Content

Definition

The use of mostly bony landmarks to identify the position of underlying anatomic structures.

What use is surface anatomy?

Nerves. A knowledge of the surface anatomy of nerves enables us to avoid injuring these structures with intramuscular injection. For instance we can avoid injury to the sciatic nerve by knowing that it emerges in the gluteal region at the mid point of a line joining hte ischial tuberosity and the greater trochanter. Injection given into the upper and outer quadrant of the buttock will avoid the sciatic nerve. Alternatively we need to know the position of nerves to enable them to be blocked by an injection of local anaesthetic, when employing regional anaesthesia.
Arteries. We need to know the position occupied by arteries in the limbs to determine whether or not pulses are present. For instance by knowing that the common femoral artery commences at the mid inguinal point (midway between a line joining the anterior superior iliac spine and the pubic symphysis) we can diagnose proximal arterial obstruction if there is no pulse at this point.

In penetrating injuries we need to know the position of underlying nerves and arteries to determine the likelihood of these being injured.
Veins. Tenderness over a deep vein is an important sign in patients with deep vein thrombosis. Eliciting valvular incompetence at the saphenofemoral junction is an important physical sign in the examination of a patient with varicose veins. The surface anatomy of the veins of the upper and lower limbs is also important in obtaining percutaneous venous access, such as a subclavian venous line.
Lymph glands. Knowledge of the position of limb glands in the upper and lower limbs is necessary to diagnose spread of infection or malignant neoplasm.
Tendons. Eliciting the presence or absence of tendon reflexes is an important part of physical examination of the nervous system.
Meniscus. Tenderness over the lateral or more commonly the medial meniscus (cartilage) is an important sign in trauma resulting in a torn cartilage
Bones. Bony landmarks are essential in determining the length of limbs. In the case of shortening of one limb relative to the contralateral side, the site of the shortening can be identified (below the knee, above the knee in the shart or neck of the femur).

Upper limb

Brachial artery
The surface marking of the brachial artery, with teh arm abducted to 90 degrees, is along a line from the middle of the clavicle, along the medial bicipital groove of the arm to a point medial to the biceps tendon in the cubital fossa, where it is readily palpable.

Radial artery
The surface marking of the radial artery is along a line slightly convex laterally from medial to the biceps tendon in the cubital fossa to a point medial to the styloid process of the radius.

Ulnar artery
The surface marking of the ulnar artery is along a line, slightly convex medially, from medial to the biceps tendon in the cubital fossa to the lateral side of the pisiform.

Median nerve
The surface marking of the median nerve is along a line fmor lateral to the brachial artery in the proximal arm, to medial to the artery in the cubital fossa. The surface marking of the median nerve in the forearm is along a line from the point in the cubital fossa medial to the brachial artery to a point at the wrist on the ulnar side of the tendon of flexor carpi radialis.

Ulnar nerve
The surface marking of the ulnar nerve is along a line posterior to the brachial artery in the proximal arm to a groove behind the medial epicondyle of the humerus where it is readily palpable. The surface marking of the ulnar nerve of the forearm is along a line from the medial epicondyle of the humerus to the lateral side of the pisiform bone.

Radial nerve
The surface marking of the radial nerve is from the point where the posterior wall of the axilla and the arm meet to a point two thirds of the way along the line from the acromion to the lateral epicondyle, and then to the front of the lateral epicondyle. In the flexor compartment of the lower arm the surface marking of the radial nerve is from a point in the intermuscular slit between brachialis and brachioradialis, to the anatomical snuffbox (the snuffbox lies between the extensor pollicis longus tendon on the ulnar side and the tendons of the extensor pollicis brevis and abductor pollicis longus on radial side). Note, after giving off the deep branch, the remnant of the radial nerve (superficial branch) is slender and purely cutaneous in function.

Lymph glands

Supratrochlear group. These lymph nodes lie in the subcutaneous fat just above the medial epicondyle.
Infraclavicular group. This group of lymph nodes lie along the cephalic vein in the upper part of the deltopectoral groove.
Axillary lymph glands. The axillary lymph glands lie against the anterior, posterior and lateral walls of the axilla.

Lower limb

Femoral artery
The surface marking of the femoral artery, with the hip slightly flexed and laterally rotated, is from the mid point between the pubic symphysis and the anterior superior iliac spine, along the upper two thirds of a line towards the adductor tubercle.

Popliteal artery
The surface marking for the popliteal artery runs in the midline of the popliteal fossa from one hands breadth above the knee joint (adductor hiatus) to one hands breadth below the knee joint (soleal arch).

Posterior tibial artery
The surface marking of the posterior tibial artery is form a point in the midline of the popliteal fossa one hands breadth below the knee joint line to a point behind the medial malleolus, 2.5cm in front of the medial border of the tendocalcaneous.

Anterior tibial artery
The surface marking for the anterior tibial artery is a line frmo a point midway between the neck of the fibula and tibial tuberosity to a point in front of the ankle joint midway between the malleoli.

Sciatic nerve
The surface marking of the sciatic nerve is from the mid point midway between the ischial tuberosity and greater trochanter to the apex fo the popliteal fossa.

Tibial nerve
The surface marking for the tibial nerve is from the middle of the popliteal fossa to midway between the medial malleolus and the tendocalcaneous. The nerve lies posterior to the posterior tibial artery at the medial malleolus level.

Common peroneal nerve
The surface marking for the common peroneal nerve is from the apex of the popliteal fossa one hands breadth above the knee joint line to the neck of the fibula, at which point it can be palpated and rolled on the bone.

Lymph glands
The surface marking the inguinal lymph glands is two intercepting lines. One runs parallel to and 2cm distal to the inguinal ligament while the other runs vertically over the upper 10cm of the long saphenous vein.

Long saphenous vein
The surface marking of the long saphenous vein is a line running anterior to the medial malleolus, passing one hand\'s breadth behind the medial border of the patella to a point 3cm lateral and inferior to the pubic tubercle. The latter point marks the sapheno-femoral junction.

Musculoskeletal sciences & substance abuse