350 MUSCLES AND FASCIAE. 



then terminates in a short quadrilateral 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 ten- 

 don of the Pectoralis Major. The lower border of the tendon of this muscle 

 is united with the Teres Major, the surfaces of the two being separated by a 

 bursa; another bursa is sometimes interposed between the muscle and the 

 inferior angle of the scapula. 



A muscular slip, varying from 3 to 4 inches in length, and from to f of an inch in breadth, 

 occasionally arises from the upper edge of the Latissimus Dorsi, about the middle of the poste- 

 rior 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 (Joraco-brachialis, or of 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 ligature, 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 seven 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 Spiuae, the Serratus Posticus Inferior, the lower Intercostal muscles 

 and ribs, the Serratus Magnus, inferior angle of the scapula, Ehomboideus 

 Major, Infraspinatus, and Teres Major. Its outer margin is separated below, 

 from the External Oblique, by a small triangular interval ; and another trian- 

 gular 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, detach the muscle from its attachment to the clavicle and spine of the scapula, and turn it 

 back towards the spine. 



The Levator Anguli Scapulae 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 back- 

 wards, 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 (anterior) surface, with the integument, Trape- 

 zius, and Sterno-mastoid. By its deep (posterior) surface, with the Splenius Colli, 

 Transversalis Colli, Cervicalis Ascendens, and Serratus Posticus Superior, and 

 with the transverse cervical and posterior scapular arteries. 



The Rhomboideus Minor arises from the ligamentum nuchas, and spinous 

 processes of the seventh cervical and first dorsal vertebrae. Passing down- 

 wards and outwards, it is inserted into the margin of the triangular smooth 

 surface at the root of the spine of the scapula. This small muscle is usually 

 separated from the Rhomboideus Major by a slight cellular interval. 



The Rhomboideus Major is situated immediately below the preceding, the 

 adjacent margins of the two being occasionally united. It arises by tendinous 

 fibres from the spinous processes of the four or five upper dorsal vertebrae and 

 the supraspinous ligament, and is inserted into a narrow tendinous arch, at- 

 tached above, to the triangular surface near the spine ; below, to the inferior 

 angle, the arch being connected to the border of the scapula by a thin mem- 

 brane. When the arch extends, as it occasionally does, but a short distance, 

 the muscular fibres are inserted into the scapula itself. 



