B + H Chapter 2 CSD530

Spinal cord

link between brain and body

transmits efferent signals from the motor cortex, descending motor fibers

transmits afferent signals to the sensory cortex, ascending sensory fibers

foramen magnum

exit point

with brain edema, the brainstem may herniate and push through this structure

central pattern generators

groups of interneurons that make up neural circuits

control of rhythmic movements

31 pairs of nerves

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

spinal anatomy (internal and external)

internal: gray matter is cell bodies; white matter is ascending and descending projection fibers

external: 1 spinal nerve on each side from each spinal segment

spinal nerve roots

each spinal nerve contains motor and sensory fibers

each spinal cord segment has 4 roots

anterioir: efferent (motor) fibers

posterioir: afferent (sensory) fibers

path of spinal nerves

remus to plexus

nerve plexus: nerve fibers from anteior rami that are redistributed into a network of nerves

cervical plexus: supplies anteroir neck

types of fibers

somatic efferent: motor innervation of skeletal muscles

somatic afferent: sensory info from skin, joints, and muscle

visceral efferent: automatic fibers that supply the organs

visceral afferent: autonomic sensory info from organ

dermatome vs myotome

dermatome: areas of skin whose sensory distribution is innervated by the afferent nerve fibers from the dorsal root of a specific spinal nerve

myotome: muscles innervated by the motor neurons of a signal spinal segments

cranium

cranial fossa: house adjacent portions of the cerebrum and brainstem

boney projections can cause damage but are protective normally

Cerebrospinal fluid functions

protect CNS during acceleration or deceleration

waste removal

homeostasis of intracranial pressure

communication by release of transportation of neurohormones

ventricle functions

CSF production, circulation, and storage

produced by choroid plexus (network of blood vessels that line each ventricle)

hydrocephalus

CFS circulation disorder

impaired reabsorption of CSF or blockage of flow

caused by enlarged ventricles or increased intracranial pressure

normal pressure and developmental

can be managed with shunts

normal pressure hydrocephalus

in older age

expanded ventricular size

slow, shuffling gait, bladder incontinence, cognitive impairment

can be misdiagnosed

lumbar puncture

examines CSF for presence of blood, white blood cells, bacteria, or proteins

meninges

three layers

dura mater, arachnoid, pia mater

meningitis: inflammation of meninges

dura mater

adheres to inner surface of cranium and spinal column, very tough

potential spaces due to hematoma: epidural or subdural

arachnoid

porous

contains CSF and blood vessels

subarachnoid space can hemorrhage

pia mater

adheres to brain and spinal cord

porous

potential spaces due to hemorrhage: intracerebral

hemorrhage

escape of blood from arteries or veins, can cause neuronal death due to loss of blood supply

hematoma

blood that pools outside of blood vessel, can cause neuronal death due to increased intracranial pressure