288 PROF. OWEN ON THE ANATOMY 



Muscles of the Anterior Extremity. 



Serratus magnus anticus (PI. XXXII. XXXIV. i). — This muscle consists of three por- 

 tions ; the first and anterior portion (PI. XXXIV. fig. 2. i) arises by a short, strong 

 aponeurosis from the last cervical rib, and is inserted into the lower edge of the anterior 

 two-thirds of the scapula : the second and middle portion arises from the lower end of 

 the second vertebral rib, near the attachment of the costal process, and from the anterior 

 margin of the same rib, and is inserted into the lower edge of the posterior two-thirds 

 of the scapula : the third, posterior and smallest portion (PI. XXXII. i) rises from the 

 costal process of the third rib, and ascends to be inserted into the posterior extremity 

 of the scapula. 



This muscle is a direct inspirator : by drawing down the scapula it depresses the 

 sternum through the medium of the strong coracoideum, increases the angle between 

 the vertebral and sternal ribs, and dilates the thoracic air-cells. 



Levator scapula (PI. XXXII. XXXIV. k). — This seems to be the most anterior portion 

 of the series of muscles which constitute the serratus magnus. Origin. Two flat fleshy strips 

 from the inferior transverse and costal processes of the last and penultimate cervical ver- 

 tebrae. Ins. Into the inner and upper side of the middle third of the scapula. It depresses 

 as well as draws forwards the scapula, and thus aids the serratus in the action of inspiration. 



Serratus anticus minor.— Origin. From the outer part of the costal process of the 

 sternum. Ins. Into the posterior part of the base of the coracoideum. 



Trapezius (PL XXXIV. I). — This flattened oblong quadrilateral muscle arises from the 

 fascia, extending upon the back from the spinous processes of the posterior cervical 

 vertebrae, and is inserted into the conjoined extremities of the scapula and coracoideum. 



There is no representative of the rhomboidei. 



Latissimus dorsi (PI. XXXIV. m). — This muscle consists, as usual in Birds, of two por- 

 tions, both of which have their origin from a continuation of the fascia, attached to the 

 spinous processes, which gives attachment to the trapezius : the fibres of the smaller and 

 anterior strip converge to their insertion : the fibres of the posterior and broader strip are 

 slightly twisted, the posterior edge being folded inwards as they also converge to join 

 the preceding, and to be inserted with it into the posterior and inner side of the proximal 

 extremity of the humerus. 



Deltoides (PI. XXXI. XXXIV. n). — This is a single long and narrow triangular muscle, 

 of which the base is attached to the conjoined extremities of the scapula and coracoid, 

 and to the capsule of the shoulder-joint ; the apical insertion is into the upper and outer 

 third of the humerus, which this muscle directly raises. 



Infraspinatus (PI. XXXII. o'). — A muscle which may be compared either to the infra- 

 fpinatus or teres major comes off" from the lower margin of the anterior two-thirds of the 

 scapula, passes behind the shoulder-joint, where it is closely attached to the capsule, 

 and is inserted into the inner and posterior part of the proximal end of the humerus. 



Muscidi pectorales. — The pectoral muscles, which present their feeblest condition and 



