Lab 9: Neurology - Histology, Brain Anatomy & Radiology

cerebrum

largest region of the brain

longitudinal fissure

deep groove that divides the cerebrum into the right and left hemisphere

lateralization

specialization

what are hemispheres covered with?

folded cerebral cortex of gray matter where neurons are not myelinated

gyrus

fold in the cerebral cortex

sulcus

shallow groove in the cerebral cortex

corpus callosum

white matter than connected 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 up multipollar neuron cell bodies and attendant dendrites

the white matter deep to the gray matter

composed of tracts of myelinated axons that project from the overlaying gray matter

• can connect one cortical region to another, to brain nuclei, and to motor neurons of the spinal cord

pyramidal cells

multipolar neurons of the cortex, shaped in a pyramid or triangular shape

5 layers of the cerebral cortex

1. molecular layer

2. outer granular layer

3. outer pyramidal cell layer

4. inner granular layer

5. inner pyramidal and polymorphic layer

molecular layer

mainly dendrites synapsing with cortical neuron axons

outer granular layer

mostly made up of stellate cells, axons, and dendrites

outer pyramidal cell layer

pyramidal cells that increase in size as you move deeper into the layer

inner granular layer

densely packed stellate cells

inner pyramidal and polymorphic layer

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

3 parts of the diencephalon

1. thalamus

2. hypothalamus

3. epithalamus

what do the gray matter areas of the thalamus, hypothalamus, and epithalamus enclose?

the third ventricle

thalamus

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

• control of endocrine system functioning

mamillary bodies

relay stations in the olfactory pathways

infundibulum

stalk of hypothalamic tissue that connects to the pituitary gland

epithalamus

superior-most part of the diencephalon, contains the pineal gland that secretes the hormone melatonin that helps regulate the sleep-wake cycle

pineal gland

located in the epithalamus

• under control of a complex feedback loop with the suprachiasmatic nucleus (SCN) of the hypothalamus

• secretes melatonin

melatonin

• an indoleamine derived from tryptophan

• regulates the circadian rhythm

cerebellum

dorsal to the pons and medulla oblongata

• coordination of the somatic motor function, primarily skeletal muscle contractions, learned muscle patterns, and complex movements

sectioned into the gray matters and white matter

cerebellum gray matter

3 layers: (superficial to deep)

1. molecular layer: largely unmyelinated fibers and scattered basket cells and stellate cell

2. intermediate layer: laden with Purkinje cells

3. granular layer: rich in granule cells

which layer of the gray matter of the cerebellum has basket cells and stellate cells?

molecular layer

brain stem

the medulla oblongata, pons, and midbrain

where is the midbrain located

between the diencephalon and the pons

midbrain

inhibits 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 the medulla oblongata

pons

composed of conduction tracts between higher brain centers and the spinal cord or between the motor cortex and the cerebellum

medulla oblongata

most inferior part of the brain stem

control over the cardiovascular and the respiratory system

anterior median fissure

dividing line between the mirrored right and left halves of the spinal cord

spinal cord gray matter

occupies a butterfly-shaped region that is bilaterally symmetrical about the median fissure

spinal cord white matter

surrounds the gray matter and 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

run from the nasal mucosa to the olfactory bulbs

optic nerve II - sensory

develops as an outgrowth of the brain = brain tract

oculomotor nerve III - motor

supplies four of the six extrinsic muscles that move the eyeball in the orbit, are the inferior oblique, medial rectus, inferior rectus, and superior rectus

trochlear nerve IV - motor

“pulley,” innervates that superior oblique, and extrinsic eye muscle that loops through a pulley-shaped ligament in the orbit, termed the trochlea

trigeminal nerve V - both motor and sensory

three branches 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

controls the lateral rectus

facial nerve VII - both motor and sensory

a large nerve that innervates muscles of facial expressions (among other things)

vestibulocochlear VIII -sensory

for hearing and balance

glossopharyngeal nerve IX - both motor and sensory

innervates the tongue and pharynx, primarily sensory to the throat

vagus nerve V - both motor and sensory

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

runs inferior to the tongue and innervates muscles of the 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

true or false. peripheral nerves often provide two-way communication

true (efferent and afferent)

epineurium

surrounds the nerve

perineurium

bounds axons clusters into fascicles

endoneurium

sheaths each individual atom within a fascicle

saltatory conduction

increases action potential velocity

three meninges covering the brain and spinal cord

(outside to inside)

1. dura mater

2. arachnoid mater

3. pia mater

subarachnoid space

area between the arachnoid and pia maters, filled with cerebrospinal fluid and houses blood vessels that supply the brain