versão impressa ISSN 0716-9868
Rev. chil. anat. v.20 n.2 Temuco 2002
Rev. Chil. Anat., 20(2):193-196, 2002.
ANATOMICAL VARIATIONS OF THE OCCIPITAL ARTERY:
RELATE OF TWO CASES
CONSIDERACIONES ANATÓMICAS DE LA ARTERIA OCCIPITAL: RELATO DE DOS CASOS
Marques, S. R.; Itezerote, A. M.; Saviolo Moreira, R.; De Angelis, M. A. & Prates, J. C. Anatomical variations of the occipital artery: relate of two cases. Rev. Chil. Anat., 20(2):193-196, 2002.
SUMMARY: Due to the great importance of the knowledge about variations occurring in the vascular system to surgeons and professionals who work with imaging, we describe in this article a variation of the origin of the occipital artery.
110 cadavers of male and female individuals had they carotid vascular tree in the region of the neck carefully dissected using loupe magnification and its origin and course were measured as well as a simple diameter.
This artery usually branches off from the posterior part of the wall of the external carotid artery at the same level of the facial artery branching however, the two cases presented showed the occipital artery branching off very close to the carotid bifurcation, which characterize it as a trifurcation instead. The occipital artery branching off too close to the carotid bifurcation is a rarity as demonstrated by our results and the its literature is insufficient.
KEY WORDS: 1. Anatomy; 2. Common carotid artery; 3. Occipital artery; 4. Anatomical variation.
Due to increasing need of finding out new safe accesses for surgical procedures in the region of neck and head, vascular variations are more and more frequently being described (Benson & Hamer, 1988).
Procedures which need a greater knowledge of the course of the occipital artery include: 1 the biopsy of this artery when one suspects of cranial arteritis with involvement of the occipital artery (Schmidt & Adelmann, 2001); 2 transfer of hair-bearing tissue blood-supplied by the occipital artery (Matloub et al., 1992); 3 surgical procedures involving flap management in the head and neck region (Sharma et al., 1996) as well as 4 angiographic studies (Gluncic et al., 2001).
Many authors describe variations of the origin of the occipital artery (Adachi & Hasebe, 1928, Altmann, 1947; Newton & Young, 1968; Matsuda et al., 1977, Benson & Hamer). Bergman et al., (2001) and Kaneko et al., (1996) describes this artery as sometimes branching off the internal carotid artery, the thyrocervical trunk and the inferior thyroid artery or its ascending cervical branch. A few authors report a variation of the occipital artery origin as a close branching to the carotid bifurcation (Adachi & Hasebe). Our study adds to the ones of the latter authors in that greater occurrence frequency and closeness difference were observed.
MATERIAL AND METHOD
110 cadavers of male and female individuals who died at ages ranging from 23 to 78 years old had they carotid vascular tree in the region of the neck carefully dissected using loupe magnification. The origin and course of the occipital artery were measured as well as a simple diameter "in loco" measurement with a digital caliper (Storm -0.05 mm accuracy) was taken.
In 2 of the 110 cadavers (1,8%), the occipital artery origin was about a third of its usual length from the carotid bifurcation which could characterize a trifurcation instead.
In the cadaver of a 65 years old individual, the occipital artery originated 5 mm from the carotid bifurcation, 45 mm from the hyoid bone (figure.1). The occipital and carotid artery diameters were 9 and 20 mm respectively. The superior thyroid artery branched from common carotid artery 0,8 mm below the carotid bifurcation and the occipital artery was the first of the external carotid.
|Fig. 1. A. Common carotid artery; B. Superior thyroid artery; C. Lingual artery; D. External carotid artery; E. Occipital artery; F. Internal carotid artery. Arrow show the carotid bifurcation.|
In the cadaver of a 46 years old individual, the occipital artery had its origin 9 mm away from the carotid bifurcation, 3 mm above the lingual artery and 32 mm away from the hyoid bone. The occipital and external artery diameters were 10 and 13 mm, respectively. The superior thyroid artery branched from the common carotid artery 3 mm below the carotid bifurcation and the occipital artery was the second branch of the external carotid artery.
Classically, the occipital artery arises from the posterior face of the external carotid artery Poirier & Charpy (1902), Testut & Latarjet (1945), Lasjaunias et al. (1978), Williams et al. (1995), 20 mm further the carotid bifurcation. Although many studies have supported variations of the origin of the occipital artery (Adachi & Hasebe), Benson and Hamer take this fact as rarity. Newton & Young reported 3 cases where in 2 of them this arterial vessel branched from the internal carotid artery 20 mm from the carotid bifurcation. Lasjaunias et al. showed that the occipital artery could arise either from the internal carotid artery, the vertebral artery (suboccipital part) or the faringo occipital trunk.
Anatomy treatises presents the occipital artery as usually branching off the posterior face of the external carotid artery, 20 mm from the carotid bifurcation in average at the same level of the lingual artery and a just below the hyoid bone (Sappey, 1876). It runs medially all over the posterior bundle of the digastric muscle and ends in the posterior aspect of the head, in the nape (Hollinshead & Rosse, 1991).
We agree with the authors although our results showed the occipital artery as the first branch of the external carotid artery only in one case. Its closeness with the carotid bifurcation figures out a trifurcation instead. Adachi & Hasebe studied 298 subjects and described only 2 cases of left occipital artery branching off the carotid bifurcation, characterizing a trifurcation of the carotid tripod. We agree with these authors since we found similar results.
The two cases presented here, resemble those recently described by Gluncic and Gurbuz et al.
The occipital artery branching off too close to the carotid bifurcation is a rarity as demonstrated by our results and the literature. This important variation could lead to severe complications when radiographics evaluation or surgical proceedings were done in the neck region.
RESUMEN: Debido a la importancia que tienen las variaciones musculares para cirujanos, como también para los profesionales del área de las imágenes, describimos dos variaciones de origen de la arteria occipital.
Disecamos la región del cuello en 110 cadáveres de individuos, adultos, brasileros de ambos sexos, determinándose el origen, trayecto y diámetro de la arteria occipital.
La arteria occipital que se origina generalmente de la pared posterior de la arteria carótida externa, a nivel de la arteria facial, fue encontrada en dos casos, originándose muy próxima a la terminación de la arteria carótida común, asemejándose mucho a una trifurcación carotídea. Este modo de origen de la arteria occipital, próximo a la bifurcación carotídea constituye una variación anatómica muy rara, como también lo demuestra la literatura existente.
PALABRAS CLAVE: 1. Anatomía; 2. Arteria carótida común; 3. Arteria occipital; 4. Variación anatómica.
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Dirección para correspondencia:
Dr. Sergio Ricardo Marques
Disciplina de Anatomia Descritiva e Topográfica
Departamento de Morfologia
Universidade Federal de São Paulo (UNIFESP)
Rua Botucatú, 740 - CEP 04023-900
São Paulo - BRASIL