Skeletal System Flashcards
What are the main components of the skeletal system?
Bone and cartilage
What is the role of hyaline cartilage in the skeletal system?
Provides firm support with some pliability
Covers the ends of long bones providing springy pads that absorb compression at joints
What is the structure of hyaline cartilage?
Has cartilage cells (chondrocytes) located within lacunae in the tissue matrix
Vascularized perichondrium surrounds the cartilage, nourishing the tissue and producing new tissue.
What is the role of fibrocartilage in the skeletal system?
Strong and compressible. Found in the knees and discs between vertebrae and pubis
What is the structure of fibrocartilage?
Has rows of chondrocytes alternate with rows of thick collagen fibres.
What are the main functions of the skeleton and of bone?
Support Protection Movement Mineral Storage Blood cell formation Fat storage Hormone production
What are the 4 shapes of bones?
Long bones
Short bones
Flat bones
Irregular bones
Describe the structure of long bones.
Bones that are longer than they are wide. Has a shaft plus two ends
All limb bones are long bones. (named after elongated shape, not overall length)
Describe the structure of short bones.
Cube shaped. The wrist and ankles are examples.
Sesamoid bones are a special type of short bone forms in a tendon.
Describe the structure of flat bones.
Thin, flattened and usually a bit curved.
The sternum, ribs and most skull bones are flat bones
Describe the structure of irregular bones.
Complicated shapes that fit none of the proceedings.
The vertebrae and hip bones are examples.
What are the two types of bone?
Spongey bone
Compact bone
Describe the gross anatomy of a compact bone.
Bone riddled with passageways that serve as channels for nerves, blood vessels and lymphatic vessels
Describe the gross anatomy of a spongey bone.
Bone that aligns precisely along the lines of stress and help the bones resist stress.
What are osteoblasts?
They are the ‘builder’ cells.
Matrix-synthesizing cells that are responsible for bone growth.
Osteoblasts produce calcium to the tissues, calcifying the tissue.
What are osteoclasts?
They are bone-resorbing cells.
Polynuclear, meaning they produce a lot of proteinaceous enzymes and acidic compounds
The cells will push the ruffled border against bony material to digest it away.
What do osteoblasts and osteoclasts work together to do?
They work together to continuously remodel the bone.
What are osteocytes?
Mature bone cells that maintain the bone matrix.
Sit in the lacunae for years acting as sensory cells.
What do bone lining cells do?
Work with and communicate with osteocytes to help regulate remodelling and repair of bony tissue.
What is an osteon?
Group of hollow tubes of bone matrix.
Tiny weight-bearing pillars providing strength.
What is the Haversian canal?
Runs through the core of each osteon. Contains small blood vessels and nerve fibres that serve the needs of the osteon’s cells.
What are Volkmann’s canals?
Canals of a second type called Volkmann’s canals lie at right angles to the long axis of bone and connect the blood and nerve supply of the periosteum to the central canals.
What are interstitial lamellae?
Incomplete lamelle. They fill the gaps between forming osteons
What are circumferential lamellae?
Located just deep to the periosteum.
Resist the twisting of long bone.
What is the chemical make-up of bone?
30% organic (for flexibility and strength)
70% minerals (for hardness)
What is osteoid?
Makes up ~1/3 of bone matrix.
Contribute to bone structure and flexibility. Helps resist stretch and twisting.
Explain why a bone is so tough and has great tensile strength.
A bone’s resilience comes from the presence of sacrificial bones in or between collagen molecules.
The bones break easily on impact, dissipating energy to prevent the force from rising to a fracture value. These bonds can re-form.
What are synovial joints?
Joints in which the articulating bones are separated by a fluid-containing joint cavity.
The arrangement permits substantial freedom of movement, and all synovial joints are freely moveable.
Structure of synovial joint - Articular cartilage.
Glassy, smooth hyaline cartilage covers the opposing bone surfaces as articular cartilage.
The thin but spongey cushions absorb compression placed on the joint.
Structure of synovial joint - Joint cavity.
A feature unique to synovial joints, the joint cavity is really just a potential space that contains smalls mount of synovial fluid.
Structure of synovial joint - Articular capsule.
The joint cavity is enclosed by a 2-layered articular capsule that is tough and fibrous.
Strengthens the joint so the bones are not pulled apart.
Structure of synovial joint - Synovial fluid.
Small amount of slippery fluid occupies all free spaces within the joint capsule. Delivered by filtration from blood flowing through capillaries in the synovial membrane.
Structure of synovial joint - reinforcing ligaments.
Joints are reinforced and strengthened by ligaments.
Structure of synovial joint - Nerves and blood vessels.
Joints are richly supplied with sensory nerve fibres that detect pain and monitor joint position and stretch.
What are the 6 types of synovial joints?
- Ball-and-socket joint
- Hinge joint
- Saddle joint.
- Pivot joint
- Condyloid joint
- Gliding joint
What is the bursae? (Synovial joint accessory structures)
The bursae are not strictly part of synovial joints, but often found closely associated with them.
The bursae are bags of lubricant that reduce friction during joint activity.
What are fat pads? (Synovial joint accessory structures)
Cushioning pads that absorb forces.
A condition called Hoffa’s disease is where this pad swells and gets pinched when the knee moves
What are ligaments? (Synovial joint accessory structures)
Ligaments unit the bones and prevent excessive or undesirable motion.
As a rule, the more ligaments a joint has, the stronger it is.
What are the menisci? (Synovial joint accessory structures)
The medial and lateral meniscus are made of fibrocartilage and act as shock-absorbers of the stresses of walking, running, moving etc….
What are the tendons and tendon sheaths? (Synovial joint accessory structures)
A tendon sheath is essentially an elongated bursa that wraps completely around a tendon subjected to friction.
Common where several tendons are crowded together.
