WALKING: THE GAIT CYCLE Lymphatic Drainage of Foot The lymphatics of the foot begin in the subcutaneous plex uses. The collecting vessels consist of superficial and deep lymphatic vessels, which follow the superficial veins and major vascular bundles, respectively. Superficial lymphatic vessels Locomotion is a complex function. The movements of the lower limb during walking on a level surface may be divided into alternating swing and stance phases. The gait cycle con sists of one cycle of swing and stance by one limb. The stance phase begins with heel strike when the heel strikes the ground and begins to assume the body’s full weight and ends with push-off from the forefoot. The swing phase begins after push-off, when the toes leave the ground, and ends when the heel strikes the ground. The swing phase occupies approximately 40% of the walking cycle and the stance phase, 60%. Walking is a remarkably efficient activity, taking advan tage of gravity and momentum so that a minimum of physical exertion is required. The muscle actions during the gait cycle are summarized in Figure 5.43 and Table 5.12. CHAPTER 5 • LOWER LIMB 368 Modified from Rose J, Gamble JG. Human Walking. 2nd ed. Baltimore: Lippincott Williams & Wilkins; 1994. TABLE 5.12 MUSCLE ACTION DURING GAIT CYCLE Phase of Gait Mechanical Goals Active Muscle Groups S T A N C E P H A S E Heel strike (initial contact) Lower forefoot to ground Ankle dorsiflexors (eccentric contraction) Continue deceleration (reverse forward swing) Hip extensors Preserve longitudinal arch of foot Intrinsic muscles of foot Long tendons of foot Loading response (flat foot) Accept weight Knee extensors Decelerate mass Ankle plantarflexors Stabilize pelvis Hip abductors Preserve longitudinal arch of foot Intrinsic muscles of foot Long tendons of foot Midstance Stabilize knee Knee extensors Control dorsiflexion (preserve momentum) Ankle plantarflexors (eccentric contraction) Stabilize pelvis Hip abductors Preserve longitudinal arch of foot Intrinsic muscles of foot Terminal stance (heel off) Accelerate mass Ankle plantarflexors (concentric contraction) Stabilize pelvis Hip abductors Preserve arches of foot; fix forefoot Intrinsic muscles of foot Long tendons of foot Preswing (toe off) Accelerate mass Long flexors of digits Preserve arches of foot; fix forefoot Intrinsic muscles of foot Long tendons of foot Decelerate thigh; prepare for swing Flexor of hip (eccentric contraction) S W I N G P H A S E Initial swing Accelerate thigh, vary cadence Flexor of hip (concentric contraction) Clear foot Ankle dorsiflexors Midswing Clear foot Ankle dorsiflexors Terminal swing Decelerate thigh Hip extensors (eccentric contraction) Decelerate leg Knee flexors (eccentric contraction) Position foot Ankle dorsiflexors Extend knee to place foot (control stride); prepare for contact Knee extensors