Intro to Bone and Soft Tissue Flashcards
What is the purpose of cartilage?
- structural support
- protect tissues
- attachment sites
How many bones are there n the adults compared to children?
-206 in adults and 270 in children
What is the appendicular skeleton comprised of?
- pectoral girdle
- upper and lower limbs
- pelvic girdle
What is the axial skeleton comprised of?
- cranium
- vertebral column
- rib cage
What are the 5 main functionsof the skeletal system?
- movement
- support
- protection of vital organs
- calcium storage
- haematopoesis
What are the classifications of bones by shape?
- flat
- short
- sesamoid
- long
- irregular
- sutured
What type of connective tissue connects bone to bone?
-ligament
What type of one is the patella?
-sesamoid
What are osteogenic cells?
-bone stem cells
What are osteocytes?
- mature bone cells
- formed when osteoblasts become embedded in its secretions
- sense mechanical strain to direct osteoclast and osteoblast activity
What are osteoblasts?
- bone forming
- secrete osteoid
- catalyse mineralisation of osteoid
What are osteoclasts?
- bone breaking
- dissolve and resorb bone by phagocytosis
- derived from bone marrow
Where are osteocytes found?
-embedded in matrix
Where are osteoclasts found?
-bone surfaces and at sites of old, injured or unneeded bone
Where are osteogenic cells found?
-deep layers of periosteum
Where are the osteoblasts found?
-growing portions of bones, including periosteum and endosteum
What is the bone matrix made up of?
- Organic component (40%) :
- Type 1 collagen (90%)
- Ground substance (10%) - proteoglycans, glycoproteins, cytokine and growth factors - Inorganic component (60%):
- Calcium hydroxyapatite
- Osteocalcium phosphate
Tell me about immature bone.
- first bone that is produced
- laid down in a ‘woven’ matter - relatively weak
- mineralised and replaced by mature bone
Tell me about mature bone.
- mineralised woven bone
- lamellar (layer) structure - relatively strong
What are the types of mature bone?
- Cortical (stronger):
- compact, dense
- suitable for weight bearing - Cancellous:
- ‘spongy’ - honeycomb structure
- not suitable for weight-bearing
How do the structure of cortical and cancellous bone differ?
- Cancellous have trabeculae (matrix of inorganic tissue)
- Cortical has lacunae, mineralised matrix and
Tell me about the structure and organisation of compact bone.
- few spaces
- provides protection, support and resides stresses produced by weight of movement
- repeated structural units ‘Osteons’ - concentric ‘lamellae’ around a central ‘Haversian canal’
What is the Haversian Canal?
- found in compact bone
- contains blood vessels, nerves and lymphatics
What are lacunae?
- found in compact bone
- small spaces containing osteocytes
- tiny canaliculi radiate from lacunae filled with extracellular fluid
What is the volkmans canal?
- found in compact bone
- transverse perforating canals
What is intramembranous ossification? (flat sheets)
-bone development from fibrous membranes
-forms flat bones of skull, clavicle and mandible
-mesenchymal cell template
-
1.condensation of mesenchymal cells which differentiate into osteoblasts- ossification centre forms
2. secreted osteoid traps osteoblasts which become osteocytes
3. trabecular matrix and periosteum form
4. compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
What is endochondral ossification? (cartilage precursor)
- development of long bone from a hyaline cartilage model
- takes longer than intramembranous ossification
Bone collar formation Cavitation Periosteal bud invasion Diaphysis elongation Epiphyseal elongation
What is the primary ossification centre?
-diaphysis
What is the secondary ossification centre?
-epiphysis
What is interstitial growth?
-long bone lengthening
Epiphyseal plate:
- zone of elongation in long bone
- contain hyaline cartilage
- epiphyseal side- hyaline cartilage active and dividing to form hyaline cartilage matrix
- diaphyseal side- cartilage calcifies and dies and then replaced by bone
What are the zones/sections of the epiphyseal plate?
- growth plate zone
- reserve zone (matrix production)
- proliferative zone (mitosis)
- maturation and hypertrophy (lipids, glycogen and alkaline phosphatase accumulate; matrix calcifies)
- calcified matrix (cell death)
- zone of ossification (primary and secondary spongiosa)
What is the periosteum?
-outside covering of the bone
What is appositional growth?
-deposition of bone beneath the periosteum to increase thickness
What is the process of appositional growth?
- ridges in periosteum create groove for periosteal blood vessel
- periosteal ridges fuse, forming an endosteum-linked tunnel
- osteoblasts in endosteum build new concentric lamellae inward toward centre of tunnel, forming a new osteon
- bone grows outwards as osteoblasts in periosteum build new cirucmferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessel.
What is the role of bone in calcium homeostasis?
- when body needs Ca, parathyroid hormone and vitamin D causes breakdown of bone
- OR calcitonin causes decreased osteoclast activity to reduce Ca levels
What are tendons?
- attaches skeletal muscle to bone
- transmit muscle force to bone
- made of collagen fibres
- stiff and strong
- collagen fibres arranged in bundles
What are the functions of tendons?
