Develpment Of The Muscular And Skeletal Systems Flashcards

1
Q

The Myotome forms _______

A

All the muscles of the body except the constrictor and dilater papillae in the eye

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2
Q

The somite divides into what two parts

A

Ventromedial part and dorsolateral part

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3
Q

The ventromedial part of the somite develops into what

A

Sclerotome

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4
Q

The dorsolateral part of the somite develops into what

A

Dermatomes and myotome

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5
Q

The sclerotome gives rise to

A

The mesenchyme - embryonic connective tissue

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6
Q

The mesenchyme gives rise to what three things

A

Hyaline cartilage
Endochondral ossification
Intramembranous ossification

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7
Q

Intramembranous ossification

A

Mesenchyme —> bone

  • the mesenchyme forms in the shape of the bone you want first
  • clavicle, flat bones of skull, face bones
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8
Q

Endochondral ossification

A

Mesenchyme —> cartilage —> bone

  • the mesenchyme forms cartilage in the shape of the bone first
  • most bones in the body
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9
Q

How is hyaline cartilage formed (4 steps)

A

Chondrification centers —> prechondrocytes —> chondroblasts —> chondrocytes

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10
Q

Two parts of the sclerotome

A

Caudal dense part

Cephalic loose part

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11
Q

What two parts fuse to form the vertebrae

A

Casual dense part and cephalic loose part of the sclerotome

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12
Q

Two parts of the intervertebral discs

A

Nucleus pulposus and annulus fibrosus

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13
Q

Annulus fibrosus

A

Part of the intervertebral disc; consist of fibrous tissue from the sclerotome and fibrocartilage

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14
Q

Nucleus pulposus

A

Part of the intervertebral discs; made of mucous substance and notochord cells
- it’s the only remaining part left over from the notochord at this point

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15
Q

How do ribs form

A

Sclerotome cells grow out from costal processes of thoracic vertebrae; the costal cartilage is also from the sclerotome

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16
Q

How does the sternum form

A

It develops in the somatic lateral plate mesoderm; mesenchymal condensations chondrify and fuse together

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17
Q

Cervical rib formation

A

An abnormality in rib formation; causes the brachial plexus to compress against the rib and compresses the subclavian
- one of the causes of thoracic outlet syndrome

18
Q

Pectus carinatum

A

Abnormality in rib/sternum formation; causes a protrusion of the sternum called “pigeon chest”

  • unknown what causes this
  • patients are otherwise normal
19
Q

Pectus excavatum

A

Abnormality in rib/sternum formation; causes steal depression “funnel chest”

  • can compress the heart and/or shift the heart to the side
  • sx include SOB, fatigue with exercise
  • can need surgical correction
  • cause is unknown
20
Q

Hox genes

A

Group of genes that control the body plan along a cranio-caudal axis

21
Q

Caudalization

A

Gain of function via hox gene defect; upper vertebrae appear like lower vertebrae

22
Q

cranialization

A

loss of function via hox gene defect; lower vertebrae appear like upper vertebrae

23
Q

gain of function (caudalization) in Hox6 in cervical vertebrae

A

those vertebrae start to look more similar to vertebrae that are lower (thoracic)

Hox 6 is normally found in upper thoracic region; cervical vertebrae can over express Hox 6 and they will now look like thoracic vertebrae

24
Q

gain of function (caudalization) of Hox 10

- normally found in lumbar region

A

expressed in thoracic region; the thoracic vertebrae will then look like lumbar vertebrae

25
loss of function (cranialization) of Hox 4
C2, C3, C4 | those vertebrae will look like the vertebrae above them (C1)
26
loss of function (cranialization) of Hox 5
the vertebrae that lost Hox 5 will appear like C2 | - Hox 5 normally found C3-T2
27
loss of function (cranialization) of Hox 6
Hox 6 normally found in C6-T6; those thoracic vertebrae would look like cervical vertebrae and we wouldn't have ribs attached
28
loss of function (cranialization) of Hox 10
hox 10 normally found L1-S4; the lumbar vertebrae that aren't expressing hox 10 will look thoracic
29
Hox 9 function
gene that encodes for floating ribs
30
loss of function (cranialization) of hox 9
normally T8-L4 | - won't have floating ribs with cranialization
31
Hox 11 location
S1-coccyx
32
epimere
derived from the myotome; develops into the epiaxial muscles
33
epaxial muscles
true muscles of the back (erector spinae muscles, splenius capitus, etc) - innervated by the dorsal rami
34
hypomere
derived from the myotome; develops into the hypaxial muscles
35
hypaxial muscles
all other muscles of the body except the true muscles of the back (epaxial muscles) and the constrictor and dilator of pupils - innervated by ventral rami
36
cervical myotomes form:
scalene, prevertebral, geniohyoid, and infrahydoid muscles
37
thoracic myotomes form:
later and ventral flexor muscles of the vertebral column
38
lumbar myotomes form:
quadratus lumborum
39
sacrococcygeal myotomes form:
muscles of the pelvic diaphragm
40
4 hypaxial divisions of the muscles
- cervical myotomes - thoracic myotomes - lumbar myotomes - sacrococcygeal myotomes
41
poland syndrome
a result of absence of migration of hypomere cells into the chest; patient's do not have pectoralis major and/or minor; patients have ipsilateral breast hypoplasia associated with syndactyly and sometimes loss of 2-4 ribs
42
prune-belly syndrome
partial or complete absence of abdominal musculature as a result of absence or abnormal migration of hypomere cells into the abdominal wall - primarily affects males - associated with crytorchidism and malformation of urinary tract and bladder