Central Nervous System

Central hemispheres

The diencephalon

the Cerebellum

The brain stem

• 1. Cerebral hemisphere
• 2. Diencephalon
• 3. Cerebellum
• 4. Brain Stem

• 1. Thalamus
• 2. Hypothalamus
• 3. Epithalamus
• *Pineal Gland

• 1. Recieves afferent impulses from all the senses and parts of the body
• 2. Relays impulses to and from the cortex

• located below the thalamus _{(indundibulum connects it to the pituitary gland)}
• It is the main control center of the body
• 1. heart muscle
• 2. smooth muscle
• 3.glandular secreation_{naturally and chemically form the pitutary}
• 4. body temp
• 5. hunger and thirst
• 6. sleep and wake cycles

• pineal gland
• choroid plexus

• Pineal secreates melatonin (sleep inducing signal)
• Choroid Plexus secretes CFS

• 1. Midbrain
• 2. Pons
• 3. Medulla Oblongala

• helps control and coordinate movement
• contains the reticular formation

• It is the awareness center
• sends messages to the cortex to keep it awake
• filters out 99% of all input to keep us focused

ADD

conduction tracts

• connects
• 1. higher brain centers with spinal cord
• 2. motor cortex with the cerebellum

• function
• 1. crossover point for motor neurons from the cortex
• 2. Crucial role in homeostasis

• centers control
• 1. force and rate of cardiac contraction
• 2. rate and depth of breathing
• 3. vomiting, swallowing, and sneezing

• there are 4 of them
• *paired lateral ventricles
• *drains to third ventricles though interventricular foramen
• *from third to fourth ventricle through cerebral aqueduct
• *fourth ventricle continues into the spinal cord in the central canal

• 1. Cortex - Thin gray matter on the outside
• 2. White matter - Under cortex
• 3. Basal nuclei - Islands of gray in the white matter

• 1. Motor areas
• 2. Sensory areas
• 3. Association areas

elevated ridges in the gross tissue structure of the cerebral hemisphere

shallow grooves in the gross tissue structure of the cerebral hemispheres

• they are found anterior to the cental sulcus
• Primary motor cortex is in the precental gyrus
• 1. It controls voluntary movements
• 2. Descending tracts project from here to spinal cord and transmit motor information
• 3. Premotor cortex controls learned motor skills

• They are found posterior to the central sulcus
• The primary somatosensory cortex is found in the post central gyrus
• 1. Recieves sensory information from skin and proprioceptors (position and movement) in skeletal muscles

Integrates sensory inputs so what is felt is understood (size shape, temp)

They cover most of the occipital lobe

On the superior portion of the temporal lobe

above orbits on the medial aspect of the temporal lobe

information, language, and general interpretation

because of the myelin in it

• ceberal areas
• between cortex and lower CNS centers

myelinated fibers bundled into large tracts

connect left and right hemispheres together

Connect different parts of the same hemisphere

Connect cerebral hemispheres with lower brain or spinal cord

• 1. Intensity of movement
• 2. Starting and stopping movements
• 3. Inhibit unnecessary movements

they cause to much or to little movement

• Parkinson's disease
• Huntington's disease

fibers that enter stay on the same side _ipsilateral

provides precise timing for smooth coordinated movements

structures that encircle the brain with connections to higher and lower areas

it is our emotional center

Psychomatic illness

• 1. meninges
• 2. CSF
• 3. Blood-brain barrier
• 4. Skull

• * cover and protect
• *protect blood vessels and venous sinuses
• *contain CSF
• *form partitions on the skull

• 1. Dura Mater "hard mother"
• 2. Arachnoid Mater "spidery mother"
• 3. Pia Mater "loving mother"

thick outer layer

forms dural sinuses where CSF drains back into the blood

middle layer

space below is filled with CSF the space has the largest blood vessel that goes to the brain

layer in direct contact with the brain

thin with small blood vessels

It is found around the brain and in the spinal cord

• functions
• 1. cushions the brain
• 2. floats brain
• 3. Nourishes the brain

It is made in the chorodid plexus that hang from the roof of the ventricles

150 ml in and around the brain

it circulates in ventricles and subarachnoid space

most is found in subarachnoid space and it bathes the outter surface of the brain

• 1. Continuous endothelium inside cappillaries
• 2. Thick outter layer surrounding cappillaries
• 3. Tight processes of astrocytes surrounding cappillaries _{astricytes function in connecting neurons to blood supply}

It only allows some things to diffuse through it

• it is good because it allows good things in and the bad things are kept out
• it is bad because sometimes things like medications can't get in when you need them to

• 1. Has pathways to and from the brain
• 2. Starts at the foramen magnum
• 3. Continuation of neurons and neuronal processes from the brain stem down to L₁ or L₂
• 4. Has white and gray matter
• 5. Covered buy continuation of meninges
• 6. After it wnds spinal nerves continue on to supply lower extremities

Gray matter centrally forms an H shape

• Anterior horns: relay motor information from brain to muscle
• Posterior horns: relay sensory information from the body and organs to the brain
• Lateral horns: relay motor messages fromt he brain to organs and glands

with posterior horns

anteriorly from the anterior horns

nerve roots joined together

myelinatedc and unmyelinated fibers that connect with the brain and other spinal levels

• 1. Posterior funiculus
• 2. Anterior funiculus
• 3. Lateral funiculus

Carries sensory information to the brain

afferent pathway

• 1. Starts at receptora in the skin or muscle then connects and runs to spinal cord
• 2. Cell bodies of these neurons found in the dorsal root ganglion
• 3. from spinal cord pathway it runs to the brain
• 4. Crosses over in spinal cord to opposite side
• 5. transmitts impulsesw to thalamus or cerebellum
• 6. from thalamus, ascending pathway continues to somatosensory cortex in the posterior portion of the ceberal hemisphere where it is interpreted

• 1. begins at sensory receptor in skin or organ
• 2. carries sensory information
• 3. terminates in the brain posterior to the central sulcus

carries motor information

efferent tracts

they Cross to opposite sides in either the medulla or at the spinal cord level, it then connects with the anterior horn cells of gray matter in the spinal cord.

acsending descending

startpoint: sensory receptors... brain anterior to central sulcus

type of info: sensory... motor

• termination point: brain posterior to muscle or organ
• ...central slucus