Question

what ligament is mainly responsible for the rotation of the clavicle during full arm abduction?
a) glenohumeral ligaments
b) acromioclavicular ligament
c) trapezoid ligament
d) conoid ligament

Explanation:

• Glenohumeral ligaments: These ligaments are related to the glenohumeral joint (shoulder joint between the glenoid cavity and humerus), not directly to clavicle rotation.
• Acromioclavicular ligament: This ligament connects the acromion (of the scapula) to the clavicle. While it is part of the acromioclavicular joint complex, its main role is more in providing stability to the acromioclavicular joint rather than being the main ligament for clavicle rotation during full - arm abduction.
• Trapezoid ligament: Along with the conoid ligament, it is part of the coracoclavicular ligament complex. The trapezoid ligament specifically resists anterior and inferior displacement of the clavicle relative to the coracoid process and also plays a role in clavicle rotation during arm abduction.
• Conoid ligament: Part of the coracoclavicular ligament complex. Its main role is more in resisting posterior and superior displacement of the clavicle relative to the coracoid process compared to the trapezoid ligament's role in rotation during abduction.

Answer:

c) Trapezoid ligament