Chapter 8: The Lower Extremity: The Knee, Ankle, and Foot

Outline

• The Knee Joint

  Structure

  Menisci

  Patellofemoral Joint

  Ligaments of the Knee

  Movements

• Muscles of the Knee Joint

  Location

  Characteristics and Functions of Individual Muscles

• Muscular Analysis of the Fundamental Movements of the Leg at the Knee Joint

  Flexion

  Extension

  Outward Rotation of the Tibia

  Inward Rotation of the Tibia

• The Ankle and the Foot

  Structure of the Ankle

  Ligamentous Reinforcement

  Structure of the Foot

  Movements of the Foot at the Ankle, Tarsal, and Toe Joints

• Muscles of the Ankle and Foot

  Location

  Characteristics and Functions of Individual Muscles

• Muscular Analysis of the Fundamental Movements of the Ankle and Foot (Tarsal Joints and Toes)

  The Ankle

  The Tarsal Joints

  The Toes (Exclusive of the Intrinsic Muscles)

  Maintenance of the Arches

• Common Injuries of the Leg, Knee, Ankle, and Foot

  The Leg

  The Knee

  The Ankle

  The Foot

• Laboratory Experiences

Objectives

At the conclusion of this chapter, the student should be able to:

1. Name, locate, and describe the structure and ligamentous reinforcements of the articulations of the knee, ankle, and foot.

2. Name and demonstrate the movements possible in the joints of the knee, ankle, and foot, regardless of starting position.

3. Name and locate the muscles and muscle groups of the knee, ankle, and foot, and name their primary actions as agonists, stabilizers, neutralizers, or antagonists.

4. Analyze the fundamental movements of the lower leg and foot with respect to joint and muscle actions.

5. Describe the common injuries of the leg, knee, and ankle.

6. Perform an anatomical analysis of the lower extremity in a motor skill.

The Knee Joint

The knee joint is the largest and most complex joint in the human body. It is a masterpiece of anatomical engineering. Placed midway down each supporting column of the body, it is subject to severe stresses and strains in its combined functions of weight bearing and locomotion. To take care of the weight-bearing stresses, it has massive condyles; to facilitate locomotion, it has a wide range of motion; to resist the lateral stresses due to the tremendous lever effect of the long femur and tibia, it is reinforced at the sides by strong ligaments; to combat the downward pull of gravity and to meet the demands of such violent locomotor activities as running and jumping, it is provided with powerful musculature. It would be difficult, indeed, to find a mechanism better adapted for meeting the combined requirements of stability and mobility than the knee joint.

Structure

Although the knee is classified as a hinge joint, its bony structure resembles two condyloid or ovoid joints lying side by side, yet not quite parallel (Figure 8.1). The lateral flexion permitted in a single ovoid joint is not possible in the knee joint because of the presence of the second condyle. The two rockerlike condyles of the femur rest on ...