W3 - The musculoskeletal system Flashcards
What are the four functions of the skeleton?
- Movement
- Support
- Protection
- Physiological functions
How does the skeleton provide movement?
- Muscle attatchment
- Provide levers
How does the skeleton provide support?
It gives the body shape
How does the skeleton provide protection?
The bones in the skeleton protect vital organs
What are the physiological functions of the skeleton?
- Ca2+ regulation
- Endocrine regulation
- Blood cell production (bone marrow)
What is a lever?
A lever is a relatively rigid object that may be made to rotate about an axis by the application of force
Which par
Which part of the lever system do body parts play?
- Joint = Fulcrum
- Muscle = Effort
- Body part = Load (resistance)
What is the order of the components a first class lever?
Effort - Fulcrum - Load
What is the order of the components a second class lever?
Effort - Load - Fulcrum
What is the order of the components a third class lever?
Fulcrum - Effort - Load
What are the three types of musculoskeletal tissue?
Skeletal - Bone and cartilage
Muscular
What percentage of bone are made up of organic and inorganic componds?
Inorganic - 65%
Organic - 35%
What are the features of the organic component of bone?
Matrix: mostly type 1 collagen (elasticity)
Cells: osteoblasts, lining cells, osteocytes, osteoclasts
What are the features of the inorganic component of bone?
Mineral content: hydroxypatite (rigidity)
What is hydroxyapatite?
A complex salt of calcium and phosphate
What is the general strucure of bone?
- Long bones consist of a diaphyses (shaft) and two epiphyses (knobs at the ends)
- The metaphysis is where the epiphyseal growth plate resides -it lies between the diapyses and epiphyses
See diagram for locations
What are the two types of bone?
Compact/ cortical
Cancellous/ spongey/ trabecular
What are the features of Compact/ cortical bone?
80% of bone mass
External surface of bone
Walls of diaphyses
Principally mechanical function
What is the function of cancellous/ spongey/ trabecular bone?
20% of bone mass
Lattice of fine plates
Epiphyeses of long bones vertebral bodies and flat bones
Spaces filled with bone marrow
Reduces skeletal mass without compromising strength
What are the two types of bone growth?
Longitudinal
Circumferential/ radial growth
Where does longitudinal growth occur?
Epipheseal plates
When does longitudinal growth stop?
18-20 years (epipheseal line)
When does circumferential growth occur?
The diameter increases throughout lifespan, most rapud growth occurs before adulthood
What is “Wolff’s Law”?
The form of bone will adapt to the load placed upon it
Increasing or decreasing load will cause the bone to remodel, increaing or decreasing mass and density
Describe bone remodelling
A balanced integration of osteocyte signalling osteoblast bone formation & and osteoclast bone resorbtion, in response to load
What causes hypertrophy of bone?
An increase in bone mass is caused by the predomincance of osteoblast activity
This may be a response physical activity
The greater habitual load = more bone mineralisation
What causes atrophy of the bone?
A decrease in bone mass resulting from a predominance osteoclast activity.
What are the effect of bone atrophy?
Decrease in
* Bone calcium
* Bone mass and strength
Where is bone atrophy commonly seen?
Bed ridden patients, sedentry elderly and astronaughts
How many bones are in the axial skeleton?
74
How many bones are in the appendicular skeleton?
126
Which bones don’t the appendicular/ axial skeleton include how many are there?
Sesamoid bones
6
What are flat bones?
Thin curved bone
They serve as points of attatchment for muscle
They protect internal organs
What are short bones?
Cube-shaped bone that is approximatly equal in length width and thickness
Provides limited motion
What are long bones?
Cylinder shaped bones that are longer than wide
Function as levers
What are sesamoid bones
Bones embedded within tendons to protect them from stress
What are irregular bones?
Bone of complex shape
Protects internal organs from compressive forces
What is the function of a joint?
To facilitate movement between bones
To transmit force from one bone to another
What is the articular surface?
The contact point between 2 skeletal bones
Whats is a synathroses joint?
Joints that don’t move
What is the function of a synarthoses joint?
Shock absorb (attenuate force)
What are amphiathroses joint?
Joints that move slightly
What is the function of amphiathroses joints?
Attenuate forces and permit some motion between adjacent bones
What are the two types of amphiarthosis joints?
Synchrodroses ( think between ribs and sternum)
Sympheses e.g. pubic symphyses/ intervertebral discs
What is a diarthroses joint?
Joints that freely move (aka synovial)
Name the six types of diarthoses joints?
- Gliding/ plane
- Hinge
- Pivot
- Condyloid
- Saddle
- Ball and socket
Describe a gliding/ plane joint
Articulating surfaces are flat permitting on non-axial gliding
E.g. joints between the carpals and tarsals
Describe a hinge joint
E.g. Interphalangeal joints
One convex and one concave articulating surface. Strong collateral ligaments restrict to single axis hinge-like movement (uni-axial)
Describe a pivot joint
Joints where rotation is permitted around one axis (uni-axial)
E.g. proximal and distal radioulnar joints
Describe a condyloid joint
An ovoid articular surface allowing movement around two axes (bi-axial)
E.g. Metacarpophalangeal joints; radiocarpel joint
Describe a saddle joint
Similar to condyloid but greater range of motion due to saddle shape of both bones (tri-axial)
E.g. carpometacarpal joint of thumb
Describe a ball and socket joint
Rotation around three axis (tri-axial)
E.g. Glenohumeral/ hip joints
What is articular cartilage?
Protective layer of connective tissue, covering ends of articulating bones
What is the function of articular cartilage?
- Reduces stress by distributing force
- Reduces friction and wear
What is the articular capsule?
Double-layered membrane that surrounds every synovial joint
What is the synovial membrane?
Lines the deep surface of the capsule; secretes synovial fluid
Define joint stability
The ability of a joint to resist abnormal displacement of the articulating bones
What provides joint stability?
- Shape of articulating bone surfaces
- Arrangement of ligaments an muscle
- Other connective tissues
