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Kinesiology Exam 1 > Musculature of the Shoulder > Flashcards

Musculature of the Shoulder Flashcards

1
Q

elevation

A

require muscle activity to overcome or control the weight of the limb and its load

usually involves glenohumeral flexion and/or ABD and scap upward rotation

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2
Q

muscles included in elevation

A

deltoid

supraspinatus

infraspinatus and teres minor

subscapularis

biceps

pec major

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3
Q

deltoid in elevation

A

middle deltoid is always active

anterior deltoid is for flexion

posterior deltoid is for extension

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4
Q

when are the anterior and middle heads optimally aligned for elevation

A

in the scapular plane

30-45 degrees in front of the coronal plane

when the humerus is in plane of the scapula

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5
Q

what happens as the humerus continues to elevate

A

fibers of the deltoid are becoming actively insufficient

more motor units are recruited to maintain tension

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6
Q

how can we prevent active insufficiency of the deltoid during elevation

A

the deltoid is strongly dependent on simultaneous scapular movement

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7
Q

what else is the deltoid actively dependent on during elevation

A

intact rotator cuff

w/ a complete rupture of RC, deltoid actively will result in a shrug rather than ABD

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8
Q

how does the deltoid depend on the RC during elevation

A

as the deltoid draws the humeral head up

the RC tugs on the head and centers it in the glenoid fossa

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9
Q

supraspinatus during elevation

A

working in all active planes of elevation

will provide a depressing force, offsetting the deltoid’s superior shearing effect

has secondary functions as well

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10
Q

how does the supraspinatus provide a depressing force

A

tendon will become shorter and widen and push down (vertical motion)

keeps the humeral head away from the acromion by depressing it

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11
Q

secondary functions of the supraspinatus during elevation

A

acts as a vertical steerer of the humeral head

assists in maintaining the stability of the dependent arm

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12
Q

infraspinatus and teres minor in elevation

A

compress the GH joint

act in a force couple to depress the humeral head during elevation, allowing for humeral rotation

serve as a posterior barrier against translation

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13
Q

subscapularis in elevation

A

acts synergistically w/ the posterior cuff muscles to depress and compress the humeral head

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14
Q

biceps in elevation

A

long head can assist with ABD when the humerus is in ER

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15
Q

pec minor in elevation

A

only contributes to flexion of GH

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16
Q

muscles that perform extension GH joint

A

posterior deltoid

latissimus dorsi

teres major

infraspinatus

teres minor

triceps

middle deltoid

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17
Q

ER GH joint muscles

A

infraspinatus

posterior deltoid

teres minor

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18
Q

muscles that help with ER beyond 30 degrees

A

scapular adductors

trapezius

rhomboids

stabilize the origin of the infraspinatus, posterior delt and teres minor, preventing the medial border of the scap from winging

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19
Q

IR GH joint muscles

A

subscapularis

teres major

pectoralis major

latissimus dorsi

anterior deltoid muscles

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20
Q

what are the scapulothoracic muscles

A

traps (all)

serratus anterior

levator scap

rhomboids

pec minor

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21
Q

what do the scapulothoracic muscles do

A

provide a stable yet mobile base from which the GH joint and associated muscles can function

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22
Q

upward rotation muscles (ST)

A

serratus anterior and trapezius force couple

middle traps and rhomboids

23
Q

4 functions of serratus anterior and trapezius force couple

A

orient the scapula

provide scapular upward rotation

prevent impingement

provide a stable base

24
Q
  1. orient the scapula
A

will maintain the glenoid fossa in an appropriate position to support the humeral head

25
Q
  1. provide scapular upward rotation
A

this will maintain efficient length of the deltoid fibers through the ROM

this enhances the power and stabilizing effect

26
Q
  1. prevent impingement
A

the upward rotation will prevent impingement of the RC and bursa in the subacromial space

27
Q
  1. provide a stable base
A

for the axiohumeral and scapulohumeral muscles that are moving the arm against gravity

28
Q

middle traps and rhomboid upward rotation

A

active in humeral elevation, esp ABD

stabilizing synergists to the muscles tha rotate the scapula

contract eccentrically to control the motion created by the traps-serratus anterior force couple

