|
Muscles Acting On The Shoulder |
|
|
Origin |
Insertion |
Innervation |
Action |
|
Rhomboid minor |
Spines & supraspinous ligaments of C7 – T1 |
Posteromedial end of spine of scapula |
Dorsal scapular nerve (C4 – C5) |
Retracts scapula. Rotates lower scapula back to rest position |
|
Rhomboid major |
Spines & supraspinous ligaments of C7 – T1 |
Medial border of scapula between root of spine & inferior angle |
Dorsal scapular nerve (C4 – C5) |
Retracts scapula. Rotates scapula to rest position |
|
Trapezius (upper fibres) |
Spinous processes & supraspinous ligaments of C7 – T12 |
Posterior border of lateral third of clavicle |
Accessory nerve (XI), Ventral Rami (C3 – C4) |
Elevate scapula |
|
Trapezius (middle fibres) |
Spinous processes & supraspinous ligaments of C7 – T12 |
Medial border of acromion, superior lip of spine of scapula |
Accessory nerve (XI), Ventral Rami (C3 – C4) |
Retract scapula |
|
Trapezius (lower fibres) |
Spinous processes & supraspinous ligaments of C7 – T12 |
Tubercle at medial end of spine of scapula |
Accessory nerve (XI), Ventral Rami (C3 – C4) |
Rotate scapula & depression of shoulder |
|
Levator scapulae |
Transverse processes of C1 – C3/C4 |
Upper part of medial border of scapula between superior angle & base of spine |
Ventral Rami (C3 – C4), Dorsal scapular nerve (C5) |
Elevates medial border of scapula |
|
Serratus anterior |
Outer & superior borders of upper 8-10 ribs & anterior intercostals membranes |
Inner medial border of scapula. 1st & 2nd ribs: upper angle; 3rd & 4th ribs: length of costal surface; 5th to 8th ribs: inferior angle |
Long thoracic nerve (C6 – C7) |
Laterally rotates & protracts scapula |
|
Pectoralis minor |
Outer surface of 3rd – 5th ribs & intercostal fascia |
Upper surface & medial border of coracoid process of scapula |
Medial & lateral pectoral nerves (C5 – T1) |
Elevates ribs if scapula fixed, protracts scapula (assists serratus anterior) |
|
Pectoralis major |
Clavicular head-anteromedial ½ of clavicle. Sternocostal head-anterolateral manubrium & body of sternum |
Lateral lip of bicipital groove of humerus and anterior lip of deltoid tuberosity |
Medial & lateral pectoral nerves (C5 – T1) |
Clavicular head: flexes & adducts arm. Sternal head: adducts & medially rotates arm |
|
Deltoid (anterior fibres) |
Anterior border of lateral 1/3 of clavicle |
Deltoid tuberosity of humerous |
Axillary nerve (C5 – C6) |
Flexes & medially rotates the shoulder |
|
Deltoid (middle fibres) |
Lateral margin of acromion process |
Deltoid tuberosity of humerus |
Axillary nerve (C5 – C6) |
Abducts the shoulder |
|
Deltoid (posterior fibres) |
Lower edge of crest of spine of scapula |
Deltoid tuberosity of humerus |
Axillary nerve (C5 – C6) |
Extends & laterally rotates the shoulder |
|
Biceps brachii (long head) |
Supraglenoid tubercle of scapula & glenoid labrum |
Posterior part of radial tuberosity & bicipital aponeurosis |
Musculocutaneous nerve (C5 – C7) |
Supinates forearm, flexes elbow, weakly flexes shoulder |
|
Biceps brachii (short head) |
Coracoid process of scapula with coracobrachialis |
Posterior part of radial tuberosity & bicipital aponeurosis |
Musculocutaneous nerve (C5 – C7) |
Supinates forearm, flexes elbow, weakly flexes shoulder |
|
Coracobrachialis |
Apex of coracoid process |
Midway along medial border of humerus |
Musculocutaneous nerve (C5 – C7) |
Flexes & weakly adducts arm |
|
Latissimus dorsi |
Spinous processes & supraspinous ligaments of all lower thoracic, lumbar and sacral vertebrae, lumbar fascia, posterior 1/3 of iliac crest, last four ribs (interdigitating with external oblique abdominis) and inferior angle of scapula |
Bicipital groove of humerus |
Thoracodorsal nerve (C6 – C8) |
Extends, adducts &medially rotates arm. Costal attachment helps with deep inspiration &forced expiration |
|
Teres major |
Lower 1/3 of lateral side of inferior angle of scapula below teres minor |
Medial lip of bicipital groove of humerus |
Lower subscapular nerve (C6, C7) |
Medially rotates & adducts arm. Stabilises shoulder joint |
|
Teres minor |
Middle 1/3 of lateral border of scapula above teres major |
Inferior facet of greater tuberosity of humerus (below infraspinatus) & capsule of shoulder joint |
Axillary nerve (C5 – C6) |
Laterally rotates arm & stabilises shoulder joint |
|
Triceps (long head) |
Infraglenoid tubercle of scapula |
Posterior part of upper surface of olecranon process of ulna & posterior capsule |
Radial nerve (C7 – C8) |
Extends shoulder & elbow |
|
Triceps (lateral head) |
Upper half posterior humerus (linear origin) |
Posterior part of upper surface of olecranon process of ulna & posterior capsule |
Radial nerve (C7 – C8) |
Extends the elbow |
|
Triceps (medial head) |
Lies deep on lower half of posterior humerus inferomedial to spiral groove & both intermuscular septa |
Posterior part of upper surface of olecranon process of ulna & posterior capsule |
Radial nerve (C7 – C8) |
Elbow the elbow |
|
Supraspinatus |
Medial 3/4 of supraspinous fossa of scapula, upper surface of spine (bipennate) |
Superior facet on greater tuberosity of humerus & capsule of shoulder joint |
Suprascapular nerve (C4 – C6) |
Abducts arm & stabilises shoulder joint |
|
Subscapularis |
Medial 2/3 of subscapular fossa |
Lesser tubercle of humerus, upper medial lip of bicipital groove, anterior capsule of shoulder joint |
Subscapular nerve (C5 – C6) |
Medially rotates arm & stabilises shoulder joint |
|
Infraspinatus |
Medial ¾ of infraspinous fossa of scapula & fibrous intermuscular septa |
Middle facet of greater tuberosity of humerus & posterior aspect of capsule of shoulder joint |
Suprascapular nerve (C5 – C6) |
Laterally rotates arm & stabilises shoulder joint |
|
Subclavius |
Costochondral junction of 1st rib |
Middle 1/3 of clavicle |
Direct branch of the upper trunk of the brachial plexus from C5 – C6 |
Depresses clavicle & stabilises it during shoulder movements |
