The Shoulder Joint (Glenohumeral Joint) - 2023 PDF

 The shoulder joint (glenohumeral joint) is a ball and socket joint between the scapula and the humerus. It is the major joint connecting the upper limb to the trunk. It is one of the most mobile joints in the human body, at the cost of joint stability. Articulating Surfaces...

 The shoulder joint (glenohumeral joint) is a ball and socket joint between the scapula and the humerus. It is the major joint connecting the upper limb to the trunk. It is one of the most mobile joints in the human body, at the cost of joint stability. Articulating Surfaces The shoulder joint is formed by the articulation of the head of the humerus with the glenoid cavity (or fossa) of the scapula. This gives rise to the alternate name for the shoulder joint – the glenohumeral joint. Like most synovial joints, the articulating surfaces are covered with hyaline cartilage.  The head of the humerus is much larger than the glenoid fossa,giving the joint inherent instability. To reduce the disproportion in surfaces, the glenoid fossa is deepened by a fibrocartilage rim, called the glenoid labrum. Joint Capsule and Bursae The joint capsule is a fibrous sheath which encloses the structures of the joint. It extends from the anatomical neck of the humerus to the border of the glenoidfossa and ending at the surgical neck. The joint capsule is lax:non-rigid:, permitting greater mobility (particularly abduction). Natural position of the joint gives more flexibility to the direction of abduction. (cause inferior side has large space compare with superior one)  The synovial membrane lines the inner surface of the joint capsule, and produces synovial fluid to reduce friction between the articular surfaces. To reduce friction in the shoulder joint,several synovial bursae are present. A bursa is a synovial fluid filled sac, which acts as a cushion between tendons and other joint structures. Bursae Subacromial – Located inferiorly to the; **deltoid and acromion, superiorly to the; **supraspinatus tendon **the joint capsule. --It supports the; **deltoid Subscapular **the tendon of supraspinatus. – Located; – Bursitis can cause; **Between the subscapularis tendon and the scapula. – It reduces wear and tear on the tendon during movement at the shoulder joint Bursae (1) and (6) subacromial- subdeltoid bursa, (2) subscapular recess, bursa. (3) subcoracoid bursa, (4) coracoclavicular bursa, (5) supra-acromial bursa.  Ligaments In the shoulder joint, the ligaments play a key role in stabilising thebony structures. The majority of the ligaments are thickenings of the joint capsule: -they are anatomically much much closer to make the thickening -they keep the capsule strong Glenohumeral ligaments (superior, middle and inferior)  ALWAYS KEEP IN MIND; THEY ARE THICKENING LIGAMENT Literally looks like almost the capsule itself. Actually they are the same but the specific areas are thicking so that they are named. The joint capsule is formed by this group of ligaments connecting; **the humerus to the glenoid fossa. They are the main source of stability for theshoulder, holding it in place and preventing it from dislocating anteriorly. They act to stabilise theanterior aspect of the joint.  Coracohumeral Ligament Attaches the base of the coracoid process to the greater tubercle of the humerus. It supports the superior part of the joint capsule. Transverse humeral ligament– Spans the distance between the two tubercles of the humerus. kılıf It holds the tendon of the long head of the biceps in the: intertubercular sulcus or bicipital groove; there is passing the structure of long head of biceps brachii muscle’s tendon which is attaches to SUPRAGLENOID TUBERCLE. Coraco–clavicular Ligament This is composed of the trapezoi and conoid ligaments and runs from the clavicle to the coracoid process of the scapula. They work along side the acromioclavicular ligament to keep the scapula attached to the clavicle. Coracoacromial ligament Unlike the others, It runs between the acromion and coracoid process of the scapula, forming the coraco-acromial arch. This structure overlies the shoulder joint, Movements Extension (upper limb backwards in sagittalplane) Produced by the posterior deltoid, latissimus dorsi, teres major. Flexion (upper limb forwards insagittal plane) Produced by the anterior deltoid, the pectoralis major, coracobrachialis. Biceps brachii weakly assists in forward flexion Movements Abduction (upper limb away from midline in coronal plane) The first 0-15 degrees of abduction is produced by **the supraspinatus: only can start initiated movement kind of a initiater The next 15-90 degrees of abduction is produced by **the middle fibres of the deltoid Past 90 degrees, the scapula needs to be rotated to achieve abduction that is carried