Module 2

Question 1

What are the five major function of the skeletal system

Answer 1

Support, protection, assistance with movement, blood cell production, storage

Question 2

Cartilage:

Answer 2

• made of matrix.
• avascular.
• no nerves.

Question 3

Cartilage growth:

Answer 3

2 ways:

1. Appositional growth (cartilage is added to outside of the existing cartilage)
2. Interstitial growth (chondrocytes within the matrix divide and add more matrix between the chondrocytes)

Question 4

cartilage types

Answer 4

hyaline cartilage:
-collagen fibres are small and evenly dispersed in the matrix therefore matrix appears transparent and is firm but flexible. Chondrocytes are found in lacunae.
-allows the growth of long bones.
-contain chondroblasts that produce the matrix.
Fibrocartilage:
-more collagen bundles than hyaline and are arranged in thick bundles.
Elastic cartilage:
-Matrix collagen similar to hyaline but also contains elastic fibres.

Question 5

What are the components of bone tissue (ie the matrix) and how do they relate to its properties?

Answer 5

Organic - Collagen fibres and proteoglycans -> stops bone from being too brittle.

Inorganic - Hydroxyapatite -> stops bone from being too bendable.

Question 6

Name the three main bone cell types and state their function

Answer 6

Osteoblasts - Bone forming cells; produce the chemicals and structures that make up the matrix (lay down the matrix).
Osteoclasts - Bone destroying cells; breaks down the matrix.
Osteocytes - Maintain the matrix.

Question 7

What is the role of collagen in bone tissue?

Answer 7

Bone strength -> stops it from being brittle.

Question 8

Distinguish between compact and spongy (cancellous) bone?

Answer 8

Spongy bone:
• Appears porous and contains columns of bone called trabeculae. It usually surrounded by a sleeve of compact bone.
• provides strength and support without the greater weight of compact bone.
• In the interior of the bones of the skull, vertebrae, sternum and pelvis; in the ends of the long bones.

Compact bone:
• very organised.
has a hard bong matrix with many osteocytes.
basic unit: osteon/harvesian system.
• great strength and support; prevents breaks and punctures.
located in the outer portions of all bones and the shafts of long bone.

Question 9

Classify bones according to their shape, give examples.

Answer 9

• long: upper and lower limbs e.g. femur, tibia.
• short: carpals and tarsals.
• flat: ribs, sternum, skull, scapulae.
• irregular: vertebrae, facial.

Question 10

Describe the general structure of a long bone.

Answer 10

• diaphysis.
• epiphysis.
• epiphyseal plate.
• epiphyseal line.
• medullary cavity.

Question 11

Describe in detail the arrangement of bone tissue in compact bone.

Answer 11

Layers of bone (lamellae) form around the central canal form the osteon. Osteocytes sit in the spaces between the lamellae (called lacunae). Periosteum is a dense, irregular CT sheath surrounding the bone. Endosteum is the thin membrane lining the medullary cavity.

Question 12

What is the embryonic precursor tissue and cell of bone?

Answer 12

Mesoderm and mesenchymal tissue.

Question 13

How does bone ossify and how is this different for flat and long bones?

Answer 13

• intramembranous - flat
• endochondral – long

Intramembranous: Bone forms directly from mesenchyme. Takes place within connective tissue membranes. Flat bones.

Endochondral: Takes places within a cartilage template. Bone forms from mesenchyme producing a hyaline cartilage model first which is replaced by bone tissue. Long bones.

Question 14

Distinguish epiphyseal lines and plates on an X-ray and explain what the presence of each will tell about the growth of bone.

Answer 14

• epiphyseal plate is a band of cartilage left between primary and secondary ossification centres
• the plate includes rows of young cartilage cells undergoing mitosis and new cartilage cells are being produced
• as bone ages the cartilage cells are progressively converted to bone
• when all the cartilage cells become bone an epiphyseal line is formed. growth in length stops

Question 15

What are the components of the axial and appendicular skeleton?

Answer 15

Axial:

• 80 bones.
• bones of the head and trunk; ossicles (inner ear), skull, hyoid bone, rib cage and the vertebral column.

Appendicular:

• 126 bones.
• consists of the bones and cartilages that support the appendages.

Question 16

Name and describe the various terminology given to bony features and landmarks.
head, body, neck, margin, angle, ramus, condyle, facet, process, tubercle, tuberosity, trochanter, epicondyle

Answer 16

Head : rounded projection

Body : Main part of bone

Neck : Constriction between head and body

Margin/border : Edge

Angle : Bend

Ramus : Branch off body of bone

Condyle : large rounded protuberance

Facet : Small flattened articular surface

Process : Prominent projection

Tubercle : Small rounded bump

Tuberosity : rounded projection

Trochanter : large projection

Epicondyle : Near or above a condyle

fossa : shallow depression

meatus : passageway

fissure : narrow slit

process : projection

crest : prominent ridge

foramen : opening

Question 17

Distinguish the general features found on a typical vertebrae, and determine how these features differ across the various regions of the vertebral column.

Answer 17

Lamina, spinous process, transverse process, pedicle, body and vertebral foramen.
Increases in size down the spine to accomodate for weight.

Question 18

Identify the features found on a typical rib and how these attach onto the vertebra and the sternum.

Answer 18

Head, neck, body and tubercle. Articulate posteriorly with the vertebrae- each rib head articulates with the thoracic vertebrae.
Ribs articulate anteriorly with the sternum.

Question 19

What is the difference between the pelvic girdle and the bony pelvis?

Answer 19

• bony pelvis: includes the complete ring around the hip bones including the hip bones, pubic symphysis and sacrum.
• pelvic girdle consists of only the two hip bones.

Question 20

Explain how joints are classified based on structural and functional differences.

Answer 20

• structural: based on the major connective tissue type that binds bones (fibrous, cartilaginous, synovial).
• functional: based on degree of motion (non-moveable, slightly moveable, freely moveable).

Question 21

Describe the characteristics and sub-classification of fibrous and cartilaginous joints, giving examples.

Answer 21

Fibrous:

• united by fibrous connective tissue.
• have no joint cavity.
• move a little or not at all.

Subclassifications:

• gomphoses e.g. Hold teeth into place.
• sutures e.g. Coronal suture.
• syndesmoses e.g. Radioulnar.

Cartilaginous joints

• unite two bones by means of cartilage.
• little or no movement.
• may be permanent or replaced by other types of joints.

Subclassifications:

• hyaline cartilaginous joints e.g. Epiphyseal plates.
• fibrocartilaginous joints e.g. Symphysis pubis.

Question 22

Explain the features common to all synovial joints and give examples synovial joints.

Answer 22

Synovial

• contains synovial fluid.
• allows considerable movement.
• complex joints.
• most are joints that unite bones of appendicular skeleton.
• reflect greater mobility of appendicular skeleton compared to axial.

Question 23

Define various terms of movement that occur at synovial joints.

Answer 23

• gliding.
• angular.
• circular.
• combination of types.