10 - M.sternocleidomastoideus and M.omotransversarius

Question 1

M.sternocleidomasteoidus consists of which muscles?

Answer 1

• M.sternocephalicus: M.sternomastoideus and M.sternooccipitalis
• M.brachiocephalicus: M.cleidobrachialis and M.cleidocephalicus (“cranial”): M.cleidomastoideus and M.cleidocervicalis

Question 2

M.sternocephalicus

Answer 2

O: Manubrium sterni
I: M.sternomastoideus to the mastoid part of temporal bone and M.sternoocipitalis to the nucheal crest of occipital bone.
A: Unilat. contraction draws head and neck to one side, and bilateral contracion draws head down.

Question 3

M.brachiocephalicus - M.cleidobrachialis

Answer 3

O: Clavicular intersection
I: Dist. cran. surface of humerus
A: If forelimb is fixed: unilat. contraction moves head into lat. direction, bilat. contraction fixes/bend downward head and neck. If limb is free (elevated) is moves the forelimb cran.

Question 4

M.brachiocephalicus - M.cleidocephalicus

Answer 4

O: M.cleidomastoideus from the proc.mastoideus of the temporal bone. M.cleidocervicalis from raphe cervicis over the cranial half of the neck.
I: Clavicular intersection
A: If forelimb is fixed: unilat. contraction moves head into lat. direction, bilat. contraction fixes/bend downward head and neck. If limb is free (elevated) is moves the forelimb cran.

Question 5

M.omotransversarius

Answer 5

O: Dist. part of spina scapula
I: Cau. border of the wing of atlas (Ala atlantis)
A: Free limb; draw shoulder cran., fixed limb: flex neck lat.