FUNDAMENTAL PRINCIPLES OF ANATOMY. 19 



introducing the subject of shape of a muscle as an index to the nerve-supply 

 entrance is to impress the necessity of tracing out, as far as possible, in your dis- 

 section the branches of the nerves ; possibly the scheme introduced may aid the 

 memory. 



HILTON'S LAW : Nerve trunks that supply muscles that move a joint supply 

 the joint acted upon with articular brandies ; they also supply the skin, covering 

 the fullest insertion of the muscle. Given, then, the number of antagonistic 

 groups of muscles, you are by this rule able to know the source from which the 

 joint is innervated. 



ANATOMICAL APPOSITION Is NOWHERE FOUND. In dissecting in any region of 

 the body bear this in mind. Structures arc a fa ays disjunctively connected by a 

 layer of connective tissue. Found between muscles, it is called areolar or inter- 

 muscular connective ; beneath the pleura, subpleural ; beneath the peritoneum, 

 subperitoneal ; beneath mucous membrane, submucous ; beneath the periosteum, 

 subperiosteal. Notice the mortar between the bricks in a wall ; this corresponds 

 to connective tissue in anatomy. 



DISSECTING Is THE ART OF DIVIDING THE CONNECTIVE TISSUE THAT INTER- 

 VENES BETWEEN ADJACENT STRUCTURES, and the division must be made in such a 

 manner as to do no violence to anatomical compounds, their nerve-supply, their 

 blood-supply, their excretory ducts, their capsules, and their anatomical relations. 



FANCIFUL NAMES FOR MUSCLES, names founded on some one dominant idea, are 

 frequently met. It is to be regretted that our nomenclature could not have been 

 founded on the idea of function throughout. Note here that the substantive, 

 imtscitlns, while seldom expressed in our texts, is afaars implied. The following 

 will show you some of the names of muscles founded on fanciful ideas, and also 

 the full name as it should appear if founded on the idea of function : 



FANCIFUL NAMES. PHYSIOLOGICAL NAMES. 



Sartorius (tailor), .... Musculus extensor tibialis et adductor femoris. 

 Rhomboideus (geom.), . . Musculus levator scapulas rhomboideus. 

 Transversals (direct.), . . Musculus compressor abdominis transversalis. 



Recius (geom.) Musculus flexor thoracis rectus. 



Pyramida/is(geom.). . . . Musculus tensor lineas albae pyramidalis. 



Vastus Externus, .... Musculus extensor vastus externus. 



External Oblique, .... Musculus compressor abdominis obliquus externus. 



Serratus Magnus, .... Musculus depressor scapulae serratus magnus. 



Quadratus Lumborum, . Musculus flexor spins lateralis quadratus lumborum. 



Latissimus Dorsi, .... Musculus abductor brachii latissimus dorsi. 



Longissinms Dorsi, . . . Musculus extensor spinse longissimus dorsi. 



ORBICULAR MUSCLES AND SPHINCTER MUSCLES. You will find the above 

 terms often used interchangeably. The important areas occupied by these 

 muscles make the majority of the same of prime interest to the general surgeon, 

 the genitp-urinaiy specialist, the gynaecologist, the obstetrician, the oculist, 

 the laryngologist, the rectal specialist, the patient. Still, no rational classification 

 of these muscles exists. At the present all orbiculars are sphincters, but not all 

 sphincters are orbiculars, as the following table, founded on usage, will show : 



SYNONYMOUS USAGE. 



Orbicularis oris Sphincter oris. 



Orbicularis ani External sphincter ani. 



Orbicularis palpebrarum, Sphincter palpebrarum. 



