MSS 2 Muscle

Question 1

What is the role of EMG in assessing muscle function?

Answer 1

EMG test muscle action during a particular movement. When an individual axon is depolarized, an AP propagates down nerve. Depolarization of all fibers in a motor unit creates a motor unit action potential (MUAP). EMG asseses MUAPS (size, complexity, frequency)

Question 2

Shoulder muscle movements: Abduction

Answer 2

Deltoid

Question 3

Shoulder muscle movements: Adduction

Answer 3

Pectoralis major and lat dorsi

Question 4

Shoulder muscle movements: Flexion

Answer 4

Pect major, anterior fibers of deltoid

Question 5

Shoulder muscle movements: Internal Rotation

Answer 5

Subscapularis, lat dorsi, pec major

Question 6

Shoulder muscle movements: External Rotation

Answer 6

Infraspinatus and teres minor

Question 7

What is a prime mover? What is an antagonist? What is a synergist?

Answer 7

Primer movers are the muscles that are responsible for initation and execution of a specific action at the joing. Gravity can be a prime mover. An antagonist is a muscle or group of muscle that oppose the actions of a prime mover. Synergists can provide additional pull or reduce undesirable movements to assist the primer mover.

Question 8

Compare and contract isometric, concentric and eccentric muscle contraction. Isometric contraction?

Answer 8

Isotonic: muscle changes in legth as it generates force
Concentric: Muscle shortens as it generates force
Eccentric: muscle lengthens as it generates force
Isometric: contraction without movement

Question 9

Components of a synovial joint

Answer 9

Synovial joint: cavity between bones comprising the joint. Apposing surfaces of bone are covered by articular cartilage. Bound by a fibrous capsule that is lined by a synovial membrane that secretes fluid

Question 10

Types of synovial joints:
Gliding
Hinge
Pivot
Saddle
Elisoidal or condyloid
Ball and socket

Answer 10

Gliding: flat surface sliding across each other (AC joint)
Hinge: movt occurs in a single plane (elbow, knee)
Pivot: permit only rotation between apposing parts (alanto-axial)
Saddle: shaped like a saddle (CMC of thumb)
Elisoidal or condyloid: oval articular face apposes a depression ( wrist)
Ball and socket: round head w/ cup shaped fossa (hip joint)

Question 11

What is muscle tone?

Answer 11

Muscle fibers remain under slight contraction in relaxed state.

Question 12

What will you see clinically with a lesion to UMN?

Answer 12

LMN received feedback from UMN from CNS to relax when agonist is functioning. Lesion to UMN will remove inhibition–> hypertonia and spasticity.

Question 13

What is the Hennenman size principle?

Answer 13

Smallest MU are recruited first. Increase in freqeuncy will recruit additional units

Question 14

How is botulinum toxin used in treatment of UMN lesions?

Answer 14

Intra-musclar injections can be used to reduce focal muscle overactivity