University of Mount Saint Vincent 5

Overview of Lower Extremity Anatomy

• Focus on the appendicular skeleton, specifically the lower leg (shank region).

Bones of the Lower Leg

• Primary Bones: The lower leg consists of two primary bones: the tibia and the fibula.

  • Tibia: Located medially and larger; supports weight from the femur.

  • Fibula: Located laterally; smaller and does not bear weight.

Anatomical Terms and Sections

• Fibular Region: Refers to the lateral aspect of the lower leg.

• Sural Region: Refers to the posterior aspect of the lower leg.

Proximal End Features

• The proximal end of the tibia articulates with the femur at the condyles (the knuckle-like structures).

  • Important Note: The fibula does not articulate with the femur directly and therefore does not contribute to the knee joint.

Joint Anatomy and Ligaments

• Ligaments: Connect bone to bone, such as ligaments associated with the knee joint and fibula.

  • The fibula provides stability but is not a weight-bearing bone; it has a ligament that attaches to the femur.

• Proximal Head of Fibula: This area has a groove that assists in holding the condyle of the femur in place.

Joint Classification

• Structural Classification of Joints:

  • Fibrous Joint: Involves bones connected by fibrous tissue; typically immovable (synarthrosis).

  • Cartilaginous Joint: Bones connected by cartilage; may allow slight movement (amphiarthrosis).

  • Synovial Joint: More complex with a joint cavity containing synovial fluid; facilitates free movement (diarthrosis).

• Functional Classification of Joints (make two columns in notes):

  • Synarthrosis: Immovable joints (e.g., fibrous).

  • Amphiarthrosis: Slightly movable joints (e.g., pubic symphysis).

  • Diarthrosis: Freely movable joints (e.g., knee, elbow).

Synovial Joints Features

• Joint Cavity: Space filled with synovial fluid that lubricates articulating surfaces.

• Axes of Movement:

  • X-axis: Horizontal (e.g., elbow flexion).

  • Y-axis: Vertical (e.g., shoulder abduction).

  • Z-axis: Depth (e.g., rotation).

Shoulder Joint Mechanics

• Ball and Socket Joint: Characterized by movements across multiple planes (multiaxial).

  • Proximal Humerus Head: Fits into the glenoid cavity of the scapula.

Elbow Joint Mechanics

• Uniaxial Joint: Allows movement in one plane (e.g., flexion and extension).

  • Rotates around the X-axis.

Articular Cartilage and Bursa

• Articular Cartilage: Covers bone ends to reduce friction during movement.

• Bursa: Fluid-filled sac that reduces friction; important for shoulder and knee movement.

  • Bursitis: Inflammation of the bursa, often due to repetitive motion.

Arthritis Overview

• Osteoarthritis (OA): Degenerative joint condition commonly associated with aging.

• Rheumatoid Arthritis (RA): Autoimmune condition leading to bilateral joint inflammation.

Developmental Aspects of the Skeleton

• Fetal Skeleton: Primarily composed of cartilage rather than bone.

• Kyphosis: Present at birth as a primary curve in the thoracic spine.

• Lordosis: Secondary curves develop in cervical and lumbar regions as the child grows.

Osteoporosis Effects

• Bone Health: Promoted by physical activity and estrogen in females; inactivity leads to decreased bone density.