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CCDB > embryology - block 3 > Flashcards

embryology - block 3 Flashcards

1
Q

Main hox gene sequence for limbs

A

Hox - tbs5 - > Pitx1 -> fgf10 -> fgf8

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2
Q

main ideas in limbs - ?

A

gene sequence

direction develop
proxima/distal
anter/pos (cranial/caudal)
dorsal/ventral

digits

skeleton

rotation

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3
Q

How does it start? what week, what type of germ cells?

A

Lateral plate meso - 4th week

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4
Q

What gene controls the body plan?

A

Hox - determines cranial/caudal, etc

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5
Q

What two genes does HOX transcribe? what do they mark?

A

Tbx5 (arms - to box), Pitx1 (legs - podiatry)- two limb areas -

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6
Q

what does FGf10 do?

A

tells cells to produce FGF8

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7
Q

Proximal/distal axis? How do the limbs develop?

A

shoulder to fingers, hips to toes

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8
Q

what is apical Ectodermal Ridge AER?

A

Where is all starts

The apical ectodermal ridge (AER) is a structure that forms from the ectodermal cells at the distal end of each limb bud and acts as a major signaling center to ensure proper development of a limb.

The AER is known to express FGF2, FGF4, FGF8, and FGF9, while the limb bud mesenchyme expresses FGF2 and FGF10.

(AER) is a structure that forms from the ectodermal cells at the distal end of each limb bud and acts as a major signaling center to ensure proper development of a limb. After the limb bud induces AER formation, the AER and limb mesenchyme—including the zone of polarizing activity (ZPA)—continue to communicate with each other to direct further limb development.[1]

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9
Q

What induces AER - BMP?

A

MSX2

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10
Q

Radical fringe?

A

restricts AER to end of buds

Radical fringe is a signaling enzyme involved in the arrangement of the embryonic limb buds. It is a member of the fringe gene family, which also includes manic fringe and lunatic fringe.

Chr. Beta-1,3-N-acetylglucosaminyltransferase radical fringe, also known as radical fringe is a protein that in humans is encoded by the RFNG gene. Radical fringe is a signaling enzyme involved in the arrangement of the embryonic limb buds.

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11
Q

what genes does AER talk to ?

A

FGF4, FGF 8 - proliferate and maintain undifferentiated zone? which is which?

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12
Q

Retinoic Acid? what secrete it?

A

paraxial meso secrete - begins genetic cascade

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13
Q

Anterior/Posterior? Cranial/caudal?

A

Sonic HH - high does - caudal (3rd finger to little); low dose - (cranial - 1st to third)

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14
Q

starts with which digits?

A

1st - 5th

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15
Q

Where is the zpa?

A

Polarizing activity zone

The zone of polarizing activity (ZPA) is an area of mesenchyme that contains signals which instruct the developing limb bud to form along the anterior/posterior axis. Limb bud is undifferentiated mesenchyme enclosed by an ectoderm covering.

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16
Q

3 genes in dorso-ventral devel?

A

Wnt7, lmx-1b (dorsal

en-1 - ventral - represses wnt7, therefore lmx-1b becomes ventral limb

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17
Q

what does AER do?

A

restricts

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18
Q

radical fringe?

A

dorsal ectoderm

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19
Q

what does en1 do?

A

forms ventral ectoderm

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20
Q

how do digits form after initial start… apoptosis?

A

AER regresses - only persisting on digits, causes apoptosis. BMP2 , 4, and 7 strongly expressed in NON_digit spaces

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21
Q

Prime movers of digits?

A

BMP4 and MSX2

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22
Q

irony of FGF2?

A

usually causes growth, here causes death. balance betwe proliferatino and apoptosis

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23
Q

skeletal develop

A

BMP2 and 4 establish precartilage bone template

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24
Q

what does BMP6 do?

A

hypertrophy in maturing cartilage

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25
Q

What is the base to become bones?

A

chodrocytes? So what cause the chondrocytes to lay down bone? BMP2 and 4

26
Q

what is built first/ Post or pre axial?

A

post - humerous, ulna, dig 2 -5, metacarpals

Pre follows - thumb, carpal

27
Q

how is musculature formed

A

migrate from 30 -100 somites - from ventral area

28
Q

scatter factor?

A

Hepatic growth factor, stim cells to leave somite and migrate toward limbs to form muscles??

29
Q

roll of Pax3?

A

regulates expression of MET - regulated migration

30
Q

Innervation? what week?

A

5th week - neurons in spinal cord - migrate to limb buds - medial to ventral
lateral to dorsal

31
Q

Limb rotation? what weeks?

A

6 - 8 along long axis

upper laterally - arms turn out. 90 degrees
lower medially - legs turn in 90 degree

because of this rotation - extensors end up posteriorly - and flexors anteriorly

keep in mind the dog is standing

32
Q

Which embryonic limb structure causes limbs to grow out from the body?

A

Limb formation begins in the morphogenetic limb field, as mesenchymal cells from the lateral plate mesoderm proliferate to the point that they cause the ectoderm above to bulge out, forming a limb bud.

33
Q

What is the principal function of the AER?

Function.

A

The AER acts to: Maintain the limb mesenchyme in a mitotically active state and focused on its task – the distal outgrowth of the limb. This is achieved by secretion of FGF8, which signals the limb mesodermal cells to continue proliferation, and secreting FGF10, which winds up maintaining the AER.

34
Q

lateral plate mesoderm forms what part of limbs?

A

vasculature and skeleton

35
Q

somites from mesoderm form what structures in limbs?

A

muscles

36
Q

What is AER from?

A

ectoderm - a thickened ridge at the apex of the limb buds

37
Q

What does AER do?

