muscles of the elbow

Question 1

elbow flexion primary movers

Answer 1

brachialis

biceps brachii

brachioradialis

pronator teres

Question 2

secondary or assist muscles for elbow flexion

Answer 2

extensor carpi radialis longus and brevis

flexor carpi radialis

palmaris longus

flexor carpi ulnaris

pass anterior to the elbow axis

used when needed to move a larger load

Question 3

how do we determine whether a muscle is or isnt active during elbow flexion

Answer 3

location of muscle

position of the elbow or adjacent points

position of forearm

magnitude of applied load

type of muscle contraction

speed of motion

Question 4

location of muscle

Answer 4

refers to its insertion

is it close to the joint or is it far from the joint (spurt v. shunt muscle, stability v. mobility)

Question 5

position of the elbow or adjacent joints

Answer 5

fully extended v. fully flexed

affects angle of insertion and what muscles we recruit

shoulder position will dictate what elbow flexors we recruit

Question 6

position of forearm

Answer 6

pronated or supinated

Question 7

magnitude of applied load

Answer 7

what is the resistance

how much are we trying to move

Question 8

type of muscle contraction

Answer 8

isometric

eccentric

concentric

Question 9

speed of motion

Answer 9

are we moving quickly or are we moving slowly

Question 10

brachialis

Answer 10

is a 1 joint muscle

inserts close to the joint axis and is considered a spurt muscle (mobility muscle)

“work horse” of the elbow flexors

not affected by shoulder position (b/c it is a one joint muscle)

produces greatest torque at approximately 100 degrees of elbow flexion (length tension relationship is optimized)

Question 11

how is the brachialis the “work horse”

Answer 11

always active, despite forearm position, with or without resistance, fast or slow movements and during all types of contractions

Question 12

is the biceps brachii a spurt or shunt muscle

Answer 12

spurt or mobility muscle

Question 13

how many joints does the biceps brachii cross

Answer 13

2 joints

the position of the shoulder will effect its function at the elbow

Question 14

when is the biceps brachii active

Answer 14

during unresisted elbow flexion as long as the forearm is supinated or in mid position

quick or slower movements

concentric and eccentric contractions (except when the forearm is pronated)

Question 15

when is the biceps brachii active despite forearm position

Answer 15

when the resistance is great

Question 16

when does the biceps produce the greatest force

Answer 16

b/w 80-100 degrees of elbow flexion

Question 17

functions at the shoulder of the biceps

Answer 17

assisting in shoulder flexion

abduction when the shoulder is in ER

Question 18

effects of shoulder position on biceps function

Answer 18

when the shoulder is slightly extended, the length tension relationship is maximized

biceps are actively insufficient when the shoulder is in the too short or too long position

biceps are passively insufficient when its in the too long position

Question 19

too short biceps brachii

Answer 19

shoulder is flexed

elbow is flexed

forearm is supinated

Question 20

too long biceps brachii

Answer 20

shoulder is extended

elbow is extended

forearm is pronated

Question 21

is the brachioradialis a shunt or spurt muscle

Answer 21

shunt muscle

acts for joint stability

Question 22

when is the brachioradialis active

Answer 22

when the forearm is neutral or pronated

when the speed of the motion increased

when resistance is applied

Question 23

is the brachioradialis affected by shoulder position

Answer 23

no

it doesnt cross the shoulder

Question 24

pronator teres

Answer 24

will assist with elbow flexion when resistance is applied

Question 25

elbow extension primary movers

Answer 25

triceps with assist from the anconeus

Question 26

what is the overall effectiveness is affected by

Answer 26

changes in elbow position

BUT NOT CHANGES IN THE FOREARM

Question 27

how many joints does the triceps cross

Answer 27

2 joints

is affected by shoulder position

Question 28

when does the triceps produce the greatest force

Answer 28

at 90 degrees of flexion

Question 29

parts of the triceps

Answer 29

medial head

lateral head

long head

Question 30

medial head

Answer 30

“work horse” of the extensors

active all the time

Question 31

lateral head

Answer 31

strongest of the 3 heads

only recruited w/ resistance

Question 32

long head

Answer 32

only active during resisted elbow extension

Question 33

effects of shoulder position on the triceps

Answer 33

when the shoulder is slightly flexed, the length tension relationship is maximized

when its actively insufficient and passively insufficient

Question 34

actively insufficient –> triceps

Answer 34

too short –> elbow extension and shoulder extension

too long –> elbow flexion and shoulder flexion

Question 35

passively insufficient –> triceps

Answer 35

elbow flexion and shoulder flexion

Question 36

anconeus

Answer 36

assists in elbow extension

acts as a stabilizer during pronation and supination

Question 37

supination primary movers

Answer 37

supinator

biceps brachii

Question 38

supinator

Answer 38

is always active during forearm supination

not affected by forearm position

Question 39

biceps brachii (supination)

Answer 39

is active with resisted supination, including when elbow is extended

at 90 degrees of elbow flexion –> is the primary supinator

Question 40

pronation primary movers

Answer 40

pronator quadratus and pronator teres

Question 41

pronator quadratus

Answer 41

active in any position of the forearm or elbow regardless of speed of motion

with or without resistance

will maintain compression of the distal radioulnar joint

Question 42

pronator teres (pro)

Answer 42

is active during resisted or fast pronation regardless of elbow position

also works as an elbow flexor

Question 43

synergies at the elbow

Answer 43

biceps and triceps

Question 44

biceps and triceps synergy (1)

Answer 44

when a forceful grip is made they will work synergistically to stabilize the elbow

also prevent movement that could be caused by strong contraction of the wrist and finger flexors and extensors

co-contraction

Question 45

biceps and triceps synergy (2)

Answer 45

actions of turning a door knob or using a screw driver

triceps will stabilize the elbow and prevent elbow flexion that could be caused by the biceps or pronator teres as they participate in supinator or pronation