272 MUSCLES AND FASCIAE. 



vertebras, and from the supra-spinous ligament. Over the sacrum, the aponeurosis 

 of this muscle blends with the tendon of the Erector spinae. It also arises from 

 the external lip of the crest of the ilium, behind the origin of the External oblique, 

 and by fleshy digitations from the three or four lower ribs, being interposed 

 between similar processes of the External oblique muscle. From this extensive 

 origin the fibres pass in different directions, the upper ones horizontally, the 

 middle ones obliquely upwards, and the lower ones vertically upwards, so as to 

 converge and form a thick fasciculus, which crosses the inferior angle of the 

 scapula, and occasionally receives a few fibres from it. The muscle then curves 

 around the lower border of the Teres major, and is twisted upon itself, so that 

 the superior fibres become at first posterior and then inferior, and the vertical 

 fibres at first anterior and then superior. It then terminates in a short quadri- 

 lateral tendon, about three inches in length, which, passing in front of the tendon 

 of the Teres major, is inserted into the bottom of the bicipital groove of the 

 humerus, above the insertion of the tendon of the Pectoralis major. The lower 

 border of the tendon of this muscle is united with that of the Teres major, the 

 surfaces of the two being separated by a bursa ; another bursa is sometimes inter- 

 posed between the muscle and the inferior angle of the scapula. 



A muscular slip, varying from 3 to 4 inches in length, and from | to of an inch broad, occa- 

 sionally arises from the upper edge of the Latissimus dorsi, about the middle of the posterior 

 fold of the axilla, and crosses the axilla in front of the axillary vessels and nerves, to join the 

 under surface of the tendon of the Pectoralis major, the Coraco-brachialis. or the fascia over the 

 Biceps. The position of this abnormal slip is a point of interest in its relation to the axillary 

 artery, as it crosses the vessel just above the spot usually selected for the application of a liga- 

 ture, and may mislead the surgeon during the operation. It may be easily recognized by the 

 transverse direction of its fibres. DR. STRUTHERS found it in 8 out of 105 subjects, occurring 

 7 times on both sides. 



Relations. Its superficial surface is subcutaneous, excepting at its upper part, 

 where it is covered by the Trapezius. By its deep surface, it is in relation with 

 the Erector spinae, the Serratus posticus inferior, lower Intercostal muscles and 

 ribs, the Serratus magnus, inferior angle of the scapula, Rhomboideus major, 

 Infra-spinatus, and Teres major. Its outer margin is separated, below, from the 

 External oblique, by a smaller triangular interval ; and another triangular interval 

 exists between its upper border and the margin of the Trapezius, in which the 

 Intercostal and Rhomboideus major muscles are exposed. 



Nerves. The Trapezius is supplied by the spinal accessory and cervical plexus; 

 the Latissimus dorsi, by the subscapular nerves. 



SECOND LAYER. 



Levator Anguli Scapulae. Rhomboideus Minor. 



Rhomboideus Major. 



Dissection. The Trapezius must be removed in order to expose the next layer ; to effect this, 

 the muscle must be detached from its attachment to the clavicle and spine of the scapula, and 

 turned back towards the spine. 



The Levator Anguli Scapulse is situated at the back part and side of the neck. 

 It arises by four tendinous slips from the posterior tubercles of the transverse 

 processes of the three or four upper cervical vertebrae ; these becoming fleshy are 

 united so as to form a flat muscle, which, passing downwards and backwards, is 

 inserted into the posterior border of the scapula, between the superior angle and 

 the triangular smooth surface at the root of the spine. 



Relations. By its superficial surface, with the integument, Trapezius, and 

 Sterno-mastoid. By its deep surface, with the Splenius colli, Transversalis colli, 

 Cervicalis ascendens, and Serratus posticus superior, and with the transverse cer. 

 vical and posterior scapular arteries. 



The Rhomboideus Minor arises from the ligamentum nuchae, and spinous pro 

 cesses of the seventh cervical and first dorsal vertebrae. Passing downwards and 



