Introduction
The ankle and foot form a highly specialized structure designed for weight-bearing, balance, and movement. They provide stability and flexibility required for standing, walking, running, and jumping. The foot also serves as a shock absorber, adapting to different surfaces and distributing forces evenly.
Movement of the Fibula and Tibia
The tibia (shinbone) and fibula form the lower leg and contribute to ankle stability. While the tibia bears most of the weight, the fibula assists in lateral stability and serves as an attachment site for muscles.
- Movements of the fibula:
- Slight rotation and gliding at the proximal and distal tibiofibular joints.
- Assists in accommodating ankle movements.
Bones of the Foot
The foot is composed of 26 bones, categorized into three sections:
1. Tarsal Bones (Rearfoot)
- Talus: Connects the foot to the leg via the ankle joint.
- Calcaneus: The heel bone, which supports body weight.
- Navicular: Located medially, helps in arch support.
- Cuboid: Positioned laterally, provides stability.
- Cuneiform Bones (Medial, Intermediate, Lateral): Support the arch of the foot.
2. Metatarsal Bones (Midfoot)
- Five long bones that connect the tarsal bones to the toes.
- Provide structural support and function as levers during walking.
3. Phalanges (Toes)
- Three phalanges per toe (proximal, middle, distal), except for the big toe, which has two.
- Allow fine adjustments for balance and movement.
Joints of the Foot
The foot consists of multiple joints that allow flexibility and adaptation to movement.
1. Ankle Joint (Talocrural Joint)
- Type: Hinge synovial joint.
- Articulates between: The tibia, fibula, and talus.
- Function: Allows dorsiflexion and plantarflexion.
2. Subtalar and Midtarsal Joints
- Subtalar Joint (between the talus and calcaneus): Allows inversion and eversion.
- Midtarsal Joint (between tarsal bones): Assists in adjusting the foot to uneven surfaces.
3. Metatarsophalangeal Joints (MTP)
- Connect the metatarsals to the toes.
- Allow flexion, extension, abduction, and adduction.
4. Interphalangeal Joints
- Found between the phalanges.
- Function as hinge joints for toe movement.
Movements of the Foot Joints
The foot is capable of various movements necessary for locomotion and stability.
Ankle Joint Movements
- Plantarflexion (pointing the toes downward)
- Muscles Involved: Gastrocnemius, soleus, tibialis posterior.
- Dorsiflexion (lifting the foot upward)
- Muscles Involved: Tibialis anterior, extensor digitorum longus.
Movements of the Tarsal Joints
- Inversion (Supination)
- Tilting the sole of the foot inward.
- Muscles Involved: Tibialis anterior, tibialis posterior.
- Eversion (Pronation)
- Tilting the sole of the foot outward.
- Muscles Involved: Peroneus longus, peroneus brevis.
Movements of the Metatarsophalangeal Joints
- Flexion (curling the toes)
- Muscles Involved: Flexor digitorum longus, flexor hallucis longus.
- Extension (lifting the toes)
- Muscles Involved: Extensor digitorum longus, extensor hallucis longus.
The Arches of the Foot
The foot has three primary arches that assist in weight distribution and shock absorption:
- Medial Longitudinal Arch (inner arch)
- Supported by the plantar fascia and tibialis posterior.
- Lateral Longitudinal Arch (outer arch)
- Provides stability during weight-bearing.
- Transverse Arch (across the midfoot)
- Maintains foot shape and flexibility.
Conclusion
The ankle and foot function as a dynamic and stable foundation for movement. Their complex anatomy allows shock absorption, balance, and propulsion during walking and running. Understanding their biomechanics is essential for preventing injuries and improving performance in physical activities.