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Functional Anatomy of the Ankle and Foot
CHAPTER 88 FUNCTIONAL ANATOMY OF THE ANKLE AND FOOT
155
Inflamed iliotibial bursa Inflamed iliotibial band
FIGURE 87–1 The iliotibial band bursa. (From Waldman SD: Atlas of Pain Management Injection Techniques. Philadelphia, Saunders, 2007, p 471.)
CHAPTER
88
Functional Anatomy of the Ankle and Foot To best understand the functional anatomy of the ankle and foot, the clinician is best served by viewing the ankle as being composed of three distinct functional units: (1) the hindfoot, which is made up of the calcaneus and talus; (2) the midfoot, which is made up of the five tarsal bones; and (3) the forefoot, which is made up of the metatarsals and phalanges (Fig. 88-1). While these units are functionally distinct, normal walking requires a highly and subtly coordinated interaction between them.
The Hindfoot The distal joint between the tibia and fibula allows very little movement with the hinge joint formed by the distal ends of the tibia and fibula and the talus providing dorsiflexion and plantar flexion needed for ambulation. The medial and lateral malleoli extend along the sides of the talus to form a mortise that provides stability and prevents ankle rotation (Fig. 88-2). This joint is further
strengthened by the deltoid ligament medially and the anterior talofibular, posterior talofibular, and calcaneofibular ligaments laterally. These ligaments are subject to strain and sprain and are often the source of ankle pain and dysfunction following seemingly minor trauma. The talocalcaneal joint, which lies between the talus and calcaneus, allows for additional range of motion of the ankle joint and makes up for the limitations of motion placed on the joint by the mortise structure of the talus and medial and lateral malleoli by permitting approximately 30 degrees of foot inversion and 15 to 20 degrees of foot eversion, which allows walking on uneven surfaces.
The Midfoot The midtarsal joints are made up of the calcaneocuboid and talonavicular joints. These joints contribute to further range of motion by allowing 20 degrees of adduction of
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SECTION 1 ANATOMY
the foot and approximately 10 degrees of abduction of the foot. These movements add to the flexibility of the foot and are thought to aid in climbing, and they are aided by the gliding motions of the intertarsal joints between the navicular, cuneiform, and cuboid bones.
The interphalangeal joints are made up of proximal and distal units. The proximal interphalangeal joints do not extend but allow approximately 50 degrees of plantar flexion. The distal interphalangeal joints allow approximately 25 degrees of dorsiflexion and 40 to 50 degrees of plantar flexion.
The Forefoot The metatarsophalangeal joints allow additional dorsiflexion and plantar flexion of the foot with the first joint allowing 80 to 90 degrees of dorsiflexion with the remaining metatarsophalangeal joints allowing approximately 40 degrees of dorsiflexion. The first metatarsophalangeal joint allows about 40 to 50 degrees of plantar flexion with the remaining joints allowing 35 to 40 degrees of plantar flexion.
SUGGESTED READINGS Netter FH: Bones of the foot. In: Atlas of Human Anatomy, ed 4. Philadelphia, Saunders, 2006. Netter FH: Ligaments and tendons of the ankle. In: Atlas of Human Anatomy, ed 4. Philadelphia, Saunders, 2006. Waldman SD: Functional anatomy of the ankle and foot. In: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006.
Phalanges
Tibia Metatarsals
Fibula
Cuneiform bones Navicular
Cuboid
Talus
Lateral malleolus
Talus
Calcaneus Calcaneus
FIGURE 88–1 The foot and ankle. (From Waldman SD: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006, p 360.)
FIGURE 88–2 The hindfoot. (From Waldman SD: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006, p 361.)
155
Inflamed iliotibial bursa Inflamed iliotibial band
FIGURE 87–1 The iliotibial band bursa. (From Waldman SD: Atlas of Pain Management Injection Techniques. Philadelphia, Saunders, 2007, p 471.)
CHAPTER
88
Functional Anatomy of the Ankle and Foot To best understand the functional anatomy of the ankle and foot, the clinician is best served by viewing the ankle as being composed of three distinct functional units: (1) the hindfoot, which is made up of the calcaneus and talus; (2) the midfoot, which is made up of the five tarsal bones; and (3) the forefoot, which is made up of the metatarsals and phalanges (Fig. 88-1). While these units are functionally distinct, normal walking requires a highly and subtly coordinated interaction between them.
The Hindfoot The distal joint between the tibia and fibula allows very little movement with the hinge joint formed by the distal ends of the tibia and fibula and the talus providing dorsiflexion and plantar flexion needed for ambulation. The medial and lateral malleoli extend along the sides of the talus to form a mortise that provides stability and prevents ankle rotation (Fig. 88-2). This joint is further
strengthened by the deltoid ligament medially and the anterior talofibular, posterior talofibular, and calcaneofibular ligaments laterally. These ligaments are subject to strain and sprain and are often the source of ankle pain and dysfunction following seemingly minor trauma. The talocalcaneal joint, which lies between the talus and calcaneus, allows for additional range of motion of the ankle joint and makes up for the limitations of motion placed on the joint by the mortise structure of the talus and medial and lateral malleoli by permitting approximately 30 degrees of foot inversion and 15 to 20 degrees of foot eversion, which allows walking on uneven surfaces.
The Midfoot The midtarsal joints are made up of the calcaneocuboid and talonavicular joints. These joints contribute to further range of motion by allowing 20 degrees of adduction of
156
SECTION 1 ANATOMY
the foot and approximately 10 degrees of abduction of the foot. These movements add to the flexibility of the foot and are thought to aid in climbing, and they are aided by the gliding motions of the intertarsal joints between the navicular, cuneiform, and cuboid bones.
The interphalangeal joints are made up of proximal and distal units. The proximal interphalangeal joints do not extend but allow approximately 50 degrees of plantar flexion. The distal interphalangeal joints allow approximately 25 degrees of dorsiflexion and 40 to 50 degrees of plantar flexion.
The Forefoot The metatarsophalangeal joints allow additional dorsiflexion and plantar flexion of the foot with the first joint allowing 80 to 90 degrees of dorsiflexion with the remaining metatarsophalangeal joints allowing approximately 40 degrees of dorsiflexion. The first metatarsophalangeal joint allows about 40 to 50 degrees of plantar flexion with the remaining joints allowing 35 to 40 degrees of plantar flexion.
SUGGESTED READINGS Netter FH: Bones of the foot. In: Atlas of Human Anatomy, ed 4. Philadelphia, Saunders, 2006. Netter FH: Ligaments and tendons of the ankle. In: Atlas of Human Anatomy, ed 4. Philadelphia, Saunders, 2006. Waldman SD: Functional anatomy of the ankle and foot. In: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006.
Phalanges
Tibia Metatarsals
Fibula
Cuneiform bones Navicular
Cuboid
Talus
Lateral malleolus
Talus
Calcaneus Calcaneus
FIGURE 88–1 The foot and ankle. (From Waldman SD: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006, p 360.)
FIGURE 88–2 The hindfoot. (From Waldman SD: Physical Diagnosis of Pain: An Atlas of Signs and Symptoms. Philadelphia, Saunders, 2006, p 361.)