Draft:Blood vessels and nerves in compact bone

In the beginning Vascular supply is crucial for bone health, providing oxygen, nutrients, and regulatory factors, and removing waste products. Bone receives 10% of cardiac output, allowing higher cellularity, remodeling, and repair than cartilage.

Bone tissue is divided into compact and spongy types, with three types of cells contributing to bone homeostasis: osteoblasts, osteoclasts, and osteocytes, ensuring equilibrium.

Healthy long bones' main blood supply comes from principal nutrient arteries, perfusing medullary sinusoids and exiting via small veins. Cortical bone is perfused by a mixture of nutrient and periosteal arteries, largely centrifugal.

Blood supply and innervation to compact bone
Through the Haversian canal, mature, compact bone receives blood supply. Individual lamellae create concentric rings surrounding larger longitudinal canals (about 50 m in diameter) within the bone tissue, which results in the formation of Haversian canals. Haversian canals normally follow the long axis of the bone and run parallel to the surface. A Haversian system or an osteon is the name given to the canals and the lamellae (8–15) that surround them. One or two capillaries as well as nerve fibers are often present in a Haversian canal. Along with communicating with osteocytes in lacunae through canaliculi, the Haversian canals also surround nerve cells throughout the bone.

Volkmann's canals are vital blood and nerve supply channels from the periosteum to the Haversian canal. They are facilitated by one or two main diaphyseal nutrient arteries entering the shaft through nutrient foramina, with entry and angulation sites being constant.

90% of long bones have a single nutrient foramen in the middle third of the shaft, with nutrient arteries dividing into ascending and descending branches in the medullary cavity. These branches approach the epiphysis, dividing into smaller rami and anastomosing with metaphyseal and epiphyseal arteries near the epiphysis. The blood supply of immature bones is similar, but the epiphysis is a discrete vascular zone separated from the metaphysis by the growth plate

Both of these sources as well as an anastamotic collar in the nearby perichondrium supply blood to the growth cartilage. Compared to mature periosteum, young periosteum is more vascular, has more metaphyseal branches, and has more open communication with the shaft's arteries.

links

 * Bone.
 * Haversian canal.
 * Blood vessel.