CNS: the brain   

the nerves exterior to the spinal cord are part of the PNS

    grey matter contains many cell bodies but few myelinated axons,
while white matter 
​contains few cell bodies but myelinated axons...
    the color difference is due to the white myelin

periosteum
cranium
dura mater
arachnoid mater

pia mater

The brainstem includes the pons, midbrain, and the medulla.

​functions: movement of eyes/mouth, sensory relay of heat/pain, respiration, consciousness, cardiac function, involuntary muscle movements, sneezing, coughing, vomiting/swallowing.

The medulla is the control center for the heart/lungs.

brain ventricles are interconnected cavities within the brain that produce and circulate cerebrospinal fluid. CSF circulates through the ventricles, the subarachnoid space and the central canal of the spinal cord.

major regions of the Brain:
Cerebrum
​Cerebellum
Brainstem

interneurons are found in the spinal cord and relays signals between (afferent) sensory neurons, and (efferent) motor neurons. Reflexes depend on these signals 

CSF is a clear, colorless fluid that protects the brain and spinal cord. It  also transports nutrients and removes waste products.

   there are meninges   (membranes) covering            cord and brain
​   a. dura mater
   b. arachnoid mater
   c. pia mater​      

sagittal and inferior views:
​Corpus callosum (connects left/right hemispheres)

​Fornix (connects limbic system) 

Thalamus (relay station to cerebral cortex)
Hypothalamus (homeostatic regulator)

Pineal gland (secretes melatonin  regulates wake/sleep cycle)

Pituitary gland (master gland controls endocrine glands)

Infundibulum (attaches pituitary gland to hypothalamus)
Optic chiasm:vision 
Olfactory bulbs:smell
Optic nerve:vision
Mammillary body (memory)

dorsal nerve roots carry
    sensory info via
​ afferent
nerve fibers to the CNS 
from the PNS. 

external features of the Cerebrum:
​​Cerebral cortex (= crinkled surface of grey matter)
Longitudinal fissures
Cerebral hemispheres
Cerebral lobes: frontal, parietal, temporal, occipital
Gyrus (gyri) & sulcus (sulci)
         (= ridges & grooves on cerebral cortex)

 exiting and entering cord through the bone of the vertebrae from the PNS are dorsal and ventral nerves called nerve roots

like the brain, the spinal cord is  divided into grey matter and white matter

    PNS = Peripheral Nervous System

reminder:
the ventral root carrying instructions away from the spinal cord and the dorsal root carrying sensory information to the spinal cord
form a spinal nerve.

​Ventricles

             spinal cord:
    from outside to inside...
vertebrae bone
dura mater
arachnoid matter
​   sub-arachnoid space
pia mater
white matter
grey matter                   

​ CNS: Central Nervous System
PNS: Peripheral Nervous System

Nervous System lab

cerebral spinal fluid (CSF)
​ fills the ventricles of the brain, the spinal canal and the subarachnoid space.  

    gray matter forms three pairs of horns:
    1. dorsal/posterior horns have neurons that receive sensory                   information from the body which is relayed via                               ascending pathways to the brain.
    2. ventral/anterior horns have motor neurons that leave
               the spinal cord to control skeletal muscle.
    3. intermediate columns and lateral horns contain neurons                     that control visceral organs.​

fourth ventricle

CNS: Spinal Cord & Brain 

extra credit:
 cerebral spinal fluid is  located in the epidural  space. 

epidurals check for infection by removing and testing this fluid.

The cerebellum's functions include:
coordinating voluntary muscle movements/maintaining posture, balance, and equilibrium.

​The cerebrum has a right and left hemisphere joined by the corpus callosum.

functions: initiate/coordinate movement, vision, hearing, touch, judgment and
reasoning along with problem solving, emotions, and learning.

   a ganglion is a cluster
    nerve cell bodies (soma) located outside the CNS. 
Dorsal root ganglia 
are found on the dorsal root 
    of nerves entering the spinal cord.
Dorsal root ganglia
    transmit sensory info
from receptors (PNS)
​to the spinal cord (CNS). 

   spinal nerves

   white matter is subdivided
    into dorsal, lateral and ventral columns.
    Each column contains axons with specific functions.
    Ascending tracts of column fibers carry sensory information
up to the brain.
    Descending tracts carry motor instructions from the brain.

  spinal nerve plexi

     spinal nerves which combine their nerve fibers form a nerve plexus      

​1. Cervical Plexus: (nerves C1-C5) 
    ​(ears, neck, back of head, shoulders and diaphragm) 

​2. Brachial Plexus: (nerves C5-T1) 
      (controls muscles of the shoulder, elbow, wrist and hand) 

3. Lumbar Plexus: (nerves L1-L4) 
     (controls muscles of the lower limbs)
    
4. Sacral Plexus (nerves L4-S4) 
    ( controls lower legs and feet)

​    Thoracic Nerves T2-T12
     Spinal nerves arising from the thoracic vertebrae
     do not form a plexus for nerves T2-T12...
     each nerve runs along one rib to innervate the rib,
     skin and muscle in that thoracic area

​​​Cerebellum
Arbor vitae...white matter
Cortex...grey matter

     meninges

​    Ventral roots carry info from the CNS
viaefferent
    fibers to a muscle/gland
    to initiate a response.