124 MUSCULAR SYSTEM. 



rior aorta, and vena cava, and the iliac vessels ; on the outer side, 

 with the iliacus. 



Direction. — Longitudinal. 



Structure. — Anterior attachments, fleshy; with tendinous 

 chords intermixed : posterior half, a long flattened tendon, which 

 arises out of the middle of the fleshy parts and broadens in its 

 passage backwards. 



Action. — To draw the pelvis forwards. When one acts by 

 itself, the same part will be inclined to one side. Or, the pelvis 

 being made a fixture, it will have efl'ect in arching or flexing the 

 spine. 



2.— ABDOMINAL REGION. 



An intervening stratum of cellular substance attaches the 

 abdominal portion of the panniculus carnosus to a glistening ex- 

 pansion of tendon, situated underneath it, which is the aponeu- 

 rosis of the external oblique muscle. This cellular substance 

 being removed, several white lines, marked upon the subjacent 

 tendon, come into view. The principal of these is one which 

 runs along the middle of the belly, extending from the ensiform 

 cartilage to the pubes : it takes the name of /inea alba ; and de- 

 notes the line of junction and demarcation between the abdomi- 

 nal muscles on one side and those of the other. About midway 

 between its two terminations, this line has a perforation, the «m- 

 bilkiis or navel, through which passes the umbilical chord. At 

 some short distance from the sides of the linea alba are two 

 curved or waving lines, called the linea semiliinares : they mark 

 the line of union between the fleshy and tendinous fibres of the 

 external oblique muscle. Traversing the interspaces between the 

 linea alba and linese semilunares, at short intervals from one ano- 

 ther, are several transverse lines, named the linece tratisversales : 

 they are produced (as will hereafter be discovered) by the ten- 

 dinous intersections across the straight muscles ; and are, in 

 some subjects, but obscurely marked. 



There are four pairs oi^ abdominal muscles: — two pairs o^ oblique 

 muscles; one pair of transverse; and one pair of straight mus- 

 cles. Three of these pairs are ranged in strata, one upon another, 

 and have sheets of tendon connected with them, which take the 

 name of aponeuroses. 



OBLiQuus EXTERN us ABDOMINIS. ( Costo-abdomiualis. ) 



Situation. — Upon the inferior and lateral parts of the belly. 

 ]'lgu)e, — Broad, thin; quadrilateral. 



Ailachment. — Anteriorly, by fleshy digitations, to the posterior 

 borders of the fourteen hinder ribs, below their middles ; posteri- 



