Anatomy of the Nervous System

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Anatomy of the Nervous System

Structure of the Vertebrate Nervous System
• Neuroanatomy is the anatomy of the nervous system. • Refers to the study of the various parts of the nervous system and their respective function(s). • The nervous system consists of many substructures, each comprised of many neurons.

Structure of the Vertebrate Nervous System
• Terms used to describe location when referring to the nervous system include: – Ventral: toward the stomach – Dorsal: toward the back – Anterior: toward the front end – Posterior: toward the back end – Lateral: toward the side – Medial: toward the midline

Structure of the Vertebrate Nervous System
• The Nervous System is comprised of two major subsystems: 1. The Central Nervous System (CNS) 2. The Peripheral Nervous System (PNS)

Structure of the Vertebrate Nervous System
• The Central Nervous System consists of: 1. Brain 2. Spinal Chord

Structure of the Vertebrate Nervous System
 The spinal cord is the part of the CNS found within the spinal column and communicates with the sense organs and muscles below the level of the head.  The Bell-Magendie law states the entering dorsal roots carry sensory information and the exiting ventral roots carry motor information.  The cell bodies of the sensory neurons are located in clusters of neurons outside the spinal cord called dorsal root ganglia.

Structure of the Vertebrate Nervous System
• The spinal cord is comprised of: – grey matter-located in the center of the spinal cord and is densely packed with cell bodies and dendrites – white matter – composed mostly of myelinated axons that carries information from the gray matter to the brain or other areas of the spinal cord. • Each segment sends sensory information to the brain and receives motor commands.

Structure of the Vertebrate Nervous System
• The Peripheral Nervous System (PNS) is comprised of the: 1. Somatic Nervous System 2. Autonomic Nervous System

Structure of the Vertebrate Nervous System
• The Somatic Nervous System consists of nerves that: – Convey sensory information to the CNS. – Transmit messages for motor movement from the CNS to the body.

Structure of the Vertebrate Nervous System
• The autonomic nervous system sends and receives messages to regulate the automatic behaviours of the body (heart rate, blood pressure, respiration, digestion, etc). • Divided into two subsystems: 1. The Sympathetic Nervous System. 2. The Parasympathetic Nervous System.

Structure of the Vertebrate Nervous System
• The sympathetic nervous system is a network of nerves that prepares the organs for rigorous activity: – increases heart rate, blood pressure, respiration, etc. (“fight or flight” response) – comprised of ganglia on the left and right of the spinal cord – mainly uses norepinephrine as a neurotransmitter at the postganglionic synapses.

Structure of the Vertebrate Nervous System
• The parasympathetic nervous system facilitates vegetative, nonemergency responses. – decreases functions increased by the sympathetic nervous system. – comprised of long preganglion axons extending from the spinal cord and short postganglionic fibers that attach to the organs themselves. – dominant during our relaxed states.

Structure of the Vertebrate Nervous System
• Parasympathetic Nervous System (cont’d) – Postganglionic axons mostly release acetylcholine as a neurotransmitter

Structure of the Vertebrate Nervous System
• Three major divisions of the brain include: 1. Hindbrain. 2. Midbrain. 3. Forebrain.

Area
Forebrain

Also Known As
Prosencephalon (“forward-brain”) Diencephalon (“between-brain”) Telencephalon (“end brain”)

Major Structures

Thalamus, Hypothalamus

Cerebral cortex, hippocampus, basal ganglia Tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra

Midbrain

Mesencephalon (“middlebrain”)

Hindbrain

Rhombencephalon (“parallelogram-brain”) Metencephalon (“afterbrain”)...
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