Skeleton, bone bio and joints Flashcards
week 4
What makes up 2/3 of the Extracellular matrix and proved 65% of compression strength?
inorganic components of the ECM
Osteoprogenitors
mesenchymal stem cells
found in endosteum and periosteum
mitotically products stem cells
What are the four types of bone cells?
Osteoprogenitors
Osteoblasts
Osteocytes
Osteoclasts
What is the function of osteocytes and osteoblasts?
Osteoblasts – form bone matrix and bone deposition
Osteocytes – maintain matrix and communicate
What is the structure and function of osteoclasts?
large, multinucleate cells that dissolve in bone and release Ca.
What type of bone makes up the internal and external surfaces of the bone respectively?
internal = cancellous/ spongy
external= compact
Osteon
Basic unit of compact bone
= cylinders arranged parallel to each other
What are the canalicului and what do they allow?
little canals in ECM between lacunae. Contain slender osteocytes= communication and exchange of nutrients and wastes.
Perforating (volkmann’s)
perpendicular connections to central canal.
What are the three main canals of compact bone?
Central canal
Cannaliculi
Perforating
Do compact or cancellous bones contain osteons?
Compact
Diaphysis
Elongated cylindrical shaft, surrounds medullary cavity
Mostly compact bone
Epiphysis
Knobby, enlarged regions
Mostly spongy
Metaphysis
Flared region between epi and diaphysis
Articular cartlidge structure and function
Thin layer of hyaline Cartlidge covering epiphysis
Reduces friction and absorbs shock
Medullary cavity structure and function.
Hollow, cylindrical space in diaphysis
lightens bone
Periosteum
CT surrounding diaphysis
covers most external surafces
Endosteum
thin membrane lining medullary cavity
covers most internal surfaces
Periosteum function
Anchor for blood vessels and nerves
Contains osteoprogenitor cells and osteoblast = active remodeling, growth and fracture repair.
Endosteum function
covers internal surafces
Contains osteoprogenitor cells, osteoclasts and osteoblast = active remodeling, growth and fracture repair.
What is ossification and when does it occur?
formation and development of bone
8th wk of development –> adulthood
What are the two patterns of ossification?
Intramebrous ossification
endochondral ossification
What does intramembranous ossification arise from and produce?
from mesenchyme cells
= flat bones, skull, facial bones, mandible and central portion of clavicle.
What does Endochondral ossification arise from and produce?
Begins with hyaline Cartlidge model
Produces majority of bones in body
What are the first three stpes of Endochondral ossification and when do they occur?
In utero
Hyaline Cartlidge template formed by
Cartlidge template continues to grow
Primary ossification center appears:
What are the 4th and 5th steps of Endochondral ossifcation and when does it occur?
Birth
Formation of medullary cavity: elongation of osteoclast action of trabeculae, Diaphyseal wall become compact bone
A secondary ossification center appear
What is the 6th step of Endochondral ossification and when does it occur?
postnatal
hyaline Cartlidge forms at growth plate (allows for growth until late adolesence)
Describe the deposition of osetoblasts
Osteoblasts produce and secrete organic component (osteoid) which undergo mineralization = mature bone
Large GA = involved in much secretion
when bone formation ends, what happens to the osteoblasts?
They mature into osteocytes
What are the two aspects of bone remodeling?
Deposition by osetoblasts
Bone reabsorption by osteoclasts
what does bone reabsorption create?
Howships lucuna
What is osteoporosis and what bone type does it affect first?
Bone resorption (osteoclasts) outpaces deposition (osteoblasts)
Affects cancellous bone first
What are the four overall steps in bone repair?
Hematoma formation
Fibrocartilaginous callus formation
Bony callus formation
Bone remodelling
What occurs during hematome formation?
Broken blood vessels hemorrhage
Clotted blood accumulates and bone cells start to die
What occurs during fibrocartilaginous callus formation?
Callus splint ends
New capillaries
Phagocytes clean up dead tissue, fibroblasts, chondroblasts and osteoblasts begin reconstruction.
What occurs in bony callus formation? and how long does it take?
Hard callus
Bone trabeculae form (about 2 months)
what occurs in bone remodelling of a fracture and how long does it take?
