Jpn. J. Oral Biol., 31: 83-88, 1989. ORIGINAL On the external carotid artery and its branches in hens Toshiaki Nakajima, Junzo Okugawa and Hideomi Ikuta 2nd Department of Oral Anatomy , Meikai University, School of Dentistry 1-1 Keyakidai, Sakado, Saitama 350-02, Japan (Chief: Prof. Masayoshi Kumegawa) 〔Accepted for publication : June 17, 1988•l Key words: Hen/external crotid artery/plastic injection method/comparative anatomy Abstract: The external carotid artery and its branches were investigated in hens by an acrylic plas- tic injection method. The common carotid artery of hens bifurcated into the internal and external carotid arteries at the level of the second cervical vertebra. The external carotid artery advanced antero-superiorly within the platysma, stylohyoid, and occipitomandibular muscles at the postero-lateral side of the pharynx. Thereafter, it bifurcated into the anterior palatine and facial arteries between the pharynx and capitis rectus muscle at the posterior side of the medial mandibular process of the articular bone. The exter- nal carotid artery sent out the following branches: the occipital, hyomandibular, anterior temporal, sublingual, anterior palatine, and facial arteries. artery in birds. Introduction The external carotid artery in birds is de- The appearance of the jaw is the most scribed by Bhaduri et al.5) for the pigeon, important event which occurred in the proc- and Gobeil6) and Midtgard7) for the herring ess of evolution of the vertebrates. The jaw gull. But, there is no paper which addresses is transformed from the gill arches, and these the relationship of the skull, jaw formation, traces remain in the jaws of animals lower and their arterial distribution. Thus, in the than birds1). The jaw began to excute an present study, we examined the external carot- important function as an apparatus for prey- id artery of hens, and discussed the relation- ing in fishes and an apparatus for mastication ships of the skull, jaw formation, and arte- in mammals. The jaw is supplied with the rial distribution. external carotid artery which arose with the Materials and Methods development of the jaw. The external carotid arteries of mammals Forty adult White Leghorn hens were developed from the anastomosis of branches used in this study. They were injected with from the internal carotid and stapedial arteri- acrylic plastic from the common carotid artery es2,3). In the ontogeny of man, the external into the arterial system of the head using carotid artery is thought to have developed the acrylic plastic injection method described from the branches of the stapedial artery4). by Taniguchi et al.8,9). Thirty-five heads On phylogetic grounds Romer1) agrees with were macerated in 20% NaOH solution Padget4) that the external carotid artery orig- to obtain corrosion casts. The remaining 5 inates from the stapedial artery. But he heads were embalmed in 10% formalin does not explain about the external carotid solution for dissection. The specimens were 84 Jpn. J. Oral Biol., 31: 83-88, 1989. Fig.1 Schematic illustration of the external carotid artery and its branches. ro-superiorly meandering slightly in the medi- al side of the platysma, stylohyoid, and occip- itomandibular muscles at the postero-lateral side of the pharynx. Thereafter, it bifurcated into the anterior palatine and facial arteries between the pharynx and the capitis rectus muscle at the infero-medial side of the exter- nal auditory pore and on the posterior side at the medial mandibular process of the artic- ular bone. Branches of the external carotid artery 1. Occipital artery (Figs. 1, 2, 3) The occipital artery arose from the exter- Fig.2 Lateral aspect of the external carotid nal carotid artery at the medial side of the artery and its branches of which are platysma, with which the ventral capitis rec- the occipital artery, hyomandibular, and tus, trachlomastoideus, complexus, and lateral anterior temporal arteries. capitis rectus muscles, and the skin and mus- cles of the occipital part are supplied. In 4 dissected and observed with an stereoscopic of the 70 cases, the occipital artery arose microscope. from the internal carotid artery. In one case, this artery arose from the common caro- Observations tid artery. After its divergence, the artery The common carotid artery ascended in advanced postero-supero-laterally, entered the middle groove of the precervical area to between the stylohyoid and ventral capitis form the longus colli, and it bifurcated into rectus muscles, and bent supero-medially to- the internal and external carotid arteries at ward the lateral side of the internal carotid the level of the second cervical vertebra. artery. After that, it entered between the External carotid artery (Figs. 1, 2, 3, 4, 5) ventral capitis rectus and lateral capitis recuts The external carotid artery advanced ante- muscles, and then passed between the trachlo- T. Nakajima, et al: On the external carotid artery and its branches in hens 85 Fig.3 Lateral aspect