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Brainstem David A. Morton, Ph.D. Jan 10 th, 2013 Midbrain and Pons.

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Presentation on theme: "Brainstem David A. Morton, Ph.D. Jan 10 th, 2013 Midbrain and Pons."— Presentation transcript:

1 Brainstem David A. Morton, Ph.D. Jan 10 th, 2013 Midbrain and Pons

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 CN’s 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.

3 Directional terms with Brain

4 CN I – Olfactory nerve Cranial nerve overview

5 CN II – Optic nerve Cranial nerve overview

6 CN III – Oculomotor nerve Cranial nerve overview

7 CN IV – Trochlear nerve Cranial nerve overview

8 CN V – Trigeminal nerve Cranial nerve overview

9 CN VI – Abducens nerve Cranial nerve overview

10 CN VII – Facial nerve Cranial nerve overview

11 CN VIII – Vestibulocochlear nerve Cranial nerve overview

12 CN IX – Glossopharyngeal nerve Cranial nerve overview

13 CN X – Vagus nerve Cranial nerve overview

14 CN XI – Spinal accessory nerve Cranial nerve overview

15 CN XII – Hypoglossal nerve Cranial nerve overview

16 Brainstem Midbrain Pons Medulla Brain Overview Medulla Pons Midbrain

17 Diencephalon Thalamus Hypothalamus Pineal gland Brain Overview P HTh Th

18 Corpus callosum Lateral ventricle 3 rd ventricle Cerebral aqueduct 4 th ventricle Brain Overview 4 Corpus callosum 3 LV aq

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

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?

21 External anatomy: Quadrigeminal plate Superior colliculus Inferior colliculus Cerebral peduncles CN IV Midbrain (mesencephalon) SC CP IC IV Dorsal view of brainstem

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

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

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

25 Internal anatomy Oculomotor nucleus Edinger-Westphal nucleus Midbrain (Rostral) Substantia nigra Cerebral peduncle Aq Rostral midbrain

26 Internal anatomy Trochlear nucleus Midbrain (Caudal) Caudal midbrain Horizontal section Red nucleus Substantia nigra

27 Functional significance of midbrain: Visual and auditory reflexes Coordinates eye movements Pupillary reflex Consciousness and arousal (RAS) Midbrain

28 Arterial supply. Branches off the: Posterior cerebral artery Basilar artery Midbrain

29 Pupillary and Accommodation Reflexes CN II Bilateral contraction of sphincter pupillae and ciliary muscles CN III

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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

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

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

35 Pons (caudal) Facial nucleus Branchial motor nucleus Innervate muscles of face

36 Pons (caudal) Superior salivatory nucleus Visceral motor (Para) Origin of preganglionic parasympathetic neurons

37 Pons (caudal) Abducens nucleus Origin of Abducens n. (CN VI) Homolog to ventral horn

38 Pons (caudal) Internal anatomy Facial nucleus Superior salivatory nucleus Abducens nucleus

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

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

41 Pons Arterial supply. Branches off the: Basilar artery Median and Circumferential branches

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

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

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.

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46 What reflex would be abnormal in a patient with a lesion that included the circled area?

47 Abducens nucleus Facial nucleus

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