Lower Limb: Foot and Ankle Radiographic Anatomy and Positioning

Vocabulary practice flashcards covering lower limb anatomy, tarsal bones, joint relationships, motion terminology, and radiographic positioning protocols for the foot and ankle.

Phalanges (Foot)

The $14$ bones of the toes (digits), consisting of two in the first digit (proximal and distal) and three in the second through fifth digits (proximal, middle, and distal).

Metatarsals

The $5$ long bones comprising the mid-anterior foot, each featuring a distal head, body (shaft), proximal base, and a prominent tuberosity on the lateral aspect of the fifth metatarsal base.

Tarsals

The $7$ bones constituting the posterior and mid-tarsal regions of the foot: the calcaneus, talus, cuboid, navicular, and $3$ cuneiforms (medial, intermediate, and lateral).

Sesamoid Bones (Foot)

Small bones embedded in tendons on the plantar surface near joints of the foot, categorized specifically as the medial (tibial) and lateral (fibular) sesamoids at the first metatarsophalangeal (MTP) joint.

Tendon

A band of fibrous connective tissue that attaches muscle to bone.

Ligament

A band of fibrous connective tissue that binds bone to bone.

Sinus Tarsi

A space or canal located between the superior surface of the calcaneus and the inferior surface of the talus (talocalcaneal or subtalar joint), through which blood vessels, nerves, and ligaments pass.

Subtalar Joint

The articulation formed between the talus and calcaneus; also called the talocalcaneal joint.

Longitudinal Arches

The two length-spanning arches (medial and lateral) of the foot that provide shock absorption and structural load-bearing support.

Transverse Arch

The side-to-side arch across the midfoot formed primarily by the three cuneiforms and the cuboid tarsal bone.

Dorsum (Dorsum Pedis)

The anterior or superior surface of the foot.

Plantar Surface

The inferior or posterior surface (sole) of the foot.

Dorsiflexion

The upward flexion motion of the foot that decreases the angle between the dorsum of the foot and the lower leg.

Plantar Flexion

The downward motion of the foot extending the ankle joint and pointing the toes toward the sole.

Inversion (Varus)

Inward turning or angling of the foot and ankle toward the medial sagittal plane of the body.

Eversion (Valgus)

Outward turning or angling of the foot and ankle away from the medial sagittal plane.

Ankle Mortise

A rectangular socket or bony arch formed by the tibial plafond, medial malleolus, and lateral malleolus that articulates with the trochlea of the talus.

Bone Densitometry

A low-dose x-ray scan that checks skeletal regions such as the hip, hand, or foot for evidence of bone thinning and mineral loss.

Lisfranc Injury

A common foot dislocation or fracture-dislocation involving the tarsometatarsal (TMT) joints, indicated radiographically by a space greater than $2\text{ mm}$ between the medial cuneiform and the base of the second metatarsal.

AP Mortise Projection (Ankle)

A radiologic ankle view performed with $15^\circ - 20^\circ$ medial rotation of the lower leg to align the intermalleolar line parallel to the image receptor, demonstrating the entire ankle mortise open.

AP $45^\circ$ Medial Oblique Projection (Ankle)

An ankle view obtained with the leg and foot rotated internally $45^\circ$, designed specifically to open and demonstrate the distal tibiofibular joint.

Plantodorsal (Axial) Calcaneus Projection

An axial projection of the heel demonstrating the full calcaneus, sustentaculum tali, and talocalcaneal joint free of rotation.

AP Stress Projections (Ankle)

Special forced inversion (varus) and eversion (valgus) radiographic examinations performed to evaluate ankle joint separation and ligament tears or ruptures.

True Lateral Ankle Alignment

The radiographic position in which the distal fibula is superimposed directly over the posterior half of the tibia.