OAP - Bones of the Skull & Orbit - Topic 3

Question 1

Differentiate between different bone shapes

Answer 1

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

Question 2

List the mineral composition of bone

Answer 2

33% = Organic Compound (cells & extracellular matrix)
(67% = Inorganic Compounds)
39% = Calcium
17% = Phosphate
9.8% = Carbonate
0.7% = Sodium
0.5% = Magnesium
0.2% = Potassium

Question 3

Describe the microstructure of bone

Answer 3

Bone is connective tissue
-Made up of Osteogenic,osteoblast,osteocyte and osteoclast cells and extracellular matrix (fibres [collagen] and ground substance),

Question 4

Describe the differences between spongy and compact bone?

Answer 4

Compact bone

• Found on external surfaces
• Dense, strong and heavy

Spongy bone

• Found internal to compact bone
• Light and loose

Question 5

How does the structure of a compact bone relate to its function?

Answer 5

• Surrounded by a thin dense layer of connective tissue forming an external layer
• Contains canals for vessels (blood and lymphatic) to run through

Question 6

How does the structure of Spongy Bone relate to its function?

Answer 6

• Doesn’t contain osteons
• Lots of empty space
• Consists of trabeculae, to protect bone marrow

Question 7

Describe the function of bone tissue

Answer 7

Supportive

• Movement
• Protection

Mineral Homeostasis

• Blood cell production
• Triglyceride storage

Question 8

Define Articulations

Answer 8

The region where adjacent bones contact each other – a joint

Question 9

Define Cavities?

Answer 9

Spaces within the skull

Question 10

Define Foramina?

Answer 10

An small opening which allows passage of structures from one region to another

Question 11

Define Fissures.

Answer 11

Similar to foramina. Small opening which allows passage of structures. Shape is more like a crack or cleft.

Question 12

Define Fossa.

Answer 12

A shallow depression in the bone

Question 13

What are some of the cavities of the skull?

Answer 13

• Nasal Cavity

- Orbital Cavity

Question 14

What are bone sutures?

Answer 14

-Bones of the skull unite at sutures
-Form immovable joints
Except mandible (bone holding lower teeth and jawline)

Question 15

List the 6 different type of Cranial Bones.

Answer 15

1) Parietal (x2)
2) Temporal (x2)
3) Occipital
4) Sphenoid
5) Ethmoid
6) Frontal

Question 16

List the 8 different types facial bones?

Answer 16

1) Nasal (x2)
2) Maxillary (x2)
3) Zygomatic (x2)
4) Mandible
5) Lacrimal (x2)
6) Palatine (x2)
7) Inferior nasal conchae (x2)
8) Vomer

Question 17

Describe the Ethmoid of the cranial bones.

Answer 17

• Extends out from the midline
• Major supporting structure of the nasal cavity
• Forms part of the orbit

Question 18

Name the articulations of bones of the skull.

Answer 18

Facial bone
-Maxillae has most articulations

Cranial bone
-Sphenoid has most articulations

Question 19

Name the 7 bones of the orbit.

Answer 19

1. Frontal
2. Sphenoid
3. Ethmoid
4. Lacrimal
5. Palatine
6. Maxilla
7. Zygomatic

Question 20

What is contained in the orbital cavity?

Answer 20

• Eyeball
• Optic Nerve
• Connective Tissue
• Muscles
• Adipose Tissue (fat)

Question 21

What is the volume of the orbital cavity and how much volume do the other structures have?

Answer 21

Total Volume= 30mL

6. 5mL= Eyeball
7. 6mL= Optic nerve, Connective tissue, Muscles, Adipose Tissue

Question 22

Describe a medical condition relating to the orbit

Answer 22

-Blow-out fracture ( a break of one or more of the bones that surround the eye)

Question 23

Explain how age-related changes can affect the orbit

Answer 23

• Osteoporosis (Over time, low calcium intake)

- Weakening of orbital septum (allows fat to prolapse forward into the eyelid)