. Journal of anatomy . The last-named structure ultimately becomes chondrified by extensionfrom the thyroid, so that the nodule is attached to the ala of this cartilage,but in the meantime it undergoes modification. Fig. 16 is a diagram from model VII., and shows the state of the nodulein the seventh week; its connection with the other structures named is wellshown, but it is considerably smaller, and its cell-continuity with the The Development of the Larynx 177 arytcenoid rudiment is becoming elongated. This degeneration of thenodule goes on, and as its ventral connections appear to be stron
. Journal of anatomy . The last-named structure ultimately becomes chondrified by extensionfrom the thyroid, so that the nodule is attached to the ala of this cartilage,but in the meantime it undergoes modification. Fig. 16 is a diagram from model VII., and shows the state of the nodulein the seventh week; its connection with the other structures named is wellshown, but it is considerably smaller, and its cell-continuity with the The Development of the Larynx 177 arytcenoid rudiment is becoming elongated. This degeneration of thenodule goes on, and as its ventral connections appear to be stronger thanthose on its dorsal side it remains closely attached to the ventral laminarstructures, but the cell-strands that connect it with the arytsenoid anddorsal part of the cricoid become thinned out and weak; the latter seemto become broken down, but the former—those connecting it with thearytcenoid—remain and thicken as the true vocal cord. The cord is thus very obliquely placed at first, but, as the arytsenoid. Fig. 16.—A semi-diagrammatic sketch from a 22 mm. embryo showing thechordal nodule, already smaller, with its attachments to the cricoid andarytsenoid behind, and centnil crico-thyroid membrane and lower part ofinter-thyroid lamina in front. The front attachments seem stronger thanthe others, so that these latter thin out and disa}(p)ear, with the exception ofthe arytsenoid attachment, which thickens somewhat subsequently andforms the true cord (B). The arytsenoid ends above in a column of condensed cells, and is joined to thecricoid by similar tissue. T is placed in the transverse cavity and points to the indicating line of the wallof the cavity. (The inter-thyroid lamina appears to be derived from the ventral lamina in itslowest part: its upper part is presumably formed as a 4th arch structurecontinuous with the thyroid rudiments.) settles down into its place, and the depth of the thyroid increases ventrally,it assumes its final position. At the end of tlie s
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