- transmit muscle force
- elastic energy storage/recoil
- PG resists compressive stresses
What is the microstructure of tendons?
-water, collagen, elastin, proteoglycans, inorganic components
What is collagen?
- most abundant protein in the human body
- lon, rigid structure
- three polypeptides (alpha chains) T1, T2, T3
- rope-like triple helix
- crimping of fibres
- non-elastic behaviour
- fibre component of connective tissue
Which type of collagen is found in skin, vessel walls and reticular fibre?
-Type III
Which type of collagen is found in tendons, ligaments and bone?
-Type I
Which type of collagen is found in cartilage?
-Type II
What are ligaments?
- connects bone to bone to stabilise joints
- enables proprioception (awareness of movement)
- prevent excessive movement that could damage joints
- have functional subunits that tighten or loosen depending on joint position
- not densely innervated or vascularised
- contain some blood vessels and nerves in outer covering (epiligament)
- contain proprioceptors
- transmit pain signals via type C fibres
What is proprioception?
-the ability to know where the joints are in space (whether they are flexed or extended)
What do ligaments consist of?
- 90% T1 collagen (strong)
- 10% T3 collagen (immature, greater proportion in healing tissue)
- 1% fibroblast cells (cells that produce collagen)
What is hyaline ?
-shiny, smooth, translucent surface of bone
What is cartilage?
- acts as shock absorber to reduce friction
- covers and protects long bones at joints
- structural component of ribs & IV discs
- made up of chondrocytes- produce large amounts of collagenous ECM, ground substance
-avascular and worn down in oseoarthiritis
What are chondrocytes?
-a cell which has secreted the matrix of cartilage and become embedded in it.
What are the types of cartilage?
- elastic
- hyaline
- fibrocartilage
Which type of cell is responsible for bone resorption?
-osteoclasts
What are the classifications of joints?
- fibrous- very stiff
- cartilaginous- bit stiff
- synovial- not stiff
Where exactly are fibrous (synarthrosis) joints found?
- in the skull
- sutures
- syndesmosis
- interosseous membrane
Where are cartilaginous (amphiarthrosis) found?
- synchondroses
- symphyses
Where are synovial (diarthrosis) joints found?
-plane (e.g between C1 and C2 vertebrae)
-hinge (e.g elbow)
-condyloid (e.g between radius and carpal bones of wrist)
-pivot (e.g between tarsal bones)
-saddle (e.g between trapezium carpal bone and 1st metacarpal bone)
-ball & socket (e.g hip joint)
(-have synovial that lines the capsule)
What are synovial joint?
- most common type of joint
- most mobile type of joint
Joint capsule:
- articular capsule (outer)- keeps bones together structurally
- synovial membrane (inner) - contain synovial fluid
What is the purpose of synovial fluid?
-reduces friction during movement
Are tendons or ligaments more elastic?
-ligaments are more elastic than tendons
What effect do more ligaments and tighter ligaments have on stability and mobility?
- greater stability
- less mobility
(trade off between stability and mobility)
What effect do fewer ligaments and laxer ligaments have on stability and mobility?
- less stability
- greater mobility
(trade off between stability and mobility)
What is poor joint stability bad?
-increased risk of dislocation
Why is excessive ligament laxity bad?
-hypermobility = greater risk of injury
Which factors affect joint stability?
- joint shape e.g hip vs shoulder
- ligaments
- tendons
- cartilage (e.g glenoid labrum)
Compare the stability of hip vs shoulder.
Hip:
- complete fit- deep socket
- strong joint capsule
- strong network of ligaments
- supported by muscles
- stable
- less mobile
Shoulder:
- mismatch- shallow socket
- weak joint capsule
- lacks strong ligaments
- rotator cuff dependent (no muscles)
- unstable
- extremely mobile
Why might gymnasts and dancers be more prone to ligamentous injury?
(-they’re more flexible, more elastic)
-excessive ligament laxity & overuse
=hypermobility
=greater risk of injury
What features of the shoulder joint make it more prone to subluxation/dislocation than the hip joint?
- shallow socket
- weak joint capsule
- lack of strong ligaments
- greater mobility
lecture slides
https://d3c33hcgiwev3.cloudfront.net/Q8Lf_FZMR4OC3_xWTGeDbA_9922fdf3079340e8b4aa9349d95424fb_2Final_MSK_LE01Introduction-to-Bone-and-Soft-Tissue-SV_v2.pdf?Expires=1580774400&Signature=dTxLeBLrbIY4PzJG8pFfqk0E21czXvn2J36G3fWlHRbWgQNzAbj6YyvvQdIsSAUWHhAdNRqOBRWWnQQvZJAwUnn-v137d3kLLwmQ9iX1osrusp3Xn6zZIvYdrmRpte6IVY2rfvyWL4uzgfIDnbYD4jMvTzVcm0YrgTvk42NemRg&Key-Pair-Id=APKAJLTNE6QMUY6HBC5A
