Musculoskeletal structure and function

Question 1

Bone as a living tissue

Answer 1

Main functions
* Protection
* Support
* Mineral storage
* Red blood cell formation

Grouped into three main types
* Long bones
* Flat bones
* Irregular bones

Question 2

Internal structure

Answer 2

Two types
Cortical bone:
* Dense
* Forms outer surface of all bones

Trabecular bone:
* Less dense
* Honeycomb/sponge-like structure
* Forms interior of bones

Question 3

Long bones

Answer 3

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

Question 4

Flat bones

Answer 4

Example, cranial bones and
scapula
* Thin cortical bone surfaces with
trabecular filled middles

Question 5

Irregular bones

Answer 5

Majority of bone is trabecular
* E.g. sacrum
* Thin cortical bone wall

Question 6

Additional components

Answer 6

Periosteum
* Membrane covering the majority of outer surfaces

Endosteum
* Membrane covering internal surfaces, including the trabecular bone

Question 7

Microscopically two types of bones

Answer 7

Woven and Lamellar

Question 8

Trabecular bone

Answer 8

The physical structure of
trabecular bone allows blood
vessels to pass through it close
enough to supply the bone
directly

Question 9

Cortical bone

Answer 9

• Dense
• Forms surface of all bones
• At joints, is covered by cartilage-
  known as subchondral bone

Question 10

Bone structure

Answer 10

All mammalian bone is compositionally the same

Question 11

Bone formation

Answer 11

Three main types of cells involved
* Osteoclasts – resorption
* Osteoblasts – deposition of osteoid
* Osteocytes – maintains the tissue

Question 12

Ossification

Answer 12

Ossification begins around fifth
week of foetal life

Majority of bones have begun
ossification at birth

Question 13

Types of muscle

Answer 13

3 types:
* Cardiac
* Skeletal
* Smooth

Question 14

Smooth muscle

Answer 14

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

Question 15

Cardiac muscle

Answer 15

Function- forms wall of the heart
* Autorhythmic
* Controlled involuntarily by
endocrine and autonomic
nervous systems
* Sufficient calcium is important
for normal function

Question 16

Skeletal muscle

Answer 16

Responsible for locomotion,
facial expressions, posture,
respiratory movements,
other types of body
movement

Voluntary in movement

Question 17

Types of skeletal muscle

Answer 17

• Circular
• Convergent
• Multipennate
• Parallel
• Unipennate
• Bipennate
• The shapes of muscles are
  determined by the way the
  fascicles are aligned

Question 18

Skeletal muscle pairs

Answer 18

Agonist: muscle that causes
action when it contracts

Antagonist: muscle working
in opposition to agonist

Synergists: muscles that work
together to cause a
movement

Question 19

Skeletal muscle fibres

Answer 19

A muscle fibre is a single cell consisting of a plasma membrane
(sarcolemma), cytoplasm (sarcoplasm), several nuclei, and
myofibrils

Question 20

Cartilage

Answer 20

Three types:
* Hyaline
* Fibrocartilage
* Elastic cartilage

Question 21

Tendon

Answer 21

Connects muscle to bone

Question 22

Ligament

Answer 22

Connects bone to each other

Question 23

Fibrous joints

Answer 23

*Classed as a synarthrosis (non-moveable) joint
*Little to no movement
* Dense fibrous tissue
* Cranial sutures

Question 24

Cartilaginous joints

Answer 24

• Mostly amphiarthrosis joints
• Allow little movement
• Bones articulate with only cartilage between

Question 25

Synovial joints

Answer 25

Greatest degree of movement:
Uniaxial
Biaxil
Multiaxil

Types of movement:
Gliding
Angular
Circular

Question 26

Synovial joint structure

Answer 26

*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

Question 27

Plane joints

Answer 27

Uniaxial - some rotation
possible but limited by
surrounding structures
e.g. intervertebral, intercarpal
* Sliding

Question 28

Saddle joints

Answer 28

Biaxial
e.g. thumb, sternoclavicular
* Rocking

Question 29

Hinge joints

Answer 29

Uniaxial
Convex cylinder in one bone;
corresponding concavity in other
e.g. elbow, ankle, interphalangeal
* Swinging with limit

Question 30

Pivot joints

Answer 30

Uniaxial. Rotation around single
axis.

Cylindrical bony process rotating
within circle of bone and ligament
e.g. proximal radioulnar, distal
radioulnar

Question 31

Ball-and-socket joints

Answer 31

Multiaxial
e.g. shoulder, hip joints
* Rotation of ball/head

Question 32

Ellipsoid joints

Answer 32

Modified ball-and-socket;
ellipsoid articular surfaces
Biaxial
e.g. atlantooccipital
* Tilt back and forth