M. complexus.

<p>A) Dorsolateral view of M. complexus sinister (c) held up with tweezers; fleshy insertion site on the cranium (cr) and originating muscle slips from cervical vertebrae C4-C6 are indicated by asterisks. The M. splenius capitis (sc) and M. rectus capitis lateralis (rcl) are indicated as a reference. The coordinate system indicates dorsal (D), caudal (Ca), ventral (V) and cranial (Cr). Scale bar represents one centimetre. B) Dorsal view on both M. complexus sinister and dexter (c) showing variation between the sides. The insertion of the M. complexus dexter was separated from the cranium (cr). Individual slips (attaching to C4-C6) are indicated by asterisks. The M. complexus sinister has an extra slip originating from C3. The coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. C) Insertion site of M. complexus indicated with red line in three-dimensional model of a part of the skull from dorsal view. Foramen magnum (FM) and condylus occipitalis (CO) are indicated. Scale bar represents one millimetre (adapted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134272#pone.0134272.ref005" target="_blank">5</a>]). D-F) Origins of the M. complexus indicated with red circles in the three-dimensional models of the vertebrae of <i>T</i>. <i>f</i>. <i>pratincola</i>; vertebrae (C4-C6) from lateral left view, cranial is to the left. Scale bars in D-F represent one millimetre (adapted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134272#pone.0134272.ref005" target="_blank">5</a>]). G) Connection diagram from lateral view of M. complexus in <i>T</i>. <i>f</i>. <i>pratincola</i>; origin and insertion sites are connected with lines representing the muscle slips. H) Connection diagram from dorsal view of M. complexus in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle.