musculoskeletal

• greatest ROM in any joint in the body • the most unstable joint in the body large spherical head and small glenoid ‘golf ball on tee’

requires inter-relationships between: • humerus and scapula: humerus rotates about the scapula within the GH joint • scapula and clavicle: scapulae rotates about the clavicle at the AC joint • Clavicle and sternum: clavicle rotates around the sternum at the SC joint

• optimal positioning of all joints • ideal excursion/mobility of all joints • motor control of all joints

• provides GHJ stability and mobility • scapula is concave over ribs, dictating the scapular resting position • transfers loads from the upper limb to torso and vice versa -site of attachment b/w shoulder complex and thoracic/cervical spine

• elevation • depression • protraction • retraction

• sits b/w T2 and T7 • approx. 7cm from thoracic midline • slight upward rotation (3 degrees) • flat against thoracic cage

refers to the coordinated movement between the scapula (shoulder blade) and the humerus (upper arm bone) during shoulder (glenohumeral) elevation, such as when raising your arm overhead. It’s a biomechanical relationship that ensures efficient, pain-free arm movement.

serratus anterior lower traps upper traps

2:1 2 degrees come from GHJ 1 degree comes from scapulothoracic

• passive stabilizers • active stabilizers

• bony geometry • glenoid labrum -glenoid depth and orientation -vacuum effect -capsuloligamentous structures

The humeral head is large and spherical, while the glenoid fossa is relatively small and shallow. This mismatch allows for a wide range of motion but makes the GHJ inherently unstable.

A fibrocartilaginous rim attached around the edge of the glenoid fossa. Increases the depth of the glenoid cavity by ~50%, improving congruency, allowing for attatchments

The glenoid is angled slightly superiorly, anteriorly, and laterally — this “upward tilt” helps resist inferior displacement of the humeral head. Its shallow depth allows mobility, but even minor changes in orientation can influence stability (e.g., in dysplasia or injury).

Negative intra-articular pressure creates a suction force that holds the humeral head against the glenoid.

prevent HH translation superior GHJ middle GHJ inferior GHJ

• supports the dependent arm • resists inferior subluxation of GH -becomes taut in ER

• resists inferior subluxation • extends to HOH lesser tuberosity

• absent or poorly defined in 30% of shoulders • resistance to anterior humeral displacement

• maintains ant and inf stability • helps form inferior sling

• oxford shoulder score -Disabilities of the shoulder, arm and hand (DASH) • shoulder pain and disability index

• weakness • stiffness • instability

area: single or multi joint function: functional limitations, pain and pt distress pain: 24/7 medical hx: diabetes, arthritis, cancer treatment, family history

single or multi joint movement function: functional limitations (popping, feeling loose, popping out), positional (cocking position) Mx: hypermobility