362 PULMONARY MUCOUS TISSUE. 



but really represents the series of fibres which this great 

 nerve trunk borrows from the accessory of Willis, or spinal 

 nerve (internal branch of the spinal nerve). Section of the 

 spinal nerve entirely destroys the voice : this might, there- 

 fore, be called the vocal nerve. It is remarkable that the 

 other branches of the spinal nerve (the external branch) lead 

 to two superficial and well-known muscles, the sterno-cleido- 

 mastoideus and the trapezius, both which muscles play an 

 important part in expressions by signs, or what may be called 

 the language of the neck and shoulders (shrugging the shoul- 

 ders, making a sign of negation with the head, etc.). The 

 spinal nerve thus appears to be the nerve of mimicry and 

 phonation. 



While serving for purposes of mimicry, the external branch 

 of the spinal nerve takes an active though indirect part in 

 phonation : this nerve innervates the sterno-mastoideus and 

 trapezius muscles, when, during sonorous expiration, these 

 muscles contract for the purpose of preventing the thoracic 

 cage from sinking suddenly. This peculiarity is easily ob- 

 served in singers, in whom it constitutes what Manal calls 

 the vocal struggle / which consists in a struggle between the 

 spinal nerve and the expiratory movement ; CL Bernard has 

 demonstrated, by numerous vivisections, that the spinal 

 nerve plays the same part in animals during the utterance of 

 a prolonged cry, and thus has proved that, in a physiological 

 point of view, the spinal nerve is not the accessory, but rather 

 the antagonist of the pneumo-gastric nerve, since it produces, 

 both in the glottis (by its internal branch) and the walls of 

 the thorax (by its external branch), movements which are 

 opposed to those of respiration. 



It is now proved that the nerve centre of phonation is 

 situated in the spinal cord : it is plain that this centre is not 

 found in the brain, for anencephalous patients have been 

 known to scream under the influence of external excitation 

 or internal pain. The centre of articulate speech, or rather, 

 the centre of the memory of words, 1 appears to reside in the 

 brain ; attempts have been made to fix its seat in the anterior 

 lobes, but the observations made on this subject are, so far, 

 contradictory. Both centres are independent of each other, 

 for a cry may be easily uttered when articulation is very 

 difficult. Amnesia, or the loss of memory of words, there- 



1 See Aug. Voisin, Art. " Amne'sie," in " Nouveau Diet, de 

 Med. et de Chirur. Prat." Vol. II. p. 53. 



