Outline I. Skeleton of the Shoulder and Attachment of M1 Gross and Developmental Anatomy the Upper Extremity to Trunk Scapular and Deltoid II. Positions and Movements of the Scapula Regions Extrinsic Muscles of the Shoulder III. Glenohumeral (Shoulder) Joint Dr. Peters IV. Movements at the Shoulder Joint Intrinsic Muscles of the Shoulder Prime Movers of the Arm
1 2 V. Neurovascular Relationships
Bony Landmarks -- Scapula
• Borders thickened from muscle attachments 3 4
Scapular Processes and their Ligaments Anterior View • Acromion Process: – Free (lateral) end of spine – Articulates with the clavicle (acromio-clavicular joint)
• Coracoid Process: Shaped like a Crow’s beak – Pectoralis Minor Inserts – Coracobrachialis and Short Head of Biceps Arise
• Ligaments: – Acromioclavicular – Coracoclavicular
5 – Coracoacromial 6 7 8
Shoulder Separation
II. Positions and Movements of the Scapula
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Muscles Suspending the Shoulder Muscles Pulling on Shoulder Girdle Girdle from Vertebral Column from Anterior Chest Wall Trapezius (Elevates, Serratus Anterior retracts, Upwardly (Upwardly rotates scapula; rotates, protracts, Spinal Accessory holds scapula Nerve) against thorax; Levator Scapulae long thoracic n.) Rhomboid Major Rhomboid Minor (all Pectoralis minor: elevate medial border (Depresses, and downwardly down-wardly rotate scapula; rotates scapula; Dorsal Scapular medial pectoral 11 12 nerve;) nerve) Summary of Scapular Movements
Elevation Depression
See Fig. 6.40 Grant’s 12th 13 14
Protraction Upward Rotation
Retraction Downward Rotation
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III. Glenohumeral Joint •2/3 sphere articulates with shallow glenoid fossa •Designed to maximize movement •Large muscles (e.g. Deltoid) act across it •Little ligamentous 17 18 support Capsule of the Shoulder Joint •Capsule thickened anteriorly as gleno- humeral ligaments •Rotator Cuff muscles blend with capsule as they cross •Capsule not reinforced inferiorly •Dislocation initially inferior – SUB- 19 GLENOID position 20
Glenohumeral Ligaments
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Subacromial Bursa Synovial Cavity of Shoulder Joint
•Normally communicates with subscapular bursa •Only pathologically communicates •A bursa is a closed synovial membrane to decrease friction with subacromial •Bursae may become inflamed and sore (“bursitis”) bursa •Subacromial and subdeltoid bursae lie between these •Is prolonged downward around structures and supraspinatus tendon and humerus 23 24 •They often fuse biceps tendon Bursitis
Rotator Cuff Tendonitis
Rotator Cuff Tears
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Muscular Support: Rotator Cuff
Joint surrounded by 4 muscles: IV. Movements at Anterior: Subscapularis the Shoulder Superior: Supraspinatus Posterior: Infraspinatus & Teres Minor
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Intrinsic Shoulder Muscles: Supraspinatus Rotator Cuff • O: Supraspinous fossa • I: Greater • SITS Muscles: tubercle of • Supraspinatus – initiates abduction humerus (upper facet) • Infraspinatus – laterally rotates humerus • A: Initiate • Teres minor – laterally rotates humerus abduction • Subscapularis – medially rotates humerus •N: Suprascapular • Arise on scapula; insert on greater & lesser •AS: tubercles of humerus Suprascapular • Stabilize joint by pulling head of humerus into Artery glenoid fossa 29 30 Infraspinatus Teres Minor • O: Infraspinous • O: Middle fossa half, lateral • I: Greater border of tubercle of scapula I: humerus (middle Greater facet) tubercle of humerus • A: Lateral lower facet) rotation • A: Lateral •N: rotation of Suprascapular humerus •AS: • N: Axillary suprascapular and circulflex •AS: scapular aa. subscapular and circumflex 31 scapular aa. 32
•O: Subscapular Subscapularis fossa of scapula •I: Lesser tubercle of Prime Movers of ABduction and humerus ADduction of the Arm at the •A: Medial Shoulder rotation of humerus •N: Upper & Lower Subsca- pular nerves •AS:
Subscapular a. 33 34
Deltoid Muscle
Innervation: Axillary Nerve (SURGI- CAL NECK FRACTURE)
Arterial Supply: Deltoid Branch of Thoracoacromial Artery
Heads: Anterior and Posterior (not physically, but FUNCTIONALLY separate)
Actions: Primarily Abduction Shoulder flexion - Anterior Head Shoulder extension -Posterior Head 35 36 Abduction of the Upper Extremity • Initiated by Supraspinatus Muscle • Deltoid continues powerful Abduction • Abduction beyond 90 degrees involves two muscles that move the scapula via upward rotation - Trapezius muscle (spinal accessory n.) - Serratus anterior muscle (long thoracic n.) - Differential diagnosis: Lesion of Spinal
Accessary versus Long Thoracic Nerve 37 38
Pectoralis Major Muscle Teres Major Muscle
Innervation: Medial & Lateral Actions: ADduction of Humerus Pectoral Nerves Medial Rotation of Humerus Arterial Supply: Pectoral Branch of Thoracoacromial Truck Innervation: Lower Subscapular Nerve Heads: Clavicular and Sternal
Actions: ADduction of Humerus Arterial Supply: Subscapular and Medial Rotation of Humerus Circumflex Arteries
Shoulder Flexion - Clavicular Head 39 40
Latissimus Dorsi Inserts on Humerus between “Two “The lad has two Majors” (Floor of Intertubercular majors” Groove) Action: Extends, Adducts, and Medially Rotates Humerus Innervation: Thoracodorsal N. Arterial Supply: Thoracodorsal A. 41 42 Dorsal scapular n.
V. Neurovascular Relationships
43 Fig 6.3 Grant’s 12th 44
Erb-Duchenne paralysis
- C5-C6 lesion of brachial plexus or spinal cord - Loss of muscles innervated by these segments, including Supraspinatus, Deltoid, Biceps brachii and Supinator -This results in loss of shoulder abduction, some shoulder flexion and external rotation, as well as loss of supination of the forearm. -The patient’s upper extremity assumes a position similar to a waiter hinting for a tip.
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Quadrangular Space
Notice: Axillary nerve relationship to the Surgical Neck of the Humerus 47 48 Injection into Shoulder Joint through Suprapinous Fossa
- Muscles Penetrated
- Artery and Nerve in jeopardy
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