Organization of the Nervous System Lesson 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 Forebrain 1. Telencephalon 2. Diencephalon ~

Divisions of the Brain Midbrain - 3. Mesencephalon Hindbrain 4. Metencephalon 5. Myelencephalon ~

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

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 ~

Terminology Afferent - toward Sensory Efferent - away from Motor ~

Telencephalon Cortical areas Fiber systems Landmarks Fissures /Sulci Lobes Gyri ~ Superior surface

Gyri

The Meninges Tough connective tissue Dura mater - tough outer layer Arachnoid membrane Subarachnoid space Cerebrospinal Fluid (CSF) Pia mater - soft inner layer, next to brain ~

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

Ventricular System 4 interconnected ventricles chambers Cerebrospinal Fluid (CSF) manufactured in choroid plexus 125 ml, t1/2 = 3 hrs Hydrocephalus blockage of CSF flow ~

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