Laboratory Dissection
The Pectoral Region

Upon completion of this session, the student will be able to:

1. Be familiar with the surface and bony anatomy of the pectoral girdle.
2. Identify the muscles of the pectoral region, their related fascia, nerve and regional blood supply.
3. Understand the movements and general functions of the muscles of the pectoral girdle.

Summary of Dissection Procedure

1. Remove the skin from the chest wall.
2. Remove the mammary gland and nipple in its entirety on each side. It will not be studied at this time.
3. Clean the cephalic vein and deltopectoral triangle.
4. Clean, identify and reflect the pectoralis major muscle and its blood and nerve supply.
5. Clean and identify the pectoralis minor muscle, identify its blood and nerve supply and clavipectoral fascia.
6. Identify the visible portion of the serratus anterior muscle.

Materials to be learned:

1. Surface anatomy      (Identify landmarks on both a living person and the cadaver)
(1) jugular notch
(2) sternal angle
(3) xiphisternal junction
(4) nipple
(5) axillary folds
(6) mid-clavicular line
(7) clavicle
(8) acromion
(9) coracoid process
(10) costal arch
(11) sternal line
(12) intercostal spaces
2. Osteology
Study the clavicle, which forms the ventral portion of the shoulder girdle. It is one of the most commonly fractured bones in the body.

The sternum or breast bone forms a portion of the ventral wall of the thorax. It consists of three parts: Manubrium, body and xiphoid process.

Determine the vertebral levels of the jugular notch, sternal angle, and xiphoid. The sternum articulates with the costal cartilages of ribs one to seven.

3. Muscles
            Study the origins, insertions, blood and nerve supply of the:
(1) pectoralis major
(2) pectoralis minor
(3) subclavius
(4) serratus anterior muscles.
Removal of the pectoralis major was common in radical mastectomies and post operative complaints of limited motion were common, explain why.
What is meant by a "winged scapula?"

4. Fascia
The superficial fascia surrounds the mammary gland will be studied with the reproductive system. The deep membranous fascia forms the clavipectoral fascia.
What structures pierce the clavipectoral fascia?

5. Blood vessels
1. pectoral branches from the thoracoacromial artery
From what vessel does the thoracoacromial artery arise?
2. perforating branches from the anterior intercostal arteries.

6. Nerves
The pectoral muscles are innervated by the medial and lateral pectoral nerves, which are derived from the medial and lateral cords of the brachial plexus.
What is the relationship of the medial pectoral nerve to the pectoralis minor muscle, the lateral pectoral nerve?