Organization of the Nervous System Lesson 4

The Central Nervous System CNS Brain Spinal cord ~

Peripheral Nervous System Somatic Nervous System - SNS Sensory Division Motor Division Autonomic Nervous System - ANS Sympathetic Division Parasympathetic Division Homeostasis ~

Divisions of the Brain Different schemes 5 major subdivisions Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon ~

Divisions of the Brain Forebrain cortex sub-cortical areas Midbrain tectum & tegmentum Hindbrain cerebellum & pons medulla ~

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

In reference to the BRAIN Dorsal Ventral Inferior Superior Anterior Posterior Rostral Caudal

In reference to brainstem & spinal cord Superior Inferior Rostral Caudal Ventral Dorsal Anterior Posterior

Neural Axis

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

Medial: toward the midline Lateral: away from midline

Ipsilateral same side mid-line Contralateral opposite side of mid-line

This tract of fibers decussates. It crosses the midline

Terminology Afferent - toward Efferent - away from ~ Afferent Efferent

Planes Coronal or frontal cross-section - salami Sagittal - side view hot-dog bun Horizontal top view ~

Coronal Section

Horizontal Section View from top

Mid-sagittal Section Side view

Forebrain Cortical areas Fiber systems Landmarks Fissures /Sulci Gyri Lobes ~

Superior surface Longitudinal Fissure (sulcus)

Central sulcus Lateral sulcus

Major Lobes

Major Lobes & Primary Function Frontal planning motor control emotion Parietal somatosensory maps of body & space Temporal auditory memory Occipital vision ~

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 Cerebrospinal Fluid (CSF) Brain floats in CSF ~

The Meninges Brain Dura mater Arachnoid membrane Subarachnoid space CSF Pia mater Brain

Ventricular System *Continuous with subarachnoid space 4 interconnected ventricles chambers Cerebrospinal Fluid (CSF) manufactured in choroid plexus 125 ml, t1/2 = 3 hrs *Buoyancy: 1400 g  50 g Hydrocephalus blockage of CSF flow ~

Ventricular System L V L V 3rd 4th Lateral Ventricles Third Ventricle Cerebral Aqueduct Fourth Ventricle 4th Central Canal