29
Q

muscles of shoulder depression

A

latissimus dorsi and pectoralis muscles

30
Q

shoulder depression

A

forceful downward movements of the arm in relation to the trunk

forceful movement of the trunk upward in relation to the fixed arm

31
Q

what does the scapula tend to do during humeral motion

A

rotate downward and ADD

32
Q

lattissimus dorsi during downward rotation when the arm is free

A

adduct, medially rotate, and extend the humerus

adduct and depress the scap

33
Q

lattissimus dorsi during downward rotation when the arm is fixed

A

lifting the body up as in a seated push up

reverse action of a muscle

34
Q

pectoralis major during upward rotation

A

primary depressors of the shoulder complex

35
Q

pectoralis minor

A

will assist with depression

acts directly on the scapula to depress and rotate downward

36
Q

scapulohumeral rhythm

A

essential for normal shoulder function

synchronous motion of the humerus and scapula during arm elevation

coordinated movements of the shoulder of the shoulder girdle provide the smoothest and greatest ROM possible for the upper extremity

37
Q

can GH motion alone have full ROM

A

not for full ROM in flexion or ABD

the rest of the motion is contributed by the scapulothoracic joint through SC and AC linkages

38
Q

ration of scapulohumeral rhythm

A

2:1

for every 2 degrees of humeral movement

there is 1 degree of scapular motion

39
Q

what joints are included in scapulohumeral rhythm

A

scapulothoracic

GH

SC

AC

40
Q

what chain is the scapulothoracic joint

A

closes kinematic chain

movement of the scap can only occur through movement of the SC and AC joints

41
Q

if movement occurs in one place

A

movement will occur is another place

42
Q

phase one of scapulohumeral rhythm

A

the setting phase

when the humerus elevates up to 30 degrees of ABD or 60 degrees of flexion

scapula seeks a position of stability on the thoracic wall

43
Q

where does motion primarily take place during phase 1

A

GH joint

44
Q

what does the scap begin to do during the setting phase

A

scapula begins to link with the clavicle

ligaments and capsule tighten so they will move together

45
Q

phase 2 of scapulohumeral rhythm

A

occurs from 30 degrees of ABD and 60 degrees of flexion to 150 degrees of both motions

GH contribution decreases and scapulothoracic joint increases and upwardly rotates

46
Q

how does upward rotation occur (phase 2)

A

upper and lower traps w/ the serratus anterior

AC motion is prevented d/t the conoid ligaments, so motion must occur elsewhere –> SC joint –> clavicle elevates

clavicular elevation causes 30 degrees of upward rotation

clavicular elevation (90 degrees) is checked by the costoclavicular ligs

AC joint permits some winging and tipping to maintain contact b/w the scap and thoracic wall

by this point there is 90 degrees of either flexion or ABD

47
Q

as phase 2 continues

A

upward rotation is restrained by the costoclavicular ligaments and coracoclavicular ligaments

muscles continue to produce force, coracoid continues to move inferiorly, causing more clavicular rotation

this carries the scap through another 30 degrees of upward rotation

continued winging and tipping of the scap via the AC joint

48
Q

phase 3

A

ranges from 150-180 degrees of flexion or ABD

GH contribution increases and ST decreases

to complete ABD the humerus must ER

for full flexion, the scap must ABD and upwardly rotate (keeps the glenoid in good alignment w/ shaft of the humerus)

49
Q

rotator cuff

A

supraspinatus

infraspinatus

teres minor

subscapularis

“S.I.T.S” muscles

50
Q

important role of the RC

A

shoulder elevation and reinforcing the joint capsule

51
Q

what does the RC do during shoulder elevation

A

will secure the humerus to the glenoid fossa and compress the joint

adds dynamic stability to the shoulder

52
Q

what does the RC do during ABD

A

ER the humerus (infraspinatus and teres minor) at the end of ROM of ABD

53
Q

force couple in RC

A

deltoid/supraspinatus with infraspinatus and teres minor

54
Q

without adequate strength of the RC muscles

A

there is risk of injury

Kinesiology Exam 1 (9 decks)

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