M1.1 — 8 review + 12-16

Question 1

what do somites become?

Answer 1

dermatome - dermis and subcutaneous tissue

myotome - axial muscle

sclerotomes - surround neural tube and notochord to become bones and supporting ligaments of the spine

Question 2

what is intramembranous ossification?

Answer 2

embryonic mesenchymal tissue slowly converts to a network of collagen fibers and ground substance. Over time this slowly converts to osteoblasts which will begin ossification

Question 3

what is endochondral ossification?

Answer 3

mesenchyme slowly convert to chondrocytes which form cartilaginous model for bone

typical in bones of the extremities

Question 4

with endochondral ossification, the primary ossification center is separated from the secondary ossification center by a _____ which will eventually close and the secondary ossification center will ___ to the primary ossification center

Answer 4

growth plate/ growth center

fuse

Question 5

what are the layers of a growth center / growth plate?

Answer 5

reserve zone
proliferative zone
hypertrophic zone
provisional calcification zone

Question 6

what is in the reserve zone of a growth plate?

Answer 6

a layer of quiet cartilage cells that are the source for bone growth

Question 7

what is in the proliferative zone of a growth plate?

Answer 7

the chondrocytes divide, flatten and form into columns

Question 8

what is in the hypertrophic zone of a growth plate?

Answer 8

the cells mature, expand in size, spread apart from each other creating extra cellular space

• location of physeal fractures = weak

Question 9

what is in the provisional calcification zone of a growth plate?

Answer 9

cartilage begins to calcify, then convert to immature osteoid

Question 10

what is the zone of ranvier?

Answer 10

small notch around the periphery of the growth center - largely responsible for the circumferential growth of the bone

Question 11

one a bone scan of children, radiotracer collects in _____

Answer 11

growth centers

Question 12

when does spheno-occipital synchondrosis start? complete?

Answer 12

12-13 F, 14-15 M

completed by 17-18

forms the clivus

Question 13

when does petro-occipital synchondrosis start? complete?

Answer 13

doesn’t fuse, joined by fibrocartilage

Question 14

by age 25, the disc will have lost __% of water content in the nucleus pulls us and __% in the annulus fibrosis

Answer 14

75%

70%

• this is not considered desiccation - adult degeneration

Question 15

bone marrow is evaluated on which imaging modality?

Answer 15

MRI

Question 16

what are the two marrow types?

Answer 16

red marrow (hematopoietic) - red blood cells, platelets, some lymphocytes

yellow marrow - fatty storage

Question 17

all marrow remains red until __ yo. Then, a portion of red marrow converts to ______ marrow, a process which ends at about __-__ yo

Answer 17

7yo

yellow marrow

25-30yo

Question 18

which marrow will be brighter on a T1 MRI? T2?

Answer 18

T1 - fat (yellow marrow) is brighter
T2 - yellow marrow is the same or brighter than red

Question 19

will marrow enhance in an MRI with IV contrast?

Answer 19

no, if it does = pathology

Question 20

what is an oppenheimer ossicle?

Answer 20

small, united secondary ossifcation center of a lumbar IAP (mostly L2 and L3)

generally not clinically significant