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PT 5131 (30)
L Day (25)

Shoulder Joint.docx

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Northeastern University
Physical Therapy
PT 5131
L Day

Shoulder Joint Joints of Shoulder • Scapulothoracic Joint: sits between Scapula and Thorax o Not a true joint because there is not capsule, connective tissue, or cartilage that connects these joints together • Sternoclavicular Joint: located between Manubrium of Sternum and Clavicle • Acromioclavicular Joint: located between Acromion of Scapula and Clavicle • Glenohumeral Joint: between Glenoid Fossa and Head of Humerus Anatomical Orientation of the Shoulder Complex • Clavicle: angled posteriorly about 20° from Frontal Plane • Scapula: sits anterior about 35° from Frontal Plane o Sits in Scapular Plane  Abduction and Adduction in this plane called Scaption • Humerus: Humeral Head rotated 30° posterior to Medial-Lateral Axis Line o Humeral Head is Retroverted Sternoclavicular Joint • Sits between medial portion of Clavicle and Clavicular notch on Manubrium • Saddle Joint o Clavicle is Convex longitudinally (up and down) and Concave transversely (anterior to posterior)  These convex and concave facets are reciprocated on the Manubrium, thus a saddle joint • Articular Disk: between Saddle Joint o Divides joint into 2 cavities o Attaches inferiorly to Manubrium and superiorly to clavicle  Anterior and posterior edges attached to joint capsule o Reinforces joint and increases congruity of joint o Absorbs Shock, especially Fall On Outstretched Hand (FOOSH) o Dislocation and arthritis rare • Fibrous Capsule: runs from Manubrium up to Clavicle • Movements of Clavicle o Elevation/Depression o Protraction/Retraction o Posterior Rotation Sternoclavicular Joint Ligaments • Anterior and Posterior Sternoclavicular (SC) Ligaments o Runs on anterior and posterior surface of joint o Blended with capsule (runs in between Sternum and Clavicle o Prevents:  Clavicle from being pulled laterally (out of socket)  Anterior and posterior displacement  Too much depression of shoulder girdle • Costoclavicular Ligament o Ties Costal Cartilage and 1 Rib to Clavicle o Rhomboid and flat shaped o Prevents:  Clavicle Elevation  Anterior/Posterior Translation of Clavicle • Interclavicular Ligament o Connects 2 clavicles o Runs along top part of Manubrium o Prevents:  Separation and Upward Pull of medial end of Clavicle • This can occur during excessive depression of pectoral girdle Acromioclavicular Joint • Plane joint o Acromial Facet: faces laterally and inferiorly  Clavicular Facet o Facet on Acromion: faces medial and superiorly  Scapular Facet • Loose capsule strengthened by Deltoid and Trapezius • Blood Supply o Acromial Rete: network of vessels  Anastomosis of Acromial Branch of Thoracoacromial Artery, Posterior Circumflex Humeral Artery, and Suprascapular Artery • Movement of joint is subtle o Some Horizontal and Sagittal plane adjustments occur  Allow for a little upwards/downward rotation and some gliding Acromioclavicular (AC) Joint Ligaments • Acromioclavicular Ligament: sits on top and underneath AC joint o Prevents separation of Clavicle from Scapula  Would occur during AC Joint separation • Coracoclavicular Ligament: o Main supportive ligament of AC Joint o Helps to ensure Clavicle and Scapula stay together o Help suspend Scapula from Clavicle o Prevent backward and inferior movement of Scapula o 2 Parts  Conoid Ligament: runs from Base of Coracoid Process to Conoid Tubercle on Clavicle • Cone shaped • More medial of 2 ligaments • Vertical fibers • Prevents: o Superior movement of Clavicle o Inferior movement of Scapula  Trapezoid: runs from Base of Coracoid Process to Trapezoid Line on Clavicle • More lateral of 2 ligaments • Fibers angled more horizontally • Prevents: o Medial movement of Scapula Scapulothoracic Joint • Not a true joint o No joint capsule, connective tissue, or cartilage o Since Scapula moves on Thorax, we talk about it like a joint • In order for arm to move above head, Scapula needs to move on Thorax • Motions work with SC and AC Joints • Located o Between ribs 2-7 o Medial border 2.5 inches from Spine Scapula Movement Refresher • Motions at SC Joint directly relate to motions of Scapula due to Clavicle and lack of significant motion in AC Joint Glenohumeral Joint Glenohumeral (GH) Joint • Ball in Socket Joint o Convex Humeral Head in Concave Glenoid Fossa o Humeral Head is 30° Retroverted and sits pointing more superiorly o Glenoid Fossa faces anteriorly and superiorly o Longitudinal diameter of Head of Humerus is 1.9x larger than Glenoid Fossa o Transverse diameter of Head of Humerus is 2.3x larger than Glenoid Fossa o Head of Humerus does not fully sit in Glenoid Fossa  Glenoid covers about 1/4 to 1/3 of Head of Humerus • Glenoid Labrum: fibrocartilaginous lip that runs around Glenoid Rib o Triangular shape o Helps to deepen socket by about 50%, adding stability o Enlarges contact area by about 75% o Long head of Biceps Tendon attaches onto Glenoid Labrum at most superior portion of labrum • Low stability, high mobility joint 4 Things Giving GH Joint Stability • Ligaments and Capsule o Capsular structures pull head of Humerus into Socket (passive stability) • Muscle o Rotator cuff muscles provide dynamic stability • Intra-Articular Pressure o Negative pressure exists due to slight suction of surrounding capsule o Can be disrupted after surgery or dislocations • Osteology o Scapula and Glenoid Fossa slightly Upwardly Rot
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