Neuromuscular Flashcards
What is a motor unit?
A single motor neuron and the multiple muscle fibers it innervates
What are myofibrils?
Multiple bundles of small fibers that make up muscle cells
What are myofilaments?
Smaller fibers inside the myofibril that are made up of the proteins actin and myosin
What are sarcomeres?
Short segments of actin and myosin
Characteristics of Skeletal muscle contraction
A minimum amount stimulus is needed to initiate a muscle contraction
All fibers contract one a stimulus is applied (all or none)
Muscle contractions stop once the stimulus is removed
There is a change in the number of motor units stimulated based on the need (graded response based on activity)
What is Reciprocal Inhibition?
Smooth movement requires a coordinated contraction in the agonist an a slight relaxation in the antagonist (but not complete inhibition)
What is the Stretch Reflex?
When a rapid lengthening of a muscle occurs, a concentric contraction is signaled ( to protect muscle from tearing) by the muscle spindles
What are the two types of muscle spindles?
Alpha afferents: sensitive to lengthening of the muscle
Gamma afferents: sensitive to the rate of lengthening
What is gamma gain?
Increased sensitivity of the muscle spindle to a sudden lengthening after a muscle has been static for an extended period
What is the Inverse Stretch Reflex?
The Golgi tendon organ (a proprioceptive sensory receptor that is at the origins or insertions of muscle fibers) monitors the force of contraction to protect muscles from tearing
GTOs are sensitive to tension in the muscle and respond to increased tension by inhibiting contraction
What are postural adaptation?
Muscles held in shorter or longer than normal positions for extended periods of time that cause reduced muscle performance
What are the characteristics of Upper Crossed Syndrome?
Forward head, depressed chest, rounded shoulders, and increased kyphosis
Causes: headaches, thoracic outlet syndrome, scapular dyskinesis, and shoulder impingement
What are the characteristics of Lower Crossed Syndrome?
Excessive lordosis and protruding belly
Causes: Sciatica, SI dysfunction, chronic low back pain
What is muscle hypertrophy?
Increase in size and strength of the muscle fibers in response to exercise
Takes several weeks to build muscle
What is muscle atrophy?
Decrease in size and strength of the muscle fibers from lack of use or denervation (use it or lose it)
Occurs quickly and could impede circulation to the area
What are muscle cramps?
Acute involuntary muscle contractions caused by muscle fatigue or metabolic imbalances (involuntary)