Bones

Question 1

What is the total number of bones in an average human body?

Answer 1

206 bones = we start off with around 300 bones at birth

Question 2

What are the two types of skeleton?

Answer 2

Axial and Appendicular

Question 3

What are the two types of appendicular skeleton - include the bones that come under them?

Answer 3

1. Upper Limb
   Clavicle, Scapula, Humerus, Radius, Ulna, Carpals, Metacarpals and Phalanges
2. Lower Limb
   Innominate Bones (Ilium, Pubis and Ischium) Pelvis, Sacrum, Femur, Patella, Fibula, Tibia, Tarsals, Calcaneus, Metatarsals and Phalanges

Question 4

What bones come under axial?

Answer 4

Skull (cranial and facial bones), mandible, sternum, costal cartilage, vertebral column (cervical, thoracic and lumbar), sacrum and coccyx

Question 5

Bones can be classified into?

Answer 5

• Long Bones
• Short Bones
• Flat Bones
• Irregular Bones
• Sesamoid Bones

Question 6

Describe long bones and give the examples

Answer 6

• The length exceeds width
• shaft and two ends
• made of compact bone with spongy cancellous interior

Examples =
In the upper limb = clavicle, humerus, radius, ulna, metacarpals and phalanges
In the lower limb = femur, tibia, fibula, metatarsals and phalanges

Question 7

Describe short bones and give the examples

Answer 7

• cube like shape
• made of spongy bone

Examples =
Carpals in the wrist = scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid and trapezium

Tarsals in the foot = calcaneus, talus, navicular, cuboid and cuneiform (lateral, intermediate and medial)

Question 8

Describe flat bones and give the examples

Answer 8

• thin and flattened
• slight curvature
• compact bone surfaces with spongy layer

Examples =
In the skull = frontal, parietal, lacrimal, nasal, occipatal and vomer
In the arm = scapula
In the chest = sternum and ribs
In the pelvis = the innominate bone (ilium, pubis and ischium)

Question 9

Describe irregular bones and give the examples

Answer 9

• complicated shape
• mostly composed of spongy bone

Examples =
Facial Bones = Ethmoid, temporal, sphenoid, inferior nasal concha, zygomatic, maxilla, mandible and
Neck = hyoid
Upper body = Vertebrae (cervical, thoracic and lumbar), sacrum and coccyx.

Question 10

Describe sesamoid bones and give the examples

Answer 10

• short and round bones
• form within tendons

Examples =
Knee = patella

Question 11

State the two internal structures of Long Bones

Answer 11

Cortical or compact bone
Cancellous or trabecular, spongy bone

Question 12

What is a cortical (compact) bone

Answer 12

• dense, hard and strong outer layer of long bones
• composed of cylindrical osteons (or haversian systems)

Question 13

What is a cancellous (trabecular, spongy) bone

Answer 13

• series of small plates of softer and thinner bone
• contains a vascular network, where the red bone marrow sits
• contained within ends of long bones and inside other irregular bones such as vertebral bodies

Question 14

State the two bone tissues

Answer 14

Periosteum
Endosteum

Question 15

What is the periosteum?

Answer 15

• outer membrane of dense connective tissue covering outer surface of bones except in areas where cartilage covers articular surface
• contains nerves, lymphatic and blood vessels, osteoblasts and osteoclasts

Question 16

What is the endosteum?

Answer 16

• inner membrane that lines bone cavities, similar to periosteum.
• contains nerves, lymphatic and blood vessels, osteoblasts and osteoclasts

Question 17

State the three bone cells

Answer 17

Osteoblasts
Osteoclasts
Osteocytes

Question 18

Function of osteoblasts?

Answer 18

To make new bone

Question 19

Function of osteoclasts?

Answer 19

To break down and reabsorb old bone

Question 20

Function of osteocytes

Answer 20

To mature bone cells; responsible for maintaining a solid bone matrix by making sure they do not deteriorate and ensures any deficits are replaced

Question 21

What is osteoporosis?

Answer 21

• a medical condition where there is low bone density due to increased bone absorption rather than bone formation; therefore the low bone density increases the risk of fractures

Question 22

Describe haversian systems?

Answer 22

Haversian systems (or osteons) are what makes the compact bone hard and dense. They are cylindrical structures that composed of concentric bone layers called lamellae, which surround the haversian canal.

Question 23

State the two types of bone marrow

Answer 23

Red and Yellow

Question 24

Describe red bone marrow?

Answer 24

Red bone marrow is found in spongy bone at the ends of long bones and at the centre of other bones. They are responsible for manufacturing blood cells. At birth, all bone marrow is red.

Question 25

Describe yellow bone marrow?

Answer 25

Yellow bone marrow is found mainly in the cavities in the long bones of adults. They are predominately made up of fat, and can convert back to red when needed.

Question 26

Describe fractures?

Answer 26

A fracture refers to a break in the bone and occurs when a bone is subjected to a greater impact/force than it can support.

Question 27

Is it true that adult and paediatric bones behave differently. If true, state why?

Answer 27

True, because paediatric bone has more elastic bend potential therefore paediatric fractures present differently to adult fractures.

Question 28

What are the different fractures present in adults?

Answer 28

Transverse
Oblique
Intra-articular
Multi-partite (comminuted)
Avulsion
Impacted

Question 29

What are the different fractures present in children?

Answer 29

Greenstick
Buckle
Leadpipe
Bowing

Question 30

Describe the stages of fracture repair.

Answer 30

1. Blood escapes from ruptured vessels forming a heamatoma (clot).
2. Blood clot is invaded by fibroblasts and other cells forming the callus.
3. Calcium is deposited in the callus, knitting the ends together.
4. Osteoclasts remove excess tissue so new bone structures is like the old.