Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HSF > HSF 1 - Unit 3 Embryology > Flashcards

HSF 1 - Unit 3 Embryology Flashcards

Development of the Skeletal System

1
Q

how does skeletogenesis occur in the axial skeleton?

A

vertebrae form as intersegmental structures derived from adjacent sclerotomes which split into cranial and caudal sections; with the caudal portion of one sclerotome fusing with the cranial portion of the sclerotome caudal to it. spinal nn emerge between each vertebrae and grow out to contact myotomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

there are originally how many somites of the cervical vertebrae?

A

8 (which is why there are 8 cervical spinal nerves), but the fusion of one to the cranium results in 7 cervical vertebrae, spinal nerves of this portion of the spine exit above vertebrae of the same number while others will exit below the same-numbered vertebrae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what do sclerotomes form during development of the spinal cord?

A

neural arches surrounding the developing spinal cord, also form the vertebral body (centrum)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what happens to the notochord during spinal cord development?

A

it regresses except where it is incorporated into intervertebral discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens when you get a herniated disc?

A

the nucleus pulposus gets pushed into the spinal canal and compressed, causes pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is congenital scoliosis?

A

abnormal lateral curvature of the spine, resulting from disruption of normal vertebral development; although many types (semisegmented, fully segmented, wedge vertebrae, block vertebrae, unsegmented bar, unsegmented bar with hemivertebrae) all result from abnormal formation and segmentation of the vertebral precursors (somites)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what do ribs arise from?

A

zones of condensed mesenchyme lateral to the body of the vertebrae (from sclerotome); develop from costal processes, grow into ribs in thoracic region only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

cervical ribs

A

ribs that grow in the cervical portion of the spine; can result in thoracic outlet syndrome that can cause issues with the brachial plexus due to compression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how does the sternum develop?

A

from cartilaginous sternal bars in ventral body wall; fuse with one another in cranial-caudal direction and form the manubrium, body, and xiphoid process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is pectus carinatum?

A

an overgrowth of cartilage causing the sternum to protrude. can be evident at birth; adolescent males during growth spurt. may occur as a solitary congenital abnormality or in association with other genetic disorders or syndromes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is pectus excavatum?

A

caused by overgrowth of the costal cartilage in such a way that restricts the expansion of the ribs and pushes the sternum inward, cause is unknown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a sternal cleft?

A

an unclosed sternum that leaves this space directly over the heart vulnerable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a sternal foramen?

A

it is an ossification anomaly found in 4-10% of the population that leaves a hole in the distal portion of the body of the sternum, leaving a hold directly over the heart. This can be mistaken for a bullet wound or sternal disease by a CT scan, and is a common acupuncture point (danger danger)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how does the appendicular skeleton develop?

A
  • with patterns of Hox gene expression and inductive interactions between the mesoderm and ectoderm (epithelia)
  • there are mechanical influences (early morphogenesis-late prenatal)
  • anomalies are common and highly visible, may be related to disturbances in specific cellular or molecular interactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

when is the initiation of limb development?

A

outgrowth from the body wall late in week 4, with the frontlimb being greater than the hindlimb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how is limb positioning regulated?

A

positioning along craniocaudal axis is regulated by HOX gene expression along the axis, these are expressed in overlapping patterns from head to tail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what happens once positioning along craniocaudal axis is determined?

A

placement along proximodistal, anteroposterior, and dorsoventral axes must be decided

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is limb growth initiated by?

A

TBX5 and FGF10 in the forelimb and TBX4 and FGF10 in the hindlimb, secreted by lateral plate mesoderm cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is Holt-Oram syndrome?

A

an autosomal dominant syndrome that causes a mutation in the transcription factor TBX5, which is important in the development of both the heart and upper limbs. this always causes variable upper limb abnormalities that can be either unilateral or bilateral; asymmetric may involve the radial, carpal, and thenar bones. the most prevalent findings are malformations or fusions of the carpal bones

20
Q

what are the types of reduction defects?

A

is an arrest or failure of development, can be part (meromelia) or all (amelia) of a limb missing. phocomelia is when the feet and hands arise close to the trunk

21
Q

what is mesomelia?

A

shortened forearm or leg elements, fetal sonography performed at week 20 can demonstrate the typical finding of mesomelic dysplasia

22
Q

how does the AER form?

A

AER= apical ectodermal ridge
once limb outgrowth is initiated, BMPs, expressed in the ventral ectoderm, induce formation of the AER. the AER sends signals to grow out from the body wall and where to put characteristics of the limbs
directs limb bud organization along proximo-distal axis and maintains dorsal/ventral axes

23
Q

what is RF? what does it do?

