Identify and clean the deltoid muscle. (G 2.38A;N 409;Gl 25.21A)
- Define the posterior border of the deltoid muscle. This is often a difficult task because the deep fascia of the deltoid fuses with the deep fascia of the infraspinatus muscle. Dangle the cadaver's arm over the edge of the humidor. This often straightens out the muscles and allows you to more easily separate the deltoid, infraspinatus, teres major and triceps (long head) muscles. Use scissors to separate the posterior border of the deltoid from the infraspinatus fascia.
- With a scalpel,cut the deltoid muscle where it attaches to the spine and acromion of the scapula. Reflect (still attached to the clavicle and humerus) the deltoid in the anterior direction. Observe the neurovascular bundle entering the deltoid muscle. (G 2.41;N 413;Gl 28.30B) Identify and clean (you may remove any accompanying veins) the axillary nerve and the posterior circumflex humeral artery.
Important Relationships
- The axillary nerve passes lateral to the long head of the triceps muscle (traverses the quadrangular space).
- The axillary nerve passes directly posterior to the humerus (surgical neck).
- The posterior circumflex humeral artery passes directly medial and posterior to the humerus (surgical neck).
- The posterior circumflex humeral artery passes lateral to the long head of the triceps muscle (traverses the quadrangular space).
