Nervous System

CNS-Central Nervous System Control stimulates and coordinates all other body systems Command center

Nervous System PNS-Peripheral nervous system Nerves outside the spinal cord

Nervous System ANS-Autonomic nervous system

Nervous System Fundamental unit of nervous tissue is the neuron Neuron is a nerve cell that includes the dendrites and axons.

Nervous System Dendrite- fiber branches that receive impulses from other parts of the nervous system and bring it to the cell. Axons- transmit the impulses away from the cell body.

Nervous System Myelin- fatty sheath surrounding the axon. Speeds up impulse conduction. Grey Matter is unmyelinated fiber, in the cerebral cortex and central spinal cord White matter is myelinated fiber within spinal cord and fiber systems.

Nervous System Synapse- transmission of impulses from one neuron to another occurs at here.

Nervous System Afferent neuron- sensory neuron takes the message from the skin to the brain. Or periphery to the CNS.

Nervous System Efferent Neuron- motor neuron that takes the message from the brain to the muscle. Or CNS to the periphery.

Nervous System-CNS Central Nervous System is made up of the Brain and spinal cord. Brain is made up of the cerebrum, brainstem and cerebellum.

Nervous System Cerebrum is the largest and main portion of the brain, it is responsible for the highest level of function. It has four lobes.

Nervous System The four lobes each have different functions.

Nervous System Thalamus is inside the cerebrum, this is where the nerve cells relay body sensations, where pain is perceived.

Nervous System Cerebellum means “little brain.” The main function is to control muscle coordination, tone and posture.

Nervous System Brainstem has three parts, the midbrain, pons, and medulla. Midbrain is center for visual reflexes Medulla is the center for automatic control of respiration and heart rate.

Nervous System Brain Protection Skull- bones with fused joints for greater strength of protection.

Nervous System Brain Protection-three membranes-meninges Dura mater-outer thickest layer that means in latin

Nervous System-Injuries

Nervous System Brain Protection-three membranes-meninges Arachnoid mater- middle layer Subarachnoid space- where the shock absorbing cerebrospinal fluid is located. Pia mater- carries blood vessels to the brain.

Nervous System Spinal Cord is 17 inches long (approximate) Has the same 3 protective layers as the brain Outer dura mater Arachnoid memebrane Inner pia mater Cerebrospinal fluid flows between arachnoid layer and pia mater

Spinal cord and spinal nerves

Vertebrae Vertebral Foramen-passageway for the spinal cord. Intervertebral foramen- sides of the vertebral column, where the spinal nerve roots exit the vertebral canal

Peripheral Nervous System The part of the nervous system outside of the vertebral column: Cranial Nerves Spinal Nerves

Peripheral Nervous System Cranial Nerves have origin in the brain. They are sensory nerves, motor nerves or mixed. Sensory- I, II, VIII, Motor- III, IV, VI, XI, XII Mixed V, VII, IX, X

Peripheral Nervous System

Spinal Nerves There are 31 pairs of spinal nerves. 8 cervical-exit above their vertebrae 12 thoracic-exit below their vertebrae 5 lumbar 5 sacral 1 coccygeal

Spinal Nerves Dermatomes- Area of skin supplied with the sensory fiber of a spinal nerve. Most area have overlap, so total anesthesia will not occur unless 2 nerves lose function.

Spinal Nerves Most muscles are inervated by at least 2 spinal nerves so loss of function will not occur, likely the muscle will weaken

Spinal Nerves Significant levels C3- damage here or above would affect function of the diaphragm. Need assistance with breathing. C5- damage from her down would result in loss of upper extremity function.

Spinal Nerves Plexuses- network of nerves Root/Trunk/Cord/Peripheral nerves

Spinal Nerves There are 3 plexuses Cervical Plexus- make up C1-C4 Brachial Plexus- make up C5-T1 Lumbosacral Plexus- make up L1-S5

Spinal Nerves