A

produced FGF - fibroblast growth factor - which promotes limb growth by stimulating cell mitosis and preventing differentiation of underlying mesoderm

38
Q

What expresses Wnt7, and what does this gene do?

A

organizes limb bud along dorsal/ventral axis, AER expresses

39
Q

What’s the zpa?

A

at base of limb bud, mesodermal cells - produces SHH -

40
Q

what axis does SHH control?

A

anterior posterior - and patterns digits

41
Q

Does SHH activate BMP (bone morphongenetic protein gene and the HOX genes?

A

Yes. Retinoic acid also play significant role in limb polarization

42
Q

Digit formation?

A

apoptosis within AER - how works unclear - but BMP, MSx1 and reinoic acid may play role

43
Q

Critical days of limb development

A

days 24 - 36

44
Q

common limb deformities - 4 kinds

A

reduction - meromelia vs. amelia

duplication (polydactyly, etc)

dysplasias (fusion of digits, etc)

deformations (physical foces)

45
Q

acheiria, apodia

A

absence hands, feet (podia)

46
Q

phocomelia, memimelia?

A

absense, shortening of proximal limbs /

hemi - absense of preaxial or postaxial parts of limbs

47
Q

ectrodactyly

Polydactyly (most common)

A

absence of any number of digits vs extra digits (polydactyly - MOST COMMON 1/7000

5th toe most common,

48
Q

syndactyly, bachydactuly

A

webbing between digits, shortened digits

49
Q

split hand or foot - a

A

absense of central components

50
Q

what is one of first arteries to form in arm?

A

Median artery - in adults median artery does not persist - this is why median nerve doesn’t have an artery as do the radial and ulna never/artery combos

51
Q

Dorsal rami - EPAXIAL m

A

ventral rami HYPAXIAL

52
Q

femur from what type of cells?

A

lateral plate mesoderm

53
Q

where does apposiotional growth occur (diameter growth?

A

diaphysis

54
Q

AER - FGF 8 - 10

A

ZPA - SHH (digits)

too much creates?

BMP - ventral extoderm??

55
Q

The tendon of the flexor pollicis longus muscle courses through the carpal tunnel with the tendons of the flexor digitorum superficialis and the flexor digitorum profundus muscles and the median nerve.

A

The flexor digitorum longus is the major flexor of the DIPJ’s of the 2-5 digits. It is innervated by the tibial nerve (L5,S1).
The extensor digitorum longus is innervated by the deep peroneal nerve (L4, L5, and S1). It is part of the “hood mechanism” and is an extensor of the digits at the MTPJ.

The lumbricales, with the interossei, cause flexion of the MTPJ and extension of the PIPJ’s. Innervation is by the medial and lateral plantar nerve.

The tibialis posterior inverts and plantar flexes the ankle. It has no direct effect on the digits. The innervation is by the tibial nerve (L4, L5, and S1).

The flexor digitorum brevis causes flexion of the PIPJ of digits 2-5. The innervation is by the medial plantar nerve (L4, L5, and S1).

56
Q

The superficial layer or the first layer consists of the flexor digitorum brevis, abductor hallucis, and the abductor digiti minimi muscles.
The second layer consists of the quadratus plantae and the lumbrical muscles.

The third layer includes the flexor hallucis brevis, adductor hallucis, and the flexor digiti minimi brevis.

The fourth layer, the deepest layer, contains the interossei muscles.

A

The carpal tunnel contains ten structures to include the median nerve and nine extrinsic flexor tendons of the fingers and thumb. These tendons are the four flexor digitorum profundus tendons and four flexor digitorum superficialis tendons to the fingers and the flexor pollicis longus tendon to the thumb.

57
Q

he triceps brachii has three originations. Two originate on the humerus and the third originates at the infraglenoid tubercle, making it the longest of the 3 heads.

A

A branch from the posterior cord of the brachial plexus innervates which of the following muscles

Lats

58
Q

The pubofemoral ligament of the capsule of the hip joint is attached medially to the anterior part of the acetabular rim and the adjacent part of the superior pubic ramus. The fibers pass transversely on the inferior aspect of the capsule and are attached to the inferior aspect of the neck of the femur above the lesser trochanter.

A

swimmer muscle

Lat - The latissimus dorsi is innervated by the sixth, seventh, and eighth cervical nerves through the thoracodorsal (long subscapular) nerve.

59
Q

Which of the following joints is a plane joint?

A

The intercarpal joints are plane (gliding) joints. A pivot joint rotates around the long axis of a bone (think of opening a doorknob). To do this, the radius rotates around the ulna. The radiocarpal is a condyloid (a convex surface articulating with a concave surface). The radiohumeral and humeral-ulnar are both synovial joints.

60
Q 
he radiocarpal (= wrist) joint is a synovial ellipsoid joint between the distal end of the radius and the articular disc above, and the scaphoid, lunate, and triquetral bone below. The joint allows flexion, extension, abduction, and circumduction but does not allow rotation.
Intercarpal joints (between individual bones of the proximal row of the carpus; between the individual bones of the distal row of the carpus; and finally, the midcarpal joint, between the proximal and distal rows of carpal bones), as well as carpometacarpal and intermetacarpal joints are synovial plane joints. All of them allow small amount of gliding movement. Elbow joint (between the trochlea and capitulum of the humerus and the trochlear notch of the ulna and the head of the radius) is a synovial hinge joint. This joint is capable of both flexion and extension.
A

Knee bursa: the most communicative bursae is the suprapatellar bursa, hence the suprapatellar bursa is the best answer. Effusion of the knee’s articular cavity causes this bursa to be swollen, which is palpable and visible in most cases.

CCDB (13 decks)

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