Lecture 3 - The Skeleton

Question 1

define axial skeleton

Answer 1

• skull, spine and ribcage
• the areas of the body you cannot live without (protects necessary organs)

Question 2

define appendicular skeleton

Answer 2

• the upper and lower extremities and the pelvis
• the areas of the body not necessary for life

Question 3

what are the 5 sections of the spine?

Answer 3

1. cervical spine
2. thoracic spine
3. lumbar spine
4. sacrum
5. coccyx

Question 4

why doesn’t the thoracic spine twist?

Answer 4

• due to ribs not wanting to overlap
• both lumbar and cervical though have a lot of motion

Question 5

what is the odontoid process and its role?

Answer 5

• sticks out of C2 into C1
• required to make the “no” motion

Question 6

why is the curvature of the spine so important?

Answer 6

• to take loads
• spine acts as a spring and absorbs load to keep the head steady (for the brain and the eyes)

Question 7

what are the 6 functions of the skeleton?

Answer 7

1. attachments for muscles
2. leverage for supplying torque to the joints
3. protect vital organs
4. support soft tissues
5. making new red blood cells (in the bone marrow)
6. reservoir for calcium and phosphate

Question 8

what is wolff’s law of bone?

Answer 8

• bone is laid down in areas of high stress, bone is lost in areas of low stress
• “use it or lose it”
• remodeling process (osteoblasts lay down, osteoclasts absorb)
• “stress” adjusts the balance between the two

Question 9

what is stress shielding?

Answer 9

• stiff metal implant off loafs the surrounding bone so the bone reabsorbs
• osteoclasts eat away at bones no longer under stress
• due to poor implant design

Question 10

what are the 5 types of bones?

Answer 10

• long
• short
• sesamoid
• flat
• irregular

Question 11

what are long bones?

Answer 11

• usually in the extremities
• acts as lever for muscles about the joints (so long)
• knobs on ends are for joint connections
• hollow because they need to be light

Question 12

what are short bones?

Answer 12

• tightly packed
• provide shock absorption and flexibility of movement
• can bear a lot of load

Question 13

what are flat bones?

Answer 13

• provide protection to underlying organs

Question 14

what are irregular bones?

Answer 14

• fulfill multiple roles
• protection and flexibility
• multiple muscle attachments
• vertebra or scapula
• generally a weakness in the body (high mobility so low stability)

Question 15

what is a condyle/epicondyle?

Answer 15

• a rounded process of a bone that articulates with another bone
• epi just means smaller

Question 16

what is a facet?

Answer 16

• a small, flat, smooth surface of a bone that is usually a weight-bearing surface
• usually articulate with other facets

Question 17

what is a foramen?

Answer 17

• a hole in a bone where a nerve passes through (or a blood vessel)

Question 18

what is a fossa?

Answer 18

• a shallow depression in a bone, usually space for another bone

Question 19

what is a process or tuberosity?

Answer 19

• a raised section of bone, usually for the attachment of a ligament or tendon

Question 20

what is diaphysis?

Answer 20

• the shaft of the long bone made of hard cortical bone
• outer lining is the periosteum
• inner lining is the endosteum
• hollow middle is called the medullary canal

Question 21

what is metaphysis?

Answer 21

• the ends of the long bone made of spongy trabecular bone
• separated from the diaphysis via an epiphyseal plate of cortical bone

Question 22

what are the bone cell types in short bones?

Answer 22

• more metaphysis and made of spongy trabecular bone

Question 23

what are the bone cell types in flat bones?

Answer 23

• more diaphysis with a layer of trabecular bone

Question 24

what are the bone cell types in irregular bones?

Answer 24

• a combination of cortical bone (diaphysis) and trabecular bone (metaphysis)

Question 25

what are the types of loading on the skeleton?

Answer 25

• compression
• tension
• torsion (twisting)
• shear (sliding)