Clinical NeuroscienceTopic1: Organization of Nervous System (Dr. Poblete)

Overview:A. Central Nervous System

1. Brain- Supratentorial structures

o Cerebrum- Infratentorial structures

o Cerebellumo Brainstem

Midbrain Pons Medulla

2. Spinal cord- Begins after the f. magnum and ends at L1 (conus

medullaris)- Covered by meninges- Has 31 spinal nerves

o 8 cervical (although there are only 7 cervical segments)

o 12 thoracico 5 lumbar (conus medullaris)

o 5 sacral (conus medullaris)

o 1 coccygeal

B. Peripheral Nervous System- Has 3 functions

o Motor o Sensoryo Parasympathetic

- Based on the cranial nerve (CN) …netter na lang

CN Notes1 Olfactory bulb/tract

olfactory nervesCerebrum level

2 Optic Found beneath cerebrum (supratentorial)

3 Extraocular muscles (Infratentorial)Located in midbrain

4 Trochlear - Only CN exiting from the back- Located in midbrain

5 Sensory and motor to face Pons6 Extraocular muscles7 Facial movement; taste

(tongue)8 Hearing9 Pharyngeal muscles Medulla

10 Pharyngeal muscles11 SCM12 Tongue

Lecture per se:

A. PNSCervical enlargementLumbar enlargement

Spinal Nerves

C5-T1 Roots contribute

Brachial plexus: - Nerve roots c5-T1 - To upper extremities - Sensory/motor/autonomic damage (Manifests in upper extremities)

L1-S2 Lumbosacral plexus

- L1-S2 roots - All belong to PNS - Conus medullaris at L1 (lumbar puncture done below L1)

Nerves can regenerateCNS can’t regenerate

B. ANSSomatic Nervous System = voluntary controlAutonomic Nervous System = Internal Organs/glands

Smooth, cardiac, glandsEndocrine, homeostatic organs

Originate from CNS, has peripheral componentsSympathetic Parasympathetic

From brainstem and sacral (called: craniosacral)

Thoracolumbar (paravertebral ganglia) = origin of sympathetic autonomic outflow

CN 3: pupilllary constrictionCN 7: salivationCN 9: salivation (parotid gland)CN 10: vagus (controls thoracic organs)

Lateral hornIntermediolateral cell column (IML) uses Ach neurotransmitter to send

sympathetic preganglionic signals to paravertebral gangliaPreganglionic: shortNeurotransmitter: Ach

Preganglionic: longNeurotransmitter: Ach

Postganglionic: longNeurotransmitter: norepinephrineExcept sympathetic to sweat glands which secrete Ach

Postganglionic: shortNeurotransmitter: Ach

BRAINSTEM:Medulla cell layersAnterior Middle PosteriorBasalis Tectum TegmentumMotor pathway thalamic nucleus

specific for hearing

Has nuclei of cranial nerves; substantia nigraperiaqueductal grey

From cerebrum send projections to superior colliculi, via inferior quadrigeminal brachiumrelay center for auditory pathway

Exit of CN4

crura cerebri inferior colliculi Ventral to cerebral aqueduct

Emphasis:1. Thalamus – above midbrain/hypothalamus

– Level of cerebrum, deviates of diencephalon – Encloses 3rd ventricle – Sensory pathways (afferent) on the way to Cerebral cortex w/o passing thalamus? – V-shaped: Int. Medullary Lamina – Ant.MedialLat. Nucleus (relay nucleus)

2. Fornix – above midbrain3. Corpus callosum – connects frontal L lobe to frontal R lobe

– Association fibers or commissural fibers4. Cingulate gyrus – part of limbic system w/c goes to (#5)5. Hypothalamus – supra… = origin of releasing hormone

Autonomic, endocrine fxn – Amygdala: limbic system

6. Pituitary – infra7. Optic chiasm

C. Neurons and GangliaNeurons have 2 types of cellsNeurons – generate electrical impulses

– Nerve cell body/soma/perikaryon– Dendrite (afferent)– Function: membrane is electrically active, forming Synapsesa.b.c.d.e. pyramidal cellsf. purkinje

neuroglia – astrocytes > oligodendrites > microglia (BBB) ( myelin) (phagocytic)

Blood brain barrier (BBB) – Astrocytes have “end feet” also known as “glial feet” which are attached to the basement membrane of capillaries (via TIGHT JUNCTIONS).

D. White vs. Gray MatterWhite Matter (axons, myelinated)

- association fibers: horizontal- commissural fibers: ventral- projection fibers: ascending/descending fibers

Gray Matter (mostly nerve cell bodies: soma, perkaryon)- nuclei (CNS)- ganglion (PNS)

E. CerebellumSurface: focal areas w/ focal functionsAssociation area: integrate sensory info and initiate motor movementsImportant: 2 hemispheres, 1 midline (vermis), and 1 floculonodular lobe

Cerebrovestibular pathway: cortex white nuclei

Nuclei (lateral to medial): Dentate, Emboliform, Globus, Fastigius

Impulses: cortex nuclei exits cerebellumBrainstem: Sup. Colliculi: cerebellum connected via peduncles

Inf. ColliculiSuperior peduncle oculomotor/trigeminal n. (pons/mdbrain)Middle peduncle hypoglossal n. (medulla)

foramen magnum –separates the lowermost portion of medulla from the spinal cord

Inferior peduncle

F. Basal Ganglia1. caudate2. lenticular nucleus and globus pallidus

internal capsule-between caudate3. subthalamic nucleus4. substancia nigra

G. Limbic systemHippocampus: belongs to limbicFornix attached to mamillary bodies

H. Spinal CordOuter white = posterior, lateral, anterior columnInner gray = IML = autonomic

Post. Gray horn = sensoryAnt. Gray horn = motor

Rexed Laminae1-6 dorsal gray horn7-9 ventral gray

I. Motor Pathway

J. Ventricles

K. CSF

L. MeningesSubarachnoid space and Ventricles have CSF

M. Blood Supply and Venous DrainageInternal Carotid & Vertebral arteries = most important arteriesVenous drainages = sinuses are derivations of dura