Pig. 67. Outer Region of the Neck. Subclavian Triangle. 



The head is rotated to the right. Platysma and a portion of the Supraclavi- 

 cular Nerves have been removed, the lympliatic glands have been removed in order 

 to simplify the figure; the course of the chief lymphatic tracts has been indicated. 



Under the skin we distingxiish a Superficial and Deep Cervical Fascia, 

 separated from each other by loose connective tissue, which stretches across the 

 space between Sterno-Mastoid and Trapezius Muscles. The Supraclavicular Nerves 

 become subcutaneous b}' piercing this fascia. 



For the removal of tumours and especially, for the removal of diseased 

 lymphatic glands, a longitudinal incision is made along the posterior border of 

 the Sterno-Mastoid Muscle, the External Jugular Vein is divided. This vein runs 

 downwards from the lower end of the Parotid Gland across the Sterno-Mastoid 

 and Omo-hyoid, to pierce the Omo-hyoid Fascia and open into the Subclavian 

 Vein. Of more importance is the Spinal Accessory Nerve. Emerging at the 

 posterior border of the Sterno-Mastoid, this nerve runs obliquely downwards to 

 the Trapezius. 



As it crosses the area of operation, it cannot always be avoided: injur}' 

 to it may cause paralysis of the Sterno-Mastoid and Trapezius Muscles; but not 

 in every case as both muscles receive fibres from the 2nd, 3rd, and 4th Cervical 

 Nerves which may run separately to the muscles and independent of the Spinal 

 Accessory. 



The Brachial Plexus emerges through the slit between the Scalenus 

 Anticus and Scalenus Medius Muscles. Of particular importance is the position 

 of the Phrenic Nerve. Deriving its fibres from the 4th Cervical Nerve, as well 

 as from the 3rd and 5th, it runs obliquely inwards, superficial to the Scalenus 

 Anticus Muscle. At this point, behind the posterior border of the Sterno-Mastoid 

 Muscle, it can be best stimulated electrically. 



When the clavicular portion of the Sterno-Cleido-Mastoid does not extend 

 far backwards (eis in our figure) the Internal Jugular Vein is visible at its posterior 

 border. The Suprascapular Artery which either comes from the first, or from 

 the 3rd part of the Subclavian Artery, takes a rather high course in this 

 specimen; as a rule, it lies behind the clavicle (cf. Fig. 68). On the other 

 hand, the Transversalis Colli Artery runs usually at a higher level than in 

 our figure. 



The most important point, just above the Clavicle, is where the Subclavian 

 Artery and Vein leave the Thorax. Ascending out of that cavity, they form an 

 arch over the first rib on their way to the axilla. The Vein is in front of, the 

 Artery behind the Scalenus Anticus Muscle. The Vein is fixed to the first rib 

 and to the clavicle by tense connective tissue; it cannot, therefore, collapse, when 

 punctured (danger of air embolism). Just above the clavicle, it receives the Supra- 

 scapular Vein. The Clavicle and first Rib form the gate through which the Neuro- 

 vascular Bundle passes into the arm, most external and posterior (highest-up) being 

 the nerves; then comes the artery, and on the inner side and most anterior, 

 the vein. 



The large Lymphatic Tracts are in b 1 a c k ; the Thoracic Duct opens at the 

 junction of the left Subclavian and Internal Jugular Veins. This Duct receives 

 the Jugular and Subclavian Lymphatic Trunks. When removing the deep cervical 

 glands, which are so very frequently diseased (cf. Fig. 115), there is always a danger 

 of damage to this most important lymphatic tract of the body. 



