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250 Cards in this Set
- Front
- Back
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What is the function of the motor control system?
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To tell the lower motor neurons what to do. (alpha + gamma)
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What is the "end result" instruction for the motor control system?
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To tell the neuron to fire or not to fire.
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What are the two major systems within the motor control system?
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Pyramidal + Extrapyramidal
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What is the pyramidal system responsible for?
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Voluntary skeletal muscle activity.
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What is the extrapyramidal system responsible for?
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Involuntary skeletal muscle activity.
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Where is the supplemental motor area located?
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Frontal lobe
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What is the supplemental motor area involved with? (Pyramidal or extra pyramidal)
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Pyramidal system
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The supplemental motor area is..
anterior to: superior to: |
Anterior to the pre-central gyrus
Superior to the motor cortex |
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Functionally, the supplemental motor area is a(n) _____ area.
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Association
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The supplemental motor area is important for _____ __ _______.
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Initiation of movement
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What are two specific things that the supplemental motor area is responsible for?
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1. Orientation of the eyes + head
2. Planning sequential and bi-manual movements |
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How does information from the supplemental motor area to synapsing with LMNs?
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SMA interacts with the pre-central gyrus --> sends UMNs to cranial nerve motor nuclei --> ventral horns of spinal cord --> synapse with LMNs
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Where is the pre-motor area located?
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Frontal lobe
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The _____ is anterior to the pre-motor area.
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Pre-central gyrus
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Functionally, the pre-motor area is a(n) ________ _____.
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Association area
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What does the pre-motor area control? (2)
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1. The trunk, pelvic, and pectoral girdle musculature for stabilization
2. Anticipatory postural control + adjustments |
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What area does the pre-motor area interact with, and where does it send UMNs to?
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Interacts with the pre-central gyrus --> sends UMNs to cranial nuclei + then to ventral horns
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Broca's area is involved with the pyramidal or extra pyramidal system?
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Pyramidal
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What lobe is Broca's area located in?
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Frontal lobe
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What is Broca's area anterior to?
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The pre-central gyrus
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Broca's area is functionally a(n) ________ ____.
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Association area
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What is the primary function of Broca's area?
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To instigate speech.
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Corticofugal fibers make up _____ (motor/sensory) tracts that consist of ______ (UMNs/LMNs).
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Motor / UMNs
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What are the two cortigofugal tracts?
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1. Corticospinal tract
2. Corticobulbar tract |
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The corticospinal tract is part of the _____ (pyramidal/extrapyramidal) system that controls _____ (voluntary/involuntary) skeletal muscle activity from the _____ + _____.
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The corticospinal tract is part of the PYRAMIDAL system that controls VOLUNTARY skeletal muscle activity from the EXTREMITIES + TRUNK.
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Where are cell bodies of the corticospinal tract located?
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The pre-central gyrus of the frontal lobe
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UMNs that form the corticospinal tract descend through the ______ to the _______ through the _____ and finally to the ________ and into the _______.
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UMNs that form the corticospinal tract descend through the POSTERIOR LIMB OF THE INTERNAL CAPSULE to the through the CRUS CEREBRI OF THE CEREBRAL PEDUNCLES and finally to the VENTRAL PONS and into the VENTRAL MEDULLA.
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Of the corticospinal tract, 90% decussate in the ________.
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Pyramids of the medulla
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The part of the corticospinal tract that decussates in the pyramids in the medulla descends down the _________ of the spinal cord and are called ____________ tract.
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Contralateral lateral white column / Lateral corticospinal tract
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10% of the corticospinal tract does not decussate in the pyramids and continues its descent via the ________ of the spinal cord. It then decussates via the _________ to the contralateral side and synapses with LMNs in the _______.
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10% of the corticospinal tract does not decussate in the pyramids and continues its descent via the VENTRAL WHITE COLUMN of the spinal cord. It then decussates via the ANTERIOR WHITE COMMISURE to the contralateral side and synapses with LMNs in the VENTRAL HORN.
