Figure 5

Lateral view of head muscles of ‘myological stage 4’ newborn lambs. Typical configuration of more superficial (A) and deep (B) facial and masticatory muscles of myological stage 4 newborn lambs dissected by us (paper square = 1 cm), as seen here on the left side of specimen 199. Basically, at this stage the truncation of the head is very extreme, there is almost always a well-developed dorsal (above the region of the eye) proboscis, and usually the levator anguli oris facialis and/or the dilatator naris lateralis are fused or missing, and the levator labii superioris is continuous in the midline with that of the other side of the head, the two muscles forming a circular, constrictor-like muscle complex. For more details see text and SI1 Table 1.