1302 



SURFACE ANATOMY AND SURFACE MARKINGS 



thyroid cartilage; the space intervening between the hyoid bone and the thyroid 

 cartilage is occupied by the hyothyroid membrane. The outlines of the thyroid 

 cartilage are readily palpated ; below its lower border is a depression corresponding 

 to the middle cricothyroid ligament. The level of the vocal folds corresponds to 

 the middle of the anterior margin of the thyroid cartilage. The anterior part of 

 the cricoid cartilage forms an important landmark on the front of the neck; it 

 lies opposite the sixth cervical vertebra, and indicates the junctions of pharynx 

 with esophagus, and larynx with trachea. Below the cricoid cartilage the trachea 

 can be felt, though it is only in thin subjects that the separate rings can be distin- 

 guished; as a rule there are seven or eight rings above the jugular notch of the 

 sternum, and of these the second, third, and fourth are covered by the isthmus 

 of the thyroid gland. 



Ext. max. art. - 



___--" Facial nerve 



Ext. carotid art. 



Occipital att. 



- - Lesser occip. nerve* 



- - Great auric, nerve 

 -- Cervical cutan.iierve 

 ~ ~ Accessory nerve 



~ ~ Supraclavic. nerves 



Line of upper margin 

 of brachial plexus 





Lingual art. ~~\.-- 

 Sap. thyroid art. ' \. &? 

 Point of bifurcation - \{vh,\ 1 

 of com. carotid art. 



Com. carotid art. 

 Subclavian art. - - 



FIQ. 1210. Side of neck, showing chief surface markings. 



Muscles. The posterior belly of Digastricus is marked out by a line from the tip 

 of the mastoid process to the junction of the greater cornu and body of the hyoid 

 bone; a line from this latter point to a point just lateral to the symphysis menti 

 indicates the position of the anterior belly. The line of Omohyoideus begins at 

 the lower border of the hyoid bone, curves downward and lateralward to cross 

 Sternocleidomastoideus at the junction of its middle and lower thirds, i. e., opposite 

 the cricoid cartilage, and then runs more horizontally to the acromial end of the 

 clavicle. 



Arteries. The position of the common carotid artery in the neck is indicated 

 by a line drawn from the upper part of the sternal end of the clavicle to a point 

 midway between the tip of the mastoid process and the angle of the mandible. 

 From the clavicle to the upper border of the thyroid cartilage this line overlies 

 the common carotid artery, beyond this it is over the external carotid. The 

 external carotid artery may otherwise be marked out by the upper part of a line 

 from the side of the cricoid cartilage to the front of the external acoustic meatus, 

 arching the line slightly forward. 



The points of origin of the main branches of the external carotid in the neck 

 are all related to the tip of the greater cornu of the hyoid bone as follows: (1) the 

 superior thyroid, immediately below it; (2) the lingual, on a level with it; (3) the 

 facial, and (4) the occipital a little above and behind it. 



