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Serratus Anterior

- Discussion:
    - serratus anterior arises from upper eight ribs, inserts on vertebral border of scapula, is innervated by long thoracic nerve, and
            functions to draw scapula forward in sports such as a jab in boxing;
    - paralysis produces characteristic prominence ("medial winging") of vertebral border of the
            scapula; (consider Parsonage Turner)
            - this is in contrast to paralysis of the trapezius which is associated w/ lateral winging;
    - origin:
            - superior lateral surfaces of upper 8 or 9 ribes at the side of chest;
            - arises from the upper 8 ribs, inserts on vertbral border of scapula;
    - insertion:
            - costal surface of vertebral border along inferior angle of scapula;
            - paralysis produces winging of the vertbral border of the scapula;
    - action:
            - functions to draw scapula forward;
            - abducts scapula and rotates it to point glenoid cavity superior;
            - stabilizes vertebral border of scapla to thoracic cage, along with  rhomboids  and middle trapezius;
    - nerve supply: long thoracic, C5, C6, C7;
    - vascular supply:
            - it is supplied by circumflex scapular artery, which emerges at lateral border of scapula and divides into cutaneous scapular &
                      periscapular arteries;
            - it has the advantage of a constant vascular pedicle and a well- hidden donor site, although the scar does spread;

- Management of Serratus Paralysis: (winging of scapula)
    - paralysis causes medial winging;
    - paralysis may be traumatic (sports, MVA ect..), atraumatic (post-infectious neuritits, allergic rxns), or
             iatrogenic (mastectomy, thoracotomy);
    - patients will note weakened forward flexion;
    - in most cases, serratus paralysis will resolve over 6 months;
    - diff dx:
           - paralysis of the trapezius may also cause winging of the scapula;
           - lung carcinoma
                   - Long thoracic neuropathy caused by an apical pulmonary tumor

    - on exam, manually fix the inferior scapula to the chest wall in about of 35 deg of rotation, and note effect on forward flexion;
           - slightly more or less rotation may improve forward flexion;
    - split pectoralis major transfer:
           - reconstruction for serratus anterior palsy is a two-incision, split pectoralis major transfer without fascial graft
           - references:
                  - Pectoralis major transfer for serratus anterior paralysis
                  - Results of Transfer of the Pectoralis Major Tendon to Treat Paralysis of the Serratus Anterior Muscle
                  - Split pectoralis major transfer for serratus anterior palsy.
    - spaculopexy: (from Vukov, et al. (1996))
           - if physical exam demonstrates that manual fixation of the scapula will improve forward flexion, then a loose spaculopexy
                     (opposition of the scapula to the chest wall) may improve function;
           - incision is made along the inferomedial border of the scapula;
           - the infero-medial border of the scapula is defined;
           - the scapula is oppose to the chest wall in the appropriate degree of rotation;
           - the nearest distal rib is cleared of soft tissue;
           - w/ appropriate retractors in place, a small drill hole is made in both the tip of the scapula and the adjacent rib;
           - a Vicry ribbon (or similar material) is then passed circumferentially around rib and thru then thru the holes in rib and scapula;
           - ref: Isolated Serratus Anterior Paralysis: A Simple Surgical Procedure to Reestablish Scapulo-humeral Dynamics.
- Serratus Anterior Flaps:
    - inferior three slips of serratus anterior may be used for free tissue transfer for coverage of dorsal & palmar defects in the hand;
    - there are three separate slips that are easily divisible for contouring;
    - this flap has low donor site morbidity;
    - free scapular fascial flap resurfaced with skin graft provides less bulk than cutaneous scapular flap

Winging Scapula.  Shoulderdoc.co.uk

Serratus anterior paralysis in the young athlete.

The serratus anterior free-muscle transplant for reconstruction of the injured hand: an analysis of the donor and recipient sites.