MSK Session 1 Flashcards
principles and radiography
name the 6 functions of bone
support protection metabolic storage movement haematopoiesis
describe the support function of bone
framework for maintaining body posture
limbs = pillars to support trunk
ribcage supports thoracic wall
describe the protection function of bone
ribs protect lungs and heart
skull protects the brain
vertebrae protect the spinal cord
pelvic structures protected by bony pelvis
describe the metabolic function of bone
living, actively-metabolising tissue
involves homeostasis of calcium and phosphate
storage and release of these is under mostly endocrine control
describe the storage function of bone
reservoir of calcium and phosphate
large amount of protein - collagen
bone marrow rich in fat
storage of important growth factors and cytokines
describe the movement function of bone
movement occurs at joints between bones
bones act ass an attachment site for muscles and tendons, use bones as levers
describe the haematopoietic function of bone
generation of BCs takes place in cavities
6 functions and description of voluntary skeletal muscle
locomotion: contracting of muscles across a joint lead to movement of that joint
posture: postural muscles enable us to maintain equilibrium
metabolic: glycogen metabolism
venous return: muscles in leg compress deep veins and help to propel venous blood back up towards the heart
heat production (thermogenesis): generation of heat from shivering muscles, increases metabolic rate
continence: muscles of pelvic floor responsible for the maintenance of urinary and faecal continence
tendons
connect muscle to bone
force-transmission from contracting muscle to bone
ligaments
connect bone to bone
support joints
prevent excessive range of movement
fascia
sheets of connective tissue
envelope groups of muscles and divide body parts into anatomical compartments
some sheets are very tough and so protective as well
fascia lata
in the thigh
hyaline (Articular) cartilage
found on ends of bones contributing to joints
very smooth = frictionless motion
fibrocartilage
higher collagen content than hyaline
important role in shock absorption
increases bony congruity at joints
what gives bone compressive strength?
calcium phosphate (CaPO4) also known as hydroxyapatite this mineralises the ECM
what gives bone tensile strength?
collagen
what cell synthesises new bone?
osteoblast
what do osteoblasts lay down?
first synthesise and deposit osteoid, matrix protein of bone
contains collagen mainly but also specialised proteins such as osteocalcin and osteopontin
then osteoblasts deposit calcium phosphate into the osteoid to make bone
lineage of osteoclasts
from monocyte/macrophage lineage
formed by fusion of progenitor cells
what do osteoclasts do?
migrate over bone surface
secrete acidic chemicals to dissolve it
increase SA for absorption of minerals (Ca and P)
osteoclast absorbs them and secrete into ECF
process = resorption
what happens to osteoblasts?
become trapped in bone matrix
become osteocytes
trapped in lacunae & involved in signalling
communicate via fillipodia
name the dense and spongey types of bone
dense = cortical/compact spongey = spongey/concellous
trabeculae
thin spindles of bone tissue forming spongey bone
how many bones in adult sketelton?
206
name the two parts of the skeleton
axial = longitudinal axis of body appendicular = upper and lower limbs
5 classifications of bones
long flat short irregular sesamoid
where are most long bones found and what do they do there?
appendicular skeleton
act as levers (controlled by muscles)
diaphysis
metaphysis
epiphysis
diaphysis = shaft of long bone metaphysis = diaphysis side of growth plate epiphysis = on other side of growth plate
periosteum
endosteum
periosteum = covers bony surface endosteum = lines the medullary cavity
describe the medullary cavity
in child: full of red marrow - involved in haematopoiesis
in adult: mostly yellow marrow - high fat content
what and and where does the nutrient artery go through
through a nutrient foramen
in the middle of the diaphysis
short bones
approximately as wide as long
located in wrist (carpal) and ankle (tarsal)
provide stability
when working together provide a great range of movement
flat bones
in skull, thoracic cage and pelvis
protect internal organs
large areas of attachment for muscles
sesamoid bones
embedded in tendons
protect the tendons from stress and wear
provide mechanical advantage to a muscle crossing a joint over a wide range of movement
i.e. patella in knee
irregular bones
complex shape - don’t fit another category
protect internal organ i.e. spinal cord
no growth plate or epiphysis
head (bone)
rounded articular projection supported by a neck
condyle
large, knuckle like, articular projection
facet
smooth flat surface
epicondyle
smaller projection above the condyle (attachment muscles and ligaments)
trochanter
blunt projection (only femur)
tubercle
small knob like rounded process
tuberosity
large, often rounded, usually roughened, process (attachment site)
crest
prominent bored or ridge
line
less prominent ridge than a crest
spine
shape slender process (vertebra)
fovea
pit like land mark
sulcus / groove
furrow that accommodates soft tissue such as blood vessels, nerves or tendons
fossa
basin-like depression
cavity
spacious open area
notch
a c- or u- shaped depression
fissure
narrow slit like opening between adjacent parts of bones through which blood vessels or nerves pass
foramen
hole or window in the bone
canal
tube-like passageway
metaphyseal and epiphyseal arteries
neither cross the growth plate but an anastomoses forms when the epiphysis fuses in adulthood
avascular necrosis
death of bone due to loss of its blood supply
most common cause is fracture
more common in children as no anastomoses across growth plate (perths’ disease)
bone remodelling
occurs in response to environmental factors due to a change in balance of activity of osteoblast and osteoclasts
what is a joint
an articulation between two or more bones
3 structural classifications of joints
fibrous joints
cartilaginous joints
synovial joints
fibrous joints: features and examples
united by collagen, very limited mobility, high stability sutures of skull inferior tibiofibular joint radioulnar interosseous posterior sacroiliac joint roots of tooth and mandible or maxilla
cartilaginous joints: features
use cartilage to unite bones
typically found in the midline of the body and epiphyseal growth plates
primary cartilaginous joints: features and examples
united by hyaline cartilage, completely immobile
sternocostal joint
xiphisternal joint
epiphyseal growth plates
secondary cartilaginous joints(symphyses): features and examples
articulating bones covered in hyaline cartilage with a pad of fibrocartilage between them
symphysis pubis
intervertebral discs
manubriosternal joint
synovial joint: features and examples
joint cavity containing synovial fluid - lubrication
high degree of mobility
articulating surfaces = hyaline cartilage
surrounding fibrous capsule - continuous with periosteum
synovial membrane - produces synovial fluid
knee
D
3 exceptions to synovial joints and why
atypical
fibrocartilage instead of hyaline
acromioclavicular
sternoclavicular
temporomandibular
6 types of synovial joint
plane joints hinge joints saddle joints condyloid (or ellipsoid) joints pivot joints ball and socket joints D
6 factors affecting range of motion of joints
structure or shape of the articulating bones
strength and tension of the joint ligaments
arrangement and tone of muscles around the joint
apposition of neighbouring soft tissues
effect or hormones
disuse of a joint
where to synovial joints form?
