Lecture 3: Structure of the Skeleton (Bone I)

Question 1

What are the functions of the skeleton?

Answer 1

• Support
• Movement (Bones are levers)
• Protect major organs
• Store minerals (etc)
• Red blood cell formation in marrow

Question 2

What are the 2 types of bone tissue?

Answer 2

• Compact bone
• Cancellous (trabecular) bone

Question 3

What are compact bones?

Answer 3

Compact bones are strong and good at transmitting force in one direction.

Question 4

What are cancellous (trabecular) bones?

Answer 4

Cancellous (trabecular) bones are light, spongey bone that act as shock absorbers. They resist and channel forces that come from multiple directions.

Question 5

What are the 4 different bone classes?

Answer 5

Long bones, short bones, flat bones and irregular bones.

Question 6

Characteristics of long bones

Answer 6

• Longer rather than wider
• Composed of wider epiphyses and a longer, narrower diaphysis
• Acts as levers for movements
• Thicker compact bone in diaphysis
• Mostly limb bones

Question 7

Characteristics of short bones

Answer 7

• Close to equal width and length
• Weight bearing (from multiple directions)
• Mostly cancellous bone
• E.g. Carpals and tarsals

Question 8

Characteristics of flat bones

Answer 8

• Function usually for muscle attachment (e.g. scapula)
• Also protection (e.g. skull and sternum)
• Thin plates of compact bone (some cancellous too)

Question 9

Characteristics of irregular bones

Answer 9

• Doesn’t seem to fit into any other category? It’s probably an irregular bone!
• Not long
• Not round/square shaped
• Not just cancellous bone
• Not flat
• Often have a foramen/foramina

Question 10

What are the different divisions of the skeleton?

Answer 10

The axial skeleton and the appendicular skeleton

Question 11

What is the axial skeleton’s primary purpose and what does it consist of?

Answer 11

• Protect the vital organs
• Bones of the core: skull, sternum, ribs, vertebral, column, sacrum, coccyx.

Question 12

What does the skull consist of and what are their purposes?

Answer 12

The skull is joined at sutures (immovable)

• Cranium (vault): encloses the brain and muscle attachments
• Facial bones: protect and support sensory organs

Question 13

What does the vertebral column consist of and what are their purposes?

Answer 13

• 4 divisions: cervical (7), thoracic (12), lumbar (5), sacrum and coccyx
• Keeps the trunk upright (there are lots of muscle/ligament attachments)
• Supports the head

Question 14

What does the rib cage consist of and what are their purposes?

Answer 14

• Rib cage: ribs and sternum
• Protect the heart and lungs

Question 15

What does the appendicular skeleton consist of?

Answer 15

• Single proximal long bone (Humerus / Femur)
• Two distal long bones (Ulna and Radius / Tibia and Fibula)
• Hands and Feet
• Different form/ function in the upper snd lower limb

Question 16

Why is the human skeleton the shape it is?

Answer 16

• Form is related to function
• We walk on 2 limbs (bipedalism) vs other apes that walk in 4 limbs (quadrapedalism)
• Humans lower limbs need stability and movement

Question 17

What does being a biped mean for humans?

Answer 17

• Loss of stability
• Hands are free and are not involved in locomotion (move from one place to another)
• Hands are adapted for precision

Question 18

What are the comparable differences between the humerus and the femur?

Answer 18

• Humerus is shorter and lighter
• Deeper articulation for proximal femur than proximal humerus

Question 19

What is mobility at the forearms and wrists like?

Answer 19

• Pronation and supination of the radius and ulna
• Shape of distal articulation for wrist mobility

Question 20

What is stability of the legs like?

Answer 20

• No pronation / supination
• Tibia is very robust (able to bear alot of weight)
• Ankle joint = most stable

Question 21

What does the hand consist of?

Answer 21

• 8 carpals
• 5 metacarpals
• 14 phalanges (only 2 phalanx in the thumb)

Question 22

What doe the foot consist of?

Answer 22

• 7 tarsals
• 5 metatarsals
• 14 phalanges

Question 23

How do the limbs attach to the axial skeleton?

Answer 23

• Pectoral girdle (at the scapula and clavicle)
• Pelvic girdle: at both hip bones and the sacrum (axial)

• Pelvic bones + sacrum = pelvis

Question 24

What does the pelvic girdle consist of and what are their purposes?

Answer 24

• Clavicle: Acts as a stabilising strut
• Scapula: Alllows for free range of movement and for muscle attachementa

Question 25

What does the pelvic girdle consist of an what are their purposes?

Answer 25

• Both hip bones: Os coxae
• Pelvic bones + sacrum = pelvis
• Bears a lot of weight

• Sacrum: Part of the axial skeleton

Question 26

What is the difference between the biological male and female pelvic anatomy?

Answer 26

Biologically, the female pelvic cavity is more circular and the pelvic outlet is more open.

Question 27

Describe the functions of the skeletal system

Question 28

Describe the gross structure of bones

Question 29

Explain how the gross structure of bones reflects on their functions

Question 30

Describe the different classes of bone in the human skeleton

Question 31

Explain how the shape of a bone relates to the function

Question 32

Identify the major bones of the skeleton

Question 33

Why are some of the major bones of the skeleton sexually dimorphic?