anatomy of cns

Anatomy of the Nervous SystemDr. Mohammed AzizF.I.B.M.S Neuro.

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Nervous System

the Nervous System divided into tow major parts. 1-central nervous system 2-periphral nervous system
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The Central Nervous System

CNS Brain Spinal cord ~
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Peripheral Nervous System

Cranial Nerves - 12 Pair Spinal Nerves - 31 Pair ~ Somatic Nervous System - SNS Sensory & Motor
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Autonomic nervous system

Refers to that part of the Nervous System Concerned mainly with regulation of visceral function - sympathetic division -parasympathetic division
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Homeostasis Effectors Smooth Muscle Cardiac Muscle Glands ~
Autonomic N. S.
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The Meninges

Tough connective tissue Dura mater - tough outer layer Arachnoid membrane - soft middle layer Pia mater - soft inner layer, next to brain ~
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Subarachnoid space

Gap between arachnoid membrane and pia mater Filled with CSF Brain floats in CSF ~
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Dura mater Arachnoid membrane Subarachnoid space CSF Pia mater

Brain
The Meninges
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Ventricular System

Another circulatory system for the brain 4 interconnected ventricles chambers Cerebral Spinal Fluid (CSF) manufactured in choroid plexus Hydrocephalus - blockage of CSF flow ~
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Ventricular System
L V
L V
3rd
Lateral Ventricles
Third Ventricle
Fourth Ventricle
Cerebral Aqueduct
Central Canal
4th
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CSF Formation

140 ml spinal and cranial CSF Regulation ICP Mechanical protection Metabolic function Reduces brain weight from 1400 to 50g.
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Indications for Lumbar Puncture

Diagnostic -infection -inflammatory -oncology -metabolic -SAH
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Therapeutic -Analgesic -Anesthesia -Antibiotic -Antineoplastic
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Contraindications for LP

Absolutely contraindicated in the presence of infection in the tissues near the puncture site. Relatively contraindicated in presence of SOL or increased ICP Caution advised when lateralizing signs or signs of uncal herniation.
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Pressure Normal pressure is between 70 and 180 mm H20

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complications

• Headache (Post LP Headache)• Painful Paresthesias• Persistent Pain or Paresthesias• Spinal Hematoma• Spinal Infection• Herniation *

Brain anatomy: cerebral hemispheres

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Central

Lateral
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Frontal
Parietal
Temporal
Occipital
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The cerebral hemispheres

The cerebral cortex (consists of six lobes on each side: frontal, parietal, temporal, occipital, insular, and limbic. the underlying cerebral white matter, the basal ganglia: a complex of deep gray matter masses.
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Cerebral Dominance (Lateralization, Asymmetry)

Dominant Hemisphere Language – speech, writing Calculation Non-dominant Hemisphere Spatial Perception (3D subject) Singing Playing musical instrument *


Language Speech Writing Calculation
3D perception Singing Playing Musical instrument
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Homonculus

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Diencephalon

Thalamus Hypothalamus Epithalamus Subthalamus
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Cerebellum

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Cerebellum

- located in posterior cranial fossa - tentorium cerebelli (cerebrum), 4th ventricle (brain stem) - communicate with other structure via superior, middle, and inferior cerebellar peduncle -
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Cerebellum Function

 Maintenance of Equilibrium - balance, posture, eye movement  Coordination of half-automatic movement of walking and posture maintenace - posture, gait  Adjustment of Muscle Tone Motor Leaning – Motor Skills *

Balance

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Motor Skill

Pablo Casals
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Cerebellum Clinical Syndromes

Ataxia incoordination of movement
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- Comparable to Input-Output (IO) System of the Computer - Spinal Nerve (C8, T12, L5, S5, Cx1) - Segmental Structure of Neural Tube Origin
Spinal Cord
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- ipsilateral UMN syndrome at the level of lesion

