Joints And Muscle Action Flashcards
What is the function of a muscle?
A muscle functions to contract or shorten.
What is a muscle made of?
A muscle is composed of multiple muscle cells.
What is a muscle stimulated by?
A muscle is stimulated by a neuron.
Muscle cell contraction is characterized as…
All or none
What is a motor unit?
A motor unit is a motor neuron and all the muscle cells innervated by it.
What is the motor unit function characterized as?
All or none.
In one muscle, there are ___________ motor units.
Multiple.
How do we achieve gradation of function?
Recruitment of additional motor units.
Muscles designed for large gross movement have…
A large number of muscle cells per motor unit.
Muscles designed for small fine movements have…
A small number of muscle cells per motor unit.
What is concentric contraction?
When the muscle shortens (ex: lifting arm).
What is a isometric contraction?
When muscle length remains constant.
What is an eccentric contraction?
When a muscle lengths (ex: lowering arm).
What is a fibrous joint?
A fibrous joint is when fibrous CT connects 2 bones.
What is a cartilaginous joint?
A joint that has cartilage between the two bones and a fibrous capsule holding the bones together.
What is synovial joint?
The bones at the joint are covered with cartilage and a fibrous capsule encloses the joint. The synovium lines the inner surface of the fibrous capsule and part of the bone that is included. The synovial membrane secretes a fluid called the synovial fluid that allows for ease of movement.
What is osteoarthritis?
When the cartilage starts to break down and bare bone is exposed.
What is the fixed end of the muscle called?
Origin.
What is the movable end of the muscle called?
Insertion.
If the muscle crosses through the origin, then…
There is NO movement.
What is the most effective angle formed between the vector and axis?
90 degrees.
What angle is the least effective?
0 degrees.
What is a flexion movement?
Bending movement, decreasing the angle between two parts of the body.
What is an extension movement?
Straightening movement, increasing the angle between body parts.
What is abduction?
Pulling a structure away from the midline of the body.
What is adduction?
Pulling a structure towards the midline of the body.
