Sulci crevices or valleys o gyri mounds or hills o

Sulci: crevices or valleys
o Gyri: mounds or hills
o Central sulcus: separates frontal and parietal lobes
 Pre-central gyrus: primary motor cortex (cell bodies that
initiate & control movement)
 Post-central gyrus: somatosensory cortex (processes sensory
information
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 Central Sulcus
o Primary motor cortex
o Primary somatosensory cortex
o Particular parts of the body are connected with particular
sections of the brain in these areas – homunculus
 Basal Nuclei/Ganglia: location of manifestation of Parkinson’s Disease
o Inhibits muscle tone (free movement without restriction)
o Suppresses useless patterns of movement (tremors)

o Important for maintaining posture and balance (slow and
sustained movement)
o Dopamine- main chemical messenger used here
(neurotransmitter)
 Thalamus: initial site for processing sensory information/input
o Nearly all sensory input synapses here
o Serves integrating and processing role
o Provides a general awareness of sensation (knife in thigh
example)
 Higher awareness at cerebral cortex level
 Hypothalamus
o Connection between CNS and endocrine system
o Homeostatic regulating center (temp, thirst, hunger, etc.)
 Cerebellum
o Execution and coordination of voluntary motor activity
 Initiation is by the primary motor cortex in the cerebral
cortex
o Regulates rate, range, force, and direction of movement
o Stores procedural memories (muscle memory=cerebellar
memory)
 Brainstem: origin of most cranial nerves; site of cardiovascular,
respiratory, and digestive control centers
o Midbrain
o Pons
o Medulla
 Limbic system: don’t need to know
Spinal Cord
 Vertebral bodies: still have arachnoid, pia and dura mater
o Cervical, thoracic, lumbar, sacral, (coccyx)
 Grey matter on inside, white matter on outside – organized into tracts
o Dorsal Root: carries afferent, sensory info
o Ventral root: carries efferent, motor info
 Both are outside the spinal cord and CNS

o Dorsal root ganglion: cell bodies of afferent neurons
 Spinal nerve: combines dorsal and ventral roots outside the spinal cord
o Exit at each level of the spinal cord on the L & R sides
 Tract: collection of myelinated axons (white matter) that carry similar
information
o Ascending tracts: PNS  Spine  Brain
o Descending tracts: Brain  Spine  PNS
 Reflexes: automatic patterned response to a stimulus
o Stimulus  patellar tendon  muscle spindle stretched
(mechanoreceptor)  afferent neuron  interneuron  efferent
somatic motor neuron  quadriceps
o Efferent motor neuron  Hamstring (inhibitory)
 Afferent Division (sensory info)
o Sensory information: info transmitted to CNS via afferent neurons
 Somatic (touch, temperature, pain, position)
 Special (sight, taste, smell)
 Visceral (internal organs and blood flow)
o Most sensory info never reaches level of consciousness
o Sensation: when sensory info reaches conscious recognition
o Perception: interpretation of a sensation
o Types of sensory receptors
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