7. Reflect trapezius, identify its blood and nerve supply, and locate the greater occipital nerve.
In order to visualize the neurovascular elements that supply the muscles, it is necessary to reflect the muscles towards their insertions. For the trapezius, make an incision at its origin along the spines of the thoracic vertebrae. Deep to the trapezius muscle is a thin layer of connective tissue that contains the muscles' vessel and nerve supply. Dissect within this plane in order to reflect the muscle. Use blunt dissection as you work your way up the trapezius. As you reflect the trapezius, note the vessel that passes between the underlying rhomboid muscles. This is the muscular perforating branch of the dorsal scapular artery. You may sever this branch in order to continue reflecting the trapezius. As you approach the spine of the scapula, you will need to reflect the trapezius from the spine. Use blunt dissection to separate the trapezius muscle from the underlying tissue. Then use the scalpel to cut the muscle away from the spine of the scapula. Cut with the scalpel blade facing outward so as not to cut any underlying tissue. Trapezius muscle. Once this muscle has been reflected along the spine of the scapula, up to the acromion process, continue reflecting along the midline, superiorly. Dissect carefully in this area. As you continue superiorly, the trapezius muscle becomes thin and it may be difficult to separate it from the underlying muscles. Dissect carefully. Once the trapezius is completely reflected along the midline, hold it back toward the scapula. In the angle of the neck in the scapula, there is a considerable amount of fat. Within the fat, lie the subtrapezial plexus of nerves and branches of the transverse cervical artery, the nerve and blood supply the trapezius. The greater occipital nerve is a cutaneous nerve that supplies the back of the head and the occipital region. Under the trapezius, find it using blunt dissection in an area about an inch below and inch lateral to the external occipital protuberance. It is one of the largest cutaneous nerves in the back and is usually a couple of millimeters in breadth. Here is the greater occipital nerve.