Corticospinal Tract
Corona Radiata lnternal Capsule, Posterior Limb Crus Cerebri, Middle Portion Longitudinal Pontine Fiber Pyramid Pyramidal Decussation Corticospinal Tract - Lateral and Anterior
CR
IC
LPF
Pyr
PD
LCST
ACST
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Posterior White Column - Medial Lemniscal Pathway

medial lemniscus lemniscal decussation internal arcuate fiber posterior white column posterior root
- ipsilateral loss of discriminative touch sensation and conscious proprioception below the level of lesion
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DRG: Dorsal Root Ganglion 1. Posterior White Column A. Nucleus gracilis B. Nucleus cuneatus 2. Medial Lemniscus 3. Corona Radiata C. Thalamus (VPLc) D. Cerebral Cortex (S I)
Posterior White Column-Medial Lemniscal Pathway
DRG
D
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Spinothalamic Tract

spinothalamic tract anterior white commissure posterior root
decussation
- contralateral loss of pain and temperature sensation below the level of lesion
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DRG: Dorsal Root Ganglion A. Posterior (dorsal) horn 1. Spinothalamic tract B. Reticular formation 2. Spinoreticular tract C. Thalamus (VPLc, CL) 3. Corona Radiata D. Cerebral Cortex (S I)
Spinothalamic Tract (Neospinothalamic Tract) Spinoreticular Tract (Paleospinothalamic Tract)
DRG
D
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Posterior White Column - medial Lemniscal Pathway & Spinothalamic Tract

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Upper Motor Neuron (UMN) vs Lower Motor Neuron (LMN) Syndrome
UMN syndrome LMN Syndrome
Type of Paralysis Spastic Paresis Flaccid Paralysis Atrophy No (Disuse) Atrophy Severe Atrophy Deep Tendon Reflex Increase Absent DTR Pathological Reflex Positive Babinski Sign Absent Tone hypertonic hypotonic Fasciculation and Absent Could be Fibrillation Present
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The PeripheralNervous System

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Peripheral N. S.

Cranial Nerves - 12 pair *Optic is CNS Spinal Nerves - 31 pair Somatic Division Sensory info Body Movement
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Spinal Nerves

1 pair for each vertebral segment 8 pr. cervical (C1-C8) 12 pr. thoracic (T1-T12) 5 pr. lumbar (L1-L5) 5 pr. sacral (S1-S5) 1 pr coccygeal ~
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Olfactory Optic Oculomotor Trochlear Trigeminal Abducens

I II III IV V VI
Cranial Nerves
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Cranial Nerves
Facial Vestibulococlear Glossopharangeal Vagus Accessory Hypoglossal
VII VIII IX X XI XII
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Cortical Localization of Speech

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Speech disorder

Dysartheria Dysphasia
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Dysartheria

Difficulty in articulation whenever there is diseases in the nerves or muscles. Causes; .bulbar.[mtor n., n., nmj., m.] .pseudobulbar .cerebellar disturbance
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Dysphasia

It's language disturbances with normal articulation
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Aphasias

Speech Disturbances comprehension production cerebrovascular damage Location of lesion ---> type of deficit Anomia deficit in comprehension of nouns common vs proper ~
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W
B
Wernicke’s areacomprehension Broca’s AreaProduction Arcuate Fasciculus
Left Hemisphere
Angular gyrus
A
A1
V1
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Broca’s Aphasia Expressive or motor aphasia Lesion in left frontal lobe Motor programs Fluency deficits Slow, laborious speech great difficulty with function words Comprehension OK Aware of deficits Impaired repetition ~
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Wernicke’s Aphasia Receptive or sensory aphasia Deficits comprehension generation and of meaningful speech fluency OK Word salad Impaired repetition Unaware of deficits
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Conduction Aphasia

Damage to arcuate fasciculus

Good comprehension Fluent speech Poor repetition

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Other Aphasias
Transcortical motorlesion anterior to Broca’s area supplementary region similar deficits: except repetition OK *

Other Aphasias

Transcortical sensorylesion junction of temporal, parietal, occipital lobessimilar to Wernicke’s, but repetition OK *

Other Aphasias

Anomic lesion inferior temporal lobe inability to name things
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Paul Broca (1824-1880) Carl Wernicke (1848-1905)

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Cerebral localized sign

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Agnosia

It is the difficulty to recognize an object or item whatever it is inspite the elementary sensation are normal
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Visual agnosia
The patient can not recognize object visually despite normal elementary sensation
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Astereognosis

The patient can not identify the object put in the hand despite normal elementary sensation
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Anosognosia

phenomena of neglecting i.e neglect the whole weak side.usualy the lt.or neglect the deficit on the weak side.
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Apraxia

Difficulty in performing learned skill inspite of being able to do it's individual movement
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Apraxia

Dressing apraxia Construcional apraxia
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Alexia

inability to read.


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Gerstman syndrome

Combination of signs due to lesion in the dominant parietal lobe as Agraphia Acalculia Rt-Lt disorientation Finger agnosia
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Visuo-spatial disorientation

inability to find himself in a space
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