MUSCLES IN BIRDS. 313 



The external plantar region likewise comprises three muscles, which are : 



1. The short abductor of the little toe, which is detached from the internal tuberosity 

 of the os calcis, and is inserted into the external portion of the first phalanx of the little 

 toe. 



2. The short flexor of the little toe is attached, behind, to the sheath of the long 

 peroneus and to the process of the fifth metatarsal ; in front, to the external part of the 

 first phalanx of the little toe. 



3. The opponens of the little toe, concealed beneath the preceding, is inserted at 

 one end to the sheath of the long peroneus, and at the other to the external border of 

 the fifth metatarsal. 



C. Interosseous Muscles. 



These are divided into dorsal and plantar interossei. Their disposition is nearly 

 the same as in the hand. 



CHAPTER III. 

 THE MUSCLES IN BIRDS. 



IN birds we find the majority of the muscles already described ; though they are appro- 

 priate by their form, volume, arrangement, etc., to the particular conformation of the 

 skeleton in these animals. 



To undertake, in this essentially practical work, a special description of all these 

 organs, would be to depart from the object aimed at : and we therefore confine ourselves 

 to those points which present most interest in an animal mechanic point of view. 



1. Tendons. The tendons in birds present in the inferior limbs and at the extremity 

 of the wings an amount of ossification more or less extensive along their course. This 

 transformation of the fibrous tissue of the muscles is not the eliect of senility, for it is 

 noticed in very young animals. 



The tendons, in losing the greater part of their elasticity, doubtless gain in tenacity ; 

 and this allows them to transmit to the bony levers the muscular efforts in a more 

 integral manner. 



It is also observed that the partial ossification of the tendons does not exclusively 

 belong to the limbs ; for it is not rare to meet with this change in other regions, as in 

 the neck of wading birds. In the museum of the Veterinary School at Lyons is the 

 skeleton of a heron which shows this peculiarity in the higuest decree ; ttie cervical 

 vertebne are roughened by a multitude of filiform bony stylets, all directed backwards, 

 and whicli have originated from the ossification of the tend'inous fibrilhe annexed to the 

 muscles of the cervical region. 



2. The Pectoral Muscles. The two alternative movements which produce flight the 

 elevation and depression of the wings being due to the action of the pectoral muscles, 

 these merit special notice. 



The superficial or great pectoral, " which alone weighs heavier than all the other 

 muscles of the bird put together, is attached to the furculum, to the great ridge of the 

 sternum, and to the last ribs ; it is inserted into the very salient rugged outline of the 

 humerus. It is by this muscle that birds are able to give those powerful strokes of the 

 wings which are necessary in flight." 



The deep or small pectoral is " placed in the angle formed by the body of the sternum 

 and its crest, and in the interval between the furculum and the coracoid bone. 

 Its tendon passes through the foramen formed by the union of the furculum, the coracoid 

 bone, and the scapula, as over a pulley ; it is inserted above the head of the humerus, 

 which it raises. It is by means of this arrangement that nature has been able to place 

 an elevator and depressor at the inferior surface of the trunk so far from the centre of 

 gravity, without which the bird would have been liable to lose its equilibrium and tumble 

 over head foremost in the air. 1 



Cuvier, adopting the nomenclature of Vicq-d'Azyr. called this muscle the middle 

 pectoral, and he gave the name of small pectoral to a triangular fasciculus which leaves 

 the lateral angle of the sternum and the base of the coracoid bone, to be inserted under 



1 Cuvier, * Leeons d' Anatomic Gomparee.' 



