1. CHAPTER 11 Ankle and Foot

2. Bones Tibia Bears 90% of weight
Is easily palpated tuberosity down anterior ridge
Features the prominent medial malleolus

3. Bones
Fibula
Bears remaining 10%
Prominent lateral malleolus

4. Bones Parts of the foot Rearfoot (tarsals) Midfoot (more tarsals)
Talus and calcaneus
Midfoot (more tarsals)
Forefoot (metatarsals and phalanges)

5. Bones
Three arches
Medial longitudinal
Lateral longitudinal
Transverse

6. Bones Calcaneus Is largest and strongest tarsal bone
Is first through which ground reaction forces are transmitted
Transmits most of body weight from talus to ground

7. Bones Calcaneus Is protected by a thick fat pad
Attaches to Achilles tendon on posterior aspect

8. Bones Metatarsals Metatarsals and phalanges comprise forefoot
Numbered 1–5; medial to lateral
Two sesamoids are just posterior to first metatarsal head on plantar surface.

9. Bones
Phalanges
14 phalangeal bones
1: two
2–5: three each

10. Joints Motion terminology Dorsiflexion and plantarflexion
Occur close to sagittal plane
Inversion and eversion
Occur in frontal plane
Abduction and adduction
Occur in transverse plane

11. Joints Motion terminology Pronation and supination Functional terms
Motion occurs in three planes about an oblique axis with one degree of freedom.
Terms are typically used in reference to the subtalar joint.

12. Motion terminology—pronation
Joints
Motion terminology—pronation
Open kinematic chain, superior tibiofibular joint, and calcaneus on talus
Dorsiflexion
Abduction
Eversion

13. Motion terminology—supination
Joints
Motion terminology—supination
Open kinematic chain, superior tibiofibular joint, and calcaneus on talus
Plantarflexion
Adduction
Inversion

14. Joints Talocrural Oblique hinge with one degree of freedom
Medial collateral ligament = deltoid
Lateral collateral ligament
Anterior talofibular
Calcaneofibular
Posterior talofibular

15. Muscles Posterior group Superficial
Gastrocnemius—two-headed, two-joint phasic muscle
Soleus—tonic or slow-twitch, postural muscle
Plantaris—very small, short muscle with long tendon

16. Muscles Posterior group Deep Tarsal tunnel
Posterior tibialis—primary decelerator of pronation
Flexor digitorum longus
Flexor hallucis longus
Tarsal tunnel

17. Muscles Lateral group Peroneus (fibularis) longus
Has 2x larger in cross-sectional area compared with brevis
Passes behind lateral malleolus, through a groove on cuboid, and onto base of first metatarsal
Peroneus (fibularis) brevis
Inserts into base of fifth metatarsal

18. Muscles Lateral group Function as primary everters of ankle and foot
Innervated by superficial peroneal nerve

19. Muscles Anterior group Tibialis anterior
Primary dorsiflexor of ankle
Assists with controlling pronation
Extensor hallucis longus—extend toes, evert ankle
Extensor digitorum longus—extend toes
Peroneus tertius

20. Function of Muscles and Joints
Arches of the foot
Functions:
Allow foot to adapt to ground
Absorb forces
Provide a weight-bearing surface
Assist and support foot during supination/pronation

21. Function of Muscles and Joints
Loading of the foot
Weight is distributed 50%–50% between calcaneus and metatarsal heads.
During gait, heel and great toe experience greatest amount of force.