S1 Dissection Summary

Part 1

• • Prepare for the removal of skin and subcutaneous tissue from three areas of the anterior thorax.

  • Dissection of Area One:

    • Remove the skin and subcutaneous tissue from Area One. Work from the midline laterally. Once reflected, the superior portion of pectoralis major m. should be visible.

  • Dissection of Area Two:

    • Make an encircling cut around the nipple and areola down to, but not through pectoralis major m.,  and leave in situ for future reference. Remove the subcutaneous tissue to further expose the pectoralis major m.

  • Dissection of Area Three:

    • Remove the skin and subcutaneous tissue in Area Three. The external oblique m. and aponeurosis and the rectus sheath will be deep. A small portion of the serratus anterior m. should be visible laterally.

Part 2

• • Remove any remaining subcutaneous tissue and investing fascia from the pectoralis major mm. and the visible portion of the serratus anterior mm. Remove the investing fascia from the muscle via sharp dissection at right angles to the muscle fascicles. This will allow the visualization of basic features of a muscle: fiber directions and attachments (origins and insertions).

  • Observe attachments of pectoralis major mm. and serratus anterior mm. Identify long thoracic n. superficial to the serratus anterior m.

  • Locate the cephalic v. in the deltopectoral triangle. Keep this vein intact during reflection of the pectoralis major m.

Part 3

• • Reflect the pectoralis major mm. from their proximal attachments (clavicle and sternum/costal cartilages). Use blunt dissection to reflect the muscle laterally to protect the deep neurovasculature.

  • Bilaterally identify and clean the pectoralis minor m., lateral pectoral n., medial pectoral n., and branches of the thoraco-acromial a and v.

Part 4

• • Reflect the pectoralis minor mm. from their proximal attachments (3rd-5th ribs). Reflect the muscles superolateral (toward the coracoid process of the scapula). Locate any remaining clavipectoral fascia.

  • Observe pectoral branches of the thoraco-acromial a. and the medial pectoral n.

Part 5

• • The donor will need to be moved into a prone (face downward) position to dissect the superficial back.

Part 6

• • Make a midsagittal incision, beginning at the external occipital protuberance of the occipital bone and continuing inferiorly to the tip of the coccyx.

  • Create paired transverse incisions perpendicular to the length of the midsagittal incision. This should create “skin flaps” with subcutaneous tissue that are approximately 3-4 inches wide and extend laterally to either the posterior axillary, or the midaxillary lines.

  • Using toothed forceps or hemostats, lift the edge of skin at the corner of two incisions. Remove skin flaps and subcutaneous tissue to reveal the underlying muscle and thoracolumbar aponeurosis. The accessory nerve (CN XI) is superficial in the neck region. In the superior-most sections of this dissection, use sharp dissection to remove skin only. Blunt dissection should be used to clean and investigate areas deep to the skin.

Part 7

• • Clean and define the attachments and borders of the trapezius m. Locate the posterior layer of the thoracolumbar aponeurosis (fascia).

  • Reflect the trapezius m.

    • Incise along proximal attachments of the trapezius m. (spinous processes of the vertebrae and the ligamentum nuchae). Lift the trapezius m. off of the deep neck muscles.

    • Sever the scapular (distal) attachments of the trapezius m. (spine of the scapula and acromion); maintain the distal attachment to clavicle.

    • Reflect the trapezius m. toward the clavicle.

  • Locate and clean the neurovasculature associated with the trapezius m. Accessory n. (CN XI) is often difficult to locate. Try to find the nerve between the trapezius m. and sternocleidomastoid m.

Part 8

• • Clean and define the proximal attachments and borders of the latissimus dorsi mm.

  • Bilaterally reflect the latissimus dorsi mm. The incision of the latissimus dorsi mm. should separate the muscle fibers at the thoracolumbar aponeurosis, and reflect the belly of the muscle toward the axilla.

  • Identify thoracodorsal neurovasculature deep to the latissimus dorsi mm.

  • On each side, locate levator scapulae m., rhomboid minor m., and rhomboid major m. This musculature has distal attachments along the medial border of the scapula, sequentially from superior to inferior.