Muscular development
Terms
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- Primary type of muscle precursor:
- Mesoderm
- 3 types of muscle precursor origin:
-
-Paraxial mesoderm
-Splanchnic mesoderm
-Neural crest ectomesenchyme - What will splanchnic mesoderm form?
- Cardiac and smooth muscle (except goosebumps)
- What will paraxial mesoderm become?
- Skeletal muscle
- Where will muscle derived from Neural Crest ectomesenchyme form?
- In certain areas of the head, neck and upper thorax.
- Specific marker of cells destined to become muscle:
- MyoD gene
- ALL SKELETAL MUSCLE PRECURSORS ARE DERIVED FROM _________
- Paraxial mesoderm
- What is the main difference between Premyogenic mesoderm and Myoblasts?
-
Premyogenic = mitotic
Myoblasts = postmitotic; can migrate - What are satellite cells?
- Mitotic cells that stay with muscle fibers so that in case of injury they become postmitotic and help repair.
- What are the 4 steps of muscle formation?
-
1. Mitotic cells turn on MyoD
2. Post-mitotic myoblasts migrate & become muscle spcfc.
3. Myoblasts fuse -> Myotubes
4. Myotubes -> skeletal muscle -
What are muscles in Head/Neck derived from?
Innervated by? -
Somitomeres & Occipital myotomes
-Cranial nerves -
What are muscles in Trunk/Limbs derived from?
Innervated by? -
Paraxial mesoderm
-Spinal nerves - What is smooth muscle derived from?
- Splanchnic mesoderm
- What is unique about smooth muscle cells?
- Retain ability to divide
- What germ layers contain vscular smooth muscle precursors?
- All
- How does cardiac muscle differ from smooth?
- Immature cardiac myoblasts can divide while beating & maturing, but mature myocytes are postmitotic.
- What is the most common muscle to be absent due to malformation of muscular system?
- Sternocostal head of Pectoralis Major
- What is the syndrome where abdominal muscles are absent?
- Prune belly syndrome
- What is the disease in which there is fixed rotation and tilting of the head?
- Congenital Torticollis
-
Family of genetic diseases w/ progressive deterioration of skeletal muscle:
(what is NOT in the pathology?) - Muscular dystrophy - does not have nervous system pathology.
- Most common type of muscular dystrophy:
- Duchenne type
- Inheritance pattern of duchenne type MD
- X-linked recessive - in boys
- What is the problem in Duchenne type MD?
- Lack of Dystrophin in myocytes - myocytes susceptible to damage when physically stressed.
- How does Connective Tissue change as it matures?
-
Embryonic CT: HI CELL:ecm ratio
Mature CT: High ECM:cell ratio - What is the only muscle to form from Ectoderm/Neural crest?
- Iris muscles
-
What does lateral plate mesoderm associate with to form
-Skeletal components?
-Splanchnic mesoderm/Muscle? -
Skeleton = w/ Ectoderm
Muscle = w/ Endoderm - What muscle forms from lateral plate splanchnic mesoderm?
-
-Cardiac muscle
-Smooth muscle - What can vascular smooth muscle have as its precursors?
- Mesoderm OR neural crest