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