Introduction to Bones & Joints Flashcards
Function of the skeleton (3)
- supports body
- gives size and shape
- provides muscle attachment
Contents of skeleton (2) and characteristics.
- Bones - support structures that come in many shapes and sizes
- Joints - between bones that allow movement, many having synovial structures
Biomechanical functions of skeleton (4)
- provides framework - shape and support
- uses joints - allows motion
- provides muscle leverage - mechanical advantage in movement (more efficiency)
- sometimes protect organs - organs are contained within bones
Functional components of skeleton (2); describe what they make up
- Axial - everything along midline: vertebral column, ribcage, skull
- Appendicular - contains forelimb (thoracic) skeleton and hindlimb (pelvic) skeleton
Two parts of axial skeleton (2); describe what they make up
- Cranial: everything in skull
- Post-cranial: everything axial except for skull
What is skeletal tissue derived from?
connective tissue
Types of skeletal tissues (2) - describe each type and give two examples of each.
- Non-mineralized: lack hydroxyapatite
- includes notochord and cartilage - Mineralized: have hydroxyapatite
- includes calcified cartilage and bone
What is the notochord? (3) What does it become in vertebrate adults?
- Rod-like axial support structure
- Source of developmental signaling
- ONLY support system in non-vertebrate chordates
Becomes nucleus pulposus in each vertebral disk
What is cartilage? (1) What is it composed of? (3)
Non-mineralized
- Gel matrix - chondromucoprotein + water
- Collagen or elastic fibers - flexibility
- Chondrocytes (cartilage cells)
What are some characteristics of cartilage? (3)
- No blood supply or innervation
- Flexible - stronger under compression than it is under tension
- Easy to injure and difficult to repair - difficult to get necessary nutrients into chondrocytes; to do so, diffusion through cell matrix must occur
Where does cartilage appear in fetus/juvenile? (1) Where does it appear in adults? (4)
Fetus/juvenile - growth tissue; grows fast because of having surface and interstitial growth
Adults - cartilage in ears, nose, larynx, and joints
What is calcified cartilage? (1) What/where can it be found? (3)
Mineralized - hydroxyapetite in gel matrix; tissue is hard, brittle, and opaque
- Shark vertebrae
- Horse larynx
- Deepest articular cartilage
Characteristics of calcified cartilage (4)
- unorganized microstructure - mineral added between cartilage cells (strengthens)
- stronger than cartilage, BUT repair is more difficult due to hydroxyapetite blocking mineral diffusion
- transitional tissue - towards endochondral ossification
- calcification can be pathogenic!
What type of tissue is bone? (1) What makes it up? (2) Be specific.
Composite tissue
- Organic compounds
- osteoids
- cells - Inorganic components
- hydroxyapatite
- water
What are the osteoids that make up bone made of? (3) How much of the bone weight do they make up?
Type I collagen + bone matrix proteins
- includes osteocalcin
20-25% bone weight
What are the specific cells that make up bone? (3) Describe where each come from.
- osteocytes (most) - bone cells derived from mesenchyme
- osteoblasts - make up bones; derived from mesenchyme
- osteoclasts - break down bones; derived from hematopoietic tissue
How much of bone weight does hydroxyapatite make up?
60-70% of bone weight
What qualities make bone an active, living tissue (4)
- capable of growth which issues at the surface rather than between old bone; bones are remodeled through life!
- can repair injuries
- has blood supply from blood vessels in haversion canals, as well as 5-10% of cardiac output
- has sensory innervation
What are the physiological functions of bone? (4)
- mineral reservoir
- calcium homeostasis
- source of blood cells - bone core contains red marrow where hematopoiesis takes place
- energy source/storage - red marrow is replaced by fat during growth, which forms yellow marrow
What does endochondral ossification (EO) help with? (BROAD)
helps establish hematopoeitic homeostasis
What are the endocrine functions of bone? (1)
release osteocalcin hormone involved in:
1. insulin regulation
2. brain development and function
3. testosterone formation and release
What are the four types of bone shapes?
- long bones
- short bones
- flat bones
- irregular bones
Describe long bones (3). Give examples (1).
- cylindrical
- act as levers
- form from at least three centers of ossification - one diaphysis and two epiphyses
example: limb bones
Describe short bones. (2) Give examples (2).
- no dimension greatly exceeding others
- form from single center of ossification
example: carpal and tarsal bones
Describe flat bones (1). Give examples. (3)
- expanded in two directions
example: many skull bones, scapula, pelvic bones
Give an example of an irregular bone.
cranial elements such as mandible
Describe the external surface of bones. What can the surface be used for?
has numerous elevations (lines, crests/ridges, bumps (tubercles and tuberosities)) and depressions (fossae or grooves (sulci)) - these can be used for attachment sites of various tissues
What are the anatomical regions of a long bone? (4) Describe each region.
- diaphysis - shaft of bone
- growth plate aka physis - cartilaginous, present while bone grows
- metaphysis - contains growth plate
- epiphysis - important for stabilized joints during growth
Internal gross anatomy of bone (5)
- compact bone
- trabecular (“spongy”) bone
- medullary (marrow) cavity
- periosteum
- endosteum
What part of the bone helps to increase surface area?
Trabecular (“spongy”) bone
What part of the bone forms blood?
Medullary (marrow) cavity
What is the function of the periosteum and endosteum that make up bone? Where are each located?
living tissue helping to build and maintain bones
periosteum - outer surface made of two layers
- fibrous outer layer - fibers, elastin, vessels, nerves
- inner osteogenic cell layer
endosteum - thin membrane lining marrow cavity
Describe the complex microstructure of bone.
strong and resilient
- can bend slightly and return
- stronger under compression than concrete or granite
What makes up the mechanoreceptive syncytium of the microstructure of bone?
