The Nervous System Charles C. Cook, MD

Divisions of the Nervous System

The Central Nervous System Brain and Spinal cord Processes sensory information Produces a response

The Central Nervous System

Peripheral Nervous System Nerves that connects muscles, receptors, and glands so …. Sensory nerves sends info from the receptors to the CNS Motor nerves sends info from the CNS to muscles and glands

Peripheral Nervous System

Peripheral Nervous System Sensory Nerves

Peripheral Nervous System Motor Nerves

Peripheral Nervous System Autonomic Nervous System PNS that controls internal organs

Autonomic Nervous System

Grouping of Neural Tissue

Fibers located outside the CNS, held together by connective tissue Nerve Fibers located outside the CNS, held together by connective tissue

Aggregations of myelinated processes of many neurons White matter Aggregations of myelinated processes of many neurons

Gray Matter Contains either nerve cell bodies or bundles of unmyelinated nerve fibers

Reflexes

Reflex Arcs Behavioral unit of the nervous system Structural and functional basis for the simplest involuntary actions

Reflex Behavior Automatic and unconscious Maintain Homeostasis Changes inside or outside Maintain Homeostasis Heart rate, breathing rate, swallowing……

Examples of Reflexes

Protection & Covering of CNS

Cranial Bones

Vertebral Bones

Meninges Membranes that cover brain and spinal cord Serve as bacterial barriers

Dura mater (tough mother) Meninges (cont) Dura mater (tough mother) Outermost layer Composition is white fibrous connective tissue, blood vessels and nerves Attached to inside of cranium Sort of like periostem for cranium

Meninges (cont) Dura mater Cranium —attached to bone (skull) Spinal cord —surrounded by adipose (fatty) tissue

Meninges (cont) Arachnoid Web-like Lacks blood vessels Located between dura mater and pia mater

Pia mater (gentle mother) Meninges (cont) Pia mater (gentle mother) Innermost layer Attached to organ surface Nerves and many blood vessels Attached to inside of cranium Sort of like periostem for cranium

Meninges (cont) Subarachnoid Space Fluid filled Between arachnoid mater and pia mater Attached to inside of cranium Sort of like periostem for cranium

Ventricles and Cerebrospinal fluid (CSF)

Cavities within the cerebral hemispheres and brain stem Ventricles Cavities within the cerebral hemispheres and brain stem

Cerebrospinal Fluid Clear watery fluid secreted within ventricles Circulates within ventricles and subarachnoid space Protects and supports CNS

Spinal Cord

Structure Base of skull to 1st lumbar vertebrae Core gray matter surrounded by white matter

Structure Give rise to 31Pairs of spinal nerves Inferiorly, splits into cauda equina

Function Conduct nerve impulses Center for spinal reflexes

Largest part of the mature brain Cerebrum Largest part of the mature brain

Mirrored large masses of the brain Cerebrum structure Cerebral hemispheres (Thinking Caps) Mirrored large masses of the brain

Cerebrum structure Fissure Deep furrows

Cerebrum structure (Cont) Corpus callosum Nerve fibers that connect hemispheres

Cerebrum structure (Cont) Exterior - Gray matter Interior - White matter

Cerebral lobes (regions)

Cerebral Lobes Frontal lobe Parietal lobe Temporal lobe Occipital lobe

Frontal lobe Higher thought processes, reasoning, logic Planning, concentration, and emotions

Parietal lobe General sensations (Hot or Cold, Pressure or Pain) Understanding speech

Temporal lobe Special sensations (Hearing, Taste, Smell) Memory of visual and auditory patterns

Occipital lobe Sight and recognition of objects

Diencephalon

Diencephalon Forms central core of forebrain and consists of: --Thalamus --Hypothalamus

Thalamus Relays all sensory impulses to cerebral cortex (except smell) Understanding speech, light, touch and pressure

Hypothalamus Controls heart rate, blood pressure, and body temp. (Autonomic Nervous System) Receives sensory impulses from internal organs Connects nervous w/ endocrine system Controls release of regulating hormones from anterior pituitary gland

Brainstem

Brainstem Regions include the following: --Midbrain --Pons --Medulla Oblongata

Midbrain Between hypothalamus and the pons Visual and auditory reflex centers

Pons Separates midbrain/medulla oblongata Helps regulate breathing

Medulla oblongata Continuation of spinal cord from pons to the base of skull Transmits impulses, Contains vital visceral centers

Medulla oblongata Cardiac center Vasomotor center Respiratory center

Cerebellum Second largest structure of the brain Below the occipital lobes of the cerebrum, posterior to the pons and the medulla oblongata. Consists of two hemispheres-connects by a vermis Functions primarily in coordination of skeletal muscle movement and maintaining posture

Peripheral Nervous System (PNS)

Peripheral Nervous System Cranial Nerves Spinal Nerves Plexus

Cranial Nerves 12 pair All arise from brainstem (Except CN 1 ---Optic Nerve) Most are mixed nerves

Spinal Nerves 31 pair All arise from spinal cord All are mixed nerves Emerges as Roots

Spinal Nerves Cervical Nerves - C1-C8 Thoracic Nerves - T1-T12 Lumbar Nerves - L1-L5 Sacral Nerves - S1-S5 1pair of Coccygeal nerves

Plexus Formed by combining branches of several spinal nerves (Except in the Thoracic Region)

Cervical Plexus C-1 through C-4 Innervates muscles and skin of neck Forms Phrenic nerve which innervates the Diaphragm

Cervical Plexus

Brachial Plexus C-5 through T-1 Innervates muscles and skin of arms, forearms & hands

Brachial Plexus

Lumbosacral Plexus T-12 through S-5 Innervates lower extremity

Lumbosacral Plexus

Summary Divisions of the Nervous System Neural Tissue Behavior of Reflexes Functions of the Central Nervous System Functions of Spinal Cord

Summary Functions of Cerebrum Components of Diencephlon Functions of Brain Stem Functions of Cerebellum Components of Peripheral Nervous System

Questions THE END!!!!