Chapter 9: Knee, Ankle, and Foot - Functional Anatomy for Occupational Therapy

Vocabulary practice flashcards covering the osteology, arthrology, kinesiology, muscle actions, innervations, and clinical conditions of the knee, ankle, and foot from Chapter 9.

Functional mobility

The act of moving from one position or place to another during daily activities, including bed mobility, transfers, carrying objects, and using stairs.

Ambulation

The purposeful act of walking.

Weight-shifting

The shifting of body weight from one leg to another, which facilitates positioning and purposeful body movement.

Femur

The longest bone of the lower extremity that provides primary structural support for the thigh.

Medial and lateral femoral condyles

Convex, rounded bony projections on the inferior distal femur forming the superior articular surfaces of the knee joint; the medial condyle is longer and larger to help stabilize the knee during standing.

Intercondylar fossa

The deep notch or gap located between the medial and lateral femoral condyles on the posterior aspect of the femur.

Medial and lateral femoral epicondyles

Bony prominences on the medial and lateral sides of the distal femur that serve as attachment sites for tendons and collateral ligaments.

Tibia

The primary weight-bearing bone of the lower leg that creates a direct link between the knee and ankle; its anterior border forms the shin.

Tibial plateau

The proximal, superior articular surface of the tibia that articulates with the femoral condyles; its medial aspect is wider and more concave to accommodate greater weight-bearing during standing.

Tibial tuberosity

A rough bony projection on the anterior proximal surface of the tibia that serves as the distal insertion site for the patellar ligament.

Medial malleolus

The prominent bony projection at the distal medial end of the tibia whose inferior articular surface articulates with the talus.

Fibula

The slender lateral bone of the lower leg that bears little weight and provides a rigid structure for ligament and tendon attachments.

Lateral malleolus

The distal expansion of the fibula that forms the lateral aspect of the talocrural (ankle) joint.

Patella

The largest sesamoid bone in the human body; it stabilizes the anterior knee during flexion and functions as a lever to increase the moment arm of the quadriceps muscles during knee extension.

Talus

The tarsal bone that projects upward and forms the central articular portion of the talocrural joint.

Calcaneus

The heel bone situated inferior and posterior to the talus; its superior surface has three facets that articulate with the talus at the subtalar joint, and its rounded posterior aspect attaches the calcaneal (Achilles) tendon.

Hindfoot

The posterior anatomical segment of the foot composed collectively of the talus and calcaneus.

Midfoot

The central structural segment of the foot composed of the navicular, cuboid, and the three cuneiforms (medial, intermediate, lateral).

Arches of the foot

The three anatomical curves of the foot—medial longitudinal, lateral longitudinal, and transverse—that stabilize the foot and absorb compressive body weight.

Pes cavus

A condition characterized by atypically high longitudinal foot arches, commonly observed in ballet dancers, that can contribute to foot and ankle instability.

Pes planus

A structural or postural variation characterized by flattened or abnormally low arches of the foot.

Plantar aponeurosis

A dense band of plantar connective tissue originating on the calcaneus that fans out into five individual bands (one to each toe) to support and stabilize the longitudinal arches.

Tibiofemoral joint

A biaxial hinge joint formed between the condyles of the femur and the tibial plateau that supports upper body weight and allows knee flexion, extension, and axial rotation.

Screw-home mechanism

The obligatory rotation of the knee near full extension (lateral tibial rotation and medial femoral rotation) that locks the femoral condyles firmly into the tibial plateau to enhance stability in the close-packed position.

Anterior cruciate ligament (ACL)

An intracapsular knee ligament extending from the anterior intercondylar surface of the tibia to the medial side of the lateral femoral condyle; it resists anterior tibial translation and rotational gliding.

Posterior cruciate ligament (PCL)

An intracapsular knee ligament running from the posterior intercondylar surface of the tibia to the inner surface of the medial femoral condyle; it resists posterior tibial displacement and torsional forces.

Medial and lateral collateral ligaments (MCL & LCL)

Extracapsular knee ligaments that stabilize the tibiofemoral joint against coronal plane stresses by preventing valgus (medial collapse) and varus (lateral bowing) forces.

Menisci

Crescent-shaped fibrocartilaginous pads that deepen the articular surfaces and increase the contact surface area of the tibial plateau.

Patellofemoral joint

The gliding articulation between the posterior articular facets of the patella and the trochlear groove of the distal anterior femur; the patella glides distally/laterally in flexion and superiorly/medially in extension.

Talocrural joint

A uniaxial hinge joint formed by the trochlea of the talus nestled between the medial malleolus of the tibia and lateral malleolus of the fibula; it permits dorsiflexion and plantar flexion.

