found in a small part of the body
- e.g. vision instead of pain
Skeletal Information Type Definition
Motor and sensory functions in muscles attached to bones
Visceral Information Type Definition
Motor and sensory functions for vital organs
Cranial nerves with Afferent fibers
I, II, VIII
Cranial Nerves with Efferent Fibers
III, IV, VI, XI, XII
Cranial Nerves with both Afferent and Efferent fibers
V, VII, IX, X
CN I
- Olfactory
- Related to sense of smell
- Receptors are replaced every 30-60 days
- Degeneration of olfactory cells and fibers can occur with age or damage (Unilateral or bilateral)
Anosmia
Complete loss of smell
Hyposmia
Less sense of smell
Hyperosmia
Overly strong sense of smell
CN II
- Optic
- Carries visual information from the eyes
- Goes from retina through the lateral geniculate body to the visual cortex
- Result of damage highly dependent on location of lesion
- Mix of ipsilateral and contralateral
- Based on halves of visual field: left side of vision goes to the right and vice versa
CN III
- Oculomotor
- Controls:
- Most of the muscles for moving the eyes
- Parasympathetic pupillary constriciton
- Lens adjustments for focusing on nearby objects
CN IV
- Trochlear
- Associated with the position of the eyes
CN V
- Trigeminal
- Contains sensory nerve for face, head, oral/orbital cavities
- Motor nerve for muscles of mastication
- Gives a lot of information
CN V Damage
Results in:
* Ipsilateral loss of sensation (face, tongue, teeth, mouth, gum, and cavities)
* Trigeminal neuralgia: incredibly painful sensation, generally triggered by light touches to the face (e.g. breeze)
* Bilateral jaw paralysis
CN VI
-Abducens
-Involved in lateral movement of the eye (side to side)
Controlling Eye Movement
-The brainstem gaze centers coordinate the activity across the oculomotor, trochlear, and abducens nerve
-All work together for desired eye movement
CN VII
-Facial
-Controls muscles involved in:
>Facial expression
>Stapedial reflex (happens within middle ear in response to long-ish loud sounds. This tightens the middle ear to reduce the response to the sound)
-Mediates taste sensation in the anterior 2/3 of the tongue
CN VIII
-Auditory and Vestibular (aka vestibularcochlear)
-Related to hearing and balance
-The auditory and vestibular portions that make up this cranial nerve are often discussed as separate nerves
-One nerve from the cochlea and one nerve from the semicircular canals
-These nerves later join up
CN VIII Damage
-Depending on where the lesion occurs, can affect:
>Hearing
>Balance
>Both
-However, the vestibular nerve is not the only nerve carrying balance information
-Visual information from the optic nerve helps with balance
CN IX
-Glossopharyngeal
-Touch, pain, tension, and temperature sensations from pharynx, tonsils, eustachian tube, middle ear cavity, and soft palate
-Taste sensation for posterior 1/3 of tounge
-Swallowing
-Talking
CN IX Damage
Results in:
-Swallowing difficulties
-Loss of taste sensation from ipsilateral posterior third of tongue
-Loss of gag reflex
CN X
-Vagus
-Regulates:
>Cardiac muscles
>Stomach
>Esophagus and pharynx (swallowing)
>Larynx (phonation)
CN XI
-Spinal Accessory
-Involved in:
>Head rotation
>Shoulder elevation (shrugging)
CN XI Damage
Results in impaired ability to:
-Rotate the head laterally
-Raise the shoulders
-Damage patterns result in loss of general functioning of nerve
CN XII
-Hypoglossal
-Involved in tongue movement
-Has unilateral innervation (symptoms can affect only one side of tongue)
CN XII Damage
Can result in:
-ipsilateral paralysis of the tongue causing it to be wrinkled and atrophy
-Tongue deviation to side of lesion
-Chewing difficulty
-Bilateral damage can result in profound difficulty swallowing, eating, and speaking
Cranial Nerves Relationship with motor and sensory systems
-It is not the case that there is a one-to-one relationship between cranial nerves and motor or sensory systems
-e.g. Eyes are moved by oculomotor, abducens and trochlear
-e.g. Tongue has special system of taste: Posterior 1/3 is CN IX, Anterior 2/3 is CN VII. Also has general somatic sensation: Posterior 1/3 is CN IX, Anterior 2/3 is CN V
-e.g. Palatal and pharyngeal muscle: some by vagus, some by trigeminal, some by glossopharyngeal
Area of body that Cranial Nerves control
Sensorimotor information from the shoulders up
