- See: Rotator cuff:
- Anatomy:
- origin: entire anterior surface of the subscapularis fossa;
- insertion: lesser tuberosity of humerus and capsule of shoulder joint;
- The Subscapularis Footprint: An Anatomic Description of Its Insertion Site.
- action:
- main action: glenohumeral head depressor;
- in certain positions allows extension, adduction and medial rotation of humerus at shoulder;
- stabilization of the glenohumeral joint;
- reversed origin insertion action:
- when humerus is stabilized, abducts inferior border of the scapula;
- synergists: teres major, pectoralis major, latissimus dorsi;
- nerve supply:
- upper & lower subscapular, C5, C6;
- subscapular nerve arises from posterior division of upper trunk, rather than from posterior cord and herefore contains
fibers only from C4-C6;
- in some pts (30%) subscapular nerve does arise from posterior cord;
- ref: Nerve supply of the subscapularis during anterior shoulder surgery: definition of a potential risk area
- exam:
- belly press:
- rotation w/o elbow dropping posterior to the midsagittal plane of the trunk indicates impaired subscapularis function;
- evaluates the upper subscapularis;
- if test is positive, then elbow will drop backwards;
- lift off:
- rotation with hand off the lumbar spine without extending the elbow;
- evaluates the lower subscapularis;
- references:
- The Influence of Shoulder Position on the Bear-Hug, Belly-Press, and Lift-Off Tests. An Electromyographic Study
- The bear-hug test: a new and sensitive test for diagnosing a subscapularis tear
- Considerations for Subscapularis Repair:
- biceps tendon management
- references:
- Repair of tears of the subscapularis. (see surgical technique article)
- Stabilization of the long head of the biceps tendon in the context of early repair of traumatic subscapularis tendon tears.
- Pectoralis major tendon transfers above or underneath the conjoint tendon in subscapularis-deficient shoulders. An in vitro biomechanical analysis.
- Repair of Tears of the Subscapularis.
- Traumatic anterosuperior rotator cuff tears: the outcome of open surgical repair.
- Subscapularis tendon tear: an anatomic and clinical investigation.
- The frequency of subscapularis tears in arthroscopic rotator cuff repairs: A retrospective study comparing magnetic resonance imaging and arthroscopic findings.
- Subscapularis tendon tears: identifying mid to distal footprint disruptions
- Pectoralis Major Transfer:
- subcoracoid pectoralis major tendon transfer:
- may improve function and diminish pain;
- subcoracoid position of the transfer allows redirection of the pectoralis major in a direction recreating the vector of the
subscapularis tendon;
- references:
- Transfer of pectoralis major for the treatment of irreparable tears of subscapularis: does it work?
- Outcome of pectoralis major transfer for the treatment of irreparable subscapularis tears.
- Pectoralis major transfer in the treatment of chronic subscapularis insufficiency
- Pectoralis major transfers above or underneath conjoint tendon in subscapularis-deficient shoulders.
- Transfer of segmentally split pectoralis major for the treatment of irreparable rupture of the subscapularis tendon
- Anatomic evaluation of the subcoracoid pectoralis major transfer in human cadavers.
- Discussion: Surgical Dissection for Anterior Shoulder Reconstruction;
- w/ anterior dislocations the subscapularis is displaced forward, which creates traction injury to the axillary nerve;
- nerve is tethered above by brachial plexus & below where it wraps around behind neck of humerus;
- during anterior shoulder reconstruction, the axillary nerve may be identified by passing a digit along anterior surface of
subscapularis until the nerve is encountered at lower margin of subscapularis as the nerve passes inferior to articular
capsule on its way to quadrangular space;
- before an incision is made in subscapularis, the arm should be externally rotated to avoid damage to axillary nerve &
circumflex vessels
- ref: Nerve supply of the subscapularis during anterior shoulder surgery: definition of a potential risk area
Repair of recurrent anterior dislocation of the shoulder using transfer of the subscapularis tendon.
Operative treatment of irreparable rupture of the subscapularis.