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The corticospinal tract never experiences a _______ _____ because of the 90/10 decussation pattern.
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Complete lesion
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The corticobulbar tract is part of the _______ (pyramidal/extrapyramidal) system and controls ______ (voluntary/involuntary) skeletal muscle activity.
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pyramidal / voluntary
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List all of the structures that the corticobulbar tract controls. (10)
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Voluntary skeletal muscle to the/for:
Head Neck Facial expression Extrinsic eye mm Tongue Mastication Neck Pharynx Larynx Scalp |
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Where are cell bodies of the corticobulbar tract located?
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Pre-central gyrus of the frontal lobe
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How do cortigobulbar UMNs initiate activity?
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Using cranial nerves
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What structure do corticobulbar UMNs descend through initially?
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The posterior limb of the internal capsule
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What structure may the corticobulbar UMNs pass through?
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The crus cerebri of the cerebral peduncles of the midbrain
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Where do the UMNs of the corticobulbar tract decussate?
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In the region of the brain stem to which they are going
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Where do the UMNs and LMNs of the corticobulbar tract synapse?
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in the cranial nerve motor nuclei of the tegmentum of the brain stem
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Do the LMNs continue on individually or become part of the cranial nerve?
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Become of the cranial nerve
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What kind of projection pattern does the corticobulbar tract have, and what is that mean for the tract if it becomes damaged?
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Bilateral projection pattern
Don't lose function because there is input from both sides of the brain |
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What cranial nerve(s) are the exceptions to the rule that LMNs of the corticobulbar tract won't lose their function if damaged?
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CN 7 (facial) + CN 12 (hypoglossal)
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In a unilateral projection pattern, the left side controls the ___ and the right side controls the ___.
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Left / Right
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Which two cranial nerves will a stroke not affect? Why?
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CN 7 + 12
There is no compensation by a bilateral projection pattern. |
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What kind of tracts make up cranial nerve tracts?
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Corticobulbar
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Which nerves have no motor input? (3)
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CN 1, 2, + 8
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What kind of projection pattern does CN 7 + 12 have?
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Unilateral
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There are 2 motor functions of the oculomotor nerve. Name them.
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1. Innervate extrinsic eye muscles + levator palpebrae superioris
2. Innervate iris + ciliary bodies |
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Name the external eye muscles that CN 3 innervates. (4)
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Superior, medial, + inferior rectus muscles
Inferior oblique muscle |
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The oculomotor nerve receives _____ (bilateral/unilateral) input from the corticobulbar tract
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Bilateral
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What contains the cell bodies of the oculomotor nerve LMNs, and where is that structure located?
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Oculomotor nuclear complex
Tegmentum of the midbrain |
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What structure controls the iris + ciliary body?
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Hypothalamus
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Is the ciliary body + iris controlled by the pyramidal or extrapyramidal system?
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Extrapyramidal system
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Where are the preganglionic parasympathetic neurons of CN 3 located?
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The Edinger-Westphal nucleus in the TEGMENTUM of the MIDBRAIN
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Where do the preganglionic parasympathetic neurons of CN 3 synaps with postganglionic parasympathetic neurons?
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Ciliary ganglia
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The iris is innervated by CN 3 for ____ and the ciliary body of the lens for ____ .
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The iris is innervated by CN 3 for MIOSIS and the ciliary body of the lens for ACCOMODATION.
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CN 4 innervates what?
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Superior oblique extrinsic eye muscle
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The trochlear nerve receives _____ (bilateral/unilateral) input from the corticobulbar tract.
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Bilateral
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Where are the cell bodies of the LMNs of CN 4 located?
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Trochlear motor nucleus in the TEGMENTUM of the MIDBRAIN
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What does CN 5 innervate?
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Muscles of mastication
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What are the muscles of mastication? (4)
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Medial + lateral pterygoids, masseter, temporalis muscle
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Does the trigeminal nerve receive unilateral or bilateral input from the corticobulbar tract?
