Lecture 10: Nervous System Anatomy

Question 1

Classes of neurons by structure

Answer 1

1. Unipolar (pseudounipolar)
2. Bipolar
3. Multipolar

Question 2

3-vesicle stage of brain development

Answer 2

1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)

Question 3

5-vesicle stage of brain development

Answer 3

1. Telencephalon (cerebral cortex, basal ganglia, etc.)
2. Diencephalon (x-thalamus structures)
3. Mesencephalon (midbrain)
4. Metencephalon (pons, cerebellum)
5. Myelencephalon (medulla)

Question 4

Meningeal layers (outer to inner)

Answer 4

1. Dura mater
2. Arachnoid mater
3. Pia mater

Question 5

Dura mater

Answer 5

Fibrous outer meningeal layer; composed of external periosteal and internal meningeal layers. Has dural infoldings and venous sinuses, epidural + subdural spaces

Question 6

Dural infoldings

Answer 6

Folds in dura that help anchor brain within the skull

Question 7

Dural venous sinuses

Answer 7

Venous channels between periosteal/meningeal layers

Question 8

Arachnoid mater

Answer 8

Thin, web-like middle layer; contains sub-arachnoid space (CSF, arteries, veins)

Question 9

Pia mater

Answer 9

Very thin, deepest layer that adheres directly to the brain

Question 10

Nissl bodies

Answer 10

RER in neuronal bodies

Question 11

Unipolar (pseudounipolar) neurons

Answer 11

Peripheral + central axonal processes travel in a straight line; cell body is connected by a stalk and does not participate in signal propagation. Axon can start v. close to inputs, e.g. DRG sensory neuron

Question 12

Bipolar neuron

Answer 12

1 dendritic + 1 axonal process with soma in between; often connects sensory receptors to rest of CNS, e.g. in retina, olfactory bulb

Question 13

Multipolar neuron

Answer 13

Vast majority of neurons. Several arborized dendritic inputs and 1 arborized axonal output, e.g. primary motor neuron

Question 14

Neuron soma

Answer 14

Aka cell body. Can be recognized by Nissl bodies, lots of basophilic ER

Question 15

Synapse locations

Answer 15

Most typically axodendrite synapses; can also have axosomatic, axoaxonal synapses.

Question 16

Locations of pre-synaptic elements

Answer 16

1. Terminal bouton
2. Bouton en passant

Question 17

Blood supply for the cortex

Answer 17

Anterior, middle, and posterior cerebral arteries (ACA, MCA, PCA)

Question 18

Circle of Willis

Answer 18

Blood anastomoses at basal brain of ascending carotid/vertebral arteries. Allows arteries to supply multiple regions in case of failure.

Question 20

Sections of the spinal column

Answer 20

C1: Atlas (no spinal roots)
C2: Axis
C2-C8: Cervical
T1-T12: Thoracic
L1-L5: Lumbar
S1-S5: Sacral

Question 21

Dermatome innervation

Answer 21

Each spinal nerve innervates a dermatome “level” of the body; preserved from development onwards.

Question 22

Subcortical brain structures

Answer 22

1. Diencephalon
2. Cerebellum
3. Brain stem (midbrain, pons, medulla)

Question 23

Which types of information are transmitted in the dorsal/ventral sections of the spinal cord?

Answer 23

Sensory info to the brain is typically carried up the dorsal horns. Motor info typically travels down the ventral horns.

Question 24

Peripheral nerve connective tissue sheaths

Answer 24

1. Epineurium
2. Perineurium
3. Endoneurium

Question 25

Epineurium

Answer 25

Fibro-fatty CT sheath covering a whole nerve and its blood vessels; group of multiple fascicles

Question 26

Perineurium

Answer 26

CT sheath that covers a single nerve fascicle

Question 27

Endoneurium

Answer 27

CT sheath that covers an individual nerve fiber within a fascicle.

Question 28

Nucleus vs ganglion

Answer 28

CNS vs PNS cell body collections

Question 29

Tract vs nerve

Answer 29

CNS vs PNS axon collections