- embryonic brain and spinal cord  develops as a continuous neural tube

- enlargements and constrictions produce major regions of the adult brain

: tough connective tissue membrane; surrounding brain, consists of 2 layers

- tight junctions between cells of blood vessels: consumes about 20% of oxygen/glucose used during day

- thick basement membrane around capillaries

-  astrocytes maintain the tight junctions
-  regulates the passage of substances from the blood: glucose passes with active transport; alcohol, caffeine, nicotine, anesthesia; antibiotics do not – difficult to treat brain diseases

clear fluid that protects the brain and spinal cord
- continuously circulates thru

a. ventricles of brain

b. central canal of spinal cord

Functions of?

- mechanical protection

- buoyancy for the brain

- chemical protection

- exchange of nutrients &  waste products

CSF produced where? 

- networks of capillaries

- covered by ependymal cells joined by tight junctions

- filter CSF from blood plasma

- ependymal cells form a blood-CSF barrier

- CSF gradually reabsorbed thru arachnoid villi, located in dural sinuses

- extends between spinal cord and pons: everything goes through here before it reaches the brain

- contains all sensory & motor tracts between spinal cord & rest of the brain

- tracts: clusters of fibers, white and gray
- decussation of pyramids of medulla:  point of crossover of axons of motor tracts

- several nuclei that control vital functions

            a.  Cardiovascular center

b.  Respiratory centers

c.  Reflex centers: vomiting, sneezing, hiccupping, etc

- between pons & diencephalon- connects brainstem to diencephalon
- superior and inferior colliculi serve as reflex centers

superior:  visual reflexes

- tracking moving images

- scanning stationary images

inferior:  startle reflex

netlike arrangement of tracts & nuclei
- from upper part of spinal cord à thru brainstem à into lower part of diencephalon

- posterior to the medulla & pons

- 2 hemispheres connected by the vermis

- cerebellar cortex

- arbor vitae
- major tracts called peduncles carry\

a.  sensory input from inner ear & proprioceptors

b.  commands for voluntary movements from cerebral cortex
c.  feedback to the cerebrum about movements

- evaluates movements

- detects discrepancies in command and actual movement - provides feedback to cerebrum for adjustment
- helps to produce smooth muscle movements

- coordinates skilled movements
- regulates posture and balance
- possible role in cognition & language processing

- disease or trauma leads to ataxia – staggered gait, uncoordinated speech

- between brain stem & cerebrum
- includes

Thalamus, Hypothalamus, Epithalamus

- important functions include
i.  Control and integration of activities of the ANS

ii.  Production of hormones

iii. Regulation of the release of pituitary hormones
iv. Regulation of emotional and behavioral patterns

v.  Regulation of eating and drinking

-  major relay station for sensory impulses
- connects different areas of the cerebrum

- regulation of autonomic activities

-  major regulator of homeostasis

-  receives sensory input from other sources
-  has receptors to monitor various blood conditions
- connection to pituitary gland via infundibulum

- produces a variety of hormones

- neuroendocrine organ         

-  seat of intelligence
-  cerebral hemispheres
-  cerebral cortex – outer layer of gray matter
- surface marked by gyri, fissures, & sulci
- longitudinal fissure

- corpus callosum

- frontal

- parietal

- temporal

- occipital

- insula – deep lobe not seen on the surface, is behind the temporal/frontal area

- central sulcus – divides frontal/parietal lobes

- precentral gyrus - origin for motor signals to skeletal muscles

- postcentral gyrus - responsible for taking in sensory input from surface of body

In what?

- 3 types of tracts

            a.  Association Tracts – stay in same hemisphere

b.  Commissural Tracts – connect 2 hemispheres

c.  Projection Tracts – connect cerebrum to other parts of the brain

- nuclei embedded in white matter

-  help regulate movements
-  role in some cognitive processes

-  help to regulate emotional behaviors

- damage results in Parkinson-like symptoms

-  group of structures in cerebrum & diencephalon

-  the emotional brain

- 3 types of areas

-  sensory areas/perception

-  motor areas/initiate movement

-  mainly in posterior 1/2 of cerebral hemispheres

- primary sensory areas have direct connections with peripheral sensory receptors