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Bilateral
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Where are CN 5's LMN cell bodies located?
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Motor nucleus of V in the TEGMENTUM of the PONS
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Where are all LMNs of of CN 5 located?
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Mandibular nerve (V3)
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Where does CN 5 decussate?
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In the PONS at the motor nucleus of V
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The abducens nerve innervates what muscle? (1)
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The lateral rectus extrinsic eye muscle
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What is the function of the lateral rectus extrinsic eye muscle?
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To abduct the eyeball
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The abducens nerve receives _____ (unilateral/bilateral) input from _____ (UMN/LMNs) from the _______ tract.
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The abducens nerve receives BILATERAL input from UMNs from the CORTICOBULBAR tract.
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LMN cell bodies of the abducens nerve are located in the ________, which is located in the _______ in the ________ brain.
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LMN cell bodies of the abducens nerve are located in the ABDUCENS MOTOR NUCLEUS, which is located in the TEGMENTUM of the PONS in the brain
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CN 7 has two motor functions. Name them.
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1. Innervates muscles of facial expression
2. Innervates submandibular, sublingual, and lingual glands |
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The UMNs of the facial nerve are associated with the _______ tract.
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Corticobulbar
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The upper half of CN 7's innervation for muscles of facial expression receive ______ (bilateral/unilateral) input from the _______ tract.
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The upper half of CN 7's innervation for muscles of facial expression receive BILATERAL input from the CORTICOBULBAR tract.
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The lower half of CN 7's innervation for muscles of facial expression receive ______ (bilateral/unilateral) input from the _______ tract.
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The lowerhalf of CN 7's innervation for muscles of facial expression receive UNILATERAL input from the CORTICOBULBAR tract.
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Cell bodies of motor nuclei for CN 7's innervation of the muscles of facial expression are located in the ________ in the ______ of the _______ of the brain.
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Cell bodies of motor nuclei for CN 7's innervation of the muscles of facial expression are located in the FACIAL MOTOR NUCLEUS in the TEGMENTUM of the PONS of the brain.
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Glandular innervation of CN 7 has its preganglionic parasympathetic neurons originating in the _________ nuclei of the _______ in the brain.
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Salvitory Nuclei / Medulla
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What 2 nerves share the salivatory nucleus in the medulla for preganglionic parasympathetic fibers?
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CN 7 + CN 9
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Where are the postganglionic parasympathetic neurons of CN 7 located? (2)
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Submandiublar + Pterygoalatine ganglia
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Name the 2 motor functions of the glossopharyngeal nerve.
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1. Innervate the stylopharyngeous muscle
2. Innervate the parotid gland |
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Innervation for the stylopharyngeus muscle comes from CN __, with ______ (bilateral/unilateral) input coming from the _______ tract.
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Innervation for the stylopharyngeus muscle comes from CN 9, with BILATERAL input coming from the CORTIBOBULBAR tract.
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Where are the LMN cell bodies of CN 9's motor function located?
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Nucleus ambigulous of the MEDULLA
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What 3 CNs share nucleus ambiguous?
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CN 9, 10, 11
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Innervation of the parotid gland comes from the _________ (sympathetic/parasympathetic) function of CN __.
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Innervation of the parotid gland comes from the PARASYMPATHETIC function of CN 9.
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Preganglionic parasympathetic neurons the glossopharyngeal nerve are located in the _______ nuclei in the _______ of the _______ in the brain.
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Preganglionic parasympathetic neurons the glossopharyngeal nerve are located in the SALIVATORY nuclei in the TEGMENTUM of the MEDULLA in the brain.
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Postganglionic parasympathetic neurons of CN 9 are located in the ______ in the _______ (what part of the body?).
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Postganglionic parasympathetic neurons of CN 9 are located in the OTIC GANGLIA in the NECK.
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CN ___ innervates the larynx, pharynx, and soft palate.
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CN 10
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CN 10 receives ______ (unilateral/bilateral) input from the ________ tract.
