Anatomy - Lab 4

Question 1

Where are the cell bodies, axons and synapse of the UMN (higher command motorneurons) found?

Answer 1

Cell bodies in cerebral cortex (primary motor cortex located in precentral gyrus)
Extend axons that run through the internal capsule (posterior limb), midbrain (crus cerebri/cerebral peduncles), medulla (pyramid) and spinal cord
Terminate and make synapses onto LMN in brainstem motor nuclei (= corticobulbar - move muscles in head and neck) or ventral horn of spinal cord (= corticospinal - move skeletal muscle of body)

Question 2

Where are the cell bodies, axons and synapses of lower motor neurons (effector motor neurons) found?

Answer 2

Cell bodies in brainstem motor nuclei or ventral horn of spinal cord
Extend axons out of spinal cord via ventral root and then out of CNS in spinal (PNS) to synapse on target muscles.

Question 3

Where is the primary motor cortex mainly found?

Answer 3

Depth of central sulcus

Question 4

What is the premotor area/cortex?

Answer 4

Anterior part of the precentral gyrus and extends anteriorly into the superior frontal gyrus
Planning of complex voluntary movements requiring co-ordinated movement of several muscle groups

Question 5

Where is the cingulate gyrus found?

Answer 5

Above the corpus callosum

Question 6

Where is the paracentral lobule found?

Answer 6

Medial aspect of hemisphere - continuation of central sulcus

Question 7

Where is the supplementary motor area found?

Answer 7

Medial surface of the hemisphere, anterior to the motor area (including paracentral lobule)

Question 8

What is the function of the supplementary motor area?

Answer 8

Involved in programmed patterns of motor activity, but in more complex sequences than the premotor area

Question 9

Difficulty moving the fingers could result from the occlusion of which major artery?

Answer 9

Middle cerebral artery

Question 10

What does the ACA supply?

Answer 10

Toes, ankle, knee, hip, trunk, shoulder

Question 11

MCA supplies what parts of the body?

Answer 11

Fingers, hand, neck, brow, eyelid/brow, face, lips

Question 12

What does the PCA supply?

Answer 12

Lips, jaw, tongue, swallowing

Question 13

Name the two major neuronal cell types.

Answer 13

Pyramidal cells

Granule (stellate) cells

Question 14

How many layers does the cortex have?

Answer 14

6 layered cellular structure

Question 15

What are the functional units of the cortex?

Answer 15

Cortical columns (vertical slice down through the 6 layers)

Question 16

What shape are pyramidal cells?

Answer 16

Pyramidal (triangular) shape of their cell body

Throughout the cortex, vary in size

Question 17

Where are the largest pyramidal cells found?

Answer 17

Layer five (V) - in the motor cortex, these are upper motor neurons 
Axons extend out of the cortex into the white matter

Question 18

What shape are the granule (stellate) cells?

Answer 18

Star-like shape

Question 19

Where are the granule cells mainly found?

Answer 19

Somato-sensory cortex

Very few of them in the motor cortex (agranular cortex)

Question 20

What does a golgi stain, stain for?

Answer 20

Whole neurons in the CNS

Question 21

Name the different types of neurons we get.

Answer 21

Unipolar, bipolar, multipolar

Question 22

What does a nissl stain show?

Answer 22

Stains for neuronal cell bodies (staining of nucleus and ribosomes)

Question 23

How are pyramidal and granular cells arranged?

Answer 23

Alternating layers

Question 24

What cell is found in layer V of the cortex?

Answer 24

Special type of pyramidal cell = Betz cell

Question 25

What are Betz Cells?

Answer 25

Output neurons of the cortex | Axons are corticospinal and corticobulbar tracts

Question 26

Where do the corticospinal and corticobulbar tracts run in the internal capsule?

Answer 26

Posterior limb/genu

Question 27

What travels in the anterior limb of the internal capsule?

