10. Muscular System Devo Flashcards
Skeletal Muscle progenitor tissue
Myotome tissue of the somites Head mesoderm
Iris muscles, arrector pili muscles,
myoepithelial cells of mammary gland from which progenitor tissue
ectoderm
ciliary muscles are from what progenitor tissue
neural Crest
Cardiac muscle from what progenitor
Splanchnic mesoderm of heart fields
Skeletal muscle forms from the______. Under the influence of______ from the surface ectoderm the dorsal half of the somite remains an epithelium and is called the _______
somite
Wnt
Dermomyotome (DM).
During skeltal muscle formation, cells of the DM are exposed and influenced by a gradient of signaling molecules from the
dorsal neural tube and notochord, surface ectoderm and lateral mesoderm.
Cells at the medial edge or lip of the DM are primarily influenced by signals ________from the
dorsal neural tube and notochord. These cells undergo an (EMT) and travel where?
(Wnt & Shh)
migrate beneath the remaining epithelial cells of the DM.
Cells at the lateral edge or lip of the DM are primarily influenced by signals ______ from the lateral mesoderm. They also undergo an EMT and go where?
(Bmp)
migrate beneath the DM epithelium.
The mesenchyme cells beneath the DM become and
Myogenic (skeletal muscle precursor) Cells
The mesenchyme cells beneath the DM become Myogenic (skeletal muscle precursor) Cells and begin to express
Myogenic Regulatory Factors (e.g. Myf5 and MyoD)
The mesenchyme cells beneath the DM become Myogenic (skeletal muscle precursor) Cells and are called
Myotomes
muscle precursor cells from the central DM as a result of signals from the _______ These cells undergo an EMT and join the myogenic cells in the myotome.
overlying surface ectoderm.
Many of the central DM derived muscle precursors will
become _______ associated with differentiated skeletal muscle cells.
the satellite cells
myogenic cells derived from the somites develop in one of two domains. The domains are separated by a boundary called the _________ that is located between the paraxial and lateral mesoderm.
Lateral Somite Frontier (LSF)
boundary is and interface created by the opposing gradients of signaling molecules from the lateral mesoderm and the dorsal neural tube and
notochord.
Lateral Somite Frontier (LSF)
The domain located medial to the LSF is the _______, while that lateral to the LSF is the Abaxial Domain. muscles forming in the here attach to bones derived from scleratome cells.
Primaxial Domain
The domain located lateral to the LSF is the _______,
Abaxial Domain.
can proliferate and migrate or become displaced by differenential growth… eventually they become postmitotic and are then called _______
Myogenic Cells
Myoblasts
Myoblasts begin to express additional myogenic regulatory factors (e.g. myogenin, Mef2, Myf4) and begin to produce
myosin and actin.
Myoblasts in the chains fuse with each other by upregulating cell adhesion molecules to form ________which undergo further differentiation to become ________
Multinucleated Myotubes.
Primary Muscle Fibers.
Cardiac muscle forms from
splanchnic mesoderm of the primary and secondary
heart fields.
Cardiac myoblasts retain the capability to divide, but do not fuse into myotubes. Instead they……
they branch and form junctional complexes with each other resulting in a functional syncytium.
Visceral Smooth Muscle (associated with GI, Respiratory, UG organs) Visceral smooth muscle cells are derived from
splanchnic mesoderm.
master regulatory factors that control smooth muscle development.
Myocardin and serum response factor
Vascular Smooth Muscle Precursor cells for vascular smooth muscle are derived from
local mesenchyme that surrounds forming endothelial tubes.
Pre-muscle masses may “remodel” into specific muscles by:
Fusion of adjacent myotomes
Splitting longitudinally into parts (bellies) or tangentially into layers
changing fiber direction
atrophy of portions of the muscle mass
migrate or are displaced to regions remote from their
origin at the myotome.
Skeletal muscle is derived from myotomes in the trunk are innervated by
spinal nerves,
skeletal muscle derived from head mesoderm or occipital
somites is innervated by .
cranial nerves
myotomes in the trunk split have traditionally be subdivided into what two portions
Epaxial portion Hypaxial portion
Epaxial portion is innervated by
branches of the Dorsal Primary Ramus of a spinal nerve
Hypaxial portion innervated by
branches of the ventral primary ramus of a spinal nerve
refer to domains (regions) of the embryo in which myotomes cells develop into specific skeletal muscles.
primaxial and abaxial
terms used to designate which skeletal muscles are
innervated by branches of the ventral primary ramus or dorsal primary ramus of a spinal nerve.
Hypaxial and epaxial ar
All muscles developing in the abaxial domain are innervated by
ventral primary rami.
With respect to muscles developing in the Primaxial
domain, the intrinsic back muscles are innervated by branches of the _______, and branches of __________ innervate all other Primaxial muscles.
dorsal primary rami
ventral primary rami
family of genetic diseases that cause progressive
deterioration of skeletal muscle. The nervous system is not affected.
Muscular dystrophy
X-linked and affects boys in early childhood. The skeletal muscle myocytes are susceptible to damage when physically stressed due to a lack of Dystrophin, an actin binding glycoprotein.
Duchennes
fixed rotation of the head to one side is caused by a defect or deformation of the sternocleidomastoid muscle
Torticollis
Congenital torticollis is often acquired due to birth injury to the _________. It can also occur in childhood as a secondary effect of infections or trauma.
sternocleidomastoid muscle
condition in which the muscles of the abdominal wall
are absent. It is often associated with anomalies of the urinary bladder and urinary tract or urethral obstruction.
Prune Belly syndrome
is a condition characterized by absence of the pectoralis
major (usually sternocostal head) and pectoralis minor muscles. This influences nipple placement and axillary fold morphology on the affected side.
Poland sequence
Associated anomalies of Poland sequence
absence of breast tissue, hypoplasia of the rib cage and
upper limb defects.
Poland sequence is more common on the____ side, is more prevalent in ——– and has a frequency of 1/20,000 – 1/50,000 births
right
males
muscles forming in the here attach to bones derived from scleratome cells.
Primaxial Muscle Domain
Muslces of ventrolateral abdominal wall and limbs
Abaxial Muscle Domain
