3. Scapulohumeral rhythm Using the following procedures determine the range of m

Question

3. Scapulohumeral rhythm Using the following procedures determine the range of motion in the shoulder of the movements listed, first with the scapula fixed and then with the scapula unrestricted. For a fixed scapula in contact with both the acromion process and the heel of the hand is on the scapular place one hand across the shoulder of the subject in such a way that the little finger is scapular motion. When the scapula does begin to move instruct the subject to stop shoulder joint motion hold the position for measurement. spine. Allow no For the free scapula apply no restriction. To measure the range of motion for shoulder flexion and hyperextension place the axis of the goniometer over the greater tubercle of the humerus on the lateral aspect of the shoulder joint. Hold the fixed arm of the goniometer in a position parallel to the midline of the trunk. The free arm of the goniometer should be aligned with the lateral epicondyle of the humerus for measurement. To measure shoulder abduction place the axis of the goniometer at a center on the posterior aspect of the shoulder. Hold the fixed arm of the goniometer in a position parallel to the midline of the trunk. The free arm of the goniometer should be aligned with the lateral epicondyle of the humerus for measurement. point which approximates joint Record the total degrees of motion measured under each condition. (hes oue mo t) Fixed scapula Free scapula Flexion Hyperextension Abduction hyperextension? How much difference is there between the two conditions for flexion? Abduction? Explain why (anatomically) such differences exist.

Explanation / Answer

ANSWER:

There is a difference of 40-50 degrees in flexion ,

15 degrees in hyperextension,

50-60 degrees in abduction.

The shoulder joint is a complex joint formed by

1.Gleno-humeral joint

2.Scapulo-thoracic joint

3.Acromio-clavicular joint

4.Sterno-clavicular joint

Inorder to maintain the normal range of motion of the shoulder joint the above four joints should work in a rhythm either in closed or open kinematic chain and also all the four joints should maintain the normal range of motion for the shoulder kinematics so as to swing the upperlimb in the air to carry forward its functions.

The range of motion varies from person to person depending on their

1.Hypermobility of the joints

2.Body mass(obese and lean)

In the above condition the shoulder joint maintains its normal ROM(range of motion) as it does not have any obstructions.

But when we fix the scapula, the muscles which arise from the scapula are restricting the shoulder movement to complete the normal range. And also due to the bony end feel restriction of the scapula which glides over the thorax vertically and horizontally restricts the normal shoulder joint range of motion.

The scapula glides smoothly on the thorax and is inclined to 30 degrees in the frontal plane and is paralled to the spine,It plays an important role in the shoulder kinematics,and when the scapula is fixed, the shoulder cannot complete its full range of motion due its muscular restrictions and bony restrictions.And also the glenoid labrum cannot glide inferiorly , superiorly when the scapula is fixed.

SHOULDER MOVEMENT FIXED SCAPULA FREE SCAPULA FLEXION 130-140 degrees 180 degrees HYPEREXTENSION 30 degrees 35-40 degrees ABDUCTION 120 - 130 degrees 180 degrees

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