Osteology and Arthrology of the Leg and Foot

Osteology of the Leg and Foot

• The lecture focuses on the osteology and arthrology of the leg and foot, including the tibia, fibula, and bones of the foot.
• The arthrological features of the ankle and tarsals will be discussed, followed by the toes.
• The musculature of the leg will be examined by compartment to understand attachments and functions.

Leg Anatomy

• The leg is defined as the region below the knee and above the ankle.
• Previous lectures covered the hip (acetabular femoral joint) and thigh musculature.
• Future lectures will cover the ankle and foot.

Ankle Joint (Talocrural Joint)

• The ankle is the articulation between the tibia (medial side), fibula (lateral side), and talus (superior tarsal bone).
• The talocrural joint consists of these three bones and their articular surfaces.
• Articular surfaces have hyaline cartilage, a joint cavity, and synovial fluid within the joint capsule.

Foot Anatomy

• The foot includes tarsal bones (short bones), metatarsals (long bones within the foot), and phalanges (toes).
• Joints of the foot include:
  • Intertarsal joints (between tarsals).
  • Tarsometatarsal joints (tarsals meet metatarsals).
  • Metatarsophalangeal joints (metatarsals meet phalanges).
  • Interphalangeal joints (within the toes).

Tibia and Fibula

Proximal Tibia

• The anterior perspective shows the patellar surface, where the patella articulates with the femur.

Tibia and Fibula

• The tibia is the major weight-bearing bone of the leg.
• The lateral and medial condyles of the tibia form a plateau for articulation with the femur.
• Menisci are present to increase congruency between the femur and tibia.
• The Gertie's tubercle on the lateral condyle is an attachment site for structures like the iliotibial tract.
• The tibial tuberosity on the anterior surface is the attachment site for the patellar tendon of the quadriceps muscles, enabling knee extension.

Proximal Fibula

• The fibula has a head and neck.
• The fibula bears about 10% of the weight, primarily through its distal aspect.
• The fibula increases the surface area for muscle attachment.
• The interosseous membrane connects the tibia and fibula, allowing them to function as a single structure.

Distal Tibia

• The anterior border of the tibia is palpable on the anterior shin.
• The medial malleolus is a large mass on the medial side of the tibia, forming the medial side of the ankle joint.

Distal Fibula

• The fibula is a thin, non-weight-bearing bone.
• The lateral malleolus is the distal head of the fibula, forming the lateral side of the ankle joint.
• The internal aspects of the fibula and tibia articulate with the talus.
• This region is covered in ligaments and a joint capsule with synovial fluid for ankle joint movement and protection.

Foot Anatomy

Medial Aspect

• The medial longitudinal arch is a large arch on the medial side of the foot, important for stance, balance, and movement.
• The first toe (big toe) has only two phalanges.

Lateral Aspect

• The lateral longitudinal arch is less shallow than the medial arch.
• The fifth digit is the little toe.
• The fibula is the long, narrow bone on the lateral side.
• The tibia is the larger, more medial bone.

Dorsal and Plantar Surfaces

• The dorsal surface is the top of the foot.
• The talus bone articulates within the ankle.
• The plantar surface is the underside of the foot.
• Tarsal bones on the plantar surface contact the ground for balance and standing.

Tarsal Bones

• Tarsal bones include the talus, calcaneus, navicular, cuneiforms (medial, intermediate, lateral), and cuboid.
• The talus is the first bone.
• The calcaneus is the major heel bone, where the Achilles tendon attaches.
• The navicular is anterior to the talus.
• There are three cuneiform bones: medial, intermediate, and lateral.
• The cuboid bone articulates with the fourth and fifth metatarsals.
• The medial cuneiform articulates with the first digit, the intermediate with the second, and the lateral with the third.
• Tiger Cubs Need Milk is a mnemonic to remember the tarsal bones: Talus, Calcaneus, Navicular, Medial/Intermediate/Lateral Cuneiforms, Cuboid.

Regions of the Foot

Tarsus

• The tarsus contains all the tarsal bones.
• The hindfoot includes the talus and calcaneus.
• The midfoot includes the navicular bone (articulating with the talus), the three cuneiforms (medial side), and the cuboid bone (lateral side).

Forefoot

• The forefoot includes the metatarsals and phalanges.
• The phalanges protrude out and are exposed on the foot.

Bones in Detail

Talus

• The talus has a trochlear surface covered in articular cartilage.
• Notches exist on the lateral and medial sides.
• The lateral side articulates with the cuboid, and the medial side with the navicular.
• The tibia covers the medial side, and the fibula occupies a depression on the lateral side.
• The talus articulates with the navicular anteriorly and the calcaneus inferiorly.

Calcaneus

• The calcaneus is the large heel bone.
• The superior aspect has articular surfaces for the talus.
• The posterior aspect has the calcaneal tuberosity for the attachment of the gastrocnemius, soleus, and plantaris tendons.
• The anterior aspect articulates with the cuboid bone.

Midfoot Bones

• The navicular articulates distally with the three cuneiforms and laterally with the cuboid bone.
• The cuneiforms articulate with the first, second, and third digits.
• The cuboid is a large, square-like bone articulating with the navicular and lateral cuneiform.

Forefoot

• The big toe (digit 1) is called the hallux.
• Digits 2-5 have three phalanges: proximal, intermediate, and distal.
• The hallux has only two phalanges: proximal and distal.
• The big toe has one interphalangeal joint, while digits 2-5 have two interphalangeal joints (proximal and distal).

Clinical Application

• Ankle dislocations involve key bones. Identifying these bones helps understand the injury.
• In an inverted ankle dislocation, the lateral bone protrudes, and a bone from the hindfoot is exposed.