Dear Sir

I have not observed that the platysma contracts, either in children or adults, under the effects of simple fear, as in the immediate presence of a surgical operator which usually relaxes all the skin muscles*; but since receiving your note I shall observe more closely, and have already set sharp anatomical eyes to watch for this phenomenon¹

But I have observed it frequently, both in my own children² and in adults, to co⁠⟨⁠n⁠⟩⁠tract under the emotions of rage, disgust, & contempt, or when the two former of these are mingled with fear in the shape of horror. The muscle often, if not usually, contracts in nausea & sickness & during the effort of vomiting³

It is particularly excited, like all the muscles of the neck, in hydrophobia,—&, to a less extent, in tetanus.

I believe that it expresses chiefly the passion which indicates resistance, aggression or self defence, and that, through its upward prolongation the “risorius Santorini”, it uncovers the lower canines, as the snarling muscle exposes the upper,—and assists in opening the jaw in readiness to bite. I have observed the platysma to be most developed in persons with a thick, bull neck & broad shoulders; and in families inheriting these peculiarities,—one of which, especially, I have now in mind, it is usually associated with much voluntary power over the “occipito-frontalis”, which is supplied by the same nerve, & which causes the hair to stand on end,—like the “quills upon the fretful porcupine.⁴ These latter are acted on by the homologous muscle “the panniculus”, in those animals very powerful, as also in the hedgehog & badger.⁵ In shuddering, all the skin muscles contract in a spasmodic wave (even the “dartos scroti”) in sympathy with the cold sensation experienced by the nerves,⁶ and in this way, fear may sometimes cause the contraction of the “platysma” also. Duchenne is unquestionably wrong about the action of the “corrugator supercilli   Its inner attachment is lower than the outer. It must, therefore, draw down the brows, as well as inwards. The expression in the photograph is produced, as you say, by the contemporaneous action of the central fibres of the anterior belly of the occipito-frontalis;—but with only slight action of the “orbicularis palpebrarum”.⁷

I shall be happy at any time to afford you such knowledge as I possess, and remain, | Yours most truly | John Wood

*The expression commonly used of “a fallen countenance”, “his countenance fell” refers to the effect of relaxation of the skin muscles of expression, as in a paralyzed face.

Cha^s. Darwin Esqre