ANATOMY OF NERVOUS SYSTEM BMS 231: 2015/2016 DR SOBIA IKRAM DR AQEELA BANO DR SADIA FARHAN

INTRODUCTION DEFINITION The system which controls the sensory and motor functions of the body is called nervous system. CLASSIFICATION Nervous system can be classified in two ways 1.Anatomically (according to the structure) 2.Functionally (according to the function)

Anatomically Nervous system is divided into 1.Central nervous system Brain Spinal cord 2. Peripheral nervous system 12 pairs of cranial nerves 31 pairs of spinal nerves 2 sympathetic trunks CLASSIFICATION

Cranial nerves These nerves arise from brain within the cranial cavity and supply the face,its parts,digestive system, respiratory system and heart. Spinal nerves These nerves arise from the spinal cord and control the functions of rest of the body. Cranial and spinal nerves CLASSIFICATION

Functionally Nervous system can be classified into 1.Somatic nervous system Controls the voluntary function of the body like moving the arms, blinking the eyes etc 2.Autonomic nervous system Controls the involuntary activities of the body like heart beating, movement of the digestive tract etc Autonomic nervous system further divides into a. Sympthatic nervous system (works in danger) b. Parasympathetic nervous system (works in normal life) CLASSIFICATION

Functional unit of nervous system Neuron is the functional unit of the nervous system. All the functions of nervous system depends on the neuron. Definition It is defined as 1. The cell which carries the messages from the brain and spinal cord to the rest of the body or 2. The cell which transmits the nerve impulses.

Anatomy of a Neuron Each neuron contains: - Cell body with nucleus - Cell body with nucleus - Dendrites : fibers that receive messages from other neurons - Dendrites : fibers that receive messages from other neurons - Axons : fibers that send messages to other neurons - Axons : fibers that send messages to other neurons

Neurons Axon of another neuron Cell Body Dendrites Axon Myelin Sheath Dendrites of another neuron

Neurons do NOT touch; there is a gap between them called a synapseNeurons do NOT touch; there is a gap between them called a synapse Messages are sent across the synapses by special chemicals called neurotransmittersMessages are sent across the synapses by special chemicals called neurotransmitters Anatomy of a Neuron

TYPES OF NEURONS INTERNEURON - located entirely within CNS, integrates functions in CNS Sensory (from sensory receptor to CNS) Motor (from CNS to effector organ) Anatomy of a Neuron

Sensory (Afferent) vs. Motor (Efferent) e.g., skin e.g., muscle Gray’s Anatomy sensory (afferent) nerve motor (efferent) nerve Neurons that send signals from the senses, skin, muscles, and internal organs to the CNS Neurons that transmit commands from the CNS to the muscles, glands, and organs

TERMS RELATED TO NERVOUS SYSTEM Nerve bundles of fibers made up of neurons through which sensory stimuli and motor impulses pass between the brain and the rest of the body. Tract A bundle of nerve fibres having the same function, origin, and termination:eg the optic tract.

TERMS RELATED TO NERVOUS SYSTEM

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