Shoulder joint- muscles and movements Flashcards
planes of scapula
scapula doesn’t sit on anterior coronal plane; it is anteriorly facing- glenoid faces laterally and anteriorly. plane is 45° between frontal and sagittal planes- where normal physiological movement occurs at shoulder joint
flexion at shoulder joint
110° (anything beyond this is elevation- upto 180°)
deltoid (anterior fibres), pectoralis major (clavicular head)
extension at shoulder joint
50-70°- deltoid (posterior fibres), teres minor, latissimus dorsi, pectoralis major (sternocostal head)- from flexion to neutral
abduction at shoulder joint
100-120°- anything more than this is elevation (up to 180°)
deltoid (middle fibres), supraspinatus (initiates)
adduction at shoulder joint
30-40°- has to be slight glenohumeral joint flexion, against resistance (physical or gravity) by pectoralis major, latissimus dorsi, teres minor, coracobrachialis
medial rotation at shoulder joint
+-90°- subscapularis, pectoralis major, latissimus dorsi, anterior fibres of deltoid, teres major
lateral rotation at shoulder joint
80°- infraspinatus, teres minor, posterior fibres deltoid
elevation of arm- scapulohumeral rhythm
glenohumeral joint, scapulothoracic joint
0-30°- all glenohumeral movements- setting phase
30-80°- 2 humerus abduction and 1- scapula lateral rotation (scapulothoracic joint) ratio 2:1
prime movers of muscles acting on shoulder joint
pectoralis major, latissimus dorsi, deltoid, teres minor, coracobrachialis
the rotator cuff muscles (synergists)
supraspinatus, infraspinatus, teres minor, subscapularis, SITS- order of insertion into humerus
pectoralis major origin and insertions
origin- clavicular attachment and sternocostal attachment (2 heads- conjoined tendons)
insertions- lateral lip of the intertubercular groove
NS and actions pectoralis major
medial and lateral pectoral nerve (C5-8), actions- clavicular flex (clavicular head), sternocostal extension- from fully flexed position to neural, both heads adduction, medial rotation of humerus
latissimus dorsi origin and insertion
origin- thoracolumbar fascia (inelastic and tough band of CT) from spinous process of T6-12 and all the lumbar and sacral vertebra, iliac crest, lower 4 ribs and inferior angle of scapula
insertion- floor of the intertubercular groove, lower 4 ribs and inferior angle of scapula
latissimus dorsi NS and action
thoracodorsal nerve C6,7,8
action- extension, medial rotation, adduction of humerus
deltoid origin and insertion (anterior, mid and posterior)
origin- lat 1/3 of clavicle (anterior-strap like), acromion (mid- bipennate), spine of scapula (post-strap like)
insertion- mid shaft humerus- deltoid tuberosity
deltoid NS and action
NS- axillary nerve C5,6
action- anterior fibres flexion and extension, middle fibres- abduction, posterior fibres- extension and lateral rotation
coracobrachialis origin and insertion
origin- tip of coracoid process, insertion- mid shaft of humerus
coracobrachialis- NS and action
NS- musculotendinous nerve C5-6
Action- adduction and weak flexion of arm
teres major- origin and insertion
origin- inferior angle of scapula
insertion- medial tip of intertubercular groove
teres major- NS and action
NS- lower scapula nerve C5-6
action- adduction, MR of arm, assists extension of flexed arm
teres minor- origin and insertion
origin- upper part of lateral borders of scapula
insertion- lowermost facet ( inferior) on greater tubercle of humerus
teres minor NS and action
NS- axillary nerve C5,6
action- lateral rotation, extension and adduction of arm, main role is rotator cuff muscle
subscapularis origin and insertion
origin- subscapular fossa, insertion- lesser tubercle of humerus
subscapularis NS and action
NS- upper and lower subscapular nerves C5-7
action- MR of arm, controls unwanted slip or glide of head of humerus in glenoid fossa
supraspinatus origin and insertion
origin- supraspinous fossa of scapula, insertion- uppermost facet on greater tubercle of humerus
supraspinatus NS and action
NS- suprascapular nerve C5-6, action- assists abduction- initiating the first 20°, key role is rotator cuff group
infraspinatus origin and insertion
origin- infraspinous fossa scapula
insertion- middle fact on greater tubercle
infraspinatus NS and action
NS- subscapular nerve C5-6
action- lateral rotation and adduction of arm, key role of rotator cuff group
rotator cuff muscles- stabilize
the rotator cuff stabilizes the glenohumeral joint through force couples in both the coronal and transverse planes
rotator cuff muscles- blend into capsule
Completely controls unwanted side and glide between head of humerus and glenoid fossa, steers the head of the humerus to allow the greater movement to be produced by prime mover muscles
rotator cuff muscles- in transverse plane
subscapularis and infraspinatus
rotator cuff muscles- frontal plane
supraspinatus and teres minor
rotator cuff muscles- stabilising muscles
produce synergy movement
origin and insertions of bicep brachii
origin- 2 heads- short- coronoid process, long- tubercle above glenoid fossa (through bicipital groove)
insertion- to tuberosity of the radius and bicipital aponeurosis to soft tissue in medial aspect of proximal forearm
NS and action bicep brachii
NS- musculocutaneous nerve C5-6
flexion at shoulder/ elbow joint, supination of radioulnar joints
origin and insertion for tricep brachii
origin- three heads- long- infra- glenoid tubercle, lateral- upper part of posterior surface of humerus, medial- lower part of posterior humerus
insertion- posterior surface of olecranon process of ulna
NS and action tricep brachii
NS- radial nerve C6,7,8
action- extends the elbow, long head adducts and extends the shoulder
axilla borders- lateral
costal surface of scapula with subscapularis
axilla borders- anterior
inner aspect of pectoralis major
axilla borders- medial
serratus anterior and thoracic cage
axilla contents
brachial plexus- posterior, medial lateral and cord
axillary artery and vein
