THE MUSCLES OF FORCED RESPIRATION. 2 3" 5 



7. Mm. extensores columnae vertebralis (Ram. posteriores nervorum 

 dorsalium). 



[8. Mm. serratus anticus major (N". thoracicus longus). ? 1] 



(b.) Muscles of the Larynx. 



1. M. sternohyoideus (Ram. descendens hypoglossi). 



2. M. sternothyreoideus (Ram. descendens hypoglossi). 



3. M. crico-arytaenoideus posticus (N. laryngeus inferior vagi}. 



4. M. thyreo-arytaenoideus (N. laryngeus inferior vagi). 



(c.) Muscles of the Face. 



1. M. dilatator narium anterior et posterior (N. facialis). 



2. M. levator alae nasi (N. facialis'), 



3. The dilators of the mouth and nares, during forced respiration, 

 ["gasping for breath"] (N. facialis). 



(d.) Muscles of the Pharynx. 



1. M. levator veli palatini (N. facialis). 



2. M. azygos uvulae (N. facialis). 



3. According to Garland, the pharynx is always narrowed. 



(B.) Expiration. 

 I. During Ordinary Respiration. 



The thoracic cavity is diminished by the weight of the chest, the 

 elasticity of the lungs, costal cartilages, and abdominal muscles. 



II. During Forced Expiration. 



The Abdominal Muscles. 



1. The abdominal muscles [including the obliquus externus and 

 internus, and transversalis abdominis] (Nn. aldominis internis anteriores 

 e nerris intercostalibus, 8-12). 



2. Mm. intercostales interni, so far as they lie between the osseous 

 ribs, and the Mm. infracostales (Nn. intercostales). 



3. M. triangularis sterni (Nn. intercostales}. 



4. M. serratus posticus inferior (Ram. externi nerv. dorsalium). 



5. M. quadratus lumborum (Ram. muscular e plexu lumbali). 



113. Action of the Individual Respiratory Muscles. 



(A.) Inspiration. (1.) The Diaphragm arises from the cartilages and the 

 adjoining osseous parts of the lower six ribs (costal portion), by two thick processes 

 or crura from the upper three or four lumbar vertebrae, and a sternal portion from 

 the back of the ensiform process. 



