CENTRAL NERVOUS
SYSTEM
MENINGES
• Three separate layers of tissue that surround the
brain and spinal cord
• Provide physical stability and shock absorption
• Heavily vascularized
• Dura mater
• Arachnoid mater
• Pia mater
DURA MATER
• Dura: “tough”
• Outermost meninge layer
• Fused to bone, in some places extends into cranial
cavity forming dural folds
• When surrounding spinal cord, not fused to any
bone
• Epidural space: space between dura mater and
walls of vertebral canal
• Epidural block: injection of anesthetic into epidural
space (epidural during childbirth)
ARACHNOID MATER
• Space between arachnoid and dura is called
subdural space, filled with lymphatic fluid to reduce
friction
• Subarachnoid space: filled with CSF (shock
absorption, transport)
PIA MATER
•
•
•
•
Separated from arachnoid by subarachnoid space
Bound to neural tissue
Blood vessels fill this layer
Supplies the same amount of blood to 3.1 pounds
of brain as 61.6 pounds of muscle takes
SPINAL CORD
• Functions as a highway for nerves going towards
and away from the brain
• Integrates spinal reflexes
• Approximately 18 inches long, about half an inch
wide
• Mostly decreases in diameter the closer it gets to
the sacrum (2 exceptions)
• Cervical enlargement: supplies nerves to the
shoulder girdle and upper limbs
• Lumbar enlargement: provides innervation to the
pelvis and lower limbs
SPINAL CORD
• Central canal: internal passageway filled with CSF
• 31 segments: each segment associated with dorsal
root ganglia (cell bodies for sensory neurons)
• Ventral roots: motor neurons
• Dorsal and ventral roots leave at intervertebral foramen
• Spinal nerves are classified as mixed (combination
of sensory and motor)
• Cauda equina: ventral and dorsal roots inferior to
the tip of the cord seen in gross dissection
BRAIN
• Made up of the frontal lobe, parietal lobe, occipital
lobe, temporal lobe
• Roughly 35 billion neurons (roughly 98% of neural
tissue in the body)
• Average weight in an adult is ~pounds
• Males are generally 10% larger brain mass
• Females show no lower performance in cognition
despite size difference
MAJOR DIVISIONS OF THE BRAIN
• Cerebrum
• Divided into cerebral hemispheres (location of conscious
thought, memory, and complex movements)
• Diencephalon
• Made up of thalamus (relay and processing centers for
sensory info), hypothalamus (emotions, autonomic function,
hormone production), pituitary (hormone production), and
epithalamus (hormone production)
MAJOR DIVISIONS OF THE BRAIN
• Brain stem: processing centers and relay stations
• Midbrain (process visual and auditory info), pons (connects
cerebrum to brainstem, somatic and visceral motor
control), medulla oblongata (sensory info to thalamus,
major centers for autonomic function: HR, BP, resp,
digestion)
• Cerebellum: voluntary and involuntary motor
function, fine motor control
ACTIVITY
• Draw and color a picture of the central nervous
system.
• Label the following structures: cerebrum,
diencephalon, brain stem, cerebellum, frontal lobe,
parietal lobe, temporal lobe, occipital lobe
• Under each structure, give a basic function of them