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CN 10 receives BILATERAL input from the CORTICOBULBAR tract.
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_________ contains cell bodies of LMNs in the ________ of the ______ in the brain for CN 10.
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NUCLEUS AMBIGUUS contains cell bodies of LMNs in the TEGMENTUM of the MEDULLA in the brain for CN 10.
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_________ (preganglionic/postganglionic) parasympathetic neurons of CN 10 are located in the dorsal motor nucleus of the ______.
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PREGANGLIONIC parasympathetic neurons of CN 10 are located in the dorsal motor nucleus of the MEDULLA.
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Where do preganglionic parasympathetic fibers synapse with postganglionic neurons in CN 10?
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Ganglia located near the organ being innervated
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The spinal accessory nerve receives ______ (unilateral/bilateral) input from the ________ tract.
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The spinal accessory nerve receives BILATERAL input from the CORTICOBULBAR tract.
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The cervical portion of CN 11 has its LMN cell bodies in the _______.
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Spinal motor nucleus
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Where are the nuclei of the cervical portion of CN 11 located?
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In the rostral cervical regions of the spinal cord.
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What does the cervical portion of the spinal accessory nerve innervate? (2)
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1. The sternocleidomastoid mm
2. Trapezius mm |
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Where are the LMNs of the cranial portion of CN 11 located?
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Nucleus ambiguus
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What part of the brain is the nucleus ambiguus for CN 11 located?
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The tegmentum of the medulla.
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What does the cranial portion of CN 11 innervate?
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Intrinsic laryngeal muscles
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The hypoglossal nerve receives ____ (unilateral/bilateral) input from the ______ tract.
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The hypoglossal nerve receives UNILATERAL input from the CORTICOBULBAR tract.
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The ______ _____ nucleus contains cell bodies of LMNs for CN 12 and is located in the ____ of the ______.
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The hypoglossal motor nucleus contains cell bodies of LMNs for CN 12 and is located in the tegmentum of the medulla.
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What does CN 12 innervate? (2)
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1. Extrinsic tongue muscles
2. Intrinsic tongue muscles (genioglossus mm) |
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What are modulatory descending motor tracts?
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Pathways that subserve the corticospinal tract - they refine + finess the activity of LMNs receiving input from UMNs
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What are the four modulatory descending tracts?
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Rubrospinal tract
Tectospinal tract Vestibulospinal tract Reticulospinal tract |
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Where are the cell bodies of the rubrospinal tract located?
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Red nucleus of the midbrain
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Where does the rubrospinal tract decussate?
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Midbrain
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Where does the rubrospinal tract terminate?
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Ventral horns of the SC
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The rubrospinal tract excites ___ (flexor/extensor) activity and inhibis _____ (flexor/extensor) activity.
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The rubrospinal tract excites FLEXOR activity and inhibis EXTENSOR activity.
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The tectospinal tract has cell bodies of UMNs located in the ____ ______ of the _____.
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The tectospinal tract has cell bodies of UMNs located in the SUPERIOR COLLICULUS of the MIDBRAIN.
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Where does the tectospinal tract decussate?
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The midbrain
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Where does the tectospinal tract terminate?
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Ventral horns of the upper cervical spinal cord
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What is the tectospinal tract responsible for?
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Reflexive postural movements of the head,neck, and upper extremities in response to VISUAL stimuli
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Where are cell bodies of UMNs of the vestibulospinal tract located?
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Vestibular nuclei in the tegmentum of the pons
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Where does the vestibulospinal tract decussate?
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It doesn't!
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Where does the vestibulospinal tract terminate?
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At the ventral horns of the spinal cord
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What is the vestibulospinal tract involved with?
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"Righting reflexes" ???
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UMN cell bodies of the reticulospinal tract are located where?
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In multiple reticular nuclei throughout the brainstem
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Does the reticulospinal tract have primarily contralateral or ipsilateral function?
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Ipsilateral
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What is the reticulospinal tract's function?
