Med Neuro Histology Flashcards by Lindsay Hammons

What struture is the dark pink circle in the upper center of the image?

Pacinian corpusle

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Where is a Pacinian corpusle located? Describe what it does.

within the dermis; it is highly encapsulated and a sensitive mechanoreceptor responding to HIGH frequenccy vibration

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Which receptor would not be present in this image?

Hair follicle receptor because it is not present in thick skin

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Where are neuron cell bodies for psudounipolar, sensory neurons located?

DRGs

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Central processes from sensory neurons with cell bodies in the DRG go from the dorsal roots _______ (describe the pathway of the neurons to the thalamus).

ascend ipsilateraly within the spinal cord to terminate in the dorsal column nuclei of the medulla (nucleus gracilis/cuneatus) then synapse, and the 2nd neuron decussates and projects to the thalamus

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How does the DRG tightly pack neuron cell bodies?

the pseudounipolar shape and no synapses occur on the soma (not separated by incoming processes)

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What are the numerous, small round nuclei indicative of {in the DRG}? What is their purpose?

Satellite cells; for structure/support

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Name the 3 histological characteristics of a neuron cell body:

pale staining
euchromatic nucleus with prominent nucleolus
abundant cytoplasm

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What structure is this?

DRG

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Which spinal cord cross section is this? How do you know?

Sacral because it has the least amount of white matter; faciculus gracilis is present while fasciculus cuneatus is absent

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Which spinal cord cross section is this? How do you know?

Lumbar because it has an large overal size; lateral horn of gray matter is present to L2 level; FG present, FC absent

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Which spinal cord cross section is this? How do you know?

Thoracic; lateral horn of gray matter present; FG present; FC present in T1-T6

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Which spinal cord cross section is this? How do you know?

Cervical; largest amount of white matter; oval in shape; larger anterior horn vs thoracic region; FG and FC present

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Neuron cell bodies and the proximal parts of their processes make up the _____ matter.

gray

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Nerve fibers make up the _____ matter in the SC.

white

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What is the magenta ring in the center of the spinal cord? What is it lined by?

central canal
ependymal cells (simple, columnar epithelium with cilia)

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Is the central canal present at all levels of the SC?

yes

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_____ occupies the central canal. And ______ move CSF through the SC.

CSF
ciliated ependymal cells

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What is the transverse gray matter called?

central gray commisure

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What is the red arrow pointing to?

ventral (anterior) median fissure

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What is A pointing to?

dorsal (posterior) median sulcus

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The neurons in the ventral horn of the SC are ______ type neurons that innervate _____.

large, multipolar
skeletal muscles

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What is the red arrow point to? The blue arrow? If these are large, multipolar cell bodies, which part of the gray matter are these cells in?

euchromatin-filled nucleus
nucleolus
anterior horn

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In the anterior horn of the SC, what are the green arrows pointing to?

nuclei from glial cells

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The ventral horns are prominent at which spinal levels? Why?

cervical = largest lumbar = next largest -because both are levels that provide motor innervation to limbs

What is arrow B pointing to? What structures run through here?

dorsolateral sulcus (separates dorsal and ventral horns); where dorsal nerve roots enter the spinal cord

Dorsal neruons are ______ neurons.

sensory/afferent

Cell bodies of the dorsal horn nerve roots are found in the \_\_\_\_\_\_. These nerves send out _____ information to the \_\_\_\_.

DRGs - sensory - periphery

What structure is indicated by the arrow? What runs through this structure?

ventrolateral sulcus; ventral nerve roots exit from the spinal cord

Neuron cell bodies in this structure are which type of neurons?

preganglioic sympathetic neurons (lateral horn)

Which structures are indicated by the red arrows? Green arrows? Blue arrows?

anterior columns (funiculi) posterior columns (funiculi) lateral columns (funiculi)

Bundles of nerve fibers, called \_\_\_\_\_, relay information between the SC and brain

tracts

What area is the blue arrow pointing to and what is its function? Green arrow?

- fasciculus gracilis = relays vibration/proprioception sensory information to the lower limbs - fasciculus cuneatus = relays vibration/proprioception sensory information to the upper limbs

Which structure is indicated by the red dotted line?

glial septum (ascending tracts of white matter)

The _____ region of the spinal cord has the largest volume of white matter, whereas the ____ region has the smallest volume of white matter.

- cervial - sacral

Ventral horn cells are ______ whereas dorsal horn cells are \_\_\_\_.

- efferent - afferent

Are lateral horns present in this section? Which region of the SC is this?

no; cervical (FG/FC)

Which organelle accounts for the Nissl substance in the cytoplasm of neurons?

