ANEURYSM General

ANEURYSM General

Dilatations of localised segments of the arterial system are called aneurysms when there is a ≥ 50% increase in the diam - eter of the vessel; below 50% they are termed ectatic. They can either be true aneurysms, containing the three layers of the arterial wall (intima, media, adventitia) in the aneurysm sac, or false aneurysms, having a single layer of fibrous tissue as the wall of the sac, e .g. aneurysm following trauma. Aneu - rysms can also be grouped according to their shape (fusiform, saccular) or their aetiology (atheromatous, traumatic, mycotic, etc.). The term mycotic is a misnomer because, although it indicates infection as the cause of the aneurysm, it is due to bacteria, not fungi. Aneurysms may occur in the aorta or in the iliac, femoral, popliteal, subclavian, axillary , carotid, cerebral, mesenteric, splenic and renal arteries and their branches. The majority are true fusiform atherosclerotic aneurysms.

Tibial tuberosity 10 cm 10 cm 2/3 1/3 = Incision (b) (c)