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To excite extensor activity and inhibit flexor activity.
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List the 7 classical signs of UMN damage.
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1. Paresis
2. Paralysis 3. Exaggerated DTR 4. Clonus 5. Spastic paralysis 6. Hypertonia 7. Contralateral effects prior to decussation and ipsilateral effects after decussation |
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What is paresis?
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Weakness because skeletal mm is receiving less input
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Paralysis
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Loss of movement with large range of loss because of less input
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What is a synonym for an exaggerated DTR?
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Hyperflexia
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What is clonus?
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Spasms with alterations of contraction + relaxation in rapid succession of antagonistic + agonistic muscles
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Clonus causes what?
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Hyperreflexia of spinal reflexes
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What characterizes spastic paralysis?
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Involuntary contraction of one or more muscles with loss of function
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What is hypertonia?
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Increased muscle tone
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What isthe hallmark of an UMN lesion?
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Spastic paralysis
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What 3 things account for spastic paralysis, hypertonia, increased DTR, and clonus?
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1. Damage to UMNs
2. LMNs are still intact with reflex arcs 3. Babinski test for UMN lesion |
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What does it mean for there to be damage to a UMN?
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LMNs do not get supraspinal instruction
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When LMNs are still intact with a reflex arc, skeletal muscle ____ (is/is not) innervated.
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When LMNs are still intact with a reflex arc, skeletal muscle IS innervated.
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For a LMN with an intact reflex arc, there is _____ (increased/decreased) DTR and ________ (hyper/hypotonicity).
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For a LMN with an intact reflex arc, there is INCREASERD DTR and HYPERTONICITY.
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How do you perform a Babinski test?
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Run an object up the lateral side of the foot
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What is a positive Babinski test?
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Toes will dorsiflex and the great toe fans
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What is a normal Babinski test?
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Toes will plantarflex
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What are the classic signs of LMN damage? (6)
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1. Paresis
2. Flaccid paralysis 3. Hypotonia 4. Decreased/absent DTRs 5. Atrophy 6. Fibrillations/fasciculations |
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LMN damage ca take place in what two kinds of motor neurons?
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Alpha + gamma
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Where are alpha + gamma motor neurons found? (2)
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1. Motor nuclei of CNs
2. Ventral horns of SC |
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What are 2 ways in which LMNs can be damaged?
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1. Damage to the ventral horn itself
2. Damage to a peripheral nerve |
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What is paresis?
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Weakness; not innervating a skeletal muscle resulting in dramatic weakness
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Is paresis a sign of LMN or UMN damage?
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Both! UMN + LMN damage
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What is flaccid paralysis?
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Loss of mm tone with resultant loss of function
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What is hypotonia?
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Decreased muscle tone
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What is atrophy?
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Reduction in size of skeletal muscle as a result of decreased tone aka decreased actin + myosin fibers
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What are fibrillations of fasciculations?
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Spontaneous activity of skeletal muscle
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Does LMN damage have ipsilateral or contralateral symptoms?
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Ipsilateral
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What are the 4 major categories of LMN physiology?
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1. Spinal reflex responses
2. Brainstem reflexes 3. Posture 4. Rhythmic patterned movements |
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Noxious stimulation reflexes + DTRs are examples of what?
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Spinal reflex responses
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Brainstem reflexes include what 3 things?
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1. Coutnerpart of SC reflexes
2. Noxious reflexes 3. DTRs |
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What stabilizes a foundation for other body movements?
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Posture
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______ results from constant adjustments by your muscles to the shifts in gravity.
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Proprioception
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How do rhythmic patterned movements usually begin?
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As voluntary movement patterns
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How are rhythmic patterned movements maintained?
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As reflexive and involuntary patterns
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Finally, what do rhythmic patterned movements become?
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Central pattern generators
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What are central pattern generators associated with? (4)
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1. Basal ganglia
2. Spinal cord 3. Brainstem 4. Cerebellum |
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Do you make a new central pattern generator each time you learn a new motor task?
