Shoulder Complex Anatomy and Physiology

A set of vocabulary flashcards covering the topographical anatomy, bony landmarks, joint mechanics, and neurovascular structures of the shoulder complex.

Shoulder Girdle (Pectoral Girdle)

Comprised of the Scapula, Clavicle, and Humerus, providing mobility and stability for the upper extremity (UE).

Scapulothoracic (S-T) Joint

The articulation of the scapula and thorax; not a true anatomic joint, with movements linked to the SC and AC joints.

Normal Range for Upward Rotation

The normal range for upward rotation of the scapula is $60^{\circ}$.

Scapulohumeral Rhythm

The coordinated movement of the glenohumeral (GH) joint and the scapulothoracic (ST) joint, typically maintaining a $2:1$ ratio ($120^{\circ}$ of GH motion to $60^{\circ}$ of ST motion).

Lateral Tilt (Winged Scapula)

Movement of the medial border of the scapula away from the thorax.

Upward Tilt (Tipping)

Movement of the inferior angle of the scapula away from the thorax.

Clavicular Fracture Location

Most common at the middle $1/3$ of the shaft of the clavicle, accounting for $70-80\%$ of injuries.

Sternoclavicular (SC) Joint

A synovial saddle joint where the convex and concave joint surfaces allow for elevation/depression and protraction/retraction.

Coracoclavicular Ligament

Connects the clavicle and coracoid process to prevent superior displacement of the clavicle; composed of the Trapezoid (lateral) and Conoid (medial) ligaments.

Type III Acromion

A specific acromial shape that makes individuals more prone to primary impingement syndrome.

Surgical Neck of the Humerus

The area below the head and tubercles that is a frequent site for fractures, putting nerves and circumflex arteries at risk.

Angle of Inclination

An anatomical angle of the humerus measuring $45^{\circ}$.

Angle of Torsion

An anatomical angle of the humerus measuring between $30^{\circ}$ and $40^{\circ}$.

Glenohumeral (GH) Ligaments

Consist of the Superior (SGHL), Middle (MGHL), and Inferior (IGHL) ligaments which support and stabilize the joint.

Subacromial Bursa

A bursa that separates the supraspinatus tendon and the head of the humerus from the acromion process.

Axilla Anterior Wall

The wall formed by the pectoral muscles.

Axilla Posterior Wall

The wall formed by the scapula, subscapularis muscle, latissimus dorsi, and teres major.

Brachial Plexus Roots

The anterior rami of $C5-T1$ nerve roots, with occasional contributions from $C4$ and $T2$.

Brachial Plexus Trunks

Formed by the union of roots: $C5$ and $C6$ form the Upper trunk, $C7$ forms the Middle trunk, and $C8$ and $T1$ form the Lower trunk.

Erb-Duchenne Paralysis

Injury to the upper elements of the plexus ($C5, C6$), causing the arm to hang adducted and medially rotated with the forearm extended and pronated.