THE NECK 143 



The Thyreo-Cervical Trunk (Thyroid Axis) arises from the 

 subclavian at the medial border of the scalenus anterior, and at 

 once divides into the transverse scapular (suprascapular) (p. 

 126); the transverse cervical (p. 126); and the inferior thyreoid 

 arteries. 



The Inferior Thyreoid Artery runs upwards along the medial 

 border of the scalenus anterior a.nd behind the carotid sheath 

 (internal jugular vein). On the left side,, the artery is crossed by 

 the thoracic duct close to its origin. A little below the sixth 

 cervical vertebra it turns medially behind the sheath and, at the 

 point where it makes the bend, it gives off the ascending cervical 

 artery (Fig. 44). It crosses in front of the vertebral vein and 

 artery, and at the lateral border of the longus colli it turns 

 downwards and runs in the groove between the trachea and the 

 oesophagus, overlapped by the lateral lobe of the thyreoid 

 gland. The vessel may require to be ligated in operations on 

 the thyreoid gland, oesophagus, and larynx. 



The first part of the subclavian artery also gives off the 

 vertebral (p. 140) and the internal mammary arteries (p. 503). 



The Submaxillary Region of the neck extends upwards, 

 under cover of the mandible, to the mylo-hyoid line and down- 

 wards to the hyoid bone. Its roof is formed by the deep surface 

 of the mandible and by the investing layer of the deep cervical 

 fascia, which is attached to the lower border of the mandible 

 above and to the hyoid bone below. In front and behind it is 

 bounded by the bellies of the digastric, and the fascial roof 

 blends with the fascial sheath of the muscle, so that a collection 

 of pus in this neighbourhood is definitely circumscribed. The 

 submaxillary salivary gland and numerous lymph glands, which 

 extend from the anterior belly of the digastric in front to the 

 mandibular angle behind, occupy the area, and during their 

 examination the head should be flexed in order to relax the 

 strong fascial roof. The surgeon stands behind the patient and 

 inserts the tips of his fingers beneath the lower border of the 

 mandible. By pressing laterally against the bone, he is enabled 

 to detect even a slight enlargement of the anterior group of 

 lymph glands. The more superficial glands of the posterior 

 group, which are intimately related to the submaxillary salivary 

 gland, may be identified near the angle of the mandible if they 

 become enlarged. 



The floor of the space is formed by the mylo-hyoid in front 