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Yes!
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What is the physiological substrate for rhythmogenesis in CPG systems?
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Reciprocal inhibitory neural circuits
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Why can a cat with a tracnsected spinal cord still walk on a treadmill?
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Because cats are bionic!
But really -- there are still afferent fibers available to ender the spinal cord + efferent LMNs to perform the activity. Sensory input from the treadmill initiates the reflex arc at the spinal cord. Because the CPG is located at the spinal cord, they can still walk. |
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When a lesion occurs at the base of the medulla to deafferentate the spinal cord, what happens?
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Elimination of sensory input
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Can a cat still walk on a treadmill with a lesion on the medulla? Why?
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Yes - cat can still walk on the treadmill
CPG is in the spinal cord |
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Where are CPGs in humans?
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In the spinal cord
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What kind of children have patterned flexion/extension movements while lying down?
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Anencephalic children
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What is an example of CPG activation in infants?
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Infants can make walking movements even though they have never experienced walking
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Why can't patients people with SCIs above the lumbar spine walk? There are two reasons.
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1. It is more complex to walk on 2 limbs than on 4
2. Most CPGs are learned - but gait is innate |
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What are the 3 characteristics of spinal cord reflexes?
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1. Segmental in nature
2. May involve propriospinal loops or circuits 3. Can be modulated by supraspinal influences |
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How many segments does a spinal cord reflex involve?
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Can involve one segment or many adjacent segments
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Where are propriospinal loops/circuits located?
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Close to midline of the spinal cord in the GRAY matter
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What is the function of propriospinal circuits/loops?
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To communicate between different levels (of the spinal cord?)
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What two tracts can modulate surpaspinal influences?
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Rubrospinal + reticulospinal tracts
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What 4 fundamental anatomical parts make up a spinal cord reflex?
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1. Receptor organ
2. Afferent sensory neuron 3. Efferent motor neuron 4. Effector organ |
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What kinds of fibers are activated in a flexor reflex?
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Type III + IV
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What is a DTR/myotactic/stretch reflex arc?
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Contraction of agonistic and synergistic muscles following a stretch of a agonisitc muscle
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What kind of fibers are activated in a DTR or myotactic/stretch reflex?
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Type 1a fibers
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How does a DTR or myotactic/stretch reflex travel?
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Dorsal root --> synapse with LMNs --> returns to the same muscle that was stretched
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What is a DTR/myotactic/stretch reflex important for?
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Muscle tone
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How many neurons are involved in the pathway for DTRs/myotactic/stretch reflexes?
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2
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What is the receptor organ for a DTR/myotactic/stretch reflex?
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Muscle spindle (neuromuscular bundle)
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What does the muscle spindle detect?
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Length + rate of change of length in extrafusal fibers
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What are modified cells inside the muscle spindle called?
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Intrafusal fibers
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Name the 3 kinds of intrafusal fibers + their fiber type
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1. Dynamic nuclear bag (1a)
2. Static nuclear bag (II) 3. Nuclear chain fiber (II) |
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What is the function of intrafusal fibers?
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To differentiate between static + dynamic change in length + rate of change in skeletal muscles
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What is the noncontractile portion of a skeletal muscle?
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The middle portion of an intrafusal fiber that doesn't contract
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Name the two kinds of noncontractile portions of intrafusal fibers.
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Annulospiral endings
Flower spray ending |
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Where is an annulospiral ending located?
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Wrapped around the noncontractile portion of an intrafusal fiber
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Where is a flower spray ending located?
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Laterally on either side of an annulospiral ending
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A(n) ______ (annulospiral ending/flower spray ending) is attached to a Ia fiber whereas a(n) __________ (annulospiral ending/flower spray ending) is attached to a II fiber.
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A(n) ANNULOSPIRAL ENDING is attached to a Ia fiber whereas a(n) FLOWER SPRAY ENDING is attached to a type II fiber.
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How do type 1a fibers synapse with the spinal cord?
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Monosynaptically
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What do type Ia fibers synapse with in the spinal cord?
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Alpha motor neurons
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What do type 1a fibers innervate?
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The same muscle (homonymous) or synergistic muscle (heteronymous)
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Type II fibers synapse with ______ (alpha/gamma) motor neurons in the _______ (heteronymous/homonymous) muscle.
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Type II fibers synapse with ALPHA motor neurons in the HOMONYMOUS muscle.
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Alpha motor neurons are the _____ (afferent/efferent) component of a DTR.
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Alpha motor neurons are the EFFERENT component of a DTR.
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Where are the cell bodies of alpha motor neurons located?
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In the ventral horns of the SC
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What do alpha motor neurons innervate?
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Extrafusal fibers
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What are alpha motor neurons able to cause utilizing Renshaw cells?
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Reciporical inhibition - aka inhibition of antagonistic muscle activity
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GTO reflexes/inverses reflexes/tendon reflexes are all examples of what?
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Autogenic inhibition
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What are GTOs and where are they located?
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They are encapsulated receptor organs at the junction between mucle and tendon
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What types of reflexes are GTO reflexes?
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Proprioceptive reflexes
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What type of fiber is a GTO?
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Type Ib
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What do GTOs measure?
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Tension + rate of change of tension in a tendon
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How do GTOs prevent muscles from tearing?
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By keeping the antagonisitc muscle from being excessively stretched or contracted
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What two things contribute to a GTO's ability to adjust muscle activity?
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The muscle spindle + descending controls
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Type Ib cells synapse with ________ cells to inhibit ______ motor neuron activity.
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Type Ib cells synapse with Renshaw cells to inhibit alpha motor neuron activity.
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What is muscle tone?
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Partial state of contraction of extrafusal fibers.
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It is (more/less) efficient to contract a muscle that is already partially contracted.
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It is MORE efficient to contract a muscle that is already partially contracted.
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What is one consequence of muscle tone?
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Posture
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Posture is the result of constant responses to _________ input from adjustments of muscles to shifts in gravity.
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Proprioceptive
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What 3 factors determine muscle tone?
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1. Intrinsic characteristics of extrafusal fibers
2. Gravity pulling on skeletal muscles and activating stretch reflexes 3. Gamma bias finessing system of muscle tone |
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What causes the gamma bias finessing system of muscle tone?
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Supraspinal descending pathways that influence gamma motor neurons
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Where can supraspinal descending pathways originate from? (2)
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The cerebellum + reticular formation
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What are gamma motor neurons?
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Cell bodies located in the ventral horn of the spinal cord
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What do gamma motor neurons innervate?
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Contractile portions of intrafusal fibers
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Are gamma motor neurons smaller or larger than alpha motor neurons?
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Smaller
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Do gamma motor neurons tend to discharge spontaneously or not?
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Yes - they do tend to discharge spontaneously
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List the 5 things that gamma motor neurons do NOT do.
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1. Become excited monosynaptically by 1a fibers
2. Respond to Type II 3. Influenced by GTOs 4. Respond to peripheral input 5. Involve themselves with Renshaw cell activity |
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What is the job of gamma motor neurons?
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To alter the sensitivity of the muscle spindle by altering the length of intrafusal fibers and the tension they may exert.
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When gamma motor neurons fire, they cause ______ fibers to contract.
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When gamma motor neurons fire, they cause INTRAFUSAL fibers to contract.
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What else can gamma motor neurons do in relation to intrafusal fibers?
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They can make it harder for Ia fibers to fire + put them on slack
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When you are anticipating something, like when waiting on the blocks as a sprinter, what does Gamma Bias do?
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Primes skeletal muscle tone
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What is hypotonia?
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Decreased muscle tone
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Does hyotonia increase or decrease resistance to passive movement?
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Decreases resistance to passive movement
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What 3 things can cause hypotonia?
