Why is humeral glenoid internal rotation (HGIR) often limited on both sides with a superior T4 syndrome?
Without reviewing all the respiratory issues associated with a Superior T4 syndrome, one will usually find limitation with left apical expansion of the upper quadrant on the left side, when a PRI Apical Expansion Test is performed to assess left thoracic expansion as the right ZOA is manually maintained. If the top left 3 ribs are in a state of internal rotation and cannot externally rotate, more than likely, left upper thoracic expansion will be more limited than the right, because of the corresponding external rotation of the upper 3 ribs on the right. This is commonly seen after a left ZOA is achieved and overall right apical and medial mediastinum expansion has increased.
The upper spine remains oriented to the right in a Superior T4 state, even if a manual or a non-manual technique improved right apical and lateral chest wall flexibility and expansion. The lower ribs on the left are no longer in a state of external rotation and the lower ribs on the right are not in a state of internal rotation after repositioning. The upper 2 to 3 ribs on the left may remain in a state of obligatory internal rotation, because of the continued effort of the right scalenes, upper trapezius and subclavicular muscle to externally rotate the top right 2 to 3 ribs for assisted expansion on the right upon inhalation. This rib rotation position of the upper right ribs assists with “pulling” air in on the right side, since the middle and lower mediastinum and chest wall cannot expand efficiently, secondary to the chronic compensatory movement of these right upper rib elevators and shortness of the soft tissue that keeps these ribs externally rotated toward the right clavicle. This chronic compensatory state of the upper ribs has occurred on the same chronic compensatory pattern of the leftward thorax rotation provided by the musculature that is rotating the left lower ribs externally and right lower ribs internally. After reestablishing spinal neutrality or a neutral positioned spine below T4, compensatory activity is no longer needed from the aforementioned right upper rib external rotators. Since these overactive accessory muscles of respiration become shortened over time in their compensatory effort to offset this leftward thoracic rotation, reciprocal rotation of these upper ribs is lost, and manual activity to reduce this soft tissue shortness, especially below the clavicle, is required for alternating upper quadrant (apical compression and decompression) function to occur. In summary the upper 3 or 4 vertebral bodies remain oriented or rotated to the right because of the above non-universal hemi-rib directional influences on the spine. Keep in mind the overall neutrality of the lower vertebral bodies is not capable of offsetting the direction of the spine to the right because of the upper ribs influence on upper spinal orientation from the visual, vestibular or occlusal systems or direct rotation to the right from the upper thoracic mechanical rib direction. Thus, overall the upper spine remains ‘oriented’ to the right in a Superior T4 state.
Since spinal orientation to the right existed below T12 and above T4, before repositioning effort of the spine and diaphragm, right ‘orientation’ of the spine above T4 may remain after repositioning effort on those with Superior T4 syndrome tendencies. Reestablishment of internal rotation of the upper top ribs on the right will allow the left ribs to all work in unison and into neutral or external rotation. This is necessary for proper thoracic on scapular movement and scapular on thoracic movement to occur on either side of the thorax. If horizontal abduction of the right upper extremity also does not occur, because of pec major and minor, subscapularis, and latissimus dorsum soft tissue restriction, upper right spinal orientation would also continue to directly challenge the right gleno-humeral joint kinematics and indirectly the left gleno-humeral joint kinematics.
These brachial chain limitations are described and outlined on page 42 of the Postural Respiration manual. For the most part the positions of the left and right scapulas remain the same as if they were lying on a non-Superior T4 state. However, in addition to the over action of the latissimus and the pectoralis major on the left, the teres major and the infraspinatus become hyperactive and shortened over time in attempting to externally rotate a humeral bone that lies in glenoid that also has the top 3 ribs internally positioned. External rotation is more than likely limited on the left side because of latissimus activity as previously stated, but internal rotation could also be limited because of the compensatory activity of the short humeral external rotators, that were also previously mentioned, and the kinematic discord at the gleno-humeral joint because of the unstable scapula state. The left gleno-humeral joint kinematics are altered because of the posterior superior shift of the humeral head in the glenoid. The left humeral head could be impacted by the anterior inferior glenoid, upon internal rotation of the humerus, when there is a posterior superior shift of the humeral head. The anterior capsule is often over stretched or lengthened secondary to the ongoing attempt to horizontally abduct on a scapula that is elevated and adducted upwardly, not downwardly as you would find more typical in the non-Superior T4 state. These events contribute to the humeral glenoid instability so often seen on the left side of a person with a right Superior T4 Syndrome.