Learning Modules - Medical Gross Anatomy Movements of the Lower Limb - Page 1 of 12

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1 Movements of the Lower Limb - Page 1 of 12 Movements of the Lower Limb - Introduction This module presents the nomenclature of movement at the joints of the lower limb. When you first approach your study of the lower limb, concentrate on the motions and less on the names of muscles producing those motions. After you have studied the lower limb, use this module to review and summarize muscle actions at the joints of the lower limb. The lower limb is our primary tool for locomotion, and therefore it is adapted to provide a stable yet mobile structure. There is a great number of joints within the entire lower limb, allowing for locomotion over uneven ground at varying velocities and with rapidly changing directions. In comparing the upper and lower limbs, it is evident that the upper limb is specialized as the organ of manipulation, and the lower limb serves for locomotion. To serve these purposes, the upper limb emphasizes mobility and sacrifices stability, while the lower limb emphasizes stability and sacrifices mobility. The contrast is perhaps most striking when comparing the mobile pectoral girdle (clavicles and scapulae) to the rigid pelvic girdle (os coxae and sacrum).

2 Movements of the Lower Limb - Page 2 of 12 Thigh Flexion and Extension Flexion of the thigh is also called flexion of the hip. Muscles: iliopsoas (psoas major and iliacus) is the most powerful flexor, assisted by sartorius, rectus femoris, and pectineus. Extension of the thigh is also called hip extension. Any movement away from flexion is extension. Muscles: gluteus maximus is the most powerful hip extensor, assisted by the hamstring muscles (semitendinosus, semimembranosus, biceps femoris).

3 Movements of the Lower Limb - Page 3 of 12 Thigh Abduction and Adduction Abduction of the thigh is also called hip abduction. The thigh is pulled laterally away from the midline. Muscles: gluteus medius and minimus are the most powerful hip abductors, assisted by piriformis and tensor fasciae latae. The hip abductors are active in stabilizing the contralateral hip when the foot is lifted off the ground during walking, i.e. when the right foot is off the ground and moving forward, the hip abductors on the left are contracting. This keeps the pelvis from falling toward the unsupported right side. Adduction of the thigh is also called hip adduction. The thigh moves medially toward the midline. Muscles: adductor longus, adductor brevis, adductor magnus, and gracilis are the powerful hip adductors, assisted by pectineus.

4 Movements of the Lower Limb - Page 4 of 12 Thigh Medial and Lateral Rotation Medial rotation of the thigh or hip brings the knee and foot medially. Muscles: gluteus medius and minimus, and the adductors (longus, brevis, magnus). With the contralateral foot elevated, contraction of the gluteus medius and minimus during walking swings the pelvis anteriorly (by trying to medially rotate the fixed thigh, and thereby rotating the pelvis forward). These muscles do this while stabilizing the hip with their abduction force. Lateral rotation of the thigh or hip moves the knee and foot laterally. Muscles: gluteus maximus is most powerful, assisted by piriformis, obturator internus and externus, the gemelli, and quadratus femoris.

5 Movements of the Lower Limb - Page 5 of 12 Thigh Circumduction Circumduction at a joint is a motion that circumscribes a cone. The hip, although designed for stabile mobility, can still circumscribe a cone. Muscles: all those that move the thigh.

6 Movements of the Lower Limb - Page 6 of 12 Leg Flexion and Extension Flexion of the leg is flexion at the knee. Only slight rotation can occur at the knee joint. Muscles: sartorius, gracilis, hamstrings (semitendinosus, semimembranosus, biceps femoris), gastrocnemius, plantaris Extension of the leg is extension at the knee. Only slight rotation can occur at the knee joint. Muscles: quadriceps (rectus femoris, and vastus lateralis, medialis, and intermedius)

7 Movements of the Lower Limb - Page 7 of 12 Valgus and varus movements Genu valgum is the clinical term for "knock-knee". The medial collateral ligament limits this movement, so a valgus stress is placed on the knee to test the integrity of this ligament. Genu varus is the clinical term for "bowleg". The lateral collateral ligament limits this movement, so a varus stress is placed on the knee to test the integrity of this ligament

8 Movements of the Lower Limb - Page 8 of 12 Dorsiflexion and Plantarflexion Dorsiflexion moves the top (dorsum) of the foot up toward the anterior surface of the leg. It could be considered "true" extension at the ankle. Muscles: tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius. Plantarflexion moves the foot in line with the leg to point the toes. It could be considered "true" flexion at the ankle. Muscles: gastrocnemius, soleus, plantaris, tibialis posterior, flexor digitorum longus, flexor hallucis longus, fibularis longus and brevis.

9 Movements of the Lower Limb - Page 9 of 12 Inversion and Eversion Inversion is a movement at the ankle and foot that is similar to supination. The sole of the foot moves to face the midline. However, while supination occurs by rotation of the radius, the leg bones do not move relative to each other. Rather, inversion takes place primarily through the transverse tarsal joint. This joint is actually two joints in a line: talonavicular and calcaneocuboid. Muscles: tibialis anterior primarily, assisted by tibialis posterior. Eversion of the ankle could be considered somewhat similar to pronation, except for the fact that its completely different. The sole of the foot is moved to face away from the midline, through the transverse tarsal joint primarily. Muscles: fibularis longus, brevis, and tertius.

10 Movements of the Lower Limb - Page 10 of 12 Toe Flexion and Extension Flexion of the toes, except the hallux or great toe, occurs at three joints: metatarsophalangeal, proximal interphalangeal, and distal interphalangeal. Muscles: flexor digitorum longus flexes all 3 joints, flexor digitorum brevis flexes MP and PIP only; lumbricals and interossei flex MP and extend the PIP and DIP. Extension of the toes, except the hallux or great toe, occurs at three joints: metatarsophalangeal, proximal interphalangeal, and distal interphalangeal. Muscles: extensor digitorum longus and brevis extend all 3 joints; lumbricals and interossei extend the PIP and DIP while flexing the MP.

11 Movements of the Lower Limb - Page 11 of 12 Hallux Flexion and Extension The hallux or great toe has only 2 phalanges, and therefore it has only two joints: metatarsophalangeal and interphalangeal. Flexion of the hallux is important in pushing off during walking or running. Muscles: flexor hallucis longus and brevis. Extension of the hallux happens at the MP and IP joints. Muscles: extensor hallucis longus and brevis.

12 Movements of the Lower Limb - Page 12 of 12 Toe Abduction and Adduction The toes have limited mobility, but some degree of abduction and adduction of the toes helps to accommodate to uneven ground during gait. Abduction of the toes takes place in reference to the second toe. In the hand, abduction moves the digits away from the third digit. Muscles: dorsal interossei, abductor hallucis, and abductor digiti minimi. Adduction moves the toes toward the second toe. Muscles: plantar interossei and adductor hallucis.