Page 259 - Clinical Anatomy

ECA4 7/18/06 6:47 PM Page 244

244 The lower limb

rhomboid-shaped space of anatomical diagrams when opened up at opera-
tion or by dissection.
Its boundaries are:
•◊◊superolaterally—biceps tendon;
•◊◊superomedially—semimembranosus reinforced by semitendinosus;
•◊◊inferomedially and inferolaterally — the medial and lateral heads of
gastrocnemius.
The roof of the fossa is deep fascia which is pierced by the small saphe-
nous vein as this enters the popliteal vein.
Its floor, from above down, is formed by:
•◊◊the popliteal surface of the femur;
•◊◊the posterior aspect of the knee joint;
•◊◊the popliteus muscle covering the upper posterior surface of the tibia.
From without in, the popliteal fossa contains nerves, vein and artery.
The common peroneal nervepasses out of the fossa along the medial border
of the biceps tendon; the tibial nerve is first lateral to the popliteal vessels and
then crosses superficially to these vessels to lie on their medial side.
The popliteal vein lies immediately superficial to the artery; the popliteal
artery itself lies deepest of all in the fossa.
As well as these important structures, the fossa contains fat and the
popliteal lymph nodes.

Clinical features

The popliteal fossa is another good example of the value of thinking
anatomically when considering the differential diagnosis of a mass situated
in a particular anatomical area.
When examining a lump in the popliteal region, let these possibilities
pass through your mind:
•◊◊skin and soft tissues—sebaceous cyst, lipoma, sarcoma;
•◊◊vein—varicosities of the short saphenous vein in the roof of the fossa;
•◊◊artery—popliteal aneurysm;
•◊◊lymph nodes—infection secondary to suppuration in the foot;
•◊◊knee joint—joint effusion;
•◊◊tendons—enlarged bursae, especially those beneath semimembranosus
and the heads of gastrocnemius;
•◊◊bones—a tumour of the lower end of femur or upper end of tibia.

The arteries of the lower limb

Femoral artery
The femoral artery is the distal continuation of the external iliac artery
beyond the inguinal ligament. It traverses the femoral triangle and the
adductor canal of Hunter, then terminates a hand’s breadth above the