Brainstem David A. Morton, Ph.D. Jan 10 th, 2013 Midbrain and
Pons Slide 2 Objectives Explain how spinal nerves differ from
cranial nerves Name all the cranial nerves and know their
components and functions Identify and locate the CNs associated
with the medulla, pons and midbrain Recognize the major internal
and external landmarks on the dorsal and ventral surface of the
brain stem, so that you can determine if a gross or stained cross
section is medulla, pons or midbrain. Identify on a typical cross
section all the brain stem nuclei containing motor neurons that end
on striated muscle. List the cranial nerves that contain
parasympathetic fibers, the location of their nuclei, and their
function Explain why cranial nerves are so important in localizing
lesions. Name reflexes that test these nerves and brain stem
levels. Relate branches of the vertebrobasilar blood supply to the
medulla and pons explaining the deficits that would occur with
vascular occlusion. Slide 3 Directional terms with Brain Slide 4 CN
I Olfactory nerve Cranial nerve overview Slide 5 CN II Optic nerve
Cranial nerve overview Slide 6 CN III Oculomotor nerve Cranial
nerve overview Slide 7 CN IV Trochlear nerve Cranial nerve overview
Slide 8 CN V Trigeminal nerve Cranial nerve overview Slide 9 CN VI
Abducens nerve Cranial nerve overview Slide 10 CN VII Facial nerve
Cranial nerve overview Slide 11 CN VIII Vestibulocochlear nerve
Cranial nerve overview Slide 12 CN IX Glossopharyngeal nerve
Cranial nerve overview Slide 13 CN X Vagus nerve Cranial nerve
overview Slide 14 CN XI Spinal accessory nerve Cranial nerve
overview Slide 15 CN XII Hypoglossal nerve Cranial nerve overview
Slide 16 Brainstem Midbrain Pons Medulla Brain Overview Medulla
Pons Midbrain Slide 17 Diencephalon Thalamus Hypothalamus Pineal
gland Brain Overview P HTh Th Slide 18 Corpus callosum Lateral
ventricle 3 rd ventricle Cerebral aqueduct 4 th ventricle Brain
Overview 4 Corpus callosum 3 LV aq Slide 19 Spinal Cord and Spinal
Nerve Review Alar Basal Sulcus limitans Spinal cord Som S VS VM SM
Spinal nerve anatomy Dorsal root Somatic sensory neurons Visceral
sensory neurons Ventral root Visceral motor neurons Somatic motor
neurons Slide 20 Internal anatomy of brainstem Alar Basal Sulcus
limitans Spinal cord Som S VS VM SM Alar Basal Sulcus limitans
Medulla Som S VS VM SM BM The fate of the alar and basal laminae
Why are brain stem sensory nuclei lateral to motor nuclei in
brainstem? Slide 21 External anatomy: Quadrigeminal plate Superior
colliculus Inferior colliculus Cerebral peduncles CN IV Midbrain
(mesencephalon) SC CP IC IV Dorsal view of brainstem Slide 22
External anatomy: Quadrigeminal plate Superior colliculus Inferior
colliculus Cerebral peduncles CN III (arrows) Midbrain
(mesencephalon) Rostral midbrain Caudal midbrain SC IC CP Dorsal
view of midbrain CP Ventral Slide 23 Cranial nerve nuclei Rostral
midbrain Oculomotor nucleus Edinger-Westphal nucleus Caudal
midbrain Trochlear nucleus Oculomotor nucleus Edinger-Westphal
nucleus Trochlear nucleus Midbrain Motor Sensory Slide 24 Internal
anatomy Tectum Tegmentum Central gray matter Red nucleus Substantia
nigra Cerebral peduncles Midbrain (Rostral) Substantia nigra
Cerebral peduncle Aq Tectum Tegmentum Rn Rostral midbrain Slide 25
Internal anatomy Oculomotor nucleus Edinger-Westphal nucleus
Midbrain (Rostral) Substantia nigra Cerebral peduncle Aq Rostral
midbrain Slide 26 Internal anatomy Trochlear nucleus Midbrain
(Caudal) Caudal midbrain Horizontal section Red nucleus Substantia
nigra Slide 27 Functional significance of midbrain: Visual and
auditory reflexes Coordinates eye movements Pupillary reflex
Consciousness and arousal (RAS) Midbrain Slide 28 Arterial supply.
Branches off the: Posterior cerebral artery Basilar artery Midbrain
Slide 29 Pupillary and Accommodation Reflexes CN II Bilateral
contraction of sphincter pupillae and ciliary muscles CN III Slide
30 Slide 31 Slide 32 External anatomy: Basilar pons (pons proper)
Middle cerebellar peduncle (MC) Basilar artery 4 th ventricle CNN
V, VI, VII, VIII Pons MC V VI VII VIII Pons 4 th vent. Horizontal
section MC 4 th Slide 33 Cranial nerve nuclei Rostral Pons
Trigeminal nucleus Caudal Pons Abducens nucleus Facial nucleus Sup
salivatory nucleus Trigeminal nucleus Facial nucleus Abducens
nucleus Pons Motor Sensory Sup salivatory nucleus Slide 34 4 th
Ventricle Motor nucleus of V Tegmentum R.F. Pons Proper Axons of
the sensory part of V Axons of the motor part of V Pons
(Rostral/Mid) Internal anatomy Trigeminal motor nucleus Functional
significance Slide 35 Pons (caudal) Facial nucleus Branchial motor
nucleus Innervate muscles of face Slide 36 Pons (caudal) Superior
salivatory nucleus Visceral motor (Para) Origin of preganglionic
parasympathetic neurons Slide 37 Pons (caudal) Abducens nucleus
Origin of Abducens n. (CN VI) Homolog to ventral horn Slide 38 Pons
(caudal) Internal anatomy Facial nucleus Superior salivatory
nucleus Abducens nucleus Slide 39 Corneal reflex Spinal trigem.
Nucleus & Tract Consensual reflex Sensory: CN V-1 to spinal
trigeminal nucleus Motor: Facial nucleus out to the temporal branch
of CN VII Slide 40 Corneal Reflex Semilunar ganglion of CN V CN V-1
LR Spinal trigeminal nucleus Touch the cornea Blink (Orbicularis
occuli muscle) Facial motor nucleus Temporal branch of CN VII Slide
41 Pons Arterial supply. Branches off the: Basilar artery Median
and Circumferential branches Slide 42 Match the following reflexes
with their associated brainstem level: a. corneal reflex testing?
b. Gag reflex testing? c. pupillary light reflex testing? I IIIII
Slide 43 Match the following reflexes with their associated
brainstem level: a.corneal reflex testing? b. Gag reflex testing?
c. pupillary light reflex testing? I II III Slide 44 You have a
patient who cannot look to the right with the right eye or smile or
wrinkle the right side of their face. Characterize the lesion as to
level, side, structure(s) involved. Slide 45 Slide 46 What reflex
would be abnormal in a patient with a lesion that included the
circled area? Slide 47 Abducens nucleus Facial nucleus Slide 48
