270 SUPERIOR THYROID ARTERY. 



Plan of the relations of the External Carotid Artery. 



In Front. 

 Platysma, 

 Digastricus, 

 Stylo-hyoid, 

 Lingual nerve, 

 Facial nerve, 

 Parotid gland. 



External Carotid Artery. 



Behind. 



Stylo-pharyngeus, 

 Stylo-glossus, 

 Glosso-pharyngeal nerve, 

 Parotid gland. 



Branches. The branches of the external carotid are eleven in 

 number, and may be arranged into four groups, viz. 



Anterior. Posterior. 



1. Superior thyroid, 4. Mastoid, 



2. Lingual, 5. Occipital, 



3. Facial. 6. Posterior auricular. 



Superior. Terminal 



7. Parotidean, 10. Temporal. 



8. Ascending pharyngea I, 11. Internal maxillary. 



9. Transverse facial. 



The anterior branches arise from the commencement of the exter- 

 nal carotid, within a short distance of each other. The lingual and 

 facial bifurcate, not unfrequently, from a' common trunk. 



1. The SUPERIOR THYROID ARTERY (the first of the branches of 

 the external carotid) curves downwards to the thyroid gland to which 

 it is distributed, anastomosing with its fellow of the opposite side, 

 and with the inferior thyroid arteries. In its course it passes'be- 

 neath the omo-hyoid, sterno-thyroid, and sterno-hyoid muscle. 



Branches. 



Hyoid, 



Superior laryngeal, 

 Inferior laryngeal, 

 Muscular. 



The Hyoid branch passes forwards beneath the thyro-hyoideus, 

 and is distributed to the insertion of the depressor muscles into the 

 os hyoides. 



The Superior laryngeal pierces the thyro-hyoidean membrane, in 

 company with the superior laryngeal nerve, and supplies the mucous 

 membrane and muscles of the larynx, sending a branch upwards to 

 the epiglottis. 



