Organization of the

Nervous System

Lecture 2

The Central Nervous System

CNS Brain Spinal cord ~

Peripheral Nervous System

Somatic Nervous System - SNS Sensory & Motor

Autonomic Nervous System - ANS Sympathetic Division Parasympathetic Division

Cranial Nerves - 12 Pair Spinal Nerves - 31 Pair ~

Divisions of the Brain Different schemes

Forebrain, midbrain, hindbrain 5 major subdivisions

Forebrain1. Telencephalon

2. Diencephalon Midbrain -

3. Mesencephalon Hindbrain

4. Metencephalon 5. Myelencephalon ~

Dorsal - toward the back Ventral - toward the stomach Anterior & Posterior Rostral & Caudal ~

Terminology

Dorsal

Ventral

In reference to the BRAIN

Anterior

Posterior

Rostral Caudal

Inferior

Superior

Brainstem & spinal cord

Ventral Dorsal

Rostral

Caudal

Anterior Posterior

Superior

Inferior

Neural Axis

Terminology

Medial - toward the midline Lateral - away from the midline Ipsilateral - same side Contralateral - opposite side Decussate - crossover ~

Terminology

Afferent - toward Sensory

Efferent - away from Motor ~

Coronal or frontal cross-section - salami

Sagittal - side view hot-dog bun

Horizontal top view ~

Planes

Coronal Section

Horizontal Section

Mid-sagittal Section

Telencephalon

Cortical areas Fiber systems Landmarks

Fissures /Sulci Lobes Gyri ~

Superior surface

Longitudinal Fissure (sulcus)

Central Lateral

FrontalParietal

Occipital

Temporal

M1

Superior temporal gyrus

S1

A1

Postcentral gyrus

Precentral gyrus

Gyri

The Meninges

Tough connective tissue Dura mater - tough outer layer Arachnoid membrane - soft middle

layer Pia mater - soft inner layer, next to

brain ~

Subarachnoid space

Gap between arachnoid membrane and pia mater

Filled with CSF Brain floats in CSF ~

Dura mater

Arachnoid membrane

Subarachnoid space CSF

Pia mater

Brain

The Meninges

Ventricular System

4 interconnected ventricles chambers

Cerebral Spinal Fluid (CSF) manufactured in choroid plexus 125 ml, t1/2 = 3 hrs

Hydrocephalus blockage of CSF flow ~

Ventricular System

L V L V

3rd

Lateral Ventricles

Third Ventricle

Fourth Ventricle

Cerebral Aqueduct

Central Canal

4th