Applied Anatomy

1.) Venous cutdown

The long saphenous vein can be exposed a thumb breadth above and anterior to the medial malleolus.

It can therefore be used to rapidly infuse fluid in dehydrated individuals especially children.

This procedure is called venous cutdown .

Great saphenous vein grafts

The GSV is used for coronary bypass. During its harvesting or in cutdown, the saphenous nerve may be injured causing pain and paraesthesia after surgery.

These are dilated elongated tortuous veins. This condition can be caused by;

• Perforator valvular incompetence causing backflow from deep veins
• Compression of external or common iliac veins such as in pregnancy or pelvic tumors.
• Prolonged standing

Possible complications of this condition include;

• Thrombosis and subsequent embolism due to venous stasis
• Varicose ulcers; due to poor circulation and impaired tissue perfusion

Usually managed by;

• Muscular exercise
• Use of elastic stockings
• Ligation of faulty perforators.

• Direct trauma
• Pressure by plaster casts or over hard bends
• Fracture/ dislocation of fibula
• Superficial wounds

Other sites of injury:

• Gluteal region e.g. piriformis syndrome
• Popliteal fossa: supracondylar fractures
• Biceps femoris tenotomy
• Over the lateral femoral condyle
• Over fibula head

Injury results in

• Unopposed plantar flexion causing foot drop. This causes a high steppage gait to ensure that toes don't scrape the ground
  
• loss of eversion
• weakened inversion
• Sensory loss over the lower lateral leg and dorsum of the foot.
  

Surgical approach to the nerve is by following it medial to tendon of biceps femoris

Main effect is paralysis of calf muscles, and sensory loss on the lower calf and sole.

Tested for standing on tiptoe

Surgical approach in middle of popliteal fossa. Split gastrocnemius and soleus vertically in midline

Intermittent claudication

• Pain in the leg muscles on walking or running which stops at rest
• Caused by atherosclerosis or compression of popliteal artery
  

Each head of gastrocnemius receives one artery only, as opposed to soleus with several branches. Occlusion of the artery to gastrocnemius can cause necrosis of the muscle with soleus being spared.

The gastrocnemius has sinusoids and therefore blood flow is sluggish. In prolonged immobility there maybe thrombosis (deep venous thrombosis). This can lead to embolism.

Compartment Syndrome

See section under thigh

The anterior compartment is the tighest therefore the most commonly affected.

Precarious blood supply to the Tibia

This is because

• The tibia has a large subcutaneous surface
• Only one large nutrient artery in the proximal third
• No muscle attachment in the distal third

Therefore tibial fractures in the distal third heal slowly and may fail to unite

Testing of extensor tendons

Dermatomes

In injury to peroneal nerve, loss of sensation over dorsum with sparing of 1st inter-digital cleft localizes injury to the superficial branch.

Venous access

Subcutaneous layer is scanty on the dorsum of the foot. This allows easy visualization and access of veins.

Dorsalis Pedis

Palpation of dorsalis pedis pulse is important in evaluating peripheral vascular disease of the lower limb.