The internal rotation in mentoposterior position is :
**Question:** The internal rotation in mentoposterior position is:
A. The rotation of the humerus towards the axilla
B. The rotation of the humerus towards the lateral side
C. The rotation of the humerus towards the medial side
D. The rotation of the humerus towards the anterior direction
**Core Concept:** Internal rotation is a movement where the limb is turned inward, while mentoposterior position refers to the examination position where the patient is lying on their back with their shoulder in internal rotation. In this position, the humeral head is pushed posteriorly while the arm is internally rotated, placing the humeral head on the posterior aspect of the glenoid fossa.
**Why the Correct Answer is Right:** The correct answer is C. The rotation of the humerus towards the medial side. This is because the mentoposterior position involves internal rotation, and the correct direction of internal rotation in the context of the shoulder joint is towards the medial side. In this position, the humeral head is pushed posteriorly, and the humerus rotates internally, ending up with the humeral head on the posterior aspect of the glenoid fossa.
**Why Each Wrong Option is Incorrect:**
A. The rotation of the humerus towards the axilla is incorrect because the axilla is the bony structure connecting the scapula to the humerus, not a direction of rotation.
B. The rotation of the humerus towards the lateral side is incorrect as this direction does not align with the mentoposterior position's internal rotation.
D. The rotation of the humerus towards the anterior direction is incorrect, as this direction does not match the mentoposterous position's internal rotation.
**Clinical Pearl:** Understanding internal and external rotations of the shoulder joint is essential for accurate examination and diagnosis of shoulder pathologies. The mentoposterous position allows for efficient internal rotation assessment and helps differentiate between various shoulder joint pathologies based on the direction of rotation and the position of the humeral head.