Term
| As the notochord and neural tube form in the third week, the intraembryonic mesoderm lateral to these structures thickens to form two longitudinal columns of... |
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Definition
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Term
| Toward the end of the third week, these dorsolateral columns aka the PARAXIAL MESODERM, located in the trunk, become segmented into blocks of mesoderm |
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Definition
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Term
| Each somites develops into two parts... |
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Definition
1) sclerotome
2) dermomyotome |
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Term
| The sclerotome develops into... |
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Definition
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Term
| The dermomyotome develops into... |
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Definition
| its cells from the myotome region form myoblasts (primordial muscle cells), and those from its dermatome region form the dermis (fibroblasts) |
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Term
| Most flat bones develop in mesenchyme within preexisting membranous sheaths; this type of osteogenesis is called |
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Definition
| membranous (intramembranous) bone formation |
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Term
| Mesenchymal models of most limb bones are transformed into cartilage bone models, which later become ossified by |
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Definition
| endochondral bone formation |
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Term
| The axial skeleton is composed of? |
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Definition
1) cranium
2) vertebral column
3) ribs
4) sternum |
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Term
| What surrounds the neural tube in the 4th week and will help form the vertebrae? |
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Definition
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Term
| n the thorax, the dorsal intersegmental arteries become the |
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Definition
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Term
| Between the vertebrae, the notochord expands to form the gelatinous center of the... |
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Definition
| IV disc, the nucleus pulposus |
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Term
| What surrounds the nucleus pulposus and what does this form? |
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Definition
| annulus fibrosus forming the IV disc |
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Term
| The mesenchymal cells, surrounding the neural tube, form the |
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Definition
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Term
| he mesenchymal cells in the body wall form, |
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Definition
| costal processes, forming the ribs in the thoracic region |
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Term
| The neural arch is the primordium for the? |
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Definition
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Term
| During the 6th week what appears in each mesenchymal vertebra? |
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Definition
| Chondrification centers, two will fuse and from here spinous and transverse processes will form |
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Term
| What starts happening during the 7th week? |
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Definition
| Ossification of typical vertebrae begins, ends around 25 yrs |
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Term
| How many primary ossification centers are ther? |
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Definition
| 2 (ventral and dorsal) which unite then in the 8th week there is 3 (centrum and 2 neural arches) |
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Term
| The vertebral arch articulates with the centrum at cartilaginous |
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Definition
| neurocentral joints (allow the vertebral arches to grow as the spinal cord grows) |
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Term
| When do secondary ossification centers appear and how many and where are they? |
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Definition
-after puberty
-5 of them
1) tip of spinous process
2-3) One for each transverse process tip
4-5) Two anular epiphyses, one on the superior and one on the inferior rim of the vertebral body |
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Term
| The ribs develop from the mesenchymal |
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Definition
| costal processes of the thoracic vertebrae |
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Term
| the ribs become cartilaginous during what period and then ossify when? |
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Definition
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Term
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Definition
7 pairs of TRUE ribs
5 pairs of FALSE ribs
2 pairs of FLOATING ribs |
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Term
| A pair of vertical mesenchymal bands, _____ ______, develop ventrolaterally in the body wall. |
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Definition
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Term
| These sternal bars fuse by? |
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Definition
| 10 wks (cartilaginous models, start ossifying before birth except xiphoid process (childhood) |
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Term
| The appendicular skeleton consists of... |
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Definition
1) pectoral and pelvic girdles
2) limb bones |
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Term
| What form during the fifth week as condensations of mesenchyme appear in the limb buds? |
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Definition
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Term
| During the sixth week, the mesenchymal bone models in the limbs undergo chondrification to form |
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Definition
| hyaline cartilage bone models |
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Term
| Ossification begins in the long bones by the ____ week and initially occurs in the ______ of the bones from ______ _______ ________. |
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Definition
-8th
-diaphyses
-priamry ossification centers |
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Term
| By how many wks have primary ossification centers appeared? |
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Definition
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Term
| What begin to ossify before any other bones in the body? |
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Definition
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Term
| What starts to ossify after the clavicles? |
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Definition
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Term
| The secondary ossification centers of the bones at the ____ are the first to appear in utero. |
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Definition
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Term
| The part of a bone ossified from a secondary center is the... |
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Definition
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Term
| During bone growth, a plate of cartilage known as the _______ _______ _______ intervenes between the diaphysis and the epiphysis |
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Definition
| epiphysial cartilage plate |
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Term