Answer 27

Nerve fibres going to and from other brain areas

Question 28

Head in internal capsule

Answer 28

Near genu (corticobulbar tracts)

Question 29

Arm in Internal Capsule

Answer 29

More posteriorly, within posterior limb of capsule

Question 30

Leg in Internal Capsule

Answer 30

Posterior to arm and trunk, within posterior limb

Question 31

How do you differentiate the anterior limb from the posterior limb?

Answer 31

Anterior limb is shorter than posterior limb

Question 32

What is the function of the substantia nigra?

Answer 32

Important in controlling motor activity via its connections with the striatum

Question 33

What do the CST fibres which decussate form?

Answer 33

Form the lateral corticospinal tract of the spinal cord

Question 34

Where do the lateral corticospinal fibres terminate?

Answer 34

Terminate on the lower motor neurons of the lateral motor column on the opposite side of where the axons originated

Question 35

Where does the ventral corticospinal tract lie/run and what forms this?

Answer 35

Remaining 15% of CST fibres stay ipsilateral Ventral corticospinal tract runs in a mid-ventral position in the spinal cord These fibres terminate on the LMNs of the medial motor column on both sides

Question 36

Which spinal cord level has small ventral grey horns?

Answer 36

Thoracic level - no/very few motor neurons in this region to control the limb muscles

Question 37

Which spinal cord levels have large ventral horns and why?

Answer 37

Cervical and lumbar | Majority of lower motor neurons serving the upper (cervical) and lower (lumbar) limbs are found

Question 38

Where do neurons of the lateral column lie and at what levels are they found?

Answer 38

Neurons of the lateral motor column lie within the lateral part of the ventral horn Only present at level of cervical and lumbar enlargements of the cord

Question 39

Where are motor neurons of the medial motor column found?

Answer 39

Medial part of the ventral horn

Question 40

What muscles do the neurons of the medial motor column innervate?

Answer 40

Muscles of the axial muscles

Question 41

Which levels is the medial motor column found?

Answer 41

All spinal levels

Question 42

What type of neurons are lower motor neurons?

Answer 42

Multipolar

Question 43

Where do axons from lower motor neurons leave the spinal cord?

Answer 43

Ventral spinal roots

Question 44

Name the two main extrapyramidal motor pathways.

Answer 44

Vestibulospinal tract | Reticulospinal tract

Question 45

What is the function of the vestibulospinal tract?

Answer 45

Reflex control of balance and posture, facilitating activity in extensor muscles and inhibiting flexors

Question 46

Where is the vestibulospinal tract found?

Answer 46

Originates on each side from the lateral vestibular nucleus Inputs from semicircular canals, cerebellum and from proprioceptors of the neck muscles Fibres descend ipsilaterally in the ventral funiculus of the spinal cord

Question 47

Where does the reticulospinal tract come from?

Answer 47

Originates from nuclei of the reticular formation of the pons and medulla Mostly descends ipsilaterally

Question 48

Where does the medullary reticulospinal tract run?

Answer 48

Venterolaterally

Question 49

Where does the pontine reticulospinal tract run?

Answer 49

Venteromedially in the spinal cord

Question 50

Name the two control centres for the autonomic nervous system.

Answer 50

Limbic system | Hypothalamus

Question 51

What makes up the limbic system?

Answer 51

Septal area, cingulate gyrus and parahippocampal gyrus

Question 52

What lies deep to the parahippocampal gyrus?

Answer 52

Amygdala and hippocampus

Question 53

What are the functions of the limbic system?

Answer 53

Emotional and instinctive responses

Question 54

Where does the hypothalamus lie?

Answer 54

Anterior and inferior to the thalamus

Question 55

What separates the thalamus and the hypothalamus?

Answer 55

Hypothalamic sulcus

Question 56

What are the functions of the hypothalamus?

Answer 56

Major function - CNS control of ANS | Neuronal control of hormone secretion for control of body functions

Question 57

Where does the hypothalamus receive input from?

Answer 57

Limbic and olfactory centres

Question 58

Where is the reticular formation found in the open medulla and what is it made of?

Answer 58

Found above the inferior olivary nucleus | Made of cell bodies and connections