Anatomy of the Lower Limb: Femur, Tibia, Fibula, Ankle, and Foot

Lower Limb Anatomy: Femur, Shin, Ankle, and Foot

The Femur (Thigh Bone)

• Proximal End:

  • Connects with the pelvis to form the hip joint.

  • Features a spherical projection called the head of the femur.

  • The head is attached to the shaft by a distinct neck region, giving it a mushroom-like appearance. This can be compared to the ball-and-shaft joint of the humerus.

  • Two prominent bony projections are present:

    • Greater trochanter: The larger, superior lateral projection ($C.trochanter$).

    • Lesser trochanter: A smaller, inferior medial projection.

• Distal End:

  • Forms part of the knee joint.

  • Features two large, rounded prominences called condyles:

    • Medial condyle: Located on the medial (inner) aspect.

    • Lateral condyle: Located on the lateral (outer) aspect.

  • A significant groove is present between the condyles, which houses the kneecap.

The Patella (Kneecap)

• A small, rock-like bone that floats in the groove between the femoral condyles at the distal end of the femur.

• Its anatomical name is the patella.

The Shin Bones: Tibia and Fibula

The Tibia (Shin Bone)

• One of two smaller bones in the shin, located medially.

• Proximal End:

  • Forms part of the knee joint.

  • Also features condyles (medial and lateral), which articulate with the femoral condyles.

  • Identification of medial and lateral condyles is best done by examining the distal end of the tibia.

  • Tibial tuberosity: A prominent bump on the anterior superior aspect of the tibia. This is the attachment point for the strong thigh muscle tendon after it crosses over the patella.

• Distal End:

  • Features an asymmetric projection known as the medial malleolus.

  • This is the prominent bone on the inside aspect of the ankle, which can be felt or struck.

  • The presence of the medial malleolus confirms its side as medial, thus allowing identification of the medial and lateral tibial condyles proximally.

The Fibula

• A long, slender bone located laterally to the tibia.

• Its primary role in weight-bearing is significantly less than the tibia's.

• Lateral malleolus: The distal end of the fibula forms this prominent bone on the outside aspect of the ankle.

Ankle and Foot Bones

Tarsals (Ankle Bones)

• These are the bones that form the ankle region, articulating with the tibia.

• Two principal tarsal bones to know are:

  • Calcaneus: The heel bone.

  • Talus: The bone that directly forms a joint with the tibia at the ankle, allowing for actions like tapping the toes.

• While other tarsals exist, their individual names are typically covered in advanced anatomy courses.

Metatarsals (Foot Bones)

• These bones make up the main body of the foot, similar to the metacarpals in the hand.

• They are numbered from $1$ to $5$, starting from the medial aspect of the foot (the big toe).

  • Metatarsal one: Corresponds to the big toe.

  • Metatarsals two, three, four, five: Follow consecutively towards the little toe.

Phalanges (Toe Bones)

• These are the bones of the toes.

• Numbering also starts with the big toe.

• Big toe (Hallux): Typically has only two phalanges:

  • Distal phalanx

  • Proximal phalanx

• Other toes ($2-5$): Usually have three phalanges each:

  • Distal phalanx

  • Middle phalanx

  • Proximal phalanx