Part of development and growth of bones. Surfaces for articulating bones. Strong, flexible,
cushioning joint structure
There are three types- hyaline cartilage, fibrocartilage, and elastic cartilage
Consists of chondroblasts which produce a matrix surrounding them. When matrix
surrounds a chondroblast it becomes a chondrocyte (mature cell) which occupy a space
called a lacuna within the matrix.
Cartilage contains collagen, which provides strength, and proteoglycans, which make
cartilage resilient by trapping water.
Surrounding most cartilage is a double layer of connective tissue called the
perichondrium. The outer layer is dense irregular connective tissue containing
fibroblasts. The inner layer has fewer fibers and contains chondroblasts.
Blood vessels and nerves penetrate the outer layer of the perichondrium but do not
enter the matrix, so nutrients must diffuse through matrix to reach the chondroctyes.
Chondroblasts are at the boundary of the perichondrium and the cartilage, along with
stem cells which give rise to chondroblasts
Articular cartilage covers the ends of bones where they come together to form joints to
give a smooth friction free surface so they won’t grind each other down. These get their
nourishment from synovial fluid as opposed to having a pericardium.
• Covers ends of articulating bones in moveable joints
• Strong & flexible
• Costal cartilage – where rib bones join sternum
• Respiratory cartilage – larynx, trachea
• Flexible – external ear, auditory tube
• Great strength, supports a lot of weight
• Intervertebral discs, prevent from cracking and
• Menisci of knee joint, allow menisci of knee joint to provide support and not slip out
• TMJ- Tempomandibular joint, in your mouth when you open and close your jaw 2
Osteoblasts- bone forming cells for repair of fractures, they secrete the matrix(osteoid)
which contains mineral salts that are precipitated
Osteoclasts- responsible for reabsorption, or breakdown, of bone damaged bone during
repair or remodelling of old bone to new. They also release enzymes that digest protein
components of the matrix
More porous and has less bone matrix than compact bone. Consists of interconnecting rods or
plates of bone called trabeculae. Between the trabeculae are spaces that are filled with bone
marrow and blood vessels
thin, consist of several lamellae with osteocytes located in a lacunae (spaces occupied
by osteocyte cell bodies) between lamellae which release and maintain the minerals in
each of the lamella.
Each osteocyte is associated with others through canaliculi. Usually no blood vessels
penetrate the trabiculae, so osteocytes must obtain nutrients through their canaliculi.
Trebeculi develop beginning with woven bone (fetal production and repair of a
fracture), the trabeculae are remodelled as we start walking and then they resist the 3
forces of gravity and become structured differently to compensate for this. They
develop along stress lines. May contain red or yellow bone marrow within cavities
Lamellea- mature bone that’s organized
into sheets or layers called lamellae.
Canaliculi- spaces occupied by the
osteocyte cell processes.
There is no central canal in the spongy
bone because they can receive nutrients
by diffusion as apposed to having blood
vessels in the middle.
Denser and has fewer spaces than spongy bone. Blood vessels enter the substance of the bone
itself, and the lamellae of compact bone are primarily oriented around those blood vessels.
Central canals are lined with endosteum and contain blood vessels, nerves, and loose
Concentric lamellae are the circular layers of bone matrix that surround the canal.
Osteocytes receive nutrients and eliminate waste products through the canal system
within compact bone. Blood vessels from the periosteum enter the bone through
Pass through the concentric lamellae of the osteons.
Central canals receive blood vessels from perforating canals. Nutrients in the blood
vessels enter the central canals, pass into the canaliculi, and move through the
cytoplasm of the osteocytes that occupy the canaliculi and lacunae to the most
peripheral cells within each osteon. Waste products are removed in the reverse
Osteon (heversian system)-
Consists of a single central canal and its contents are lamellae and osteocytes. these
osteocytes are located within the lacunae between the lamellar rings and canaliculi
radiate between lacunae across the lamellae looking like minute cracks across the rings.
All the osteocytes are interconnected by their cytoplasm canaliculi connected by gap
Bone shapes and Structure
Long bones are longer than they are wide, most of the bones of the upper and lower limbs are
Structure of long bones:
Shaft, composed primarily of compact bone, but it can also contain spongy bone.
Primary ossification center for bone formation and growth is located here.