Osteons tube like structural units of the compact

Osteons: tube-like structural units of the compact bone
● Concentric lamella: ‘rings’ of bone that form the osteons
● Central canal: also called Haversian canal, they are tube-like openings
in the osteons that contain blood vessels
● Transverse canals: tiny canals that connect between the central canals
● Osteocytes: living bone cells
● Lacunae: small spaces in the compact bone that house bone cells
● Canaliculi: tiny canals that connect the lacunae with each other and
with the central canals
Joints
Where two bones meet is called an articulation or a joints
Types of joints are:
● Synarthrotic (immovable) joints

● Amphiarthrotic (slightly moveable) joints
● Diarthrodial (freely movable) joints (most common)
Cartilage is a cushion that provides protection for joints.
Types of cartilage are:
● Hyaline: most common; moderate amount of collagen fibers; found in
the trachea, nose, epiphyseal plate, articular surfaces of bones
● Elastic: contains both collagen and elastin fibers; more flexible than
hyaline cartilage; found in ears and larynx
● Fibrous: mostly collagen fibers; tough; most often used to absorb
shock; found between the vertebrae, pelvic girdle, knee, and shoulder
● Tendons attach muscles to bones.
● Ligaments connect bones to bones.
● Superficial fascia lies immediately under the skin
● Deep fascia is a dense, fibrous tissue that surrounds muscle bundles,
nerves, and blood vessels
● Fascia provides strength to muscle tissues
Bursae are small sacs of connective tissue lined with synovial membrane.

● Contains viscous synovial fluid
● Located at bony prominences or joints to relieve pressure and
decrease friction between moving parts (e.g. patella, olecranon
process)
Functions of the Musculoskeletal System
● Support and protection:
○ Sternum and rib cage protects the heart, lungs, kidneys, and liver
○ Skull protects the brain
○ Spine protects the spinal cord
● Voluntary body motion
○ Bones provide a base for the muscles, tendons, and ligaments to
attach for movement.
○ Muscles are attached to bones with tendons.
○ Muscles shorten when they contract and lengthen when they
relax. This contraction and relaxation of muscles creates
movement of the movable skeletal joints.
● Hematopoiesis and fat storage:
○ Red bone marrow is inside some of the cavities of the bone. Red
marrow produces erythrocytes, platelets, and most leukocytes.