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11 Cards in this Set

  • Front
  • Back
A motor unit is defined as...
...a single alpha motor neuron and all the muscle fibres it innervates.
Be sure to understand the three different classes of peripheral nerve injury, the potential for recovery and the rate of repair
neuropraxia - transient block only- recovers

axonotmesis - axon damaged, sheath intact- recovery likely

neurotmesis - axon and sheath disruption -requires surgery
Be able to describe and test for parasympathetic lesions to cranial nerves III, VII, IX, X (you will use the names of course!). You should be able to find their nuclei on the "see through diagram", which is VERY IMPORTANT in this course.
Lesson 18
Signs of Horner's Syndrome
-droopy eyelid because the eyelid is innervated by both the oculomotor nerve (voluntary) and the sympathetic to smooth muscle

-pupil constricted (due to unopposed action of constrictor pupillae)

-a dry, red face dry (dry= loss of sweating for cooling; red= loss of usual blood shunting to muscles).
Lesions of the central nervous system
1) mechanism of damage;
2) presenting signs;
3) consequences of the damage (arterial is more critical than venous bleeding for example).
4) means of testing;
5) clinical examples and
6) relevance
*Intracerebral hemorrhage lesions (strokes)
Review the handout and learn the common strokes caused by damage to arteries supplying the cerebral cortex. One exception is the branch of the middle cerebral artery that supplies the internal capsule. You should carefully review the figures that show the internal capsule (Figures 2-15 and 9-9 should be reviewed). You should be able to find the structures described in Modules 4 and 5 on these figures. Be able to explain why a lesion of the middle cerebral artery as it runs through the internal capsule will involve both the upper and lower limbs even though it will only involve the upper limbs and head and neck on the cortical surface. The question might be "Would a lesion of the middle cerebral artery be able to result in loss of function to both the upper and lower limbs?"). This is a very important concept!!
Motor control disorders
Lesions of the cerebellum result from strokes, trauma and tumours. These lesions involve the trunk and limbs on the SAME side as the lesion. They may involve more than one of the functional divisions. Review the table to be aware of the structural divisions (lobes), nuclei, and associated control centers associated with the cerebellum. Lesions of the cerebellum involve changes in quality of movement showing lack of quality of movement in terms of vestibular function (archicerebellum), synergy and postural control (paleocerebellum), and fine coordination (neocerebellum). Lesions in the basal ganglia involve changes in patterning of movement (quality) but do not cause paralysis. We covered three examples of basal ganglia disorders including Parkinson's (loss of secretion of dopamine from substantia nigra cells into the lentiform and caudate nuclei), hemibalismis (damage to subthalamus) and Huntington's disease (loss of neurotransmitters in the caudate and lentiform nuclei - notably GABA). These are considered
Strokes
The cerebral artery lesions were given as examples of common strokes. There may also be strokes involving the brain stem, in fact some are quite common, but we did not cover each of these. Look carefully at the handout and be able to describe the area involved in each of the signs given in cerebral artery strokes. A very important concept is the lateralization of function. For example, speech functions are controlled by the dominant hemisphere (left brain dominance is the most common - assume this usual presentation in answering exam questions). Body awareness and spatial organization are controlled by the non-dominant hemisphere in the parietal lobe. The homunculus is very important in determining the area of the body likely to be involved in a stroke involving the cerebral arteries. In the very important and commonly lesioned area of the posterior limb of the internal capsule supplied by the striate artery branches of the middle cerebral artery, both motor and sensory fibres, passing from the motor areas i
See Through Diagram
KNOW THIS
Factors that influence outcome after injury
-rerouting, sparing, compensation, or actual recovery of neuron circuits through neuro-plasticity

-Age
-Time
-Availability of collateral circulation: Some areas of the brain have considerable redundancy of circulation- others do not. This has a significant impact on potential recovery of function.

-site of injury
-Use: use it or lose it - trans-neuronal degeneration
-Potential of the area for forming new junctions
Neuro-plasticity: Can an area of the brain actually "recover"?
1. Simply repeating an activity is not enough to stimulate neuroplasticity. It is important for the activity to involve novel activity. Evidence: repetition alone won't induce neuroplasticity; it needs to be a "shaping" of novel activity that is new to the nervous system. That can include increasing the skills through additional challenges such as is encountered in athletic training, but it must be changing.

2. There are as-yet undiscovered rules by which this process responds.

This isn't simply a matter of repetition. It is necessary to find the critical time points, the essential conditions and factors involved in stimulating neuroplasticity.

3. There are combinations of effects that need to be worked out- studying these things one factor at a time may rule out factors that are only effective in combination.