the joint interzone
chondrocytes die by apoptosis to form where the joint will be
D
how many skeletal muscles are there in the human body
about 640
most present in bilateral pairs
what can muscles do?
they can only:
pull
act on joints that they (or their tendons) cross
point of origin of a muscle
stationary anchor point, usually proximal
point of insertion of a muscle
mobile attachment point, usually distal
why is muscle contraction ‘symmetrical’?
the force on the origin and the insertion is equal
stabilisation of the origin leads to the insertion becoming mobile
what dictates the action of a muscle on a joint?
the orientation of its fibres and the relation of those fibres to the joint
how do muscles work?
together, almost never in isolation
brain and spinal cord coordinate this complex task
synergist
act to assist prime mover
neutralisers
prevent unwanted actions that an agonist can perform
fixators (stabilisers)
act to hold a body part immobile whilst another body part is moving, stabilise joints
three types on muscle contraction
concentric (shortening)
eccentric (lengthening, passive, lengthens and contracts)
isometric (same length)
3 arrangements and also subdivisions of skeletal muscle
parallel: strap, fusiform and fan shaped (triangular or convergent)
pennate: unipennate, bipennate and multipennate
circular
compartmentalisation of limbs
muscles are contained within fascial compartments
the muscles within a compartment are usually share common innervation and action
what is a fascial compartment?
deep fascia surrounding muscles, nerves and blood vessels
4 ways of predicting muscle action
where does it attach
how many joints does it cross
how is it related to the joints
which direction do the fibres run in
what is superficial fascia?
a subcutaneous fatty layer, found in most regions of the body
what is deep fascia?
thickened elaboration of the epimysium, envelopes muscle
made of collagen and elastin fibres, have a wavy pattern parallel to direction of pull
what do tendons do?
connect muscle to bone
what do ligaments do?
bone to bone
what do aponeuroses do?
connect muscle to muscle
what anchors bone to tendons?
sharpey’s fibres
describe the tissues of tendons
dense regular connective tissue fascicles
enclosed in dense irregular connective tissue sheaths
low ratio of elastin to collagen
poor blood supply
low water content
poor healing
describe the tissues of ligaments
dense regular bundles of connective tissue (mostly collagen)
protected by dense irregular connective tissue sheaths
poor blood supply = poor healing
what is the useful function of ligaments
mechanical reinforcements for the joints
stabilise joints
limit their range of movement
Hilton’s law
the nerves supplying the joint capsule also supply the muscles moving the joint and the skin overlying the intersections of these muscles
what controls segmentation?
Hox genes
mutation of these is called a homeotic mutation
what is serial homology?
Convergent and parallel evolution. This has been called serial homology. There is serial homology, for example, between the arms and legs of humans
when do the limb bud appear in development?
4th week
what dermatome map should we use?
Foerster dermatome map
what is a fracture?
a complete or incomplete break in the continuity of a bone
what are the 7 types of fracture?
transverse linear oblique non-displaced oblique displaced spiral greenstick comminuted
where are the ossification centres in long bones?
primary ossification centre = middle of diaphysis
secondary ossification centres = middle of epiphysis
separated by growth plates
what hormone may cause reduction in cell division in the proliferation zone?
growth retardation can be caused by
- deficiency of thyroid hormone
- excess corticosteroids
how can you determine a bone age?
look at the degree of ossification of short bones like the carpels which aren’t fully ossified until 12years old
discrepancy between bone age and actual age may indicate pathology
8 steps in fracture healing
- haematoma formation
- tissue death
- inflammation / cellular proliferation
- angiogenesis / formation of granulation tissue / procallus
- soft (fibrocartilaginous) callus formation
- consolidation / hard callus formation
- lamellar bone
- remodelling
the 8 stages of fracture healing are broadly divided into 3 steps
- the inflammatory phase
- the reparative phase
- the remodelling phase
what does the inflammatory phase consist of in fracture healing?
haematoma formation
tissue death
inflammation / cellular proliferation
what does the reparative phase consist of in fracture healing?
angiogenesis / granulation / procallus forming
soft (fibrocartilaginous) callus formation
consolidation / hard callus formation
what are the units of density used in CT scanning?
Hounsfield units (HU) software can be used to create 'windows' to focus on different tissues
how does MRI work?
- some of the protons are moved out of alignment
- the protons realign and emit a signal as they do so
- this signal is detected and the data from this is used to create the 3-D image
on a T1 weighted MRI image how do fat and fluid appear?
fat = bright fluid = dark
on a T2 weighted MRI image how do fat and fluid appear?
fat = bright fluid = bright
