DISSECTION OF THE DOG 151 



M. scutularis. — Medial and oral to the base of the ear is a thin sheet of 

 muscle, the seutular muscle, divisible into two portions : (1) the m. fronto- 

 scutularis, springing from the zygomatic process of the frontal bone and from 

 the orbital band ; (2) the m. interscutularis , thinner than the preceding and 

 continuous with the corresponding muscle of the other ear. 



The two muscles are inserted into the scutiform cartilage. 



Mm. auriculares anteriores. — There are three auricular muscles lying mainly 

 to the nasal side of the base of the ear. The uppermost (most dorsal) continues 

 the fronto-scutularis from the scutiform cartilage to a fold of skin at the base 

 of the oral border of the conchal cartilage. The middle muscle of the group 

 is very short, and connects the scutiform and conchal cartilages. The lowest 

 (most ventral) muscle has a broad tendinous origin from the fronto-scutularis, 

 sometimes also from the zygomatic muscle, and is inserted into the antitragus. 



M. auricularis inferior. — The inferior auricular muscle is narrow and 

 long, and lies over the parotid and submaxillary glands. Arising from the 

 fascia over the region of the larynx, its insertion is into the conchal cartilage 

 close to that of the lowest anterior auricular muscle. 



Mm. auriculares posteriores. — Three muscles fall within this group. 

 One of them is the long levator ; the others are the long and short abductors. 

 The long levator rises from the mid-dorsal hne of the neck, and is inserted into 

 both conchal and scutiform cartilages. The long levator is aboral to the 

 interscutular muscle and in the same plane, and the two muscles are more or 

 less continuous. 



' Dissection. — Reflect the seutular and long levator muscles. 



Mm. auriculares superiores .— The superior group of muscles contains 

 a short and a middle levator. The short levator arises from the scutiform 

 cartilage and passes to the conchal cartilage. The middle levator lies under 

 cover of the interscutular and long levator muscles, and takes origin from the 

 sagittal crest. The muscle divides into two parts, and its fibres are partly 

 inserted into the conchal and partly into the scutiform cartilage. 



The long abductor muscle arises from the ligamentum nucha?, and is inserted 

 into the lateral aspect of the conchal cartilage. 



Dissection.— Reflect the middle levator and long abductor muscles. 



The short abductor takes origin from the occipital bone, and passes to the 

 medial side of the base of the conchal cartilage. 



Mm. auriculares profundi.— The deep auricular muscles consist of two 

 rotators— long and short— placed underneath the scutiform cartilage and 

 running from this to the conchal cartilage. 



M. tragicus.— The tragicus muscle is divided into two parts— lateral and 



medial. 



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