Human Anatomy: Skeletal System Overview

Anatomy

• Defined as dissecting the body to study its parts and their relationships.

Human Skeletal System

• Bones, joints, and cartilage make up the system.
• Provides structural support, protects organs, enables movement, and stores minerals.
• Composed of 206 bones.

Axial Skeleton

• 80 bones comprising the central axis of the body.
• Includes the skull, vertebral column, and thoracic cage.
• Skull: Cranium and facial bones.
• Vertebral Column: 7 cervical, 12 thoracic, 5 lumbar vertebrae, sacrum, and coccyx.
• Thoracic Cage: 12 pairs of ribs and sternum.

Appendicular Skeleton

• 126 bones involved in movement and limb support.
• Pectoral Girdle: Consists of clavicles and scapulae (shoulder blades).
• Upper Limbs: Humerus (upper arm), radius and ulna (forearm), carpals (wrist bones), metacarpals (hand bones), and phalanges (finger bones).
• Pelvic Girdle: Forged by hip bones (ilium, ischium, and pubis)
• Lower Limbs: Femur (thigh bone), tibia and fibula (leg bones), tarsals (ankle bones), metatarsals (foot bones), and phalanges (toe bones).

Hip Bone

• Also known as the coxal bone or pelvic bone.
• Large, irregular bone made of three fused components: ilium, ischium, and pubis.
• These components fuse during adolescence to form a single structure by adulthood.

Femur

• The longest and strongest bone in the human body.
• Located in the thigh.
• Serves as a weight-bearing bone, connecting the hip and knee.

Femur Key Landmarks

• Head: Rounded proximal end that articulates with the acetabulum of the hip bone.
• Neck: Connects the head to the shaft.
• Greater Trochanter: Prominent bony projection on the lateral aspect of the proximal femur.
• Lesser Trochanter: Smaller bony projection on the medial side of the proximal femur.
• Linea Aspera: A rough, longitudinal ridge on the posterior surface of the femur, serving as an attachment for muscles.
• Condyles: Medial and lateral, situated at the distal end of the femur.
• Intercondylar Fossa (Notch): A deep groove located between the medial and lateral condyles on the posterior side.
• Patellar Surface (Trochlear Groove): A smooth, anterior surface located between the condyles which the patella (kneecap) glides on during knee movement.

Femur Angles and Curvatures

• Angle of Inclination: The angle formed between the neck and the shaft of the femur, which is typically around 125 degrees in adults.
• Angle of Torsion: The angle between the axis of the femoral head/neck and the axis of the femoral condyles.

Femur Fractures

• Neck of Femur Fracture: Frequent in older adults, caused by falls and osteoporosis. Poor blood supply makes nonunion and avascular necrosis risks, often requiring surgical fixation or hip replacement.
• Shaft Fractures: Usually caused by high-energy trauma, requiring intramedullary nailing or plate fixation.
• Intertrochanteric Fractures: Occur between the greater and lesser trochanters. May require surgical treatment.

Tibia

• The second largest bone in the body.
• Known as the shinbone.
• Located between the femur and the ankle.
• It is a weight-bearing structure, forming the lower part of the knee joint and the medial part of the ankle joint.

Tibia Key Landmarks

• Medial and Lateral Condyles: Located at the upper end of the tibia, articulating with the femoral condyles to form part of the knee joint.
• Intercondylar Eminence: A ridge between the medial and lateral condyles that serves as an attachment point for ligaments and menisci of the knee.
• Tibial Plateau: The flat surface on top of the tibia that articulates with the femur.
• Tibial Tuberosity: A bony prominence on the anterior side of the proximal tibia where the patellar ligament inserts.

Tibia Shaft

• Anterior Border: Sharp edge running down the front of the tibia, palpable under the skin.
• Medial Surface: Smooth and subcutaneous, easily palpable on the inner side of the leg.
• Lateral (Interosseous) Border: The border that faces the fibula, where the interosseous membrane connects the tibia to the fibula.
• Soleal Line: Ridge on the posterior surface of the tibia, which is the attachment point for the soleus muscle.

Tibia Distal End

• Medial Malleolus: Prominent projection on the medial side of the distal tibia, forming part of the ankle joint.
• Fibular Notch: A notch on the lateral side of the distal tibia, where the distal end of the fibula articulates.
• Inferior Articular Surface: Smooth, flat surface on the distal end of the tibia, which articulates with the talus bone in the ankle joint.

Tibia Functions

• Essential for weight-bearing, forming part of the knee and ankle joints.
• Provides attachment points for muscles and ligaments crucial for movement and stability.

Tibia Fractures

• Proximal Tibial Fractures: Usually caused by high-energy trauma or low-energy injuries in patients with osteoporosis, often affecting knee alignment. Treatment often involves open reduction and internal fixation.
• Tibial Shaft Fractures: Caused by direct trauma or falls. Treatment typically involves intramedullary nailing.
• Distal Tibial (Pilon) Fractures: Occur near the ankle, potentially affecting the articular surface, possibly leading to developing arthritis. Treatment usually involves ORIF.

Fibula

• The lateral bone of the leg, homologous to the ulna of the forearm.
• Known as a "pin" type of bone.
• Does not participate in weight transmission.

Fibula Key Landmarks

• Head of Fibula: The upper end is rounded, articulating with the lateral aspect of the tibia at the fibular notch.

Explore the intricate details of the human skeletal system, including the axial and appendicular skeleton. This quiz covers the composition, functions, and key components of the bones and joints in the human body, providing a comprehensive understanding of skeletal anatomy.