sate 



SUPRA-SCAPULAR ARTERY. 



remarkable communication at the base of the brain is formed by the ante- 

 rior communicating branch, anterior cerebrals, and internal carotid arteries, 



Fig. 149.* 



in front, and by the posterior communicating, posterior cerebrals, and 

 basilar artery, behind. 



The THYROID AXIS is a short trunk, which divides almost immediately 

 after its origin into four branches, some of which are occasionally branches 

 of the subclavian artery itself. 



The INFERIOR THYROID ARTERY ascends obliquely in a serpentine course 

 behind the sheath of the carotid vessels, to the inferior part of the thyroid 

 gland, to which it is distributed ; it sends branches also to the trachea, 

 lower part of the larynx, and oesophagus. It is in relation with the middle 

 cervical ganglion of the sympathetic, which lies in front of it. 



The SUPRA-SCAPULAR ARTERY (transversalis humeri) passes obliquely 

 outwards behind the clavicle, and over the ligament of the supra-scapular 

 notch, to the supra-spinatus fossa. It crosses in its course the scalenus 

 anticus muscle, phrenic nerve, and subclavian artery, is distributed to the 



* The circle of Willis. The arteries have references only on one side, on account of 

 their symmetrical distribution. 1. The vertebral arteries. 2. The two anterior spinal 

 branches uniting to form a single vessel. 3. One of the posterior spinal arteries. 4. The 

 ^posterior meningeal. 5. The inferior cerebellar. 6. The basilar artery giving off its 

 transverse branches to either side. 7. The superior cerebellar artery. 8. The posterior 

 cerebral. 9. The posterior communicating branch of the internal carotid. 10. The in- 

 ternal carotid artery, showing the curvatures it makes within the skull. 11. The oph- 

 thalmic artery divided across. 12. The middle cerebral artery. 13. The anterior cere- 

 bral arteries connected by, 14. The anterior communicating artery. 



