Human Skeleton

Question 1

What is the function of the skeleton?

Answer 1

• support
• protection
• movement
• mineral reserve (calcium salts in the skeleton)
• haematopoiesis

Question 2

What are osteons?

Answer 2

• aka Haversian system
• layers of bone
• organic 30% (type I collagen)
• inorganic 70% (calcium and phosphate salts)
• ## tensile vs compressive strength

Question 3

Osteoblasts

Answer 3

Lay down new bone

Question 4

Osteoclasts

Answer 4

Break down old bone

Question 5

Discuss rickets

Answer 5

• not enough mineral content in the bone so bone becomes flexible/bendy
• due to vitamin D deficiency
• vitamin D needed for calcium absorption

Question 6

Discuss osteogenesis imperfecta (OI)

Answer 6

• congenital genetic disorder
• affects collagen production
• bones become brittle and can fracture easily

Question 7

List some terminology of bone anatomy

Answer 7

• diaphysis
• epiphysis
• epiphyseal growth plate
• periosteum
• endosteum

Question 8

Diaphysis

Answer 8

• long and tube like
• strong but some flexibility
• mostly made up of compact bone

Question 9

Epiphyses

Answer 9

• there are 2 - one at either end of diaphysis
• articular surface for joints
• mostly spongy bone but compact on the surface

Question 10

Epiphyseal growth plate

Answer 10

• this separates the diaphysis and epiphysis
• it is where growth occurs
• once growth is complete the plate ossifies and becomes the epiphyseal line

Question 11

Periosteum

Answer 11

• a connective tissue later
• covers outer surface of bone
• site of attachment for tendons

Question 12

Endosteum

Answer 12

• lines internal surfaces of cavities within bones

Question 13

How do bones grow?

Answer 13

• bone can only be laid down onto a surface
• bone cells do not divide (?)
• interstitial growth
• growth plate continues to grow and bone replaces cartilage
• eventually diaphysis and epiphysis fuse together

Question 14

Name the classifications of shapes of bones

Answer 14

• long bones
• short bones
• flat bones
• irregular bones
• sesamoid bones

Question 15

Long bones

Answer 15

• longer than they are wide
• long diaphysis
• ones of the limbs e.g. femur

Question 16

Short bones

Answer 16

• width and length are similar
• involved in movement
• e.g. bones of the wrist and ankle

Question 17

Flat bones

Answer 17

• thin, flat, usually curved
• protective in function
• e.g. skull, sternum, scapula and ribs

Question 18

Irregular bones

Answer 18

• don’t fit in other categories

- e.g. vertebrae, facial bones

Question 19

Sesamoid bones

Answer 19

• small round bones embedded in tendons
• function is to protect tendon and increase range of movement
• e.g. patella

Question 20

What is the composition of the bone?

Answer 20

• 30% organic - type I collagen
• 70% inorganic - calcium and phosphate salts
• this provides both tensile and compressive strength

Question 21

Discuss spongy/cancellous bone

Answer 21

• found within the epiphyses
• formed from struts of bone called trabeculae that make it look like honeycomb
• red bone marrow would be found in the spaces between trabeculae

Question 22

How may bones are in the human skeleton?

Answer 22

• around 206
• 270 in newborns as parts are developing separately and will later few
• number of bones can vary between individuals and vary with age

Question 23

How are bones connect?

Answer 23

By joints:

- fibrous (e.g. sutures in bones of skull)
- cartilaginous (e.g. IVDs)
- synovial/true joints have a gap between bone surfaces due to lubricating synovial fluid, greater range of movement (e.g. humerus)

Question 24

How is the skeleton organised?

Answer 24

• Axial skeleton (skull, vertebral column, ribs and sternum)
• Appendicular skeleton (upper limb - pectoral girdle, bones of arms and hands) (lower limb - pelvic girdle, bones of legs and feet)

Question 25

Discuss the skull

Answer 25

• most complex area of the skeleton
• houses brain and special sense organs so has a protective function
• viscerocranium (facial skeleton) has 14 bones
• neurocranium (surrounding brain) has 8 bones

Question 26

Discuss the vertebral column

Answer 26

• contains 33 bones
• 7 cervical vertebrae in neck region, small, relatively mobile, more susceptible to dislocation, bifid spinous process
• 12 thoracic vertebrae in region of thorax, articulate with ribs, long processes for muscle attachment
• 5 lumbar towards bottom of spine, increase in weight bearing function of bones so these are bigger, larger body, susceptible to herniated IVDs
• 5 fused bones make the sacrum, vertebrae are fused and articulate with hip bones
• 4 fused bones make coccyx, tailbone, can fracture if landed on

Question 27

Discuss the pectoral girdle

Answer 27

• made up of scapula and clavicle
• clavicle is only bone connecting upper limb to axial skeleton
• facilitate movement

Question 28

Discuss the pelvic girdle

Answer 28

• 2 hip bones (innominates)
• each hip bone has ilium, ischium, pubis
• provide stability - help to transfer weight to limbs
• protect pelvic organs
• different shape in males and females

Question 29

Discuss the limbs

Answer 29

Upper limb:

- humerus (arm)
- radius and ulna (forearm)
- 8 carpals (wrist)
- 5 metacarpals and 14 phalanges (hand)

Lower limb:

- femur (thigh)
- tibia and fibula (leg)
- 7 tarsals (ankle)
- 5 metatarsals and 14 phalanges (foot)

Also remember sesamoid bone - patella!

Question 30

Name some bone markings

Answer 30

• condyle/epicondyle
• crest/line
• facet
• foremen/notch
• fossa
• process/protuberance/spine
• trochanter/tubercle/tuberosity

Question 31

Discuss the sternum and ribs

Answer 31

• flat bones
• surround and protect thoracic organs (thoracic cage)
• important role in respiration
• flexibility provided by costal cartilages anteriorly
• sternal angle

Question 32

Discuss the sternum

Answer 32

• made up of 3 parts: manubrium, body and xiphoid process
• sternum angle is an important anatomical landmark
• sternum angle is at level of T4/T5 IVD posteriorly
• ## 2nd ribs articulate anteriorly with sternal angle

Question 33

Why do we need to count the ribs?

Answer 33

Clinical relevance - auscultation

- depending on what valve/area of the heart we want to listen to will determine which ribs we would position against