Lamellae surround the osteocytes that sit in the lacunae. This surrounds the Haversian canal. Each lacunae is connected to adjacent osteocytes by small cellular processes in cacaliculi
What is an osteon? What makes them up? (2) What do they contain? (2)
it is a Haversian system
- Haversian canals
- lamellae
- vessels
- nerves
Where does blood supply and nerve supply enter the bone? (4) Be specific.
- large nutrient artery - enters nutrient foramen in diaphysis
- epiphyseal and metaphyseal arteries supply epiphysis and metaphysis
- capillaries from periosteum and endosteum enter bone
- veins, lymphatics, and nerves accompany arteries
In what ways does the growth plate affect how blood moves through bone? What happens when an organism is done growing?
blood vessels do not cross physis (growth plate), so blood supplies are separated during growth (important in fracture repair)
when physis is closed off, epiphyseal artery and main nutrient artery meet up, creating a collateral blood supply
How does endochondral bone grow? Where is it formed? Where does ossification begin and what is the order? (2)
through endochondral ossification - grows from cartilage precursor
formed in mesenchyme
ossification begins in utero:
- first at diaphysis
- later at epiphysis
What are the two ways that bone can be added to the shaft regarding endochondral bone growth?
- replacement of cartilage - ossification of spongy bone and compact bone is performed to replace it
- conversion of perichondrium to periosteum which lays down compact bone on outer surface
How are periosteal bones formed?
intramembranous ossification
What are some ossification patterns detected in certain species? (2)
- epiphyseal centers form before birth in horses
- epiphyseal centers form after birth in kittens or puppies
Where is endochondral bone found? (3)
- axial skeleton
- limb skeleton
- ventral braincase
How does membrane (dermal) bone grow? (3) What are membrane bones?
- NO cartilaginous precursor
- intramembranous ossification - trabeculae form in membrane (mesenchyme)
- bones grow OUTWARD - growth zone is located at the suture which is the edge of developing bone
Thin, flat bones of skull roof that are derived from neural crest cells
What is a sesamoid bone? What are the functions? (2)
bones that form within tendons
- prevents muscle from deforming as it flexes or extends over bone
- helps improve muscle leverage
How does bond react to load changes or injury in regards to remodeling? (2) What can affect the remodeling rate? (2)
- repairs damage
- adds or removes bone as needed
rate can be affected by nutrition and disease
What performs bone remodeling? How does this occur? What are the stages? (3) Be specific. How often is skeleton replaced by remodeling?
Basic Multicellular Units (BMUs)
release of undercarboxylated osteocalcin (hormone) for remodeling and restrengthening
- resorption - osteoclasts remove bone
- replacement - active osteoblasts form new bone
- resting - osteocytes (trapped osteoblasts) monitor bone health (connected by cannaliculi)
every 10 years
What soft tissue structures hold the skeleton together? (4)
- ligaments
- joint capsules
- menisci
- bursae
What are ligaments? (1) What do they do? (2)
bundles of connective tissue fibers
- connect bones at joints
- permit and limit motion depending on connection to bone
Where are joint capsules found? What do they include? (4)
found at synovial joints - mobile
- synovial fluid
- synovial membrane
- fibrous outer layer
- capsular ligaments
What are menisci? Where are they found?
cartilage “spacers” or “pads”
in some but not all joints
Where are bursae located? What are they? (2) What is their distinction from joint capsules?
near joints but are NOT part of joints
- protective cushions between bone and soft tissue
- synovial membrane and synovial fluid
NOT between bones
How do joints play a part in movement of a skeleton? (2) What are the types of joints? (3)
- shape - determines how joint can move
- mobility - depends on joint’s type
- synovial
- fibrous
- cartilaginous
What are the most mobile joints? What causes them to be this way? What can restrict motion?
synovial joints
lubricated by synovial fluid, allowing smooth motion
amount of motion is restricted somewhat by ligaments
How do flat (plane) joints move?
can only slide
How do barrel shaped (hinge) joints move?
can flex and extend
How do pivot joints move?
allow a bone to pivot on its long axis (like shaking head)
How do ball and socket (spheroidal) joints move?
allow joint to flex and extend, abduct and adduct, pivot, and circumduct
Flexion
reduces angle of joint
Extension
increases angle of joint
Pronation
internal rotation
Supination
external rotation
Abduction
movement away from midline
Adduction
movement towards midline
Overextension
extension of a joint past 180 degrees
Circumduction
movement along a conical surface - moving in a circle
What are the three types of fibrous joints and what do they connect? (3)
- sutures - connect membrane bones to each other (bones in skull roof)
- syndesmoses - connect endochondral bones to each other (between radius and ulna)
- gomphosis - connection between tooth and jaw
Describe motion in fibrous joints and cartilaginous joints. Why is this motion seen?
fibrous - limited motion, joined by connective tissue, so no synovial fluid
cartilaginous joints - connected by cartilage and sometimes CT, so little to no motion is seen
What are the types of cartilaginous joints? (2)
- synchondrosis - connected by cartilage
- growth plates in young, joints between skull and hyoids, or ribs and sternum - symphysis - multiple tissues
- complex sandwich made of bone - cartilage - CT - cartilage - bone
- ex. pelvic, intervertebral, and mandibular symphysis (connect sides together at midline)
What can affect the components of the skeleton? (3)
Diseases, injuries, and genetics
