Shoulder Joint Anatomy Lecture 5 PDF

Lecture 5 Dr Sapna Shoulder joint Type: Synovial Shape: Ball and Socket Number of bones: Simple (2 articular bones). Articular surfaces: Glenoid cavity of scapula Head of humerus Ligaments of shoulder joint Fibrous capsule: Scapular attachments: Margins of the glenoid f...

Lecture 5 Dr Sapna Shoulder joint Type: Synovial Shape: Ball and Socket Number of bones: Simple (2 articular bones). Articular surfaces: Glenoid cavity of scapula Head of humerus Ligaments of shoulder joint Fibrous capsule: Scapular attachments: Margins of the glenoid fossa. Includes the supraglenoid tubercle with long head of biceps. The lower and medial parts of the capsule are lax and weakest. (no muscular support)  Humeral attachment: Surrounds the anatomical neck. Attached to the shaft ½” below anatomical neck medially--weak part. There is a gap in the capsule for the passage of biceps tendon in the inter -tubercular groove Synovial membnrane lines inner surface of capsule.  Glenoid labrum Glenoid cavity shallow ,accommodates only 1/3 of head of humerus The glenoid cavity is deepened by a fibro - cartilaginous collar (the glenoid labrum), which attaches to its margin. It deepens the socket for the head fits better. Glenohumeral ligaments They are superior , middle and inferior gleno humeral ligaments. They extend from the anterior glenoid margin to the lesser tubercle of the humerus. They are considered as thickenings of the fibrous capsule of the shoulder joint. They strengthens anterior surface of capsule. Transverse humeral ligament It stretches across the inter tubercular groove & allows passage of tendon of long head of biceps. Coracohumeral ligament Between the coracoid process and the greater tubercle of the humerus. With the body upright & arm in dependent position, it may play a role in resisting inferior dislocation Coracoacromial ligament Between coracoid process and acromion. Prevents upward displacement of the head of humerus. Flexion Abduction Anterior fibers of deltoid. First 15 degree is initiated by supraspinatus. Pectoralis major Up to 90 degree by middle Coraco- brachialis & biceps fibers of deltoid. Beyond 90 degree by moving brachii. the scapula (upwards and laterally rotated)done by trapezius & serratus anterior Extension Posterior fibers of deltoid. Adduction Teres major. Subscapularis. Latissmus dorsi. Pectoralis major. Latissimus dorsi. Long head of triceps Teres major. Medial rotation Lateral rotation Subscapularis. Infraspinatus. Pectoralis major. Teres minor. Latissimus dorsi. Posterior fibers of deltoid Teres major  Clinical anatomy Shoulder dislocation Anterior dislocation of the gleno- humeral joint occurs most often in athletes. It is usually caused by excessive extension and lateral rotation of the humerus. A hard blow to the humerus when the gleno-humeral joint is fully abducted tilts the head of the humerus inferiorly onto the inferior weak part of the joint capsule.  This may tear the capsule and dislocate the shoulder so that the humeral head comes to lie inferior to the glenoid cavity and anterior to the infra-glenoid tubercle Immediate symptoms Immediate swelling within the shoulder region Extremely difficult shoulder movements due to pain and weakness (injury to axillary nerve). Loss of abduction from 15 to 90 (deltoid) weak lateral rotation (teres minor) Pins and needles on the skin of upper arm due to injury to the upper lateral cutaneous (branch of axillary) nerve of arm. Objectives: 1. Describe the articular surfaces, type, shape and structure of the shoulder joint 2. Explain the movements, blood and nerve supply of the shoulder joint. 3. Explain the causes of shoulder dislocation and the complications that might happen. References: Netter's Clinical Anatomy. Hansen, John T. Elsevier; 2019 4th Edition. ISBN: 978-0-323-53188-7 https://www-clinicalkey-com.gmulibrary.com/#!/content /book/3-s2.0-B978032353188700007X?scrollTo=%23hl 0001694 Arm Muscles in front of the arm Coracobrachialis Biceps brachii Brachialis Nerve supply : Musculocutaneous nerve Action : flexion of elbow joint Muscles in the back of the arm Triceps bracii Nerve supply : Radial nerve Action : Extension of elbow joint Musculocutaneous nerve It’s a branch from the lateral cord (C5,6,7) It enters arm by penetrating coracobrachialis muscle. It appears lateral to the tendon of the biceps brachii muscle at the elbow, penetrates deep fascia, and continues as the lateral cutaneous nerve of forearm. It supplies coracobrachialis, biceps and brachialis muscles & the skin of lateral forearm. Brachial Artery It’s a continuation of axillary artery at the lower border of teres major muscle Main arterial supply to arm It terminates at the neck of the radius by dividing into radial & ulnar arteries Branches : Profunda brachii Superior ulnar collateral Inferior ulnar collateral Radial Ulnar Cubital fossa Is a triangular depression which is located anterior to the elbow joint. Laterally : the brachioradialis muscle. Medially : the pronator teres muscle. Base : imaginary horizontal line between the medial and lateral epicondyles. Roof Skin. Superficial fascia. Median cubital vein. The bicipital aponeurosis. Floor formed by the brachialis & supinator muscles. Contents Radial nerve laterally. Biceps tendon. Brachial artery with its terminal branches (radial & ulnar arteries). Median nerve medially.