out by **the trapezius **serratus anterior Movements Adduction (upper limb towards midline in coronal plane) Produced by contraction of pectoralis major, latissimus dorsi, teres major. Movements BOTH ROTATION CONTAIN TERES MAJOR! Medial Rotation (rotation towards the midline, so that the thumb is pointing medially) Produced by contraction of subscapularis, pectoralis major, latissimus dorsi, teres major, anterior deltoid. Lateral Rotation (rotation away from the midline, so that the thumb is pointing laterally) Produced by contraction of the infraspinatus, teres minor. **I saw the teres minor at Rotators and Lateral Rotation, other major. Teres minor and Teres major muscles although very close to each other, doing different type of movements. MAJOR= Medial rotation MINOR= Lateral rotation But how could it be possible? By; -axis of the rotation passes through the long axis of the humerus, in here we are talking aboout vertical axis. -bicipital groove attachment is important Mobility and Stability Factors that contribute to mobility: Type of joint – It is a ball and socket joint. Bony surfaces – Shallow glenoid cavity and large humeral head – there is a 1:4 disproportion in surfaces. **A commonly used analogy is the golf ball and tee. Laxity of the joint capsule. Factors that contribute to stability: Rotator cuff muscles *Supscapularis *Supraspinatus *Infraspinatus *Teres minor – Making bunle around the shoulder joint – To keep it fix or stabilize – As dynamic stabilisers, these muscles surround the shoulder joint, attaching to the tubercles of the humerus, whilst also using with the joint capsule. – The resting tone of these muscles act to compress the humeralhead into the glenoidcavity. Factors that contribute to stability: Glenoid labrum: – This is a fibrocartilaginous ridge surrounding the glenoid cavity. – It deepens the cavity and creates a seal(cap) with the head of humerus, reducing the risk of dislocation. Ligaments – The ligaments act to reinforce the joint capsule, and forms the coraco-acromialarch. – The most important factor is the inferior glenohumeral ligament which acts like a sling Biceps tendon – Another dynamic stabiliser, it acts as a humeral head depressor, thereby contributing to stability. – Through the bicipital groove with the perfect tranverse humeral ligament Dislocation of the ShoulderJoint Clinically, dislocations at the shoulder are described by **where thehumeral head lies in relation to the infraglenoid tubercle. Anterior dislocations are the most prevalent (95%), although posterior (4%) and inferior (1%) dislocations can sometimes occur. Superior movement of the humeral head is prevented bythe coraco-acromial arch.  An anterior dislocation is usually caused by excessive extension and lateral rotation of the humerus. The humeral head is forced anteriorly and inferiorly – into the weakest part of the jointcapsule. Tearing of the joint capsule is associated with an increased risk of future dislocations. Hill-Sachs lesion (compression fracture of posterolateral humeral head against anteroinferior glenoid) edge damages the head during the time and Bankart fracture (detachment of antero-inferior labrum) *can also occur following anterior dislocation. rim:jant:labrum ' Anything pathologically come front of us that rather than normal it is named LESION. Explain that some different than normal, anatomical, physiological etc. situation. **What we talked about Hill-Sacs Lesion is actually a necrosis. Because the necrotic part of the head of the humerus gets smaller and smaller so there is actually a cave inside. **Bankart lesion is the tear down of the glenoid labrum. If the labrum comes of or goes back due to the impact of power then we can talk about this lesion. Hill-Sacs; Necrotic lesion of the bone Bankart; Fracture of labrum So these are 5 of them ; TERMINAL BRANCHES OF BRACHIAL PLEXUS -Musculocutenous Nerve -Axillary Nerve -Radial Nerve -Median Nerve -Ulnar Nerve *Axillary nerve having a very close proximity to capsule *Innervates the deltoid muscle *Anterior dislocation can damage that nerve at different level  The axillary nerve runs in close proximity to the shoulder joint and around the surgical neck of the humerus, and so it can be damaged in the dislocation or with attempted reduction. Injury to the axillary nerve causes; **paralysis of the deltoid, ** loss of sensation over regimental badgearea. A dislocation can also stretch the radial nerve, as it is tightly bound in the radial groove. SO WE CAN TALK THE DAMAGE OF; AXIAL NERVE RADIAL NERVE while the dislocation of glenohumeral joint. Keep in mind ; teres minor any deltoid muscle is innervated by the same nerve which is - AXILLARY NERVE – Q) Which nerve is most likely to have been damaged and why? -Axillary nerve due to the anterior dislocation.