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1. Eliminate LMNs - no reflex arc
2. Eliminate sensory afferent input (alpha motor neurons don't know what do or when to contract) 3. Lesions of the cerebellum (no info coming down to skeletal muscles + no input to influence gamma bias) |
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What is hypertonia?
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Excessive muscle tone
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Does hypertonia cause decreased or increased resistance to passive movement?
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Increased
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Spasticity is characterized by what?
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Hyper-reflexia of DTR due to UNM damage
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Does spasticity cause decreased or increased resistance to passive movement?
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Increased
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What is the Clasp Knife Phenomenon?
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An initial increase in resistance followed by a sudden disappearance of resistance
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Rigidity is characterized by what?
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Increase in muscle tone in all muscles ALTHOUGH strength and reflexes are not affected
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What is Lead Pipe Rigidity?
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Rigidity that is uniform throughout the ROM
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What is cog wheel rigidity?
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Rigidity is a series of jerks during the ROM
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What are the functions of the cerebellum? (3)
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1. Coordinates voluntary muscle activity
2. Coordinates equilibrium activity 3. Influence muscle tone |
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Does the cerebellum initiate voluntary muscle activity?
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No!
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If you damage your cerebellum can you still move voluntarily? Why or why not?
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Yes - because the cerebellum indirectly projects to the spinal cord.
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What are the 3 types of information that the cerebellum needs?
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1. Position, state of contraction, and activity of muscles + joints
2. Equilibrium state of the body 3. Information being sent via the corticobulbar and corticospinal tracts to skeletal muscles |
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What tracts tell the cerebellum about muscle and joint activity?
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The anterior + posterior spinocerebellar tracts.
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How does the cerebellum receive info about the equilibrium state of the body?
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The vestibulocerebellar tract (transmits unconscious proprioceptive input)
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Each hemisphere of the cerebellum controls information to the _____ (ipsilateral/contralateral) side of the body.
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Each hemisphere of the cerebellum controls information to the IPSILATERAL side of the body.
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Why are cerebellar symptoms ipsilateral?
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Because of the cerebellum's several double decussation patterns
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Initiation of voluntary movement comes from where?
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Corticospinal + corticobulbar tracts - NOT the cerebellum itself
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Is there paralysis with cerebellar injury?
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No!
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Coordination of fine,voluntary movement is a function of the _______ lobe of the cerebellum.
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Posterior
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Maintenance of equilibrium is a function of the ________ lobe of the cerebellum.
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Flocculonodular
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Muscle tone, posture, gross voluntary movement, and gait are all maintained by the ______ lobe of the cerebellum.
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Anterior
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What is the primary symptom of cerebellar dysfunction?
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General ataxia - abnormality in muscular coordination leading to abnormality of voluntary movement
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There are 10 symptoms of ataxia that may indicate cerebellar dysfunction. Name them... if you can.
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1. Muscles contract weakly or irregularly
2. Unintentional tremors 3. Unsteady or drunken gait 4. Broader BOS 5. Leaning to the affected side 6. Dystmetria 7. Dysdiadokinesia 8. Hypotonia 9. Nystagmus 10. Dysarthria |
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What is dysmetria?
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Inability to stop a muscle movement at a desired point
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What is dysdiadokinesia?
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Inability to perform rapid, alternating movement (ie: rapid pronation + supination of forearm)
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What is dysarthria?
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Slurred or hesitant speech
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What characteristic of a DTR implies cerebellar dysfunction?
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Pendular swinging after a DTR
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Pendular swinging after a DTR is a function of which of the 10 symptoms of cerebellar dysfunction?
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Hypotonia
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What is nystagmus?
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Ataxia of the eyes - rapid + slow tracking phases
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Saccades is the ____ (rapid/slow) phase of nystagmus.
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Saccades is the RAPID phase of nystagmus.
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Is the name of the nystagmus in the same or opposite direction of the saccades?
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Same direction
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When diagnosing cerebellar dysfunction, what 3 things should one rule out before diagnosis?
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Proprioceptive, vestibular nuclei, or ear problems
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