Dissector Answers - Overview/Organization of the Upper Limb
Upon completion of this session, the student will be able to:
- Identify and demonstrate the areas of distribution of the major cutaneous nerves of the upper limb.
- Identify and demonstrate the major superficial veins of the upper limb.
Learning Objectives and Explanations:
1. Identify and demonstrate the areas of distribution of the major cutaneous nerves of the upper limb. (N 429,430,431, 432, 433, 437a, 437b, 474,477, 478a, 478b, 479a, 479b, 480a, 480b, 481a, 481b, 482a, 482b), TG 2-02, 2-14, 2-51A, 2-51B, 2-52A, 2-52B)2. Identify and demonstrate the major superficial veins of the upper limb. (N 479a, 479b, 480a, 480b, 483), TG 2-02, 2-53)
Images from "Anatomy of the Human Body" by Henry Gray are provided by:The major cutaneous nerves of the upper limb:
- radial nerve:
- posterior brachial cutaneous nerve
- posterior antebrachial cutaneous nerve
- inferior lateral brachial cutaneous nerve
- musculocutaneous nerve (continues below the elbow as the lateral antebrachial cutaneous nerve)
- medial cord of the brachial plexus:
- medial brachial cutaneous nerve
- medial antebrachial cutaneous nerve
- Also remember that the ulnar and radial nerves both have superficial extensions which cover the dorsum of the hand, namely the dorsal cutaneous branch of the ulnar nerve and the superficial branch of radial nerve.
Arising from the dorsal venous network (arch) on the dorsum of the hand are the two most important superficial veins: the cephalic and basilic veins. The cephalic vein ascends along the lateral aspect of the forearm. (This side of your arm is considered "cephalic" because the limbs develop projecting laterally from the body, with the lateral side closest to the head. Or, you can remember that the cephalic side is on the side of your thumb, the digit you stick in your cephalic orifice (mouth) when you are a baby.) Upon completing its ascent, the cephalic vein crosses through the deltopectoral groove before diving deep through the fascia and joining the axillary vein. The basilic vein ascends on the medial aspect of forearm and pierces the deep fascia of the inferior arm. It ascends to unite with the paired brachial veins, forming the axillary vein. The cephalic and basilic veins are connected by the median cubital vein in the cubital fossa.
Questions and Answers:1. Identify the dorsal digital veins and intercapitular veins. What do these do?Dorsal digital veins drain the dorsal cutaneous aspect of the fingers. There are two per finger. Intercapitular veins are found between the knuckles (heads of the metacarpals). They drain the fingers and palm to the dorsal side of the hand. N 480a, 480b TG 2-022. Does the basilic vein perforate the brachial fascia in your cadaver? As you traced the basilic vein did you find accompanying nerves? What are these? TG 2-02The basilic vein normally perforates the brachial fascia above the medial epicondyle, or even as high as mid-arm. Distally near the hand, the vein is accompanied by the dorsal branch of the ulnar nerve. As the vein ascends it is accompanied by the anterior and posterior branches of the medial antebrachial cutaneous nerve.N 479a, 479b3. Where does the cephalic vein penetrate the deep fascia?As mentioned above, the cephalic vein penetrates the deep fascia after it has traversed the deltopectoral groove at the clavicle. N4244. Does the cephalic vein extend into the arm? TG 2-02Of course, though in some arms it may be very small. N479a, 479b, 480a, 480b5. What is the course and direction of the median cubital vein? Look at other arms to determine pattern. What are other variations?Median cubital vein shunts blood from cephalic vein obliquely across the cubital fossa to reach the basilic vein. There is often a median antebrachial vein lying on the anterior forearm that splits to drain to both cephalic and basilic veins at the cubital fossa.6. Trace the superficial branch of the radial nerve into the hand and identify its dorsal digital branches and their areas of distributions. Do any branches communicate with branches of the ulnar nerve?
The two nerves usually communicate on the dorsum of the hand. N 480a, 480b, 481a, 481b TG 2-02, 2-51A, 2-51B
Updated: 21 Oct 2011
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