14.3 Skeletal musculature




Musculature of the tongue


Like that of the entire pharynx the musculature of the tongue stems from premyoblasts that have come from the 4 occipital somites. The connective tissue stems from the neural ridge cells that have formed on both sides of the neural tube. Both together form a hypoglossal cellular cord to the pharynx floor 14.
In the pharynx floor the myoblasts begin to differentiate.
The hypoglossus nerve 15 is responsible for the innervation of the tongue musculature.		 Fig. 17 - Embryo in stage 14,
ca. 33 days		  Legend

1
 Hypoglossal cellular cord

Fig. 17
The embryo is in stage 14, ca. 33 days. The occipital somites are depicted in green. The tongue receives material from all 4 occipital somites for muscle formation. The connective tissue and the myoblasts together form a hypoglossal cord.


External eye musculature



The external eye musculature stems from the prechordal plate.
This is a pre-otic mesenchymal condensation that stands in a close relationship with the floor of the neural groove. The myoblasts 16 differentiate already very early and form myotubes of the external eye muscles 20 (M. rectus sup., inf., med. and lat.; M. obliquus inf. and sup.)		 Fig. 18 - Embryo in stage 14,
ca. 33 days		  Legend

1
2
3
 Occipital somites
Region of the otic placode
Eye musculature from pre-otic
mesenchymal condensate of the prechordal plate

Fig. 18
Origin of the external eye musculature


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