Anatomy of Bones & Joints (S1)

Question 1

What are bones?

Answer 1

organic matrix of fibrous connective tissue and mineral salts

Question 2

What are joints?

Answer 2

Articulations - connecting one or more bones to another

Question 3

What is cartilage?

Answer 3

Joint surface - highly specialised tissue designed to withstand loads without failing

Question 4

Name 5 different types of bone?

Answer 4

• long (humerus)
• short (carpals)
• flat (frontal)
• irregular (vertebra)
• sesamoid (patella)

Question 5

What are features of bones aiding its functions?

Answer 5

• strength (trabechulae for stress + cortical/compact)
• flexibility (connective tissue/collagen)
• hardness + rigidity (organic salts eg calcium)
• light (trabechulae, porous)

Question 6

What is the difference between compact/cortical and spongy/trabechulae bone?

Answer 6

Compact bone tends to be thin over edges, thickest at midshaft, denser (5-10% porous)

whereas, spongy bone are 50-90% porous, towards the centre of bone.

Question 7

What is a pneumatic bone?

Answer 7

Eg. Skull - air filled sinuses, with single and many spaces.

Question 8

What are some functions of bones?

Answer 8

• protective
• contribute to mobility
• attachments for discs, ligaments + muscles
• supplies nutrients to body -> make RBCs
• stores calcium + releases in response to body’s need

Question 9

What is endochondral ossification?

Answer 9

• process during foetal development in creating bone tissue (eg long, short, irregular)
• long bones elongate
• partially minerlizaed cartilaginous matrix formed at the growth plate
• resorbed and replaced by woven bone
• then subsequently remodelled into lamellar bone

Question 10

What is intramembranous ossification?

Answer 10

• different to endochondral ossificaiton, this one forms flat bones
• not from the cartilage template formed first
• bone lining cells differentiate to form mature osteoblasts
• osteoblasts secrete osteiod (unmineralised organic matrix)
• osteoid undergoes maturation
• mineralisation: calcium and phosphate is deposited within the organic matrix
• remodelling - osteoclasts resoprtion while osteoblast formation - ongoing process

Question 11

What are the main 3 types of joints and how much movement do they allow?

Answer 11

• fibrous
• NO movement - eg sutures in skull, bound closely by fibrous tissue
• cartilaginous
• no/little movement, intervertebral disc
• synovial
• freely mobile, eg. knee, hip etc

(some mixed joints eg sacroiliac)

Question 12

What are the 3 types of fibrous joints?

Answer 12

• suture (seam)
• a joint with a thin fibrous layer that binds skull bones
• syndesmosis (band)
• bigger space than suture, fibrous tissue arranged as a sheet or in a bundle called ligament eg. tibiofibular
• gomphosis (bolt)
• consists of a peg and socket, such as the root of a tooth which is anchored into a socket by its fibrous ligament

Question 13

What are the 2 types of cartilaginous joints?

Answer 13

• synchondrosis
• hyaline cartilage is the connective tissue, eg. epiphyseal plate between epihysis and diaphysis of bones
• symphysis
• connecting material is fibrocartilage eg. pubic symphysis

Question 14

What are features of a synovial joint?

Answer 14

• articular surfaces covered with articular hyaline cartilage for lubrication and absorption of impacts
• capsule contains synovial fluid -> limits movement
• capsule lined by synovial membrane which produces lubricating syovial fluid

Question 15

What are the 6 types and examples of synovial joints?

Answer 15

• ball and socket (shoulder, hip)
• hinge (elbow)
• gliding (intercarpal)
• saddle (thumb)
• pivot (neck)
• condyloid (wrist/radiocarpal)