Central Nervous System

The CNS is made up of the spinal cord and brain

The Meninges

  Special covering membranes, the meninges , protect and support the spinal cord and delicate brain The cranial meninges: the dura mater , arachnoid, pia mater , are continuous with those of the spinal cord.

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   Dura mater : covers the brain and spinal cord Epidural space mater from the walls of the vertebral canal separates the spinal dura The subarachnoid space of the arachnoid layer contains cerebrospinal fluid (CSF)

  CSF acts as a shock absorber and a diffusion medium for dissolved gases, nutrients, chemical messages and waste products Pia mater is bound to the underlying neural tissue.

The Spinal Cord

  In addition to relaying information to and from the brain, the spinal cord integrates and processes information own its own.

The spinal cord as of ventral roots.

31 segments , each associated with a pair of dorsal root ganglia and their dorsal roots and a pair

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 The white matter contains myelinated and unmyelinated axons   The gray matter contains the cell bodies of neurons and glial cells The projections of gray matter toward the outer surface of the spinal cord are called horns.

The Brain

 There are 6 segments to the adult brain       Cerebrum Diencephalon Midbrain Cerebellum Pons Medulla oblongata

  The central passageway of the brain expands to form four chambers called ventricles.

CSF continuously circulates from the ventricles and central canal of the spinal cord into the subarachnoid space of the meninges that surround the CNS

Cerebrum

The cerebrum is responsible for: conscious thought intellectual functions, memory complex involuntary motor patterns

   The surface of the cerebrum contains gyri (elevated ridges) separated by sulci (shallow depressions) or deeper groves ( fissures ) The longitudinal fissure cerebral hemispheres.

separates the two The central sulcus marks the boundary between and frontal lobe and the parietal lobe.

 Other sulci form the boundaries of the temporal lobe and the occipital lobe .

  Each cerebral hemisphere receives sensory information and generates motor commands that concern the opposite side of the body.

The primary motor cortex precentral gyrus directs voluntary movements.

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  The primary sensory cortex receives somatic sensory information from touch, pressure, pain and temperature receptors.

Association areas , control our ability to understand sensory information and coordinate a motor response

 The left hemisphere is usually the categorical hemisphere which contains the general interpretive and speech centers and is responsible for language based skills.

 The right hemisphere, or representational hemisphere is concerned with spatial relationships and analyses

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  The basal nuclei lie within the central white matter and aid in the coordination of learned movement patterns and other somatic motor activities.

The limbic system includes the hippocampus, which is involved in memory and learning and the mamillary bodies which control reflex

  The limbic system hippocampus, includes the which is involved in memory and learning and the mamillary bodies which control reflex movements such as eating.

The functions of the limbic system involve emotional states and related behavioral drives.

The Diencephalon

 Provides the switching and relay centers necessary to integrate the conscious and unconscious sensory and motor pathways.

Contains pineal gland choroid plexus thalamus hypothalamus

Thalamus

   Final relay point for ascending sensory information Only a small portion of the arriving sensory information is passed to the cerebral cortex Rest is passed to the basal nuclei and centers in the brain stem

Hypothalamus

      Important control and integrative centers Produces emotions and behavior drives Coordinates activities of the nervous and endocrine system Secretes hormones, Coordinate voluntary and autonomic functions Regulates body temperature

The Brain Stem

 Three regions  The midbrain processes visual and auditory information and generates involuntary somatic motor responses.

  Pons connects the cerebellum to the brain stem and is involved with somatic and visceral motor control Medulla oblongata functions.

: connects to spinal cord relays sensory information and regulates autonomic

Cerebellum

  Oversees the body’s postural muscles and programs and tunes voluntary and involuntary movements Cerebellar peduncles are tracts that link the cerebellum with the brain stem, cerebrum and spinal cord.

More medulla…

   Medulla oblongata connects the brain to the spinal cord.

Its nuclei relay information from the spinal cord and brain stem to the cerebral cortex.

Its reflex centers including the cardiovascular centers and the respiratory rhythmicity centers , control or adjust the activities of one or more peripheral systems.