Deltoid ligament

A broad, strong ligament originating from the medial malleolus that fans downward to attach to multiple tarsal bones, providing primary medial stability to the talocrural joint.

Subtalar joint

The articulation formed between the inferior facets of the talus and the superior facets of the calcaneus that produces inversion and eversion of the foot.

Transverse tarsal joint

The midtarsal joint formed by the articulations of the calcaneus with the cuboid and the talus with the navicular; it permits gliding and rotation between the hindfoot and midfoot during inversion and eversion.

Hamstrings

The posterior thigh muscle group (semimembranosus, semitendinosus, and biceps femoris) sharing an origin on the ischial tuberosity; they flex the knee, extend the hip, tilt the pelvis posteriorly, and provide forward acceleration during gait.

Popliteus

A deep posterior knee muscle originating on the lateral femoral condyle and inserting on the proximal posterior tibia (innervated by tibial L4, L5, S1); it internally rotates the tibia to unlock the extended knee prior to flexion ('the key that unlocks the knee').

Quadriceps femoris

The powerful anterior knee extensor group (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) innervated by the femoral nerve (L2 to L4) and inserting onto the tibial tuberosity via the patellar ligament; essential for sit-to-stand transfers.

Tibialis anterior

An anterior lower leg muscle innervated by the deep fibular nerve (L4, L5, S1) that dorsiflexes the ankle and inverts the foot, providing vital ground clearance during the swing phase of ambulation.

Extensor hallucis longus

An anterior leg muscle innervated by the deep fibular nerve (L4, L5, S1) that extends the first toe at the MTP and IP joints, dorsiflexes the ankle, and inverts the foot.

Extensor digitorum longus

An anterior leg muscle innervated by the deep fibular nerve (L4, L5, S1) that extends the 2nd through 5th toes, dorsiflexes the ankle, and everts the foot.

Gastrocnemius

A two-headed superficial posterior calf muscle originating on the femoral condyles and inserting into the calcaneus via the calcaneal tendon (innervated by tibial S1, S2); it flexes the knee and plantar flexes the ankle during acceleration tasks.

Soleus

A deep, powerful plantar flexor of the superficial posterior compartment originating from the soleal line, posterior tibia, and fibular head, inserting into the calcaneus via the calcaneal tendon (innervated by tibial L5, S1, S2).

Plantaris

A small superficial posterior muscle originating from the lateral supracondylar line of the femur that provides weak ankle plantar flexion and weak knee flexion (innervated by tibial L4, L5, S1, S2).

Tibialis posterior

A deep posterior compartment muscle originating from the posterior shafts of the tibia, fibula, and interosseous membrane and inserting into all five tarsal bones and bases of metatarsals 2–4; it inverts the foot and plantar flexes the ankle, as when standing on tiptoe.

Flexor digitorum longus

A deep posterior leg muscle inserting on the distal phalanges of toes 2–5 that flexes digits 2–5, inverts the foot, and weakly plantar flexes the ankle, active during activities like ballet dancing.

Flexor hallucis longus

A deep posterior leg muscle originating on the middle posterior fibula and inserting on the distal phalanx of the great toe; it flexes the first toe, inverts the foot, and weakly plantar flexes the ankle.

Fibularis longus

A lateral compartment muscle originating on the fibular head and lateral fibula and inserting on the base of the 1st metatarsal and medial cuneiform (innervated by superficial fibular L4, L5, S1); it everts the foot and assists in plantar flexion during gait on uneven surfaces.

Fibularis brevis

A lateral compartment muscle inserting onto the tuberosity of the 5th metatarsal that everts the foot and assists ankle plantar flexion.

Foot drop

A neurological impairment marked by the inability to actively dorsiflex the foot and ankle, causing the toes to drag during the swing phase of ambulation and creating a severe fall risk.

Ankle-foot orthosis (AFO)

A supportive external brace designed to maintain the ankle and foot in a passive neutral alignment to eliminate foot drag and improve safety and functional mobility.

Circumduction gait

A compensatory walking pattern resulting from global lower extremity weakness where the individual swings the stiff or paretic leg outward in a wide lateral arc to advance it.

Rolled ankle

An acute traumatic inversion of the ankle resulting in elongation or tearing of the lateral collateral ligaments (anterior talofibular, posterior talofibular, and calcaneofibular ligaments).

Osteoarthritis

A chronic musculoskeletal condition characterized by progressive mechanical wear-and-tear and degeneration of the joint surfaces and articular cartilage.