The article deals with kinetic and somatic idioms (i.e., somatic idioms whose underlying metaphors are associated with movement and spatial orientation), in Serbian and Croatian. Based on two corpora, the Corpus of the Contemporary Serbian Language of the School of Mathematics (University of Belgrade), and the Croatian Language Repository of the Institute of the Croatian Language and Linguistics, the paper addresses the metaphorical patterns, peculiarities of usage, and possible modifications of idioms with the constituents glava ‘head’ and vrat ‘neck’. These idioms generally appear to have few modifications, which may be explained by their close ties with prototypical word groups naming gestures and movements, as well as by the fact that some idioms may have similar structure but different underlying metaphors. For instance, changing instrumental-case constructions with the preposition među ‘between’ into genitive constructions with između ‘between’ would break an idiom and create a free word group or a phrase with limited idiomaticity (e.g., nominating gestures, movements, or positions). Meanwhile, variability of a verb phrase is possible where it is not relevant for depicting the subject’s static position, e.g. sedeti / sjediti vs. stajati za vratom ‘watch sb. carefully, threaten sb.’ (lit. “stand / sit behind the neck”). Some differences are found in the use of certain Serbian and Croatian idioms. On the one hand, not all idioms occuring in text corpora can be found in academic lexicographical sources, and vice versa. On the other hand, the Croatian corpus includes idioms, not found in the Serbian corpus; e.g., stati komu na vrh glave ‘destroy’ (lit. “stand on the top of sb.’s head”). In some contexts, idioms may change their figurative meaning and have their underlying metaphor altered (e.g., stajati za vratom would mean ‘owe sb.’), with their figurative meaning becoming closer to those of sesti kome na vrat ‘become dependent on sb.’ (lit. “sit down on sb.’s neck”) and visiti kome oko vrata ‘ditto’ (lit. “hang around sb.’s neck”). The most widespread metaphors appear to be those of emotional impact and those depicting the experiencer as a surface / a container and the movement to / from the experiencer.