Download Central Nervous System

Central Nervous System
Development
• Embryo
– Begins as neural tube
• @ 4 weeks
– Brain begins to develop
– Remaining neural tube becomes spinal cord
Functional Anatomy of Brain
• 4 major regions
–Cerebral hemispheres
–Diencephalon
–Brain stem
–Cerebellum
Cerebral Hemispheres
• “cerebrum”
• Surface has ridges
– Gyri- Ridges
– Sulci- Shallow grooves
– Fissures- Deep grooves
Cerebral Hemispheres
• 3 regions
– Cerebral cortex (gray matter)
– Internal white matter
– Basal nuclei
Cerebral Cortex
• Outermost cerebrum
• Functions:
– Higher brain function
• Divided into 4 lobes
– Frontal
– Parietal
– Occipital
– Temporal
• Frontal
Cerebral Lobes
– Reasoning, planning, parts of speech, movement,
emotions, and problem solving
• Parietal
– movement, orientation, recognition, perception of
stimuli
• Occipital
– visual processing
• Temporal
– perception and recognition of auditory stimuli,
memory, and speech
Cerebral White Matter
• Myelinated axons that
connect with other brain
regions (tracts)
• Corpus Callosum
– Largest bundle
– Connects left hemisphere to
right hemisphere
Basal Nuclei
• “Islands” of gray
matter embedded into
white matter
• Help regulate motor
activities
Diencephalon
• Composed of two structures
– Thalamus
• Encloses third ventricle
• Relay station for sensory impulses
– Hypothalamus
• Autonomic functions
• Regulates body temperature, water balance,
metabolism, limbic system (emotion and
behavior), pituitary gland
Brain Stem
• Vital life functions such as breathing,
heartbeat, and blood pressure
• Composed of:
– Midbrain
– Pons
– Medulla
oblongata
Cerebellum
• Functions:
– Regulation and coordination of movement
– Posture
– Balance
• “Little brain“
– Hemispheres
– Folded surface
Protection of CNS
• Neurons are irreplaceable
• Protective features:
– Skull & vertebral column
• Bone enclosure
– Meninges
• membranes
– Cushioning
• Cerebrospinal fluid
Meninges
• Dura mater
– Outer layer, Leathery
• Arachnoid mater
– Middle layer, cobwebby
• Subarachnoid space
– Filled with CSF
• Pia mater
– Innermost layer
Cerebrospinal Fluid
• Composition similar to blood plasma
• Formed from blood by choroid plexus
– Choroid plexus
• Capillaries in brain ventricles
• Protective cushion for brain and spinal cord
• Blood brain barrier
– Brain environment must be constant
– Least permeable capillaries in body
– Prevents substances from entering brain tissue
Spinal Cord
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17 inches long (~L2 vertebrae)
Continuation of brain stem
Pathway to and from brain
Protected by meninges
31 pairs of nerves
Spinal Cord
• Gray matter
– H or butterfly shape
– Surrounds central cavity (CSF)
– Posterior projections (horns)
– Anterior projections (horns)
• White Matter
– Divided into columns
• Contains fiber tracts