Exam 2: Cranial Nerves Flashcards
Anatomy of the Brainstem
- Medulla
- Pons
- Midbrain
- Cranial Nerves and their nuclei arise from the brainstem and basic bodily functions of life are maintained here
Brainstem Parts
- Midbrain – most superior portion
- Pons – middle portion
- Medulla – lowest portion
Brainstem Functions
- Regulating major life functions (e.g., heart beat, respiration)
- Mediating head and neck reflexes (e.g., gag) via cranial nerves
- Regulating alertness and wakefulness.
Medulla Oblongata
A portion of the hindbrain that controls
autonomic functions
- Digestion
- Heart and blood vessel function
- Swallowing
- Sneezing
◦ Motor and sensory neurons from midbrain and forebrain
◦ Relay of nerve signals between the brain and
spinal cord
◦ Coordination of body movements.
Pons
◦ Connects the cerebral cortex with the medulla oblongata
◦ Communication and coordination center between the two cerebral hemispheres
◦ Helps in transferring of messages between brain and spinal cord
Midbrain
- Midbrain and hindbrain make up the brainstem
- Connects the hindbrain and the forebrain
- Involved in auditory and visual responses as well as motor function
Cranial Nerves
- Cranial nerves I through IV stem from
midbrain - Cranial nerves V through VIII stem from pons
- Cranial nerves IX through XII stem from
medulla - Cranial nerves can be efferent, afferent or
mixed - Cranial nerves always referred to with
Roman Numerals.
I. Olfactory Nerve
- Origin = Olfactory bulb
- Function(s) = Smell
- Problem(s) = Anosmia
II. Optic Nerve
- Origin = Thalamus
- Function(s) = Vision
- Problem(s) = Visual
disturbances; loss of vision
III. Oculomotor Nerve
- Origin = Midbrain
- Function(s) =
◦ GSE: Moves eyes left and right; controls eyelid
◦ GVE: pupil constrictor - Problem(s) = Loss of pupillary light reflex; ptosis
IV. Trochlear Nerve
- Origin = Midbrain
- Function(s) = Moves eyes up and down
- Problem(s) =Diplopia; nystagmus; difficulty moving eyes up and down
V. Trigeminal Nerve
- Origin = Pons
- Function(s) =
◦ GSA: touch, pain, temp. and vibration for face, mouth, ant. 2/3
of tongue
◦ GVE: Chewing muscles - Problem(s) = Loss of above sensations; difficulty chewing; abnormal jaw-jerk reflex
VI. Abducens Nerve
- Origin = Pons
- Function(s) = Rotates eyes out
- Problem(s) = eye rotates in (strabismus) and diplopia; nystagmus
VII. Facial Nerve
- Origin = Pons
- Functional Category = SVE, GVE, GSA, SVA
- Function(s) =
◦ SVE: Muscles of face
◦ GSA: Sensation near ears
◦ SVA: Taste in ant. 2/3 of tongue
◦ GVE: Salivary glands - Problem(s) = Facial paralysis/paresis; taste loss
VIII. Vestibulocochlear Nerve
- Also known as auditory nerve
- Origin = Pons/medulla junction
- Function(s) = Hearing and balance
- Problem(s) = Hearing loss; balance problems
IX. Glossopharyngeal Nerve
- Origin = Pons/medulla junction
- Fiber type = SVE, GVE, GVA, SVA
- Function(s) =
◦ SVE: Pharyngeal movement
◦ GVE: Parotid gland (salivation)
◦ GVA: Middle ear, pharynx, post. 1/3 of tongue
◦ SVA: Taste on post. 1/3 of tongue - Problem(s) = Absent gag and swallow reflex; loss of taste; loss of pharyngeal movement
X. Vagus Nerve
- Origin = Medulla
- Fiber type = SVE, GVE, GSA, GVA, SVA
- Function(s) =
◦ SVE: Pharyngeal and laryngeal muscles
◦ GVE: Heart, lungs; digestive tract
◦ GSA: Tactile sensation to external ear canal
◦ GVA: Pain from mucous membranes
◦ SVA: Taste from epiglottis and pharynx - Problem(s) = Absent gag and swallow reflex; loss of velar movement; loss of voice
XI. Spinal Accessory Nerve
- Origin = Medulla, spinal cord
- Fiber type = SVE
- Function(s) = Neck and shoulder muscles
- Problem(s) = Droopy shoulder; movement of neck
XII. Hypoglossal Nerve
- Origin = Medulla
- Fiber type = GSE
- Function(s) = Muscles of tongue
- Problem(s) = Loss of tongue movement; tongue fasciculations, tongue atrophy
Cranial Nerves (where they stem from)
- Cranial nerves I through IV stem from
midbrain - Cranial nerves V though VIII stem from pons
- Cranial nerves IX through XII stem from
medulla - Cranial nerves can be efferent, afferent or
mixed
All Cranial Nerves (their order + sensory/motor/both)
I. Olfactory (S)
II. Optic (S)
III. Oculomotor (M)
IV. Trochlear (M)
V. Trigeminal (B)
VI. Abducens (M)
VII. Facial (B)
VIII. Vestibulocochlear (S)
IX. Glossopharyngeal (B)
X. Vagus (B)
XI. Spinal Accessory (M)
XII. Hypoglossal (M)
