Shoulder Movement Quiz and Flashcards

What contributes to increasing the mobility of the shoulder?

Without scapula movement, how much shoulder elevation would the glenohumeral joint achieve?

What acts like a fulcrum for the clavicle during arm elevation?

Which joint shifts as the axis of motion above 90° during arm elevation?

What is the timing of movement between the GHJt and scapula referred to as?

Which structure allows room in the subacromial space for soft tissue structures?

What is the main role of both upper and lower trapezius in scapula movement?

When does the action of the lower trapezius change from a scapular depressor to upward rotator?

Which muscles form a force couple with the upper and lower trapezius to assist upward rotation of the shoulder?

What is a common observation associated with scapular dyskinesis during shoulder movements?

What is defined as dysrhythmia in the context of scapula movement?

What might contribute to scapular dyskinesis, causing the scapula to rest/move in an anteriorly tilted position?

Shoulder Mobility and Joint Mechanics

Increased shoulder mobility is influenced by joint capsule flexibility, ligaments, muscles, and neuromuscular control.
Without scapula movement, the glenohumeral joint can achieve approximately 30 degrees of shoulder elevation.
The acromioclavicular joint acts as a fulcrum for the clavicle during arm elevation.

Joint Dynamics

Above 90° of arm elevation, the scapulothoracic joint shifts as the primary axis of motion.
The timing of movement between the glenohumeral joint (GHJ) and scapula is referred to as scapulohumeral rhythm.

Subacromial Space and Muscle Function

The subacromial bursa allows for increased space in the subacromial area, accommodating soft tissue structures during shoulder movements.
Both the upper and lower trapezius muscles play crucial roles in scapula movement, particularly stabilizing and positioning the scapula.

Muscle Action and Force Couples

The action of the lower trapezius changes from a scapular depressor to an upward rotator when the arm is elevated above 90 degrees.
The serratus anterior, along with the upper and lower trapezius, forms a force couple to facilitate upward rotation of the shoulder.

Observations and Dyskinesis

Common observations associated with scapular dyskinesis include abnormal scapular motion, winging, and asymmetry during shoulder movements.
Dysrhythmia in scapula movement is characterized by the lack of synchronous movement between the scapula and the humerus.
Factors contributing to scapular dyskinesis may include poor posture, muscular imbalances, and tightness leading to an anteriorly tilted scapula.

Learn about the important role of the scapula in shoulder movement. Understand how scapula movement contributes to increasing mobility and maintaining muscle length tension relationships in the shoulder. Discover how the scapula allows room for soft tissue structures in the subacromial space.