RER

Nissl staining is absent in which regions of a neuron?

axon hillock and axon

Name the structures:

A = Dorsal horn B = fasciculus gracilis C = Glial septum D = fasciculus cuneatus E = posterior sulcus F = gray commisure G = anterior fissure H = central canal I = anterior horn J = dorsolateral sulcus

This is a section of the cerebral cortex. What is the purple substance? The lightly-stained substance?

gray matter; white matter

Which arrow indicates the sensory cortex? How do you know?

red arrow because the sensory cortex (postcentral gyrus) has DISTINCT LAYERING

What are kind of cells are the circled triangle-shaped cells? Where are they located and where do their dendrites point?

pyramidal cells; in deep layers of cortex; dendrites point toward the surface (apical) side of cortex

Which arrow indicates the central sulcus? How do you know?

The green arrow because the precentral gyrus cortex is not striated and the postcentral gyrus cortex is striated

The overall thickness of the motor cortex of the precentral gyrus is _____ than the sensory cortex of the postcentral gyrus.

thicker

What is the red arrow pointing to? What is contained in this section of the cerebral cortex?

Layer I (superficial layer); consists of mostly axons and dendrites from cells located in deeper layers of the cortex

In the motor cortex, which type of cell is indicated by the red circle? How do you know?

Betz cells = pyramidal cells in motor cortex (in layer V)

This is showing a pyramidal cell. What kind of staining is this? What is the red arrow pointing to? The blue arrow?

Golgi stain red = thick apical dendrite blue = axon

To which direction does the apical dendrite of the pyramidal cells in the cortex of the cerebrum point?

toward the cortical surface

What structures is labeled by A?

OUTER NUCLEAR LAYER; Photoreceptor layer (cell bodies); [rods/cones]

What structures is labeled by B?

OUTER PLEXIFORM LAYER; Bipolar/horizontal cell axons

What structures is labeled by C?

INNER NUCEAR LAYER: Bipolar cell bodies

What structures is labeled by D?

Ganglion cell bodies

What structures is labeled by E? Where do these fibers pass?

optic neural layer; pass toward the OPTIC DISC where they exit the eyeball as the OPTIC NERVE

What structures is labeled by F?

INNER PLEXIFORM LAYER (ganglion cell dendrites)

What structures is labeled by H? What structure is on its inner membrane of the cells?

retinal pigment epithelium (RPE); microvilli; pigment absorbs stray light as it passes through the retina

What structures is labeled by G?

CHOROID (highly vascular, heavily pigmented layer)

What structure is labeled by I?

INNER SEGMENTS of rods and cones

What structure is labeled by J? What is the called in the MACULAR region?

OUTER SEGMENTS/OUTER PLEXIFORM LAYER [rods/cones]; photoreceptor layer In macular region = FIBER LAYER OF HENLE

What "structure" is indicated by the red dotted line?

What structure is indicated by the green dotted line?

BRUCH'S MEMBRANE = between choroid and first layer of retina; type of basement membrane

What structure is indicated by the blue arrows?

OUTER LIMITING MEMBRANE = between nuclei and inner segments of rods/cones

What structure is indicated by the solid red line?

RETINA

What structure is labeled by K?

Blood vessel and lumen

What structure is labeled by L?

What structure is labeled by A?

Cornea

What structure is labeled by B?

PUPIL

What structure is labeled by C?

IRIS

What structure is labeled by D?

LENS

What structure is labeled by E?

ORA SERRATA (junction between photosensitive (posterior) and non-photosensitive (anterior) parts of the neural layer)

What structure is labeled by F?

FOVEA

What chamber is labeled by 1?

VITROUS CHAMBER

What chamber is labeled by 2?

POSTERIOR CHAMBER

What chamber is labeled by 3?

ANTERIOR CHAMBER

What corneal layer is labeled by arrow A?

CORNEAL EPITHELIUM = stratified, squamous, non-keratinized layers about 5 cells thick; many free nerve endings here

What corneal layer is labeled by arrow B?

BOWMAN'S MEMBRANE = basement membrane of anterior epithelium

What corneal layer is labeled by arrow C?

STROMA (SUBSTANTIA PROPRIA) = 200-250 lamellae of dense, collagenous tissue interspersed witht glycosaminoglycans, glycoproteins and cells (Type I collagen fibrils)

What corneal layer is labeled by arrow D?

DESCEMET'S MEMBRANE = basement membrane underlying corneal endothelium

What corneal layer is labeled by arrow E?

CORNEAL ENDOTHELIUM

Corneal abrasions are detected by placing a drop of fluorescein in the eye. Damage to the corneal epithelium is revealed by yellow fluorescence of the exposed basement membrane. Name this membrane.

BOWMAN'S MEMBRANE (anterior basement membrane)

LASIK surgery involves removing a superficial flap of cornea then reshaping the underlaying cornea with a laser. What layer is scraped away during the procedure?

STROMA

What structure is labeled by the red arrow?