Musculoskeletal structure and function Flashcards
Bone as a living tissue
Main functions
* Protection
* Support
* Mineral storage
* Red blood cell formation
Grouped into three main types
* Long bones
* Flat bones
* Irregular bones
Internal structure
Two types
Cortical bone:
* Dense
* Forms outer surface of all bones
Trabecular bone:
* Less dense
* Honeycomb/sponge-like structure
* Forms interior of bones
Long bones
Consist of three regions:
Diaphysis (shaft)
* Thick cortical bone wall
* Hollow medullary cavity
Metaphysis (flared ends)
* Thin cortical bone wall
* Filled with trabecular bone
Epiphysis (sites of articulation)
* Thin cortical bone wall
* Filled with trabecular bone
Flat bones
Example, cranial bones and
scapula
* Thin cortical bone surfaces with
trabecular filled middles
Irregular bones
Majority of bone is trabecular
* E.g. sacrum
* Thin cortical bone wall
Additional components
Periosteum
* Membrane covering the majority of outer surfaces
Endosteum
* Membrane covering internal surfaces, including the trabecular bone
Microscopically two types of bones
Woven and Lamellar
Trabecular bone
The physical structure of
trabecular bone allows blood
vessels to pass through it close
enough to supply the bone
directly
Cortical bone
- Dense
- Forms surface of all bones
- At joints, is covered by cartilage-
known as subchondral bone
Bone structure
All mammalian bone is compositionally the same
Bone formation
Three main types of cells involved
* Osteoclasts – resorption
* Osteoblasts – deposition of osteoid
* Osteocytes – maintains the tissue
Ossification
Ossification begins around fifth
week of foetal life
Majority of bones have begun
ossification at birth
Types of muscle
3 types:
* Cardiac
* Skeletal
* Smooth
Smooth muscle
Function:
* Gastrointestinal tract - propulsion of
the food bolus.
* Cardiovascular - regulation of blood
flow and pressure via vascular
resistance.
* Renal - regulation of urine flow.
* Genital - contractions during
pregnancy, propulsion of sperm.
* In some locations, autorhythmic
* Controlled involuntarily by endocrine and autonomic nervous systems
Cardiac muscle
Function- forms wall of the heart
* Autorhythmic
* Controlled involuntarily by
endocrine and autonomic
nervous systems
* Sufficient calcium is important
for normal function
Skeletal muscle
Responsible for locomotion,
facial expressions, posture,
respiratory movements,
other types of body
movement
Voluntary in movement
Types of skeletal muscle
- Circular
- Convergent
- Multipennate
- Parallel
- Unipennate
- Bipennate
- The shapes of muscles are
determined by the way the
fascicles are aligned
Skeletal muscle pairs
Agonist: muscle that causes
action when it contracts
Antagonist: muscle working
in opposition to agonist
Synergists: muscles that work
together to cause a
movement
Skeletal muscle fibres
A muscle fibre is a single cell consisting of a plasma membrane
(sarcolemma), cytoplasm (sarcoplasm), several nuclei, and
myofibrils
Cartilage
Three types:
* Hyaline
* Fibrocartilage
* Elastic cartilage
Tendon
Connects muscle to bone
Ligament
Connects bone to each other
Fibrous joints
*Classed as a synarthrosis (non-moveable) joint
*Little to no movement
* Dense fibrous tissue
* Cranial sutures
Cartilaginous joints
- Mostly amphiarthrosis joints
- Allow little movement
- Bones articulate with only cartilage between
Synovial joints
Greatest degree of movement:
Uniaxial
Biaxil
Multiaxil
Types of movement:
Gliding
Angular
Circular
Synovial joint structure
*Synovial cavity contains
synovial fluid – hyaluronan,
lubricin, interstitial fluid
- Joint capsule secretes and
holds in fluid - Articular cartilage (hyaline
cartilage) covers ends of
articulating bones - Synovial bursa protects joint
Plane joints
Uniaxial - some rotation
possible but limited by
surrounding structures
e.g. intervertebral, intercarpal
* Sliding
Saddle joints
Biaxial
e.g. thumb, sternoclavicular
* Rocking
Hinge joints
Uniaxial
Convex cylinder in one bone;
corresponding concavity in other
e.g. elbow, ankle, interphalangeal
* Swinging with limit
Pivot joints
Uniaxial. Rotation around single
axis.
Cylindrical bony process rotating
within circle of bone and ligament
e.g. proximal radioulnar, distal
radioulnar
Ball-and-socket joints
Multiaxial
e.g. shoulder, hip joints
* Rotation of ball/head
Ellipsoid joints
Modified ball-and-socket;
ellipsoid articular surfaces
Biaxial
e.g. atlantooccipital
* Tilt back and forth
