Anatomy of Long Bones

Blood Supply to Long Bones

• A typical long bone has three separate blood supply systems: nutrient artery, periosteal vessels, and epiphyseal vessels.

Nutrient Artery

• Passes through the cortex into the medullary cavity
• Ramifies outward through haversian and Volkmann canals to supply the cortex
• Nourishes primarily the diaphysis and metaphysis

Periosteal Vessels

• Extensive vessels in the periosteum (membrane surrounding the bone)
• Supply the superficial layers of the cortex
• Connect with the nutrient-artery system
• Capable of meeting the needs of both systems in case of nutrient artery obstruction

Epiphyseal Vessels

• Form a ring of arteries entering the bone between the growth plate and joint capsule
• Supply the epiphyses
• No connection with the other two systems while the growth plate is open, making them the sole source of nutrition for growing cartilage
• Essential for skeletal growth
• In adults, connect with the other two systems at the metaphyseal-epiphyseal junction

Blood Drainage

• Veins run parallel with the arterial supply
• Veins leave the cortical periosteum through muscle insertions
• Muscle contraction causes centrifugal flow from the axial nutrient artery through the cortex and out through muscle attachments

Blood Supply to Long Bones

• A typical long bone receives blood from three separate systems: nutrient artery, periosteal vessels, and epiphyseal vessels.
• The nutrient artery supplies the diaphysis and metaphysis, passing through the cortex and into the medullary cavity, then branching out through haversian and Volkmann canals to supply the cortex.

Nutrient Artery System

• The nutrient artery is the primary source of blood supply to the diaphysis and metaphysis.
• In the event of obstruction, periosteal vessels can compensate for the nutrient artery system.

Periosteal Vessels

• Extensive vessels in the periosteum supply the superficial layers of the cortex.
• These vessels connect with the nutrient artery system.

Epiphyseal Vessels

• The epiphyses have a separate system of blood supply, consisting of a ring of arteries entering the bone between the growth plate and joint capsule.
• In adults, these vessels connect with the nutrient artery and periosteal vessels at the metaphyseal-epiphyseal junction.
• In growing bones, epiphyseal vessels are the sole source of nutrition for the growing cartilage, making them essential for skeletal growth.

Blood Drainage

• Blood drainage occurs through a system of veins parallel to the arterial supply.
• Additional veins drain blood from the cortical periosteum through muscle insertions.
• Muscle contraction helps to push blood outward, creating a centrifugal pattern of flow from the axial nutrient artery through the cortex and out through muscle attachments.