TURNER ON TUE ORBITAL AND KERATOCRICOTD MUSCLES. 109 



be attached to the posterior margin of the inferior horn of the thyroid 

 cartilage. He stated that the muscle was not found in every larynx, 

 and tliat when present it existed only on one side. 



In my remarks, I supplemented the description of Merkel with 

 some additional particulars, more especially pointing out, that, al- 

 though, as a rule, the muscle only occurred on one side, right or left 

 as the case might be, jet that a double muscle might exist. I figm-ed 

 an example of such a bilateral muscle, which at that time was the 

 only one I had seen. Since then I have met with two additional 

 cases in which a double kerato- cricoid muscle was present. One of 

 these was especially noteworthy, for the muscle, on both sides, was 

 more largely developed than in any previous example that had fallen 

 under my notice. The great size of the kerato-cricoid muscle was 

 combined with a general laryngeal muscularity. The occurrence of 

 three examples of a double kerato-cricoid muscle, during the last tw^o 

 years, within my o^vn ex]5erience, shows that the bilateral arrange- 

 ment is not so imusual as was in the first instance supposed. 



JVote. — Since the above paper was in type, my attention has been 

 directed, by Professor Huxley, to a communication by H. Miiller, 

 dated Dec. 15th, 1860, entitled " On the influence of the sympathetic 

 upon some muscles, and on the extensive occurrence of unstriped 

 muscles in the skin in the mammalia."* 



As this paper throws some additional light upon the probable 

 action of the orbital muscle I append a short abstract of it : — 



H. Miiller, after referring to the many puzzling questions which 

 have arisen respecting the function of the sympathetic nerve, and 

 its relations to the muscles supplied by it, proceeds to ask two 

 questions : 



1st. Whether and which unstriped muscles are supplied by other 

 nerves than the sjrmpathetic ? 



2nd. Wliether and which transversely-striped muscles are under 

 the influence of the sympathetic ? 



In answer to the first, the action of the oculo-motor nerve upon 

 the unstriped fibres of the iris cannot be doubted : the vagus also 

 acts upon unstriped muscles, and the experiments of Schifl" have 

 shown that the greater part of the vascular nerves are not connected 

 with the sympathetic. 



The second question may be most effectively answered by consi- 

 dering the effect produced upon the eye-ball by division or irritation 

 of the cervical sympathetic. Miiller, for this purpose, refers to the 

 experiments of Bernard, E. Wagner, and Brown- Sequard ; the 

 general tendency of which is to show, that division of the cervical 

 sympathetic produces narrowing of the paljiebral fissure, retraction 

 of the bidb, projection of the nictitating membrane and narrowing of 

 the anterior nares and the mouth. Irritation of the nerve by gal- 

 vanization, on the other hand, produces increase of the opening of 



* Uebcr den Einfluss des Sympathicus auf einige Muskeln, &c. Von H, Miiller, 

 " Vevliandlungeu der Phys. Med. Gesellschaft in WiJrzburg." 



