final exam muscular system Flashcards
what do somites form?
skin, muscles and skeleton
the muscular system develops from which layer?
mesoderm layer
muscles are formed from which layer of the dermamyotome layer of the somite?
the myotome layer
what is the muscular system composed of?
specialized cells
muscle fibers
what form the extensor muscles of the vertebral column?
epimers- dorsal primary rami
what gives rise to the muscles of the limbs and body walls?
hypomers- ventral primary rami
what are examples of changes in muscle direction?
1 migration of muscle- latissimus dorsi
2 fusion of successive myotomes- rectus abdominus
3 longitudinal splitting of the myotome- sternohyoid
4 tangenital splitting- oblique and trans ab
5 degeneration of myotomes- tensor fascia lata
what are the muscles of the cervical region?
prevertebrals scalenes trap SCM infrahyoid
what are the muscles of thoracic region?
intercostals
transverse thoracics
nerves innervating the segmental muscles are divided into?
dorsal primary and ventral primary rami
what happens to nerves when muscles change direction?
the nerves remain and muscles maintain original innervation
what is the job of the ribs?
ribs cause the muscles in the wall of thorax to maintain their segments
what is the 1st brachial/pharyngeal arch?
muscles of mastication
what is the 2nd brachial/pharyngeal arch?
facial muscles
what is the 3rd brachial/pharyngeal arch?
stylo-pharyngeal muscle
what is the 4th & 6th arch?
laryngeal, pharyngeal, palate muscles, SCM, trap
what are the innervations of the arches?
1- trigeminal
2- facial
3- glossopharyngeal
4 & 6- vagus, hypoglossal
smooth muscle is derived from?
splanchnic mesoderm
smooth muscle of the iris is derived from?
neuroectoderm
with muscles of the limbs, the mesenchyme develops into what 2 groups?
extensors- dorsal group
flexors- ventral group
what are cardiac muscles derived from?
splanchnic mesoderm
most muscle defects are?
unilateral
what is the most common unilateral muscle defect?
pectoralis is most frequent
trap and SCM- next
what is prune belly?
distended abdomen from aplasia of the abdominal musculature
the abdominal muscles are always?
bilateral
when the SCM is injured during development what develops?
torticollis
what are some characteristics of torticollis?
affects both sides equally
male and female
autosomal dominant gene
in congenital torticollis…
SCM becomes fibrous
