lab nine: neurology - histology, brain anatomy and radiology Flashcards
what are the four regions of the brain?
cerebrum, diencephalon, cerebellum, brain stem
cerebrum
largest region of the brain and is divided into right and left cerebral hemispheres
longitudinal fissure
deep groove that divided the cerebrum into right and left cerebral hemispheres
lateralization
specialization of cortical functions (differ in each cerebral hemispheres)
the cerebral hemispheres are covered with a _____ where neurons are not myelinated
folded cerebral cortex of grey matter
gyrus
fold in the cerebral cortex
sulcus
shallow groove in the cerebral cortex
corpus callosum
white matter that connects the cerebral hemispheres
gray matter
forms the outer convoluted surface of the cerebral hemispheres and the foliated surface of the cerebellum
white matter
lies deep to the cerebral and cerebellar cortices
cortical gray matter
made of multipolar neuron cell bodies and attendant dendrites
pyramidal cells
multipolar neurons that have a pyramid or triangular shaped body
what are the five layers of the cerebral cortex?
molecular layer, outer granular layer, outer pyramidal cell layer, inner granular layer, inner pyramidal and polymorphic layer
molecular layer
contains mainly dendrites synapsing with cortical neuron axons
outer granular layer
mostly made up of stellate cells, axons, and dendrites
outer pyramidal layer
mostly made up of pyramidal cells that increase in size as you move deeper into the layer
inner granular layer
mostly made of densely packed stellate cells
inner pyramidal and polymorphic layer
mostly composed of large pyramidal cells in the more superficial portion of the layer and a wide variety of cell morphologies in the deepest parts of the layer
diencephalon
consists of three paired structures: thalamus, hypothalamus, epithalamus
thalamus
a relay station for incoming information, destined for higher brain areas such as the cerebral cortex
hypothalamus
autonomic control center, center for emotional response, body temperature regulation, regulation of food intake, regulation of water balance and thirst, regulation of sleep-wake cycles, and control of endocrine system functioning
_____ bodies are relay stations in the olfactory pathways
mammillary
infundibulum
a stalk of hypothalamic tissue that connects to the pituitary gland
epithalamus
contains the pineal gland that secretes the hormone melatonin that helps regulate the sleep-wake cycle
superior-most part of the diencephalon
pineal gland (pineal body)
located in the epithalamus; is under the control of a complex feedback loop with the suprachiasmatic nucleus (SCN) of the hypothalamus
secretes the hormone melatonin
melatonin
indoleamine derived from tryptophan; regulated circadian rhythms
where is the cerebellum located?
dorsal to the pons and medulla oblongata
cerebellum
primarily involved in the coordination of somatic motor function, primarily skeletal muscle contractions
learned muscle patterns, such as those used to play a piano, are _____ and _____ in the cerebellum
stored; processed
what is the function of the cerebellum?
coordination of complex movements (walking, piano playing, shooting a basketball)
what are the three layers of the cerebellum?
molecular layer, intermediate layer, granular layer
molecular layer of cerebellum
composed largely of unmyelinated fibers and scattered basket cells and stellate cells
intermediate layer of cerebellum
laden with Purkinje cells
granular layer of cerebellum
deepest layer rich in granule cells
brain stem
collectively the medulla oblongata, pons, and midbrain
where is the midbrain located?
between the diencephalon and the pons
midbrain
associated with inhibiting inappropriate muscle movements and dopamine signals here to ease that inhibition to allow for smooth movements
where is the pons located?
between the midbrain and medulla oblongata
pons
chiefly composed of conduction tracts between higher brain centers and the spinal cord or between the motor cortex and cerebellum
medulla oblongata
most inferior part of the brain stem; has some control over the cardiovascular and respiratory system
the _____ marks the dividing line between the mirrored right and left halves of the spinal cord
anterior median fissure
gray matter of the spinal cord
butterfly-shaped region that is bilaterally symmetrical about the median fissure
white matter of the spinal cord
surrounds the grey matter; composed of axonal tracts that propagate both afferent and efferent impulses, and from neurons on one side of the spinal cord to neurons on the other side (contralateral) and same side (ipsilateral), as well as axons that project into the ventral nerve roots
olfactory nerve I
SENSORY: tiny sensory nerves of smell, which run from the nasal mucosa to the olfactory bulbs
optic nerve II
SENSORY: sensory nerve of vision that develops as an outgrowth of the brain, so it is really a brain tract
oculomotor nerve III
MOTOR: “eye mover” that supplies four of the six extrinsic muscles that move the eyeball in the orbit
what are the four extrinsic muscles that move the eyeball?
inferior oblique, medial rectus, inferior rectus, superior rectus
trochlear nerve IV
MOTOR: “pulley” that innervates the superior oblique, and extrinsic eye muscle that loops through a pulley-shaped ligament in the orbit, termed the trochlea
trigeminal nerve V
BOTH SENSORY AND MOTOR: three branched spring from this, the largest of the cranial nerves; supplies sensory fibers to the face and motor fibers to the chewing muscles
abducens nerve VI
MOTOR: nerve controls the lateral rectus
facial nerve VII
BOTH SENSORY AND MOTOR: large nerve that innervates muscles of facial expression
vestibulocochlear nerve VIII
SENSORY: sensory nerve for hearing and balance
glossopharyngeal nerve IX
BOTH SENSORY AND MOTOR: “tongue and pharynx” that reveals the structures it innervates, primarily sensory to the throat
vagus nerve X
BOTH SENSORY AND MOTOR: only cranial nerve to extend beyond the head and neck to supply motor and sensory fibers to the visceral body organs of the thorax and abdomen
spinal accessory nerve XI
MOTOR: primarily motor and supplies the trapezius and sternocleidomastoid muscles
hypoglossal nerve XII
MOTOR: “under the tongue” that runs inferior to the tongue and innervates muscles of tongue
meissner’s corpuscles
function as light pressure receptors of the dermis and are located within the dermal papillae just below the epidermal/dermal border
axons branch to motor nerve endings (_____) between axons of motor neurons and skeletal muscle fibers
neuromuscular junctions
neuromuscular junctions
(i.e. synapses) that provide targeted release of the excitatory neurotransmitter acetylcholine to the sarcolemma
sarcolemma
motor endplate that is enriched with acetylcholine gated ion channels
peripheral nerves
provide two-way communication (efferent and afferent) containing large numbers of bundled axons
axons
bundled together by connective tissue with an organization reminiscent of the way striated muscle is bundled together
epineurium
surrounds the nerve
within the epineurium-bound region, axon clusters are bound into fascicles by _____
perineurium
each individual axon within a fascicle is ensheathed by _____
endoneurium
myelin sheaths
encase axons
myelin sheaths of the peripheral nervous system are derived from glial cells called _____
Schwann cells
Schwann cell _____ serves to insulate axons from one another
myelination
nodes and Ranvier
unmyelinated gaps between Schwann cells that allow action potentials to jump from node to node
saltatory
“jumping” conduction that increases action potential velocity
arachnoid matter
middle of the three meninges covering the brain and spinal cord
dura matter
the outer meninge and the pia mater meninge found clinging to the brain and spinal cord
subarachnoid space
filled with cerebrospinal fluid and houses blood vessels that supply the brain
