OF THE BACK. 339 



Rhomboideus minor; in the back, with the Rhomboideus major, Supraspinatus, 

 Infraspinatus, and Vertebral aponeurosis (which separates it from the prolongations 

 of the Erector spinas), and the Latissimus dorsi. The spinal accessory nerve and 

 the superficial cervical artery and branches from the third and fourth cervical 

 nerves pass beneath the anterior border of this muscle. The anterior margin of 

 its cervical portion forms the posterior boundary of the posterior triangle of the 

 neck, the other boundaries being the Sterno-mastoid in front and the clavicle 

 below. 



The Ligamentum nuchse (Fig. 213) is a fibrous membrane, which, in the neck, 

 represents the supraspinous and interspinous ligaments of the lower vertebrae. 

 It extends from the external occipital protuberance to the spinous process of the 

 seventh cervical vertebra. From its anterior border a fibrous lamina is given off, 

 which is attached to the external occipital crest, the posterior tubercle of the 

 atlas, and the spinous process of each of the cervical vertebras, so as to form a 

 septum between the muscles on each side of the neck. In man it is merely the 

 rudiment of an important elastic ligament, which, in some of the lower animals, 

 serves to sustain the weight of the head. 



The Latissimus dorsi is a broad flat muscle which covers the lumbar and the 

 lower half of the dorsal regions, and is gradually contracted into a narrow fasci- 

 culus at its insertion into the humerus. It arises by tendinous fibres from the 

 spinous processes of the six inferior dorsal vertebras and from the posterior layer 

 of the lumbar fascia (see page 342), by which it is attached to the spines of the 

 lumbar and sacral vertebras and to the supraspinous ligament. 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, which are 

 interposed between similar processes of the External oblique muscle (Fig. 218, 

 page 358). From this extensive origin the fibres pass in different directions, the 

 upper ones horizontally, the middle obliquely upward, and the lower vertically 

 upward, 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 

 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, its insertion extending higher on the humerus than that 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 interposed between the muscle and the inferior 

 angle of the scapula. This muscle at its insertion gives off an expansion to the 

 deep fascia of the arm. 



A muscular slip, axillary arch, varying from 3 to 4 inches in length, and from i to f of an 

 inch in breadth, occasionally arises from the upper edge of the Latissimus dorsi about the mid- 

 dle 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-bracliialts, 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 ligature, and may mislead the surgeon during the operation. It may be easily 

 recognized by the transverse direction of its fibres. Dr. Struther found it. in 8 out of 105 

 subjects, occurring seven times on both sides. 



There is usually a fibrous slip which passes from the lower border of the tendon of the 

 Latissimus dorsi, near its insertion, to the long head of the Triceps. This is occasionally 

 muscular, and is the representative of the Dorso-epitrochlearis muscle of apes. 



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

 where it is covered by the Trapezius, and at its insertion, where its tendon is 

 crossed by the axillary vessels and the brachial plexus of nerves. By its deep 

 surface it is in relation with the Lumbar fascia, the Serratus posticus inferior, 

 the lower external intercostal muscles and ribs, inferior angle of the scapula, 

 Rhomboideus major, Infraspinatus, and Teres major. Its outer margin is 



