MMB[006] The Shoulder (1)Updated 2024-2025 PDF

MMB The Shoulder 2024-2025 Anatomy Division staff Aims To provide a basic knowledge of the clinical and functional anatomy of the shoulder Objectives At the end of the sessions you should be able to: point out the anatomical features of the scapula, the clavicle and the p...

MMB The Shoulder 2024-2025 Anatomy Division staff Aims To provide a basic knowledge of the clinical and functional anatomy of the shoulder Objectives At the end of the sessions you should be able to: point out the anatomical features of the scapula, the clavicle and the proximal half of the humerus, using anatomical specimens and radiographs use simple sketches to illustrate the joints of the shoulder girdle and its ligamentous and muscular support list the muscles responsible for movements of the shoulder girdle, with specific reference to movements of the scapula and clavicle, and give their nerve supplies Name the muscles of the back, the pectoral region & the scapular region complete the related tasks on the surface anatomy schedule 3 Regions of the upper limb: 1. Back (muscles connecting upper limb to vertebral column) 2. Pectoral region (muscles connecting upper limb to thoracic wall) 3. Shoulder region (muscles connecting scapula to humerus) 4. Axilla (Armpit, space between upper part of the arm & the side of the chest) 5. Arm & Cubital fossa 6. Front of forearm & Palm of hand 7. Back of forearm & dorsum of hand  Shoulder Skeleton Scapula Humerus Clavicle All 3 bones usually move: * Shoulder girdle joints: Sternoclavicular & Acromioclavicular * Shoulder joint (between humerus & scapula 5 HUMERUS 6 fracture dislocation surgical neck of humerus Scapula 8  Clavicle Assists shoulder movement Transmits force from upper limb to thorax Superior Inferior 9  I. Sternoclavicular joint Anterior (& Posterior) Interclavicular lig. Synovial saddle. sterno-clavicular lig. Articulation between manubrium of sternum, clavicle & 1st costal cartilage. Ligaments Intra-articular disc (joint cavity is divided into two compartments). Intra-articular disc Costo-clavicular ligament: main stabilizing factor II. Acromioclavicular joint Coraco- Trapezoid part clavicular Conoid part lig. Synovial plane. Articulation between acromion of scapula & clavicle. Ligaments. Coraco-acromial lig. Shoulder joint  Muscles of the back * They attach upper limb to vertebral column 1 2 3 The first layer: 1 1. Trapezius. 2. Latissimus dorsi. The second layer: 1. Levator scapulae. 2. Rhomboidus minor. 3. Rhomboidus major. 2 12  Superficial layer Trapezius Latissimus dorsi  Trapezius Upper fibers: elevate the scapula. Lower fibers: depress the scapula Middle fibers: retract the scapula.  Trapezius Upper & Lower fibers: Rotary movement of the scapula; moving inferior angle of scapula laterally and upward when raising the limb above head. Injury to the accessory nerve, formerly relatively common as the result of a stab injury or as a complication of operative procedures. As a result of the paralysis of the trapezius muscle a drop shoulder with rotation of the angle of the scapula towards the midline and restricted abduction of the arm is caused. Latissimus dorsi  Actions of Latissimus dorsi Latissimus dorsi help one Adduction Climbing or to scratch his back. Extension elevation of Medial rotation the trunk.  1 2 The second layer: 3 1. Levator scapulae. 2. Rhomboidus minor. 3. Rhomboidus major. Action of levator scapula : elevates the scapula together with the upper fibers of trapezius Actions of Rhomboids: o Retracts the scapula & braces back the shoulder (together with the middle fibers of trapezius). o Rotates the scapula so the glenoid cavity looks downwards (together with the levator scapula). Movements of shoulder girdle or Scapular Motion I. Elevation & Depression: II. Upward rotation & Downward rotation of glenoid cavity: * Upward (lateral) rotation: Upper & Lower fibers of trapezius & lower 5 digitations of Serratus anterior. 22 III. Protraction & Retraction of scapula: *Serratus Anterior & Pectoralis Minor *Middle fibers of Trapezius, Rhomboidus muscles. 9/12/2024  Pectoral Region Muscles of pectoral region: Connects U.L.to thoracic wall 3 4 2 1 Deep to pectoralis major are: 2. Pectoralis Minor 1. Pectoralis Major muscle 3. Subclavius muscle 4. Clavipectoral fascia (between 2 & 3) PECTORALIS MAJOR  Actions of pectoralis major Adduction, flexion & medial rotation of arm. With insertion fixed & arm raised, pectoralis major and latissimus dorsi draws trunk upward as in climbing, swimming & rowing.  pectoralis minor Actions of pectoralis minor Protraction of shoulder Depression of shoulder With fixed scapula, it can raise the ribs in forced inspiration.  Serratus anterior A muscle arising from the upper 8 ribs & inserted into scapula Actions of Serratus anterior: o The main protractor of the shoulder ( with pectoralis minor) o Rotates the scapula so the glenoid cavity looks upwards to put the arm on head= abduction > 90◦ (together with ???). o Fix the medial border of scapula to the chest wall. o When the scapula is fixed, it pulls on the ribs in forced inspiration. 28 Serratus anterior Nerve supply: Nerve to Serratus anterior (Long thoracic nerve/ nerve of Bell) (C5,6,7) (from the roots of the brachial plexus). Injury of the nerve to serratus anterior occurs during operation for carcinoma of the breast (radical mastectomy), this leads to a condition called Winging of Scapula  Shoulder (Scapular) Region Consists of a group of muscles (6) connecting the scapula with the humerus: 1. Deltoid 2. Supraspinatus 3. Infraspinatus 4. Teres minor 5. Teres Major 6. Subscapularis (seen from front of scapula)  DELTOID Flexion & medial rotation of arm Extention & lateral rotation of Abduction of arm from 15◦ to 90◦ arm  SUPRASPINATUS Action of supraspinatus: Abducts the arm from 0 – 15◦ (initiates abduction) Prevents upward dislocation of shoulder joint (steadies the head of humerus).  INFRASPINATUS Action of infraspinatus: Rotates the arm laterally Prevents backward dislocation of shoulder joint (steadies the head of humerus).  TERES MINOR Action of teres major: Abducts the arm from 0 – 15◦ (initiates abduction) Prevents upward dislocation of shoulder joint (steadies the head of humerus).  TERES MAJOR Action of teres major: Adduction, medial rotation & extention of arm (similar to latissimus dorsi).  SUBSCAPULARIS Action of subscapularis: Medial rotation & adduction of arm Prevents anterior dislocation of shoulder joint (steadies the head of humerus). Thank you