Part 12: Osteology of UL

Question 1

Where do # of the clavicle occur and why?

Answer 1

Between costoclavicular and corococlavicular liagment attachments - both of these ligaments are stronger than then clavicle

Question 2

When does the clavicle arise embryologically?

Answer 2

1st bone of skeleton, occurs before any cartilage in embryo. Centres begin ossifying in 5th week. Elongation occurs at sternal end.

Question 3

Ossification of the scapular occurs when?

Answer 3

Mesenchyme chondrifies at 6 weeks -> ossification occurs at 8 weeks. At birth acromion, coracoid and medial border are still hyaline cartilage. Secondary centres occur in these places around puberty and are fused by 25 years.

Question 4

Describe humerus development to birth

Answer 4

The whole humerus is cartilaginous by 6 weeks. Primary centres appear by 8 weeks. Upper and lower ends are cartilaginous at birth. Secondary centres occur at both ends.

Question 5

Describe the ossification of humeral head

Answer 5

Head ossifies in 1st year
GT ossifies in 3rd year
LT ossifies in 5th year
All fuse by 7th year
Epiphyseal line fuses around 20 years

Question 6

Describe ossification of lower end of humerus

Answer 6

4 centres
- capitellum and lateral ridge ossification centres occurs at 2nd year
- medial epicondyle centre occurs at 5th year
- trochlear centre occurs at 12th year
- lateral epicondyle centre occurs at 13th year
Union with shaft occurs around 18 years

Question 7

Describe radius development to birth

Answer 7

Cartilaginous at 6 weeks. Ossification centre occurs at 8 weeks with both ends cartilaginous at birth

Question 8

Describe the ossification of lower end of radius

Answer 8

Lower end is growing end. Centre appears at end of 1st year and fuses at 20y.

Question 9

Describe ossification of upper end of radius

Answer 9

Centre appears at 4 years - fuses at 12 years

Question 10

Describe development of ulna to birth

Answer 10

Cartilaginous at 6 weeks

Primary centre occurs at 8 weeks. Cartilaginous at both ends at birth

Question 11

Describe ossification of head/lower end of ulna

Answer 11

Growing end.

Not ossified until 6th year and does not fuse until 20 years

Question 12

Describe ossification of upper end of ulna

Answer 12

Small epiphysis occurs around 10th year and fuses around 18 years. Upper end grows in shape and size to adjust to trochlear

Question 13

Name the carpal bones

Answer 13

Proximal:
Scaphoid, Lunate, Triquetral, Pisiform
Distal:
Trapezium, trapezoid, capitate, hamate

Question 14

Are the carpals bone ossified at birth?

Answer 14

No, completely cartilaginous

Question 15

How does ossification occur in carpal bones?

Answer 15

Each bone has 1 ossification centre. Ossify according to size. Capitate ossifies around 1 year and pisiform ossifies around 10 years with other bones ossifying in between

Question 16

Are Metacarpals and phalanges ossified at birth?

Answer 16

Yes - shafts of MC and phalanges are ossifies at birth with cartilaginous epiphysis

Question 17

When does ossification of epiphysis occur for phalanges and MC?

Answer 17

2-3 years and fuse at 20 years.

Question 18

Which end of phalanges and MC does the cartilaginous epiphysis occur?

Answer 18

Phalanges: base
MC: head
Thumb MC - base (ossifies like a phalanx)