Page 252 - Clinical Anatomy

ECA4 7/18/06 6:47 PM Page 237

Three important zones 237

Peroneus longus tendon passes obliquely across the sole in a groove
on the cuboid bone and is inserted into the lateral side of the base of
the 1st metatarsal and the medial cuneiform. Into the medial aspect of these
two bones is inserted the tendon of tibialis anterior so that these muscles
form, in effect, a stirrup between them which supports the arches of the
foot.
The medial arch is further reinforced by flexor hallucis longus, whose
tendon passes under the sustentaculum tali of the calcaneus, and by tibialis
posterior, two-thirds of whose fibres are inserted into the tuberosity of the
navicular and support the spring ligament.
The longitudinally running intrinsic muscles of the foot also act as ties
to the longitudinal arches.

The anatomy of walking

In the process of walking, the heel is raised from the ground, the metatar-
sophalangeal joints flex to give a ‘push off’ movement; the foot then leaves
the ground completely and is dorsiflexed to clear the toes.
Just before the toes of one foot leave the ground, the heel of the other
makes contact.
Forward progression is produced partly by the ‘push off’ of the toes,
partly by powerful plantarflexion of the ankle and partly by the forward
swing of the hips accentuated by swinging movements of the pelvis. Para-
plegics can be taught to walk purely by this pelvic swing action, even
though paralysed from the waist downwards.
When one foot is off the ground, dropping of the pelvis to the unsup-
ported side is prevented by the hip abductors (gluteus medius and
minimus and tensor fasciae latae). Their paralysis is one cause of a ‘dipping
gait’ and of a positive Trendelenburg sign (see page 228).

Three important zones of the
lower limb—the femoral triangle,

adductor canal and popliteal fossa

The femoral triangle (Fig. 174)
This triangle is bounded:
•◊◊superiorly—by the inguinal ligament;
•◊◊medially—by the medial border of adductor longus;
•◊◊laterally—by the medial border of sartorius.
Its floor consists of iliacus, the tendon of psoas, pectineus and adductor
longus.
The roof is formed by the superficial fascia, containing the superficial
inguinal lymph nodes and the great saphenous vein with its tributaries,