Anatomy - Lab 4 Flashcards
Where are the cell bodies, axons and synapse of the UMN (higher command motorneurons) found?
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)
Where are the cell bodies, axons and synapses of lower motor neurons (effector motor neurons) found?
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.
Where is the primary motor cortex mainly found?
Depth of central sulcus
What is the premotor area/cortex?
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
Where is the cingulate gyrus found?
Above the corpus callosum
Where is the paracentral lobule found?
Medial aspect of hemisphere - continuation of central sulcus
Where is the supplementary motor area found?
Medial surface of the hemisphere, anterior to the motor area (including paracentral lobule)
What is the function of the supplementary motor area?
Involved in programmed patterns of motor activity, but in more complex sequences than the premotor area
Difficulty moving the fingers could result from the occlusion of which major artery?
Middle cerebral artery
What does the ACA supply?
Toes, ankle, knee, hip, trunk, shoulder
MCA supplies what parts of the body?
Fingers, hand, neck, brow, eyelid/brow, face, lips
What does the PCA supply?
Lips, jaw, tongue, swallowing
Name the two major neuronal cell types.
Pyramidal cells
Granule (stellate) cells
How many layers does the cortex have?
6 layered cellular structure
What are the functional units of the cortex?
Cortical columns (vertical slice down through the 6 layers)
What shape are pyramidal cells?
Pyramidal (triangular) shape of their cell body
Throughout the cortex, vary in size
Where are the largest pyramidal cells found?
Layer five (V) - in the motor cortex, these are upper motor neurons Axons extend out of the cortex into the white matter
What shape are the granule (stellate) cells?
Star-like shape
Where are the granule cells mainly found?
Somato-sensory cortex
Very few of them in the motor cortex (agranular cortex)
What does a golgi stain, stain for?
Whole neurons in the CNS
Name the different types of neurons we get.
Unipolar, bipolar, multipolar
What does a nissl stain show?
Stains for neuronal cell bodies (staining of nucleus and ribosomes)
How are pyramidal and granular cells arranged?
Alternating layers
What cell is found in layer V of the cortex?
Special type of pyramidal cell = Betz cell
What are Betz Cells?
Output neurons of the cortex
Axons are corticospinal and corticobulbar tracts
Where do the corticospinal and corticobulbar tracts run in the internal capsule?
Posterior limb/genu
What travels in the anterior limb of the internal capsule?
Nerve fibres going to and from other brain areas
Head in internal capsule
Near genu (corticobulbar tracts)
Arm in Internal Capsule
More posteriorly, within posterior limb of capsule
Leg in Internal Capsule
Posterior to arm and trunk, within posterior limb
How do you differentiate the anterior limb from the posterior limb?
Anterior limb is shorter than posterior limb
What is the function of the substantia nigra?
Important in controlling motor activity via its connections with the striatum
What do the CST fibres which decussate form?
Form the lateral corticospinal tract of the spinal cord
Where do the lateral corticospinal fibres terminate?
Terminate on the lower motor neurons of the lateral motor column on the opposite side of where the axons originated
Where does the ventral corticospinal tract lie/run and what forms this?
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
Which spinal cord level has small ventral grey horns?
Thoracic level - no/very few motor neurons in this region to control the limb muscles
Which spinal cord levels have large ventral horns and why?
Cervical and lumbar
Majority of lower motor neurons serving the upper (cervical) and lower (lumbar) limbs are found
Where do neurons of the lateral column lie and at what levels are they found?
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
Where are motor neurons of the medial motor column found?
Medial part of the ventral horn
What muscles do the neurons of the medial motor column innervate?
Muscles of the axial muscles
Which levels is the medial motor column found?
All spinal levels
What type of neurons are lower motor neurons?
Multipolar
Where do axons from lower motor neurons leave the spinal cord?
Ventral spinal roots
Name the two main extrapyramidal motor pathways.
Vestibulospinal tract
Reticulospinal tract
What is the function of the vestibulospinal tract?
Reflex control of balance and posture, facilitating activity in extensor muscles and inhibiting flexors
Where is the vestibulospinal tract found?
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
Where does the reticulospinal tract come from?
Originates from nuclei of the reticular formation of the pons and medulla
Mostly descends ipsilaterally
Where does the medullary reticulospinal tract run?
Venterolaterally
Where does the pontine reticulospinal tract run?
Venteromedially in the spinal cord
Name the two control centres for the autonomic nervous system.
Limbic system
Hypothalamus
What makes up the limbic system?
Septal area, cingulate gyrus and parahippocampal gyrus
What lies deep to the parahippocampal gyrus?
Amygdala and hippocampus
What are the functions of the limbic system?
Emotional and instinctive responses
Where does the hypothalamus lie?
Anterior and inferior to the thalamus
What separates the thalamus and the hypothalamus?
Hypothalamic sulcus
What are the functions of the hypothalamus?
Major function - CNS control of ANS
Neuronal control of hormone secretion for control of body functions
Where does the hypothalamus receive input from?
Limbic and olfactory centres
Where is the reticular formation found in the open medulla and what is it made of?
Found above the inferior olivary nucleus
Made of cell bodies and connections
