48 THE ANATOMY OF VEKTEBEATED ANIMALS. 



the hyposkeletal muscles. The hyposkeletal muscles of the 

 posterior moiety of the body attain a great development in 

 those Vertebrata which have no hind limbs, such as Ophidia 

 and Cetacea. 



The Muscular Systevi of the Limbs. — The muscles of the 

 limbs of Fishes are very simple, consisting, on each face of 

 the limb, of bundles of fibres, which proceed (usually in two 

 layers) obliquely, from the clavicle and supraclavicle to the 

 fin-rays. The pectoral and pelvic arches themselves are 

 imbedded in the lateral muscles. 



In the Amphibia and all the higher Vertebrata, the muscles 

 of the limbs are divisible into — intrinsic, or those which take 

 their origin within the anatomical limits of the limb (in- 

 cluding the pectoral or pelvic arch) ; and extrinsic, or those 

 which arise outside the limb. 



Supposing the limb to be extended at right angles to the 

 spine (its primitive position), it will present a dorsal aspect 

 and a ventral aspect, with an anterior, or pre-axial, and a 

 posterior, or post-axial, side. 



In the Vertebrata ahoYe fishes, the following muscles, which 

 occur in Man, are very generally represented : 



Extrinsic muscles attached to the pectoral and pelvic arches, 

 on the dorsal aspec . — In the fore limb, the cleidomastoideus, 

 from the posterolateral region of the skull to the clavicle ; 

 the trapezius, from the skull and spines of many of the ver- 

 tebrae to the scapula and clavicle ; the rhomboidei, from the 

 spines of vertebrae to the vertebral edge of the scapula, 

 beneath the foregoing. Sometimes there is a trachelo- 

 acromialis, from the transverse processes of the cervical 

 vertebrae to the scapiila. 



On the ventral aspect, the subclavius, which passes from the 

 anterior rib to the clavicle, may be regarded as, in part, a 

 muscle of the limb ; the pectm-alis minor, from the ribs to 

 the coracoid. 



Between the dorsal and the ventral aspects muscular fibres 

 arise from the cervical and dorsal ribs, and pass to the inner 

 aspect of the vertebral end of the scapula : anteriorly, these 

 are called levator anguliscapulce ; posteriorly, serratus magnus. 