Excess bone removed
Compact bone made from shaft walls
Many months to complete
What is an impacted fracture?
impacted ends of the bone jammed together
What does angulation refer to?
angle of bones relative to eachother
Displacement
% bone not touching eachother
what must be mentioned when describing a fracture?
Bone
open/ closed
location
type
length
angulation
rotation
displacement
What are the three structural classifications of joints?
Fibrous
Bones held together by collagen fibres
Cartilaginous
bones held together by cartilage
Synovial
Bones have a synovial cavity and are joined by dense irregular CT
What are the three functional classifications of joints
Synarthroses
Immobile joints
Amphiarthroses
Slightly mobile joints
Diarthroses
Freely mobile joints
What are the three types of Fibrous bones?
Sutures: thin later of DFCT between skull bones
Interosseous membranes: a sheet of dense irregular CT spans two bones
Syndesmoses: wider distance between two bones.
What are the two types of cartilaginous joints?
Synchondroses: hyaline cartilage connects bones (e.g. epiphyses)
Symphyses: Hyaline cartilage + fibrocartilage connects bones (e.g. pubic symphysis)
What is the purpose of a inner synovial membrane?
Lubricates and nourishes articular cartilages
Absorbs shock during compression of joint
What type of CT does the outer fibrous layer have and why?
Dense irregular CT = strengthens joint
What is synovial fluid?
From blood in synovial membrane
In all free spaces within joint and articular cartilage
What is the function of synovial fluid?
Function: Weight bearing, reduces friction and supplies oxygen and nutrients and removes wastes from underlying cartilage.
Role of Hyaline in Articlar capsule
Articular surfaces in synovial joints covered by hyaline cartilage (prevents bone-bone)
Tough, flexible and resilient = cushioning and support
What type of CT is in ligaments and what is the function of a ligament?
Join bone- bone = helps stabiles joints
Dense regular fibrous connective tissue
Name two synovial joint accessories and their functions.
Bursae: sac outside of synovial joint where ligaments, muscles, tendons and bones rub up.
Tendon Sheaths: elongated bursae around tendons where tendons rub each other. Especially in wrist and ankle.
How are synovial joints functionally classified?
number of movements: uniaxial (one plane), biaxial or multiaxial.
How are synovial joints structurally joined?
shape of articular surfaces
What are the 6 types of synovial joints?
Plane joints
Hinge joints
Pivot joints
Condylar joints
Saddle joints
Ball-and-socket joints
Describe the structural and functional classification, movement and example of a plane joint
Functional: Biaxial (most) or multiaxial
Movement: Gliding/sliding (Side-side, back-forth and sometimes rotary)
Structural Articulated surface = flat/slightly curved
Example: intertarsal joints
Describe the structural and functional classification, movement and example of a Hinge joint
Uniaxial diarthrosis
Convex surface, fits on concave surface
Flexion and extension
Elbow joint
Describe the structural and functional classification, movement and example of a pivot joint
Biaxial diarthrosis
Rounded or pointed surface
Fits into ring from bone/ligament
Rotation
Radioulnar joints
Describe the structural and functional classification, movement and example of a condyloid joint
Biaxial diarthrosis
Oval shaped
Fits into oval depression
Flexion, abduction, extension and adduction
Radiocarpal joint
Describe the structural and functional classification, movement and example of a saddle joint
Biaxial diarthrosis
Saddle shaped
-surface of bone it sits in = saddle
Flexion, extension, abduction, adduction
First carpometacarpal
Describe the structural and functional classification, movement and example of a ball and socket joint
Triaxial diathrosis
Ball-like surface fits in cup like depression
Flexion, extension, abduction, adduction and rotation
Hip joint/ shoulder joint
What demands does the upper limb meet?
movement and strength
What demands does the lower limb meet?
stability and movement
What determines the strength and mobility of a joint?
- the length and location ofl igaments
- the shape of bone ends and bony congruity
What is the function of Osteoprogenitors?
mitotically produce more stem cells or osteoblasts
What is the function of osteocytes?
maintain matrix and communicate between osteoblasts = further deposit of bone matrix
what is the function of osteoclasts?
dissolve bone to release Ca
where do bones grow from lenght?
Bone grows in lengths from epiphyseal plate
what is it called when bone grows in width?
appositional growth (osteoblast and osteoclast action)
How does osteoporosis affect the bone?
Trabeculaw becomes free standing (cannot transmit / withstand same mount of force)
