The Lower Extremity: Foot Anatomy, Biomechanics, and Clinical Conditions

Vocabulary flashcards covering the structural anatomy, functional biomechanics, assessment methods, and clinical pathologies of the human foot and lower extremity.

Talus

The tarsal bone that bears $100\%$ of body weight transmitted through the lower leg to the foot.

Foot Arches

The four structural arches of the foot comprising the medial longitudinal arch, lateral longitudinal arch, metatarsal arch (across distal ends of the metatarsals), and transverse arch (across the tarsometatarsal bases of the metatarsals).

Plantar Fascia

A thick band of fibrous tissue extending from the calcaneus to the metatarsal heads that functions to support the arches of the foot and absorb mechanical shock.

Foot Joints

The articulations connecting the skeletal framework of the foot, notably including the tarsometatarsal joints, intermetatarsal joints, metatarsophalangeal (MTP) joints, proximal interphalangeal (PIP) joints, and distal interphalangeal (DIP) joints.

Stance Phase

The weight-bearing support period that accounts for approximately $60\%$ of the normal walking gait cycle, progressing through heel strike (initial contact), foot flat, mid-stance (midsupport), and push-off (toe-off).

Swing Phase

The non-weight-bearing recovery period comprising approximately $40\%$ of the normal walking gait cycle, divided into acceleration (follow-through), mid-swing (forward swing), and deceleration (descent).

Flight Phase

A characteristic phase of running gait where neither foot is in contact with the ground at the same time.

Heel Striking

A running foot-strike pattern where the posterior-lateral heel makes initial contact with the ground, commonly observed among distance runners.

Forefoot Striking

A running foot-strike pattern where initial impact is taken on the ball of the foot and metatarsal heads, commonly observed in sprinters.

Excessive Supination

An abnormal foot posture wherein the ankles lean outward and arches remain elevated, causing the foot to be overly rigid and increasing the risk for inversion ankle sprains.

Excessive Pronation

An abnormal foot posture wherein the ankles lean inward and arches collapse, creating an overly flexible or mobile foot linked to flat feet and stress-related injuries.

Pes Cavus

A foot posture characterized by an abnormally high longitudinal arch, excessive supination, and reduced mechanical shock absorption.

Pes Planus

A foot posture characterized by a flat foot with depressed or absent arches, excessive pronation, and accompanying localized pain or muscular weakness.

Footwear Matching Principle

The clinical rule for athletic injury prevention dictating that pronators require rigid, controlling shoes, whereas supinators require flexible, cushioned shoes.

Shoe Wear Pattern Analysis

A diagnostic observation technique assessing tread wear on the sole of athletic footwear to identify normal wear, overpronation (medial forefoot and heel breakdown), or supination (lateral border wear).

Dorsalis Pedis and Posterior Tibial Pulses

The two primary vascular pulse palpation sites on the lower extremity used during clinical examination to assess peripheral circulation in the foot.

Sever's Disease

Calcaneal apophysitis, a traction-related overuse inflammation of the secondary ossification center or growth plate on the posterior calcaneus.

Retrocalcaneal Bursitis

Inflammation of the retrocalcaneal bursa situated between the anterior aspect of the Achilles tendon and the posterosuperior surface of the calcaneus.

Haglund's Deformity

A bony enlargement on the posterior-superior aspect of the calcaneal heel bone that frequently leads to localized irritation and painful retrocalcaneal bursitis.

Plantar Fasciitis

An inflammatory condition producing pain in the proximal medial arch and calcaneal attachment site, typically presenting with maximum pain upon taking the first steps in the morning.

Jones Fracture

A fracture occurring specifically at the base of the fifth ($5^{\text{th}}$) metatarsal, known for poor vascularization and high rates of nonunion or displacement that may require surgical screw fixation.

Sesamoiditis

Inflammation or fracture of the two small sesamoid bones embedded within the tendons beneath the great toe, typically aggravated during push-off or toe extension.

Metatarsalgia

Pain localized to the ball of the foot (most often under the second or third metatarsal heads), commonly exacerbated by tight triceps surae musculature shortening the stance phase and elevating forefoot stress.

Morton's Neuroma

A benign mass or perineural swelling that typically develops along the plantar digital nerve between the third and fourth metatarsals ($3^{\text{rd}}$ and $4^{\text{th}}$ MT), causing pain, numbness, and tingling.

Turf Toe

A hyperextension sprain of the metatarsophalangeal (MTP) joint of the great toe, causing localized pain, capsular tearing, and swelling at the first MTP.

Buddy Taping

A conservative management and immobilization technique used for toe sprains and stable phalangeal fractures by strapping the affected toe directly to an uninjured adjacent toe.

Morton's Toe

A congenital condition marked by an abnormally short first metatarsal ($1^{\text{st}}$ MT) relative to the second metatarsal, giving the appearance of a longer second toe and predisposing the second MT to stress fractures.