SHOULDER AND PECTORAL REGIONS
The scapular and pectoral regions form the attachments of the upper limb to the axial skeleton. The only traditional articulation for the upper limbs is between the clavicle and the manubrium of the sternum. For this reason, forces exerted on the upper limb are sent through the clavicle, leaving the clavicle especially susceptible to fractures, usually from falls in which an individual extends their arm to brace themselves.
During dissection of this region, particularly of the suprascapular region, be aware of the smaller nerves and arteries that supply the structures in this area, especially the suprascapular artery and nerve. This is where your palpation skills will assist in your dissection, as you will likely be able to palpate the bony suprascapular notch before dissecting the neurovasculature of this small area. Palpating in this way will help you identify the location of this neurovasculature before you can see it and thus help you preserve those structures during dissection. As the structures will likely not be initially visible, this is where blunt dissection will be necessary to accentuate natural borders between the fascia and the neurovasculature in the suprascapular notch. Likewise, the muscles form a number of important spaces through which other neurovascular structures need to be observed, and blunt dissection will be critical for these areas as well.
Still in the prone position, remove the skin and superficial fascia of the arms to the wrist in order to reveal the deltoid muscle and posterior arm compartment structures. Leave the superficial veins on one arm.
Now that you have identified the deltoid, reflect it laterally by removing its attachment to the scapular spine.
Identify the axillary nerve and posterior humeral circumflex artery on the deep surface of the deltoid muscle.
Identify the supraspinatus muscle and infraspinatus muscle on the scapula, attaching to the greater tubercle of the humerus.
Inferior to infraspinatus, identify teres minor muscle, which attaches to the lateral border of the scapula and the greater tuberosity of the humerus.
Identify teres major muscle attaching to the inferior angle of the scapula and the crest of the lesser tuberosity on the anterior surface of the humerus.
Identify long head and lateral head of triceps brachii muscle in the posterior compartment of the arm (Figure 2.1).
Posterior shoulder including scapular spaces.
The teres and triceps muscles form three spaces through which neurovascular structures travel, and these spaces can become impinged causing loss of sensation and motor control. Between the teres minor and teres major muscles, find the triangular space medial to the long head of the triceps brachii. Deep to this space courses the circumflex scapular artery. The quadrangular space, lateral to the long head, is the passage for the axillary nerve and posterior humeral circumflex artery. Finally, the triceps hiatus...