| When the epiphysial plate is replaced by bone, what does this signify? |
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Definition
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Term
| What is a good indication of general maturation? |
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Definition
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Term
| Fusion of the diaphysial–epiphysial centers, which occurs at specific times for each epiphysis, happens ______years earlier in females than in males |
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Definition
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Term
| The muscular system develops from the... |
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Definition
| mesoderm (w/ some exceptions) |
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Term
| What are embryonic muscle cells are derived from mesenchyme (embryonic connective tissue). |
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Definition
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Term
| Three types of muscle are developed during the embryonic period? |
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Definition
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Term
| Limb and axial muscles develop by ___________ __________ from myogenic precursor cells. |
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Definition
| epitheliomesenchymal transformation |
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Term
| What originate from somatic mesoderm and from the ventral dermomyotome of somites in response to molecular signals from nearby tissues? |
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Definition
|
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Term
| primordial muscle cells fuse to form elongated, multinucleated, cylindrical structures... |
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Definition
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Term
| What develop in the cytoplasm of the myotubes? |
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Definition
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Term
| Other organelles characteristic of striated muscle cells, such as _____, also form. |
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Definition
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Term
| perimysium and epimysium layers of the fibrous sheath of the muscle are produced by |
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Definition
|
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Term
| endomysium is formed by the |
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Definition
| external lamina and reticular fibers |
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Term
| he increase in the size of a muscle after the first year results from an ... |
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Definition
| increase in the diameter of the fibers because of the formation of more myofilaments |
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Term
| Do all muscle fibers persist? |
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Definition
| No, some degenrate since they are not necessary to the muscle |
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Term
| Each typical myotome part of a somite divides into what two parts? |
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Definition
1) dorsal Epaxial (Epimere)division
2) central Hypaxial (Hypomere) divsion |
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Term
| Every developing spinal nerve also divides and sends a branch to each myotome division; What supplies the epaxial division and what the hypaxial division? |
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Definition
epaxial- dorsal primary ramus
hypaxial- ventral primary ramus |
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Term
| What myogenic regulatory factors are essential for the development of the hypaxial and epaxial muscles, as well as the abdominal and intercostal muscles? |
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Definition
| MyoD, MrfH, Myf-5, and myogenin |
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Term
| What division form the extensor muscles of the neck and vertebral column? |
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Definition
| myoblasts from the epaxial divisions |
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Term
| What division form the scalene, prevertebral, geniohyoid, and infrahyoid muscles? |
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Definition
| Myoblasts from the hypaxial divisions of the cervical myotomes |
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Term
| What myotome form the lateral and ventral flexor muscles of the vertebral column? |
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Definition
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Term
| What myotome form the quadratus lumborum muscle? |
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Definition
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Term
| What myotome form the muscles of the pelvic diaphragm and probably the striated muscles of the anus and sex organs? |
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Definition
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Term
| Early myotomes are segmented or non-segmented? |
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Definition
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Term
| In terms of segmentation, what happens to the thoracic muscles (intercostal) and the limb muscles? |
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Definition
-Thoracic muscles (intercostal)- remain segmented
-Limb muscles- Fuse to become non-segmented |
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Term
| What division of muscles are back muscles, innervated by? |
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Definition
| Epaxial, innervated by dorsal rami |
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Term
| What division of muscles are lateral and ventral muscles, including limbs, innervated by? |
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Definition
| -Hypaxial, innervated by ventral rami |
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Term
| What develops first upper or lower limbs? |
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Definition
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Term
| Limbs grow which direction and then what happens? |
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Definition
| Grow laterally then turn medially |
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Term
| Initially the the thumb and big toe are pointed which way? |
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Definition
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Term
| Initially the the palm and sole of foot are pointed which way? |
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Definition
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Term
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Definition
| Thickenings on the hand/foot plate called digital rays |
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Term
| Mesoderm is from what origin? |
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Definition
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Term
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Definition
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Term
| Limb development is initiated, and the proximal-distal limb axis set up, by? |
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Definition
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Term
| Hypaxial muscles migrate into the limbs, and divide into: |
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Definition
--an extensor group posteriorly
--a flexor group anteriorly
BOTH innervated by ventral rami |
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Term
Upper limbs rotates which way?
Lower limbs rotate which way? |
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Definition
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