524 



THE BLOOD-VASCULAR SYSTEM. 



the bodies of the vertebrae in the same manner as the lateral spinal branches from 

 .the vertebral. It anastomoses with the ascending pharyngeal and occipital arteries. 

 The muscular branches supply the depressors of the hyoid bone, the Longus 

 colli, the Scalenus anticus, and the Inferior constrictor of the pharynx. 



Surgical Anatomy. This artery has been tied, in conjunction with the superior thy- 

 roid, in cases of bronchocele. An incision is made along the anterior border of the Sterno- 

 mastoid down to the clavicle. After the deep fascia has been divided, the Sterno-mastoid and 

 carotid vessels are drawn outward and the carotid (Chassaignac's) tubercle sought for. The 

 vessel will be found just below this tubercle, between the carotid sheath on the outer side of the 

 trachea and oesophagus on the inner side. In passing the ligature great care must be exercised 

 to avoid including the recurrent laryngeal nerve, which is occasionally found crossing in front of 

 the vessel. 



The Suprascapular artery (transversalis humeri), smaller than the transversalis 

 colli, passes obliquely from within outward, across the root of the neck. It at first 

 passes downward and outward across the Scalenus anticus and phrenic nerve, 

 being covered by the Sterno-mastoid ; it then crosses the subclavian artery and the 

 cords of the brachial plexus, and runs outward, behind and parallel with the cla- 

 vicle and Subclavius muscle, and beneath the posterior belly of the Omc-hyoid, to 

 the superior border of the scapula, where it passes over the transverse ligament of 

 the scapula, which separates it from the suprascapular nerve, to the supraspinous 

 fossa. In this situation it lies close to the bone, and ramifies between it and the 

 Supraspinatus muscle, to which it supplies branches. It then passes downward 



Posterior scapular. 



Suprascapular. 



Acromial branch 

 of Thoracico-acromialis. 



Anterior 

 circumflex. 



^Termination of 

 subscapular. 



FIG. 300. The scapular and circumflex arteries. 



behind the neck of the scapula, to reach the infraspinous fossa, where it anasto- 

 moses with the dorsalis scapubae and posterior scapular arteries. Besides distribut- 

 ing branches to the Sterno-mastoid, Subclavius, and neighboring muscles, it gives 

 off' a supra-sternal branch, which crosses over the sternal end of the clavicle to the 

 skin of the upper part of the chest ; and a supra-acromial branch, which, piercing 

 the Trapezius muscle, supplies the skin over the acromion, anastomosing with the 

 acromial thoracic artery. As the artery passes over the transverse ligament of the 

 scapula, a branch descends into the subscapular fossa, ramifies beneath that muscle, 

 and anastomoses Avith the posterior and subscapular arteries. It also sends branches 

 to the acromio-clavicular and shoulder joints, and a nutrient artery to the clavicle. 

 The Transversalis Colli passes transversely outward, across the upper part of 

 the subclavian triangle, to the anterior margin of the Trapezius muscle, beneath 

 which it divides into two branches, the superficial cervical and the posterior scctp- 



