A+P Lecture 1 Flashcards
Describe axial skeleton
- Long axis of the body
- Skull, vertebral column, rib cage
- surrounds our CNS
Describe long bones
- Longer than they are wide
- Limb bones
- where we house a lot of our bone marrow
Describe appendicular skeleton
- Bones of upper & lower limbs
- Girdles attaching limbs to the axial skeleton
- think appendices
Functions of the Msk system
- Support: for body & soft organs
- Protection: brain, spinal cord & vital organs
- Movement: levers for muscle action
- Mineral & growth factor storage: Ca++ & phosphorus, & growth factors reservoir
- Blood cell formation(bone marrow)
- Hematopoiesis occurs in red marrow cavities of certain bones
- Triglyceride (fat) storage and use as an energy source
- Hormone production
- Osteocalcin secreted by bones helps to regulate insulin secretion, glucose levels, & metabolism
Describe flat bones
- Thin, flat, slightly curved
- Sternum, scapulae, ribs, most skull bones
Describe short bones
- Cube-shaped bones (inwrist & ankle)
Sesamoidbones formw/n tendons (ex:patella) - Vary in size & # indifferent individuals
Describe irregular bones
- Complicated shapes
- Vertebrae & hip bones
- think of spine
Describe compact bone
dense outer layer on every bone that appears smooth & solid
Describe spongy bone
made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae
Why is the dispersal of bone marrow throughout bone important?
there’s no clear dispersal therefore bone marrow can be missed during biopsy
What is found in the trabeculae of bone?
bone marrow
Open spaces between trabeculae are filled with…
red or yellow bone marrow
Describe structure of short, irregular & flat bones.
- Consist of thin plates of spongy bone (diploe) covered by compact bone
- Compact bone sandwiched b/t CT membranes
What does periosteum cover?
covers outside of compact bone
What does endosteum cover?
covers inside portion of compact bone
or covers the trabeculae of spongy bone
What does hyaline cartilage do?
covers area of bone that is part of a movable joint
What anchors directly to the periosteum?
tendons
Describe structure of typical long bone.
All long bones have a shaft (diaphysis), bone ends (epiphyses) & membranes
Define diaphysis.
- tubular shaft
- long axis of bone
- consists of compact bone surrounding central medullary cavity that is filled w/ yellow marrow in adults
Define Epiphyses
ends of long bones that consist of compact bone externally & spongy bone internally
What sits b/t the diaphysis & epiphysis?
epiphyseal line
What is the epiphyseal line?
remnant of childhood epiphyseal plate (metaphysis) where bone growth occurs
–> growth plate
Describe structure of the periosteum.
white, double-layered membrane that covers external surfaces except joints & is an anchoring point for tendons & ligaments
What does the periosteum contain?
many nerve fibers & BVs that continue on to the shaft through nutrient foramen openings
What are the two layers of the periosteum & describe?
- Fibrous layer: secure to bone matrix
- Osteogenic layer: gives rise to most all bone cells
Describe structure of the endosteum.
Delicate CT membrane covering internal bone surface
Like periosteum, the endosteum contains
osteogenic cells that can differentiate into other bone cells
Osteogenic cells
Precursor stem cells to osteoblasts or bone-lining cells
Osteoblasts
Bone-forming cells
(osteoBlasts Build Bone)
Osteocytes
Mature bone cells & stimulate bone remodeling
Bone-lining cells
Flat cells on the surface of bone to help maintain bony matrix
Osteoclasts
Bone-breakdown
(osteoClasts Chomp bone)
Notes
Osteoclast are activated in some cancers causing the breakdown of bone
When are osteoclast activated
when serum Ca++ levels are low
–> they breakdown bone & bone releases Ca++ & other minerals
Define Ossification (osteogenesis)
- the process of bone tissue formation (a change from cartilage to bone)
When does the formation of bony skeleton begin?
month 2 in utero
When does postnatal bone growth occur until?
early adulthood
What two mechanism of bone are lifelong?
- bone remodeling
- bone repair
Up to about week 8, ___ and ___ of fetal skeleton are replaced with bone tissue
- fibrous membranes
- hyaline cartilage
Define Endochondral (cartilage) ossification
Bone forms by replacing hyaline cartilage to create most of skeleton
Define Intramembranous ossification
- Bone develops from fibrous membrane
- Bones are called membrane bones
Long bones grow lengthwise by ___ of epiphyseal plate
interstitial (longitudinal) growth
By the end of adolescence, what happens to the epiphyseal plate
- thins
- is replaced by bone
Epiphyseal plate closure occurs when the…
epiphysis & diaphysis fuse
When does bone lengthening stop in females?
around 18yo
When does bone lengthening stop in males?
around 21yo
Why is a break at the growth plate so important in pediatric pts?
it can have lifelong effects structurally & anatomically
What is appositional growth & when can it occur?
- growing bones widen as they lengthen
- occurs throughout life
Bones thicken in response to___
incr stress from muscle activity or added weight
What stimulates the growth factors?
- Growth hormone
- thyroid hormone
- testosterone/estrogen
Thyroid Hormone
Modulate & ensure proper amount of growth hormone & therefore bone growth
Growth Hormone
Stimulates growth at the epiphyseal plate in infancy & childhood
Testosterone (M) &Estrogen (F)
Promote adolescent growth spurts & end the growth of bones by inducing epiphyseal plate closure (at the end of adolescence)
Bone remodeling consists of both…
bone deposit (osteoblasts) & bone resorption (osteoclasts
Where does bone remodeling occur?
at surfaces of both periosteum & endosteum
Describe remodeling units
packets of adjacent osteoblasts & osteoclasts coordinate the remodeling process
Osteoclast activation involves…
PTH & immune T-cell proteins
Osteoblasts are activated by…
- mechanical signal
- incr Ca & phosphate ions
- appropriate amounts of alk phos
What does serotonin do?
inhibits bone growth
What does Leptin do?
opposes osteoblasts
- The more adipose tissue you have, may cause you to have more leptin, & could interfere w/ the bone remodeling
What stimulates bone remodeling?
