After you learn all that you can about a part of the body, it will add to your knowledge if you can then relate your information to clincial problems. Throughout your study of Human Anatomy, you should always keep in mind how you will use this knowledge and for most, that will be in diagnosing problems of clinical concern.
One of the things you should be able to do is to palpate arteries in order to check to see if the heart is still beating or not. There are several places in the upper limb that the arteries can be felt:
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The hand is such an important part of the upper limb that we will present its anastomoses. It is rather simple -- there are two palmar arterial arches that are interconnected:
The function of these communications can be checked easily: If you compress the the radial artery at the wrist, then make a tight fist and release the fist, the hand will be white at first but then return to a pink color in seconds if the ulnar artery is intact. On the other hand, if you compress the ulnar artery just lateral to the pisiform bone, make a tight fist and release, the hand will again be white and then turn pink in seconds if the radial artery is intact. If the hand remains white, the opposite artery is not open or does not form a functional anastomosis with the arches. (This is called the Allen test) |
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Superficial veins are probably used more in a clinical situation that any other part of the body. They are used for venipuncture, transfusion, and catheterization. It important to be able to identify the location of the major available veins in the upper limb. In an emergency situation, a patient may arrive in shock, in which case, the veins are usually totally collapsed. It might be up to you to find a vein to get into even if you have to perform a cut down. These are the veins that you should be able to locate or see:
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Sometimes, when the superficial veins have collapsed, and you have to transfuse, you must perform what is known as a cutdown. In the upper limb, the best place to perform this is at the wrist, either laterally in the cephalic vein (1) or medially in the cephalic vein (2) as they arise from the dorsal venous arch. |
The cephalic (1) and basilic (2) veins start from the dorsal venous plexus on the back of the hand.
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Lymph drainage of the upper limb usually follows the cephalic or basilic veins. The thumb, index finger and lateral part of palm usually drains along the path of the cephalic vein and empties into the infraclavicular group of lymph nodes of the axillary group. Lymph drainage from the little finger and ring finger and medial palm travels through vessels along the basilic vein and is first filtered by the supratrochlear node just above the medial epicondyle of the humerus. From this node, the lymph reaches the lateral group of axillary lymph nodes where is again filtered. Therefore, if, during a physical examination, you feel an enlarged node just above the medial epicondyle of the humerus, you should suspect some sort of infection in the medial part of the hand. Usually when there is lymphadenitis the lymph vessels draining the area are appear as reddened streaks. |
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A very important structure that should be examined is the mammary gland. Early detection of changes in this structure is of prime importance in cases of malignancy. A knowledge of the lymph drainage of the mammary gland can help as part of the diagnosis of mammary disease. For the purpose of discussing the lymph drainage, the gland is subdivided into 4 quadrants (2 medial, 2 lateral). The lymph drainage of the mammary gland is:
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Upper Lesions of the Brachial Plexus
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Lower brachial plexus lesion
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Long Thoracic Nerve Lesion
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Radial Nerve InjuryIf the radial nerve is injured, the final results will depend on where along its path it is injured. The most complete injury is one that occurs in the axilla. The radial nerve may be injured in the axilla as a result of poor positioning of a crutch, shoulder dislocation or fractures of the upper part of the humerus. This high injury results in paralysis of the triceps, anconeus and the long extensors of the wrist. The patient is unable to extend the elbow joint, the wrist joint and the fingers. One appearance of the limb when it is raised, is "wrist drop". This is a very disabling injury, since a person can't flex the fingers strongly for gripping an object. Even though the brachioradialis and supinator muscles are paralyzed, supination can still be performed. Do you know by which muscle this is done? |
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The radial nerve may be injured as it passes along the spiral groove of the humerus following factures of the humerus. The nerve has also been known to be injured due to prolonged pressure of the back of the arm on the edge of an operating table. The branches to the triceps are spared in this injury so that extension of the elbow is possible. The long extensors of the forearm are paralyzed and this will result in a "wrist drop". There is a small loss of sensation over the dorsal surface of the hand and the dorsla sufaces of the roots of the lateral three fingers. |
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Ulnar Nerve LesionThe ulnar nerve is a branch of the medial cord of the brachial plexus from C8 and T1 segments of the spinal cord. It passes into the anterior compartment of the forearm after passing behind the medial epicondyle of the humerus. It is at this site that the nerve can be injured following fractures of the medial epicondyle. The muscles paralyzed are the flexor carpi ulnaris, medial half of the flexor digitorum profundus, medial two lumbricals, all interossei and the adductor pollicis. The appearance of the hand is indicative of the muscles involved. The thumb is abducted and extended with the distal phalanx flexed. The first two fingers are fully extended with a slight flexion of the distal phalanges. The medial two fingers are hyperextended at the metacarpophalangeal joints but flexed at the distal phalangeal joints. The hand resembles a "claw" and is called a claw hand. |
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This is copyrighted© 1999 by Wesley Norman, PhD, DSc |