Anatomy and composition of bone & cartilage Flashcards
Compact bone is also known as
Cortical bone
What is the anatomical name for the bone’s shaft?
Diaphysis
Metaphysis
flared region of the long bone adjacent to the epiphysis
Epiphysis
rounded end of the long bone
Cancellous bone is also known as
trabecular or spongy bone
Bones can be classified by
- where they occur
- how they form
- what shape they are
How to classify bones based on where they occur
- Axial skeleton
- Appendicular skeleton
- Visceral bones
Axial skeleton
Bones that form the axis of the skeleton e.g. bones of head, neck, vertebral column, ribs, pelvis, tail
Appendicular skeleton
Regions that are attached e.g. bones of the forelimbs and hindlimbs
Visceral bones
Bones that develop in the soft tissues away from the rest of the skeleton.
Types of bones (shape)
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Sesamoid bones
- Pneumatic bones
What is the periosteum?
Bone producing membrane: fibrous on outside, cellular on inside
Useful for membranous ossification
Provides blood supply for and protects actively growing bone
What is interstitial growth?
Internal expansion
How do bone and cartilage differ in terms of growth?
Cartilage can undergo interstitial expansion which bone cannot.
Vasculature of cartilage
Cartilage is avascular
Innervation of cartilage
Cartilage is aneural
Types of cartilage
- Hyaline/articular
- Fibrocartilage (white cartilage)
- Elastic (yellow cartilage)
What can be said about the types of cells that exist within different cartilage types?
All cartilage types contain chondrocytes.
Hyaline and elastic contain chondroblasts also.
Fibrocartilage contain fibroblasts.
When bone is laid down, two types form one after the other. What are they?
- Woven bone: random orientation of collagen fibres, laid down first & quickly; immature
- Lamellar bone: organisation of collagen fibres, laid down second; mature
What are osteoprogenitor cells and what is their function?
Mesenchymal cells located in the bone.
Capable of self-renewal, proliferation, osteogenic differentiation.
Secrete bone matrix.
What is the function of osteoblasts?
Role in bone formation
Secrete Type 1 collagen and bone matrix proteins
What are the histological featurs of osteoblasts?
Cuboidal and polygonal cell shapes
What are osteocytes?
Once osteoblasts have been surrounded by ECM, they become known as osteocytes.
What is the role of osteocytes?
Can participate in matrix degradation
What are the histological features of osteocytes?
Sit within lacunae
Have interconnecting canaliculi
What are osteoclasts and what is their function?
Cells involved in bone resorption
Present where bone is being removed, remodelled or damaged
*originate from different cell type to other bone cells*
What are the histological features of osteoclasts?
Multinucleate cells
Structure of periosteum
Fibrous on the outside - dense connective tissue
Cellular on inside - osteoprogenitor cells
Describe the functional adaptatios of the long bone
- Cortical bone provides rigidty, resists compression
- Expanded ends enable transfer of load
- The bone acts as a lever, resisting tension during muscle contraction
What is the function of the medullary cavity?
Source of mesenchymal stem cells
What is the endosteum?
Thin vascular membrane of connective tissue; lines the medullary cavity
What is the function of tubercles, trochanters and tuberosities?
Muscle/ligament/tendon attachment
What is the function of fossae?
Positioning and seating for ligaments
What is the function of condyles and epicondyles?
Articulation and muscle/tendon/ligament attachment
What does this image show?
The general structure of hyaline cartilage
Describe the circled structure
Chondrocytes stained with an H&E stain
There are two chondrocytes in an isogenous group
They have pale cytoplasm and darkly staining nuclei
Between the two cells and in a small radius around them the background is darker staining than in the rest of the image, indicating territorial matrix
What type of cartilage is shown in this image?
Hyaline
What is the function of hyaline cartilage?
- Resist compression
- Provide cushioning
- Smooth, low-friction surface for joints
- Structural support (e.g. respiratory system)
- Precursor to bone in embryonic skeleton
- Centre of chondral ossification
- Withstands and distributes load
What types of cells does hyaline cartilage contain?
Chondroblasts
Chondrocytes
What does the ECM of hyaline cartilage contain?
Type II collagen fibrils
Aggrecan monomers
Which types of cartilage undergo calcification?
Hyaline and fibrocartilage
NOT ELASTIC
When does hyaline cartilage undergo calcification?
In endochondral bone formation
During the aging process
Perichondium
Connective tissue that envelops cartilage when it is not at a joint
Is there a perichondium present in hyaline cartilage?
Yes but not at articular cartilage or epiphyseal growth plates
Where is hyaline cartilage found?
- Foetal skeletal tissue
- Epiphyseal plates
- Synovial joints
- Costal cartilage
- Rings of trachea
What is the function of elastic cartilage?
- Provides flexible support for soft tissues
- Structural support - keeps tubes open but flexible
What cells does elastic cartilage contain?
Chondroblasts
Chondrocytes
What does the elastic cartilage ECM contain?
Type II collagen fibrils
Elastic fibres
Aggrecan monomers
Does elastic cartilage undergo calcification?
NO
Is a perichondium present in elastic cartilage?
Yes
Where is elastic cartilage found?
- Pinna of external ear
- Eustachian canals
- Larynx
What is the function of fibrocartilage?
- Resists deformation under stress
- Tough support: provides great tensile strength
- Ligament/tendon and bone interface; lines surface of bony grooves for tendon
What cells does fibrocartilage contain?
Fibroblasts
Chondrocytes
What does the ECM of fibrocartilage contain?
- Type I and II collagen fibres
- Proteoglycan monomers: aggrecan and versican
When does calcification of fibrocartilage occur?
Calcification of fibrocartilage callus occurs during bone repair
Is a perichondium present in fibrocartilage?
No
Where is fibrocartilage found?
- Intervertebral discs
- Pubic symphysis
- Articular discs
- Menisci
- Insertion of tendons
What is the name of this feature?
Osteon: concentric bone rings surrounding a Haversian canal.
What is the name of this feature?
Haversian canal
What is the name of this feature?
Lacuna
What is the name of this feature?
Canaliculis (pl. canaliculi)
What is this feature called? What does it contain?
Haversian canal
Contains blood vessels, nerves, lymphathics
What are these features called? What do they contain?
Canaliculi
Contain cytoplasmic processes of osteocytes
What is this feature called? What does it mark?
Cement line
It markes the boundary of an osteon
Discuss the differences between bone and cartilage
- Bone has a vascular and neural supply whereas cartilage is avascular and aneural
- Cartilage is able to undergo interstital expansion but bone cannot
- Cartilage is still capable of dividing in the matrix; bone cannot divide once surrounded by matrix
- Bone contains mostly Type I collagen, cartilage contains mostly Type II (1 in fibrocartilage)
