106 IOWA ACADEMY OF SCIENCE Vol.. XXVI, 191 j 



to the internal carotid and occipital branches, one forming the ex 

 ternal maxillary-lingual branches, and the third, the internal max 

 illary-superficial temporal branches. In the condition shown i; 

 figure 10, the external carotid artery is very short, terminating ii: 

 four branches, one of which is an innominate which forms the su 

 perficial temporal and occipital branches. I 



In two cases, the inferior alveola artery which normally is con 

 sidered a branch of the internal carotid artery, shows a tendency t( 

 branch well down on the external carotid trunk. This condition i: 

 indicated in figures 4 and 5. On the other hand, the external max 

 illary artery which normally is a branch of the external carotid, ir 

 two individuals (figures 3 and 6), branches well cephalad from th( 

 internal maxillary artery. 



Summary — Variations in the relative positions and points of origir 

 of the several vessels along the common carotid artery result ir 

 the formation of several innominate arteries. Those of especial 

 interest are the occipital-internal carotid, the external maxillary- 

 lingual, the internal maxillary-superficial temporal, and the super- 

 ficial temporal-occipital arteries, represented in figures 2, 4, 9 and 

 10, respectively. 



After the common carotid artery gives rise to the internal carotid 

 or to the innominate (internal carotid-occipital), the remaining 

 trunk, the external carotid artery, may terminate in a number of 

 ways; it may end as a single trunk (either the internal maxillary or 

 the superficial temporal) ; it may be bi-parted (as normally) or by 

 two innominates as in figures 9 and 12; it may be three-parted 

 formed by the two maxillaries and the temporal as in figure 7 ; it 

 may be four-parted, formed by the two maxillaries, the temporal 

 and the lingual as in figure 8 or by the lingual, the two maxillaries 

 and the innominate as in figure 10 ; or it may be five-parted, formed 

 by the two maxillaries, the lingual and the temporal and the oc- 

 cipital. 



The inferior alveola artery which normally is a branch of the in- 

 ternal maxillary, is in two cases (figures 4 and 5), well down on the 

 external carotid artery. 



The external maxillary artery in one case (figure 6) is given off as 

 a branch of the internal maxillary some distance cephalad to the 

 latter's junction with the temporal. In several cases both the lingual 

 and the external maxillary arteries pass out of the external carotid 

 artery at the level of the internal maxillary and superficial temporal 

 arteries as in figures 8, 10 and 11. 



