Blood supply of long bone 

•  Blood supply of long bone accounts for 5 to 10 % of the cardiac output.
•   Long bone receives blood supply from various sources-  

1. Nutrient arteries
2.  Epiphy­seal arteries
3. Metaphyseal arteries
4. Periosteal arteries.   

   

  

Arterial Supply 

1. Nutrient artery :   

•  One or two diaphyseal nutrient arteries enter the shaft through nutrient foramina.
•   In the medullary cavity, the nutrient arteries divide into ascending and descending branches.
• Each branch divides into number of small parallel channels, after reaching the epiphysis they divide repeatedly into small rami which pursue spiral courses.
•  Near the epiphysis, they are joined by metaphyseal and epiphyseal arteries. 
•   Primary direc­tion of the blood flow is centrifugal. 

 2. Epiphyseal arteries  : 

•   When articular cartilage and epi­physeal cartilage are continuous, the epiphyseal arteries pierce the epiphyseal cartilage and supply the epiphysis.
•  If these arteries are damaged in epi­physeal separation, avascular necrosis of epiphysis may occur, e.g. head of the femur.
• In others, where the articular cartilage is not continuous with epi­physeal cartilage, the epiphyseal arteries enter the epiphysis without piercing it.
• In these cases, epi­phy­­seal separation will not cause avascular necrosis.
•   Epiphyseal arteries are derived from the peri­arti­­cular vascular arcades.
•  Out of many vascular foramina near epiphysis, very few admit arteries and rest are venous exits.
•  Epiphyseal arteries anasto­mose with metaphyseal and nutrient arteries after fusion of diaphysis and epiphysis.

3. Metaphyseal arteries : 

• Numerous small blood ves­sels arising from the anastomosis around the joint pierce the metaphysis along the attachment of the joint capsule.
• Metaphyseal arteries freely anas­to­­mose with spiral branches of nutrient arteries, so metaphysis is the most vascular area of the long bone.

4. Periosteal arteries : 

•  Many blood vessels anasto­mose beneath the periosteum and enter the Volkmann’s canal and supply the outer third of the compact bone.
• Periosteal arteries penetrate bone at these sites where fascial sheath or aponeurosis gain attachment to the shaft. 

                              Long bone blood supply 

Venous Drainage : 

 Valveless nutrient veins accompany the arteries.

·     In medullary cavity, a central venous sinus is present which is served by radial collecting sinuses.

·     The general layout is fan-shaped with cortical sinusoids radiating outwards towards periosteal surface.

·     Each haversian canal is supplied by a solitary sinusoid.