of the external carotid artery and its branches of which are the occipital, hyomandibular, anterior temporal, and sublingual arteries. Fig.4 Ventral aspect of the external carotid artery and its branches of which are the anterior tem- poral, sublingual, anterior palatine, and facial arteries. Fig.5 Ventral aspect of the external carotid artery and its branches of which are the anterior pala- tine and facial arteries. Fig.6 Lateral aspect of the facial artery. mastoideus and lateral capitis rectus muscles divergence, the hyomandibular artery im- to bend superiorly. Finally, the occipital mediately sent out the posterior temporal artery communicated with the vertebral ar- artery. After that, this artery reached the tery which ascended to the level of the first inferior edge of the stylohyoid muscle to cervical vertebra. descend, and split into the laryngeal and 2. Hyomandibular artery (Figs. 1, 2, 3) lingual arteries. The hyomandibular artery branched off a. Posterior temporal artery (Figs. 1, 2, 3) from the external carotid artery on the medi- The skin of the temporal part, and the al side of the stylohyoid muscle. After its occipitomandibular and mylohyoid muscles 86 Jpn. Oral Biol., 31: 83-88, 1989. were supplied by the posterior temporal artery in one case. After its divergence, this artery. After its divergence, this artery pro- artery reached the antero-inferior edge of ceeded postero-superiorly between the stylohy- the external auditory port to advance supero- oid and ventral capitis rectus muscles to reach laterally between the external auditory the posterior edge of the posterior mandi- pore and the occipitomandibular muscle. bular muscle. Thereafter, it reached the tem- Thereafter, it arrived at the temporal part poral and parietal part, and then ascended to ascend under the skin at the anterior side along the lateral side of the occipitomandibu- of the external auditory pore. lar muscle and the posterior side of the ex- 4. Sublingual artery (1, 3, 4) ternal auditory pore. The sublingual artery arose from the exter- b. Laryngeal artery (Figs. 1, 2, 3) nal carotid artery on the posterior side at The mylohyoid and stylohyoid muscles, the medial mandibular process of the articu- the larynx, superior part of the esophagus, lar bone, with which the stylohyoid muscle, and the skin of the laryngeal part were sup- the anterior mandibular gland and the dentary plied by the laryngeal artery. In the begin- bone were supplied. In 26 of the 70 cases, this ning this artery advanced postero-inferiorly, artery arose from the anterior palatine artery. and then curved antero-inferiorly after the In one case, it arose from the facial artery. ramification of the superior esophageal ar- After its emergence, the artery advanced an- tery. After that, it branched off fan-like and tero-infero-laterally along the infero-medial advanced under the skin. side at the medial mandibular process of the c. Lingual artery (Figs. 1, 2, 3) articular bone, and bent antero-inferiorly on The lingual artery entered the medial side the lateral side of the lingual artery. There- of the stylohyoid muscle to advance antero- after, it reached the separation between the medially, and proceeded along the stylohyoid superficial and deep parts of the stylohyoid muscle while sending branches into the mus- muscle, and bifurcated into superficial and cle. After that, it advanced antero-medially deep branches. The superficial branch anas- on mylohyoid muscle to be situated supero- tomosed with the submental artery, and the laterally at the angle of the hyoid, and deep branch distributed itself to the anterior reached the central part at the manubrium of mandibular gland. the hyoid and the posterior end of the ante- 5. Anterior palatine artery (Figs. 1, 4, 5) rior mandibular muscle. At this point, the The anterior palatine artery distributed it- artery sent out the deep lingual artery, with self to the palate, the pharynx, and the nasal which the lingual apex and the anterior man- cavity. This artery was derived from the dibular gland were supplied. The main facial artery, proceeded antero-supero-medi- stem became the submental artery which dis- ally between the ventral capitis rectus muscle tributed its branches into the dentary bone, and the postero-superior wall of the phar- the anterior mandibular gland, and the skin ynx, went round a pointed end at the medial of the mental part. mandibular process of the articular bone, and 3. Anterior temporal artery (Figs. 1, 2, advanced antero-infero-laterally between the 3, 4) dorsal pterygoid muscle and the pharyngeal The occipitomandibular and mylohyoid wall. After that, it proceeded antero-medial- muscles, the external auditory port, and tem- ly to arrive at the inferior end of the pala- poral part of the skin were supplied by the tine bone. These arteries of the right and anterior temporal artery. This artery arose left side anastomosed with each other at a from the external carotid artery on the poste- point below the external naris.