-  sensory association areas receive input from primary areas & integrate sensory experiences

- important sensory areas include

- perception of touch, proprioception, pain, temperature

- located in postcentral gyrus

- entire body mapped on this area

- size of the cortical area per body part proportional to number of receptors present in that part

ii.   Primary visual cortex

iii.  Primary auditory cortex

iv.  Gustatory cortex

v.   Olfactory cortex

-  mainly in anterior part of cerebral hemisphere

-  motor output – direct control of muscle contractions

Include: Broca's area, Primary Motor Cortex, Frontal Eye Field Area 

- voluntary contractions of skeletal muscles

- located in precentral gyrus

- entire body mapped on this area

- size of cortical area per body part proportional to complexity of movement

- involved in articulation of speech

- usually in left cerebral hemisphere

- connected to primary motor cortex & premotor area

- activates muscles used when forming words

- damage causes nonfluent aphasia

- voluntary scanning movements of eyes

- found throughout the cortex

- connected to primary areas & one another

- include:

i.  Somatosensory association cortex

ii.  Prefrontal cortex (anterior association area)

iii.  Visual association area

iii.  Visual association area

v.  Wernicke’s area

vi.  Common integrative area (posterior association area)

vii.  Premotor cortex: 

- input from primary somatosensory area

- determination of features of objects during touch

-  storage of memories of past sensory experiences

-  located in anterior frontal lobe

- numerous connections with other regions of cerebrum & other parts of the brain

- involved in many features of one’s behavior:

personality, intellect, complex learning ability, judgment, foresight, reasoning, etc.

- receives input from primary visual area

- relates present and past visual experiences

- essential for recognizing what you see

- receives input from primary auditory area

- posterior language area

- located in left hemisphere

- interprets meaning of speech

- recognizes spoken words

- damage causes fluent aphasia

- corresponding areas to Wernicke’s and Broca’s areas in right hemisphere adds emotional content to spoken words

-  posterior parietal and temporal lobes

- integrates sensory input & interpretations

- allows formation of thoughts based on a variety of sensory inputs

- communicates with primary motor cortex, sensory association areas & other parts of the brain

- complex learned motor activities

- causes specific groups of muscles to contract in a specific sequence

- functional asymmetry 

- each cerebral hemisphere perceives sensory input from other side of body & controls muscles on other side of body

-  left hemisphere usually more important for reasoning, numerical, scientific & language skills

- right hemisphere usually more specialized for musical & artistic awareness and spatial & pattern perception

- considerable variation from one person to the next

-  less pronounced in females than in males for certain skills

- participates in fast reflexes
- integrates EPSPs and IPSPs
- highways for sensory input & motor output

- spinal nerve roots connect spinal nerve to spinal cord

- dorsal root contains sensory axons

- dorsal root ganglion contains cell bodies of sensory neurons

- fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus

- spinal vs. cranial reflex

 - pathway followed by nerve impulses that produce a reflex

- components include:

1.  Sensory receptor

2.  Sensory neuron

3.  Integrating center (gray matter within CNS)

- monosynaptic reflex arc:  single synapse between a sensory neuron and a motor neuron

- polysynaptic reflex arc:  one or more interneurons involved

4.  Motor neuron

5.  Effector

causes contraction of a skeletal muscle in response to stretching of the muscle

-  prevents overstretching of muscles & helps maintain posture

- monosynaptic reflex

- sensory receptors are muscle spindles located in the muscle

-  muscle spindles generate nerve impulses in response to being stretched

- integration center is a synapse between a sensory neuron & a motor neuron in the spinal cord

- effector is the stretched muscle

- the outcome is contraction of the muscle that is being stretched

- ipsilateral reflex (input & output on same side of body)

- reciprocal innervation of antagonistic muscles (inhibits their contraction)

occurs in response to a painful stimulus

- causes withdrawal of limb from stimulus by triggering flexor muscles in the limb to contract

-  intersegmental reflex

-  ipsilateral reflex

-  polysynaptic

may be triggered with withdrawal reflex

- helps maintain balance as body weight is shifted

- extensor muscles on opposite limb contract

- also intersegmental

- contralateral reflex arc

- reciprocal innervation (inhibition) in both reflexes