Skeletal system, bone structure and synovial joint Flashcards
Whats special about the hyoid bone?
- The only bone of 206 that doesn’t articulate (form a joint)
- Forms foundation for voice box and anchor for tongue so is an irregular bone
What is hyaline cartilage?
NOT only bones in skeleton! (Cartilage which is a connective tissue)
- Hyaline found in synovial joints with no perichondrium so it’s very smooth
- Helping freely moveable joints
- Covering end of bones, connecting ribs to sternum, supporting nose in respiratory system
- Providing support and flexibility
What is fibrocartilage?
- Very strong cartilage in skeleton which is compressible
- Role in shock absorption
- E.g., Knees and spine discs between vertebrae and pubis
What are the two divisons of the skeleton?
- Axial – skull and vertebrae column, ribcage and cocksicks – provides central axis and protects most of major organs
- Appendicular skeleton – hanging off axis – pelvic Gerda (lower limbs) and pectoral Gerda (upper)
state main functions of the skeletal system
- Support – body and soft organs
- Protection – brain, spinal cord, vital organs
- Movement – attachment points and levers for muscle action – greater trecento and lessor trochanter – hip joints
- Improving the activity of muscles, tendons and ligaments
- Mineral storage – calcium in the blood for function of brain and found in interstitial liquid
- Hormone storage – growth factors, when broken down by oastioplasts the growth factors are released causing bones to be repaired
- Blood cell formation – haematopoiesis – every 2 hours 8 billion new blood cells created – in bone marrow
- Triglyceride (fat) storage in bone cavities - diathesis (main shaft of the bone) - in yellow bone marrow
- Hormone production – osteocalcin – regulating formation of bones
what are the 5 classifications of bones?
- Long – longer than wide
- Short – wide as they are long
- Irregular – specific and cannot be classified in other groups
- Flat – skull, sternum, flatter
- Sesamoid – embedded in tendon (patella, pisiform (in hand)) - looks like sesame seeds – useful for insertion of tendons
whats a trabeculae?
Between the discs where red bone marrow is found, and blood is made
What is the periosteum?
- membrane covering bones
- sharpey fibres create strong connection between this and the bone as runs in and between – has a very high blood supply - 2 layers
- Fibrous (outer layer)
- Osteogenic (inner) – contains osteogenic cells
What is the endosteum?
- Single layer of cells lining the internal surface of compact bone and cannels
- contains osteogenic cells
- provides nutrients and supports nutrients getting into the bone to be supplied around the bone structure
Name key components of bone cells
- Osteoblast
- Osteoclast
- Osteocyte
- Bone lining cells
What is an osteoblast?
building bone cells – laying down the bone matrix and calcium binding proteins
What is an osteoclast?
- chomper bone cell
- for remodeling
- multinucleate
- a lot larger
- attach to surface of bone due to ruffling structure
- producing enzymes (proteinaceous enzymes) to break down the bone (repaired on the balance between osteoblasts and osteoclast)
What is an osteocyte?
- sitting in a lacuna of the structure of the bone (90% of cells)
- living 25-30 years
- when they die - release signals to stop osteoclasts - more clumps of bones removed
- in old age making bones more brittle osteoporosis)
What is a bone lining cell?
- squamous cells layer
- communicate with osteocytes and is part of the endosteum
- involved in maintaining a source of osteoclasts and osteoblasts
- regulate structure of the bones – but not fully understood
Explain main structure of compact bone (microscopic structure)
- osteons - consentric sylinders of bones set against longitudical axis
- **Haversian canel **– containing blood vessels vertically and volkmanns canels intersept these as they are transverse
- Osteocytes
- cells connected by dendrites – cellular extensions
- canaliculi - making contact so can pass nutrients between oestocytes
What is the process of creating compact bone?
- Osteoblasts secrete bone matrix
- Maintain close contact with each other and other bone cells.
- Mature osteocytes develop as matrix calcifies
- Very fine web of canaliculi formed (Canaliculi—hair-like canals connect lacunae to each other and central canal)
What is an osteon?
- Consentric lamellae of bones (boney tissue)
- **Collagen fibres **rubbing in different directions of osteon depending on layer
- resilience in brittle structure
– allowing bones to conform and resist with twisting forces on the bones
What is the chemical makeup of bones?
- Bone cells and Calcium phosphate makes up hydroxyapatite – mineral crystals
- Minerals – structure – without its extremely plyable – lether – very flexible
- Collagen – slightly bendable – so not brittle – fragile as glass – resilience given
- Work in syncracy to give characteristics of bones
What are spongy bones? How do they differ from other types of bones?
- Made up of trabeculae – little plates and arches
- No osteons
- Irregularly arranged lamellae
- Osteocytes interconnected by canaliculi – making sure its healthy, to communicate with osteoclasts and asteoblasts – to restructure
- Red bone marrow – maintained by oesteoblasts and osteoclasts
What are some key components of synovial joints?
- 2 bones with articular surface at ends – made of **hyaline cartilage **making extremely smooth
- Synovial fluid inside the joint capsule – reducing friction between the cartilage –containing lubracine which lubricates joint also hydrochaloric acid - !!!! – also have nutricals and macrophils – immunity
- Capsule has rich blood supply supplying nutrients which diffuse into cartilage which has no blood or nerve supply – so is reliant
- **Synovial fluid **– produced by synovial membrane
- Fibrous layer – outer tough connective tissue – collagen lots – holding the joint together giving structure (associated with muscles, tendons and other)
- Propioseptivic – nerves from synovial joint allowing us to know when limbs are without seeing them
What is propioseptivic?
nerves from synovial joint allowing us to know when limbs are without seeing them
State the types of synovial joints
- Ball and socket joint (humeroscapular) – gross movement
- Hinge joint (humeroulnar)
- Saddle joint (trapeziometacarpal)
- Pivot joint (radioulnar)
- Gliding joint (intercarpal)
- Condyloid joint (metacarpophalangeal)
State the types of synovial joints
- Ball and socket joint (humeroscapular) – gross movement
- Hinge joint (humeroulnar)
- Saddle joint (trapeziometacarpal)
- Pivot joint (radioulnar)
- Gliding joint (intercarpal)
- Condyloid joint (metacarpophalangeal)
Whats the gross structure of a synovial joint?
- bursae
- fat pads
- ligaments
- menisci
- tendons and tendon sheaths
What is a bursae in synovial joints?
fiberous sacks of synovial fluid between cartilage and tendon – protection – reduce friction and improves level of movement - cushions
What are fat pads in synovial joint?
eg. Infrapatellar (hoffers disease
- when fat pad is pinched between bones)
- they have a lot of nerve tissue
- sensory and store fat
- role to cushion bones
What do ligaments do in synovial joints?
– hold joint together – strong connective tissue stopping dislocation
What does menisci do in synovial joints?
- fibrocartilage
- shock absorb forces and stop dislocation
- lots of collagen fibres
- help congruence (fit of the bones against each other)
What do tendons and tendon sheaths do in synovial joints?
- fluid filled sheaths protecting tendons wearing
- reduce friction between tendons
What is the epiphyseal line?
- band of hyaline developed in childhood
- reflexs growth zone of bone to lengthen
- as we age it calcifies (osephied) becoming regular bone