- stressors
- physical activity
- hormones
- Ca++ levels
- Fitness
Calcium-homeostasis and bone breakdown has to do with
calcium-homeostasis & bone breakdown has to do with
What does calcitonin do?
- tones down Ca++
- stimulates building bone
- tones down the effects of the PTH
NOTE
You have high levels of Ca in the blood, so you want to tone down the amount of Ca in the blood, so you deposit it & make more bone
When does bone ossification first start occurring?
in utero
What happens to bone density as we age?
it decr
- esp postmeno women
What hormone mediates bone growth?
estrogen
Closure of the epiphyseal happens at what age?
18-25yo
Function of Vit D
helps absorb Ca++ in the small intestine
How long do you have to get sunlight exposure to maintain Vit D levels?
5 - 30 minutes
- depends on location, time of year
Who are more likely to have a lower Vit D levels?
- African Americans
- Breastfeeding /pregnant women
Function of ligaments
along w/ trunk muscles, help support vertebral column
Describe the anterior & posterior longitudinal ligaments?
continuous bands from neck to sacrum that run down front & back of spine
Function of anterior & posterior longitudinal ligaments?
Support & prevent hyperextension (backward) or hyperflexion (forward) bending
Function of ligamentum flavum
connects adjacent vertebrae
Function of short ligaments
connect each vertebra to those above & below
What are the two parts of the intervertebral discs?
- Nucleus pulposus
- Anulus fibrosus
Describe the nucleus pulposus
- Inner gelatinous nucleus
- Gives disc its elasticity & compressibility
Describe the annulus fibrosus?
- Outer collar composed of collagen & fibrocartilage
- Limits expansion of nucleus pulposus when compressed
What are joints?
sites where 2 or more bones meet
joints aka
articulations
Functions of joints?
give skeleton mobility & hold skeleton together
3 classifications of joints
- fibrous
- cartilaginous
- synovial
Why do we have fontanelles then sutures?
allows for growth of the brain
Example of syndesmoses (fibrous) joint
think b/t two bones
–> tibia & fibula
Example of a gomphoses (fibrous) joint
holding our teeth in gums
Criteria for cartilaginous joints
- Bones united by cartilage
- Like fibrous joints, have no joint cavity
- Not highly movable
What are the two types of cartilaginous joints?
- Synchondroses
- Symphyses
Criteria for a synovial joints
- bones separated by fluid-filled joint cavity
- All are diarthrotic (freely movable)
- Include almost all limb joints
What are the general features of synovial joints?
- articular (hyaline) cartilage
- joint (synovial) cavity
- articular (joint) capsule
–> 2 layers - synovial fluid
Describe articular hyaline cartilage
consists of hyaline cartilage covering ends of bones
Function of articular (hyaline) cartilage
prevents crushing of bone ends
Describe the joint (synovial) cavity
small, fluid-filled potential space that is unique to synovial joints
- big area for infx!
What are the layers of articular (joint) capsule & their function?
- External fibrous layer: dense irregular CT
- Inner synovial membrane: loose CT that makes synovial fluid
Describe synovial fluid
viscous, slippery filtrate of plasma & hyaluronic acid
What is the function of synovial fluid?
- Lubricates & nourishes the articulate cartilage
- Contains phagocytic cells to make sure the joints stay sterile
What are bursae?
reduce friction where ligaments, muscles, skin, tendons, or bones rub together
What are tendon sheaths?
elongated bursae wrapped completely around tendons to reduce friction (can get inflammation called tendonitis)
What connects muscle to bone?
tendons
What connects bone to bone?
ligaments
What is extracapsular?
outside the capsule
What is intracapsular?
- deep to capsule
- covered by synovial membrane
What is capsular?
thickened part of fibrous layer
Function of ligaments?
stabilize the joint & help prevent hyperextension/hyperflexion
Nerves function…
- detect pain
- monitor joint position & stretch
Capillary beds function…
supply filtrate for synovial fluid
What are fatty pads?
cushioning b/t fibrous layer of capsule & synovial membrane or bone
What is an articular disc (menisci)?
Fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, & reduce wear and tear
Define origin
attachment to immovable bone
All muscles attach to bone or CT at no fewer than___
2 points
Define insertion
attachment to moveable bone
Muscle contraction causes ___ to move toward ___
- insertion
- origin
6 different types of synovial joints
- Plane
- Hinge
- Pivot
- Condylar
- Saddle
- Ball-and-socket
Movements occur along what planes?
transverse, frontal, or sagittal
Plane joint
Movement type:
Examples:
- nonaxial movement (gliding)
- intercarpal & intertarsal joints
- joints b/t vertebral articular surfaces
Hinge joint
Movement type:
Examples:
- Uniaxial movement (flexion & extension)
- elbow & interphalangeal joints
Condylar joint
Movement type:
Examples:
- biaxial movement (flex/ext & ab/ad duction)
- metacarpophalangeal (knuckle) & wrist joints
Pivot joint
Movement type:
Examples:
- uniaxial movement (rotation)
- proximal radioulnar & atlantoaxial joints
Saddle joint
Movement type:
Examples:
- biaxial movement (ab/ad duction & flex/ext)
- carpometacarpal joints of thumb
Ball-and-socket joint
Movement type:
Examples:
- multiaxial movement (flex/ext, ab/ad duction, rotation)
- shoulder & hip joints
