| Ligament | Attachments | Comment |
|---|---|---|
| Joint capsule | Margin of glenoid cavity → anatomical neck of humerus | Loose fibrous capsule Weakest inferiorly |
| Glenohumeral | Supraglenoid tubercle → blend with fibrous capsule (superior, middle and inferior bands) | Reinforce anterior capsule |
| Coracohumeral | Coracoid process → greater tubercle of humerus | Strong |
| Transverse humeral | Bridges intertubercular groove between greater and lesser tubercles | Holds tendon of biceps brachii in intertubercular groove |
| Coraco-acromial | Coracoid process → acromion | Completes coraco-acromial arch protecting humeral head |
| Muscle | Proximal Attachment (Origin) | Distal Attachment (Insertion) | Innervation | Main Actions | Blood Supply |
|---|---|---|---|---|---|
| Trapezius | Superior nuchal line, external occipital protuberance, nuchal ligament, and spinous processes of C7–T12 | Lateral third of clavicle, acromion, spine of scapula | Spinal root of accessory nerve (CN XI) and C3 and C4 | Elevates, retracts, and rotates scapula; lower fibers depress scapula | Transverse cervical artery, dorsal perforating branches of posterior intercostal arteries |
| Latissimus dorsi | Spinous processes of T7–L5, thoracolumbar fascia, iliac crest, and last three ribs | Humerus (intertubercular sulcus) | Thoracodorsal nerve (C6–C7) | Extends, adducts, and medially rotates humerus at shoulder | Thoracodorsal artery, dorsal perforating branches of 9th, 10th, and 11th posterior intercostal, subcostal, and first three lumbar arteries |
| Muscle | Proximal Attachment (Origin) | Distal Attachment (Insertion) | Innervation | Main Actions | Blood Supply |
|---|---|---|---|---|---|
| Levator scapulae | Posterior tubercles of transverse processes of C1–C4 | Medial border of scapula from superior angle to spine | Ventral rami of C3–C4 and dorsal scapular nerve | Elevates scapula medially, inferiorly rotates glenoid cavity | Dorsal scapular artery, transverse cervical artery, ascending cervical artery |
| Rhomboid minor | Ligamentum nuchae, spines of C7 and T1 vertebrae | Medial border of scapula above base of spine of scapula | Dorsal scapular nerve (C4–C5) | Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity | Dorsal scapular artery OR deep branch of transverse cervical artery, dorsal perforating branches of the upper five or six posterior intercostal arteries |
| Rhomboid major | Spinous processes of T2–T5 vertebrae | Medial border of scapula below base of spine of scapula | Dorsal scapular nerve (C4–C5) | Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity | Dorsal scapular artery OR deep branch of transverse cervical artery, dorsal perforating branches of the upper five or six posterior intercostal arteries |
| Muscle | Proximal Attachment (Origin) | Distal Attachment (Insertion) | Innervation | Main Actions | Blood Supply |
|---|---|---|---|---|---|
| Deltoid | Lateral third of anterior clavicle, lateral acromion, inferior edge of spine of scapula | Deltoid tuberosity of humerus | Anterior and posterior branches of axillary nerve (C5,C6) | Clavicular part: flexes and medially rotates arm; Acromial part: abducts arm beyond initial 15 degrees done by supraspinatus;Spinal part: extends and laterally rotates arm | Posterior circumflex humeral artery, deltoid branch of thoraco-acromial artery |
| Supraspinatus | Supraspinous fossa of scapula | Superior facet of greater tubercle of humerus | Suprascapular nerve (C5,C6) | Initiates arm abduction, acts with rotator cuff muscles | Suprascapular artery |
| Infraspinatus | Infraspinous fossa of scapula and deep fascia | Middle facet of greater tubercle of humerus | Suprascapular nerve (C5,C6) | Lateral rotation of arm (with teres minor) | Suprascapular artery |
| Teres minor | Upper two thirds of posterior surface of lateral border of scapula | Inferior facet of greater tubercle of humerus | Posterior branch of axillary nerve (C5,C6) | Laterally rotates arm | Circumflex scapular artery |
| Teres major | Posterior surface of inferior angle of scapula | Medial lip of intertubercular sulcus of humerus | Inferior subscapular nerve (C5,C6) | Adducts and medially rotates arm | Circumflex scapular artery |
| Subscapularis | Subscapular fossa | Lesser tubercle of humerus | Superior and inferior subscapular nerves (C5–C6) | Medially rotates arm and adducts it; helps hold humeral head in glenoid cavity | Subscapular artery, lateral thoracic artery |