THE NECK. 



1387 



with the carotid sheath and its contents, being pulled well forwards. In approach- 

 ing the trunk of the inferior thyreoid artery from the front the sterno-mastoid and 

 carotid sheath are retracted and the dissection is continued through the cellular 

 interval between the carotid sheath and the sheath (outer capsule) of the thyreoid 

 gland, which is formed by the splitting of the pretracheal fascia. 



A glandular abscess in this compartment usually points upon the surface, 

 adhesions being formed, first, between the gland and the fascia, and, subsequently, 

 between the latter and the cutaneous structures. In diffuse suppurative cellulitis 

 of this compartment the pus burrows towards the root of the neck, and may reach 

 either the mediastinum or the axilla. 



Median Line of the Neck. The body of the hyoid bone divides the median plane 

 of the neck into supra- and infra-hyoid portions. Above the hyoid bone is the sub- 

 mental.triangle, with its apex at the inferior border of the symphysis menti and its 



Anterior belly of digastric 

 Mylo-hyoid 



Submaxillary gland 



Thyreo-hyoid membrane 



Thyreoid cartilage 



Superior thyreoid artery 

 Crico-thyreoid ligament 



Cricoid cartilage -^ 



Lobe of thyreoid gland I 

 Common carotid 4- 



Anterior belly of digastric 

 Mylo-hyoid 



Submaxillary gland 



Omo-hyoid 

 Sterno-hyoid 



Internal jugular vein 

 Superior thyreoid vein 



Common carotid artery 

 Sterno-mastoid 

 Crico-thyreoid muscle 



Lobe of thyreoid gland 

 Isthmus of thyreoid 

 Scalenus anterior 



Scalenus medius 



- First rib 

 Trachea 



Phrenic nerve . 

 Inferior thyreoid- 

 Transverse cervical -Irft 



Vertebral artery. 



^^^dNfcT 7 jf"-"^IWA V*#*r^ Subclavian artery 

 Subclavian artery -^ 

 Transverse scapular artery 



Common carotid artery 

 Internal mammary artery 



Innominate artery ' 



Inferior thyreoid vein 



PIG. 1087. DISSECTION OF THE FRONT OF THE NECK. The lower portions of the sterno-mastoid muscles 

 have been removed, and the lower part of the right common carotid artery cut away to show the deeper 

 parts. (From Cunningham. ) 



sides formed by the anterior bellies of the digastrics. In the floor of the triangle 

 are the anterior portions of the mylo-hyoid muscles, separated by the median 

 raphe (Fig. 1087). The most important structures in the triangle are the submental 

 lymph glands, which can usually be felt a little above the body of the hyoid 

 bone. In children they are a frequent seat of abscess secondary to impetigo of the 

 lower lip and chin. About 1 in. below the hyoid bone is the pomum Adami, more 

 prominent in the male than in the female. On either side of the pomum Adami 

 are the laminse of the thyreoid cartilage, while between the latter and the hyoid bone 

 is the thyreo-hyoid membrane. In the operation of sub-hyoid pharyngotomy the 

 epiglottis and the superior opening of the larynx are reached by passing through 

 the anterior wall of the pharynx at the level of the thyreo-hyoid membrane. 

 The structures divided from without inwards are : the integuments, the sterno- 

 hyoid, omo-hyoid, and thyreo-hyoid muscles, the median portion of the thyreo-hyoid 

 membrane, along with a layer of fat between it and the lower part of the 

 epiglottis, and, finally, the glosso - epiglottic ligament and fold of mucous 

 membrane. The incision must not be extended too far on either side of the 



