SHOULDER AND ARM MUSCLES Flashcards
list the 4 extrinsic shoulder muscles in the anterior compartment
- pectoralis major
- pectoralis minor
- serratus anterior
- subclavius
origin, insertion, action and innervation of pectoralis major
- origin: clavicle, sternum, upper 6 costal cartilages
- insertion: lateral lip of bicipital groove of humerus
- action: flexion, adduction and medial rotation of humerus, draws scapula anteroinferiorly
- innervation: medial and lateral pectoral nerves C5-T1
origin, insertion, action and innervation of pectoralis minor
- origin: anterior ends of ribs 3-5
- insertion: coracoid process of the scapula
- action: stabilises scapula
- innervation: medial and lateral pectoral nerves (C5-T1)
origin, insertion, action and innervation of serratus anterior
- origin: ribs 1-8
- insertion: medial border of scapula
- action: protracts and holds scapula against the thoracic wall
- innervation: long thoracic nerve (C5-C7)
origin, insertion, action and innervation of subclavius
- origin: superior surface of costal end of 1st rib and adjacent 1st rib cartilage
- insertion: inferior surface of middle 1/3 of clavicle
- action: stabilises clavicle
- innervation: nerve to subclavius muscle C5-C6
list the 5 shoulder extrinsic muscles in the posterior compartment
- latissimus dorsi
- trapezius
- levator scapula
- rhomboid major
- rhomboid minor
origin, insertion, action and innervation of latissimus dorsi
- origin: spinous processes T7-T12, the iliac crest, ribs 8-12, and lumbodorsal fascia
- insertion: floor of inter-tubercular groove of humerus
- action: adducts, medially rotates and extends humerus, raises body towards arm in climbing
- innervation: thoracodorsal nerve C6-C8
origin, insertion, action and innervation of trapezius
- origin: occipital bone, ligamentum nuchae, and spinous processes of thoracic vertebrae
- insertion: clavicle and scapula — acromion and scapula spine
- action: elevates, depresses and retracts the scapula, rotates glenoid cavity superiorly
- innervation: accessory nerve CNX1
origin, insertion, and action of levator scapula
- origin: transverse processes of 1st 4 cervical vertebrae (C1-C4)
- superior angle of scapula, vertebral border of scapula
- action: elevates scapula, and inferiorly rotates glenoid cavity
origin and insertion of rhomboid major
- origin: spinous processes of T2-T5 vertebrae
- insertion: vertebral border of scapula inferior to spine of scapula
origin and insertion of rhomboid minor
- origin: spinous processes of vertebrae C7-T1, nuchal ligament
- insertion: vertebral border of scapula adjacent to spine of scapula
what are the actions of the rhomboid major and minor
retract scapula and inferiorly rotates glenoid cavity, fix scapula to thoracic wall
what is the innervation of levator scapula, rhomboid major and rhomboid minor?
dorsal scapular nerve (C5)
list the 6 shoulder intrinsic muscles
- deltoid
- teres major
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
origin, insertion and action of deltoid
- origin: lateral 1/3 of clavicle, acromion and spine of scapula
- insertion: deltoid tuberosity of humerus
- action: flexes, medially rotates, abducts, extends and laterally rotates arm
origin, insertion and action of teres major
- origin: posterior aspect of inferior angle of scapula
- insertion: medial lip of bicipital groove of humerus
- action: adducts and medially rotates arm (at glenohumeral shoulder joint)
origin, insertion and action of teres minor
- origin: lateral border of scapula
- insertion: greater tubercle of humerus
- action: medial rotation at shoulder
origin, insertion and action of supraspinatus
- origin: supraspinous fossa of scapula
- insertion: greater tubercle of humerus
- action: abduction at shoulder
origin, insertion and action of infraspinatus
- origin: infraspinous fossa of scapula
- insertion: greater tubercle of humerus
- action: abduction at shoulder
origin, insertion and action of subscapularis
- origin: subscapular fossa of scapula
- insertion: lesser tubercle of humerus
- action: medial rotation at shoulder
what muscles are innervated by the suprascapular nerve C5?
supraspinatus and infraspinatus
what muscles are innervated by the axillary nerve C5-C6?
deltoid and teres minor
what muscle is innervated by the lower subscapular nerve (C5-C7)?
teres major
what muscle is innervated by the (upper and lower) subscapular nerves C5-C7?
subscapularis
list the 4 rotator cuff muscles
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
what do the rotator cuff muscles do? exception?
all muscles rotate humerus except supraspinatus, which initiates and assists deltoid with 1st 15 degrees of abduction of the arm
list the 3 muscles in the anterior compartment of the arm
- biceps brachii — long head and short head
- coracobrachialis
- brachialis
origin, insertion and action of long head and short head of biceps brachii
- origin: LONG HEAD = supraglenoid tubercle of scapula, SHORT HEAD = coracoid process of scapula
- insertion: tuberosity of radius and fascia of forearm via the bicipital aponeurosis
- action: flexion at elbow and shoulder, supination
origin, insertion and action of coracobrachialis
- origin: coracoid process of scapula
- insertion: medial margin of shaft of humerus
- action: adduction and flexion at shoulder
origin, insertion and action of brachialis
- origin: anterior aspect of distal half of humerus
- insertion: coronoid process and tuberosity of ulna
- action: flexes forearm at elbow
innervation of arm muscles in anterior compartment
- biceps brachii — musculocutaneous nerve C5-C6
- coracobrachialis — musculocutaneous nerve C5-C7
- brachialis — musculocutaneous nerve C5-C6 and radial nerve C7-C8
list the muscles of the arm in the posterior compartment
triceps brachii — long, lateral and medial head
what are the origins of the different heads of the triceps brachii?
- long head = infraglenoid tubercle of scapula
- lateral head = posterior shaft of humerus above spiral groove
- medial head = posterior surface of humerus inferior to radial groove (spiral groove)
insertion, action and innervation of triceps brachii
- insertion: olecranon of ulna
- action: extension at elbow
- innervation: radial nerve (C7-C8)
movement at the shoulder requires action from what 3 groups of muscles?
- anterior axioappendicular
- posterior axioappendicular
- scapulohumeral