A

=radical fringe, found in the dorsal half of the limb ectoderm, and restricts the location of the AER to the distal tip of the limbs. it also induces the expression of SER2 at the border between cells that are expressing RF and those that are not. This is the border where AER is established. expression of RF is repressed by engrailed-1 in the ventral ectoderm

24
Q

what is engrailed-1? what does it do?

A

assists in the formation of the border (AER) in ventral ectoderm cells and represses RF expression here

25
Q

how is the limb bud organized and polarized?

A

development is organized around 3 axes, and controlled by 2 regions: AER, ZPA (also PZ)

26
Q

what is the ZPA?

A
  • zone of polarizing activity
  • made of mesodermal cells located at the base of the limb bud
  • produces retinoic acid (induces Shh expression)
  • directs organization of limb bud and patterning of digits
  • misexpression of retinoic acid or Shh results in mirror image duplication of the limb structures
  • determines anterior (preaxial/thumb), posterior (postaxial)
27
Q

what is the PZ?

A

progress zone, where mitosis and limb lengthening occurs; distal growth of the limb is affected by these cells under the influence of FGFs

28
Q

what does AER express after establishment?

A

FGF4 and FGF8, which maintain the progress zone, the rapidly proliferating population of mesenchyme cells adjacent to the ridge

29
Q

duplication defects

A

=duplication of components of the limbs

  • can be of complete limbs, partial limbs, or digits
  • polydactyly: extra digits
  • misexpression of RA and or Shh
  • duplication of the AER
30
Q

what is polydactyly?

A
  • a common defect that results in an extra digit(s), often the digit is incompletely formed and useless
  • extra digit will commonly be medial or lateral; foot is commonly lateral
  • dominant trait
31
Q

how does the limb grow and develop?

A

proximo-distally

32
Q

what is the differentiation zone?

A

region of cell specialization

33
Q

HOX genes regulate the …

A

type and shape of bones formed

34
Q

what does the AER secrete?

A

FGFs that influence the closest cells (progress zone) to development into distal structures; so cells that are no longer within the range of the AER remain proximal in nature

35
Q

what is thalidomide?

A

it is a anti-emitc drug that many pregnant women took for morning sickness that causes severe birth defects due to a disruption in the progress zone and AER communication; results in shortened, malformed, or absence or limbs

36
Q

how to digits develop?

A

at the hand or foot portion of the limb, the cells that are in between the developing digits selectively go through apoptosis, to make distinct fingers and toes

37
Q

what is syndactyly?

A
  • the most common limb abnormality that is due to webbed fingers or toes, failure of programmed apoptosis in digital ray
  • most frequent between 3rd and 4th fingers and the 2nd and 3rd toes
  • simple dominant or simple recessive inheritance
38
Q

what is brachydactyly?

A

an uncommon defect that causes short digits, there is a reduction in the length of phalanges and typically short stature; inherited as a dominant trait

39
Q

what is a cleft hand/foot?

A

the absence of one or more central digits or between digits 2 and 4 causes appearance of lobster claw, an uncommon defect

40
Q

what does…develop into?

1) lateral plate mesoderm
2) hypaxial mesoderm
3) neural crest
4) neural tube

A

1) skeleton and vasculature
2) muscles
3) schwann cells
4) motor/sensory axons (dermatome map)

41
Q

in development, the upper limb rotates ….

the lower limb rotates…

A

90 degrees laterally

90 degrees medially

42
Q

what are limb malformations?

A

can be overgrowth, undergrowth, focal defects, or associated with other general/syndromic skeletal abnormalities

43
Q

what is sirenomelia?

A

“mermaid syndrome” that results in the fusion of the lower limbs; presents in varying development of the bones

44
Q

how would you separate the limbs for sirenomelia?

A

saline sacks inserted and gradually filled to stretch the skin, then 2 operations to separate the legs, using the stretched skin to cover wounds. then another procedure later to rotate splayed feet forwards

45
Q

what is achondroplasia?

A
  • most prevalent form of dwarfism from a autosomal dominant mutation in FGF-R3
  • failure of proliferation and column formation of epiphyseal cartilage cells (a defect in endochondral bone formation which impairs the longitudinal growth of tubular bones)
46
Q

what is talipes equinovarus?

A

club foot, this kind is the most common type of it, two times more frequent in males. sole of the foot gets turned medially and the foot is inverted

47
Q

what are the different kinds of club foot?

A

flexible: results from abnormal positioning or restricted movement of the lower limbs in utero. the feet are structurally normal, these abnormalities usually correct themselves spontaneously
rigid: abnormal development of the ankle and foot joints during the 6th and 7th week, bony deformities with particularly the talus

HSF (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions