Persistent stapedial arteries in human: from phylogeny to surgical consequences.

The stapedial artery is an embryonic artery which disappears during the tenth week in utero, in human species. During its short life, this artery shapes the stapes and transforms the middle meningeal artery from the internal carotid artery to a branch of the external carotid system. Nevertheless, a persistent stapedial artery is seen in 0.2-4.8 per thousand of human adults. This persistence is usually asymptomatic but can sometimes cause pulsatile tinnitus or conductive hearing loss. Despite the risk of facial palsy, hearing loss and even hemiplegia argued by several authors, some surgeons have succeeded in coagulation without side effects. Reviewing the literature, we seek to enlighten the actual knowledge about the persistent stapedial artery to evaluate the risk to coagulate it. Embryologic studies explain the four types of persistent stapedial arteries: the hyoido-stapedial artery, the pharyngo-stapedial artery, the pharyngo-hyo-stapedial artery and aberrant internal carotid with persistent stapedial artery. Phylogenetic studies show that the stapedial artery persists in adulthood in many vertebrates. Its disappearance is therefore either a random effect or an adaptative convergence. This adaptation could be partially linked to the negative allometry of the stapes. Practically, the risk to coagulate a stapedial artery seems limited thanks to anastomoses, for example with the stylomastoid artery. The risk of hemiplegia reported is in fact an extrapolation of variation in rats' embryos. A persistent stapedial artery can therefore reasonably be coagulated, with special attention to the facial nerve, because the facial canal is always dehiscent where the artery penetrates.

Unilateral variation in the origin of the inferior alveolar and buccal arteries: a case report / Variación unilateral en el origen de las arterias alveolar inferior y bucal: reporte de un caso

The maxillary artery (MA) is one of the terminal branches of the external carotid artery (ECA) and is located in the infratemporal fossa (IF). Some of the branches in this region are the inferior alveolar artery (IAA) and the buccal artery (BA), both descending branches. Here, we report an unusual unilateral origin of the IAA and the BA from a common trunk directly from the ECA. We conducted a routine dissection of both IF in a 54-year-old hispanic male cadaver. Fixed with Universidad de los Andes® conservative solution and red latex for vascular filling. On each side, the MA is observed superficially located over the lateral pterygoid muscle. On the right side, the IAA and the BA originate from a common trunk from the ECA approximately 5 mm prior to the bifurcation into their terminal branches. On the left side, the IAA originates from the MA that is immediately next to its origin, making a common trunk with the pterygoid branches. Knowing the morphology of the MA and its branches at the IF is important for oral and maxillofacial surgery procedures; and any variation in the origin or course of these arteries may result in the patient's increased morbidity during some invasive procedure in the area.

La arteria maxilar (AM) es una rama terminal de la arteria carótida externa (ACE), y se ubica en la región infratemporal (RI). Algunas de sus ramas en esta región son la arteria alveolar inferior (AAI) y la arteria bucal (AB), ambas ramas descendentes. En este trabajo informamos de un inusual origen unilateral de la AAI y de la AB a partir de un tronco común desde la ACE. Se realizó una disección de rutina de ambas regiones infratemporales en un cadáver de 54 años, sexo masculino, caucásico. Fijado con solución conservadora Universidad de los Andes® y repleción vascular con látex rojo. A cada lado, se observa la AM en ubicación superficial sobre el músculo pterigoideo lateral. Al lado derecho, la AAI y la AB se originan de un tronco común desde la ACE aproximadamente 5 mm antes de la bifurcación en sus ramas terminales. Al lado izquierdo la AAI se origina de la AM inmediato a su origen, formando un tronco común con los ramos pterigoideos. El conocimiento de la morfología de la AM y de sus ramas en la RI es de importancia en procedimientos odontológicos, de cirugía oral y maxilofacial. Por lo que cualquier variación en el origen o trayecto de estas arterias puede predisponer a un paciente a una mayor morbilidad durante algún procedimiento invasivo en la zona.

The study of arterial anastomoses in the region of the alveolar process and the anterior maxilla wall in foetuses.

The anterior maxilla wall and alveolar process are covered by the arterial network. Procedures in this region can cause heavy bleeding. Knowledge of the anatomical course of a particular artery is essential for performing surgery in this area. The aim of this study was to search for and then analyse anastomoses between the infraorbital and posterior superior alveolar artery. In the study, 19 maxillas of foetuses were analysed. The arteries were injected with coloured latex. The dissection was carried out using a surgical microscope and microsurgical equipment. The lower eyelid with cheek skin was separated and the facial muscles were cut to expose the maxilla and arteries of the alveolar process. The study revealed that in 10 out of 19 of the specimens there was an arterial connection between the infraorbital and posterior superior alveolar artery. The course of the analysed anastomosis was diverse. In all cases we observed an anterior superior alveolar artery. In all specimens the alveolar process was vascularised by many arteries originating from the analysed anastomosis. The location of the analysed anastomosis can be stated before operation, on the line between the medial eye angle and the sixth tooth of the same side. The anastomosis described in the study means that caudally running arteries are important in choosing incisions in procedures performed at the alveolar process.

[Aetiology of Angiofibromas: Reflection on their Specific Vascular Component]. / Die vaskuläre Komponente: Gedanken zur Entstehung des Angiofibroms.

BACKGROUND: Even though numerous theories have speculated either on the vascular or fibrous tumour component as tissue of origin, aetiology of angiofibroma still remain unclear. Histological investigations recently led Beham and coworkers to the assumption that angiofibromas have to be considered as vascular malformations. METHODS: After giving a literature review of the various theories on tumour origin the proposal to consider angiofibromas as vascular malformations is discussed on an embryological base. Taking typical clinical features of the tumour and knowledge of vasculogenesis into account a new explanation for origin of the vascular tumour component is presented. RESULTS: The vascular component of angiofibromas can be explained embryologically due to incomplete regression of the first branchial arch artery (vascular atavism). This vessel arises regularly between embryological day 22 and 24 and recedes during regular development completely until delivery via temporary formation of a vascular plexus. In the late stages of embryological development remnants of the plexus are found at the area of the sphenopalatine foramen, the typical site of angiofibroma origin. Incomplete regression of the vascular plexus of the former first branchial arch artery may form the vascular component of an angiofibroma arising due to growth stimulation at the time of adolescents. CONCLUSIONS: Incomplete regression of the first branchial arch artery presenting an atavism is suited to explain the vascular tumour component of angiofibromas considering main tumour characteristics (origin in the posterior nasal cavity close to the sphenopalatine foramen, main blood supply from the maxillary artery with possible feeders arising from the internal carotid artery). Our embryological contributions support to define angiofibromas as vascular malformations.

Variation in the origin of the inferior alveolar nerve.

The inferior alveolar nerve and maxillary artery were studied in 40 human heads through infratemporal dissection; in one specimen, a unusual variation in the origin of the inferior alveolar nerve and its relationship with the surrounding structures was observed. The inferior alveolar nerve originated from the mandibular nerve by two roots and the second part of the maxillary artery was incorporated between them. An embryologic origin of this variation and its clinical implications is discussed. Because the maxillary artery ran between the two roots of the inferior alveolar nerve, and the nerve was fixed between the foramen ovale and mandibular foramen, tension and compression of the nerve from arterial pulsation could cause mandibular neuralgia.

The vascular relationship between the temporomandibular joint and the middle ear in the human fetus.

PURPOSE: The aim of this work was to clarify the vascular relationships between the middle ear and the temporomandibular joint region during human fetal development. MATERIALS AND METHODS: Light microscopic studies were done on 40 human fetuses from 72 mm crown-rump length (C-R) to 150 mm C-R, which were stained by various methods. Five human fetuses were dissected. Natural latex with industrial coloring was injected through the external carotid artery. All specimens were dissected bilaterally. RESULTS: The limits of the retroarticular region and the fetal tympanosquamosal fissure are shown. The anterior tympanic artery has a variable origin. In most cases, it originates from the maxillary artery; in other cases it originates from the superficial temporal artery or the bifurcation of the external carotid artery. On its way through the retroarticular region, it gives branches to the posterior part of the temporomandibular joint. It progresses along the most lateral part of the tympanosquamosal fissure, dividing into three branches that extend throughout the middle ear. A number of venous spaces in the retroarticular region that constitute the retrodiscal venous plexus. Small venous vessels along the fetal tympanosquamosal fissure accompany the anterior tympanic artery and drain into the retrodiscal venous plexus. CONCLUSIONS: During human fetal development, there is a wide connection across the tympanosquamosal fissure between the middle ear and the temporomandibular joint region. The anterior tympanic artery and its branches, as well as small venous vessels that are connected with the retrodiscal venous plexus, extend along the most lateral part of the fissure.

Anatomic relationships of the orbital muscle of Müller in human fetuses.

A study was carried out in twenty human fetuses on the relationships of the orbital muscle of Müller. This muscle forms a lamina of smooth muscle fibres that cover the inferior orbital fissure. The latter is very wide during the fetal period because ossification of the bones that delimit this region is still incomplete. Some fibres of the orbital muscle extend along the superior orbital fissure under the inferior ophthalmic vein and the lower wall or floor of the cavernous sinus. This association suggests a possible influence on autonomically mediated vascular dynamics.

Study of pterygospinosus muscle in human fetuses.

The arrangement of the pterygospinosus muscle was analyzed in 5 human fetuses. The pterygospinosus muscle extends from the posterior border of the lateral lamina of the pterygoid process to Meckel's cartilage. Such an arrangement would permit its action on the joint formed by Meckel's cartilage and the incus of the middle ear. The pterygospinosus muscle is a remnant of the masticatory muscle group. The relationships of the pterygospinosus muscle with the mandibular nerve and its branches and the maxillary artery and its branches were analyzed.

Complete persistence of the hyoido-stapedial artery in man. Case report. Intra-petrous origin of the maxillary artery from ICA.

The authors report a case of total persistence of the hyoïdo-stapedial artery (HSA) discovered fortuitously in an adult. The external carotid artery terminated as the superficial temporal, middle deep temporal and transverse facial arteries; the HSA arose from the intrapetrous internal carotid artery, coursed within the middle ear and the middle cranial fossa where it gave off the middle meningeal artery before leaving the skull via the foramen spinosum to become the maxillary artery.

A bilateral maxillofacial trunk in man: an extraordinary anomaly of the carotid system of arteries.

In a Caucasian male, the maxillary artery (M) bilaterally arose with the facial artery anteromedially from the external carotid artery. On the right side, the M entered the infratemporal fossa between the neck of the mandible and the medial pterygoid muscle, whereas the left M pierced the medial pterygoid muscle, first being covered by the muscle and the angle of the mandible. On both sides, the M ran deep to the inferior head of the lateral pterygoid muscle and the buccal nerve. The right M lay deep to the inferior alveolar, but superficial to the lingual nerve, whereas the left inferior alveolar and lingual nerves had formed two roots, thus encircling the left M. The ascending palatine artery was replaced on both sides by palatine branches of the ascending pharyngeal artery. Since a bilaterial maxillofacial trunk with topographical relations as described herein has not been previously reported in man, the embryology and comparative anatomy of this variation are discussed.

Histomorphologic structure of the carotid rete-cavernous sinus complex and its functional importance in sheep (Ovis aries).

Paraffin sections of the carotid rete-cavernous sinus complex of sheep were studied, using different stains. The carotid rete of sheep was composed of medium-sized arteries with smooth muscle layers that were oriented in different directions. The carotid body cells may have migrated proximally in the adventitia of the intracranial portion of the internal carotid artery as its extracranial portion degenerates early in life. The cavernous sinus shared a common tunica adventitia with surrounding rete branches. At places, the wall of the cavernous sinus had a distinct tunica media interposed between the endothelial cells and the tunica adventitia. Therefore, the name cavernous venous plexus has been proposed for the cavernous sinus in sheep.

Artery distribution in the prenatal human maxilla.

Differing opinions concerning the human maxilla and its morphogenesis lead to different concepts concerning the intrinsic arterial supply to the anterior portion of the maxilla and its incisors. Microscopic and radiographic analyses of appropriately perfused infraorbital and posterior superior alveolar arteries in more than 100 human fetuses from six months to term reveal that the posterior superior alveolar artery courses to the facial midline, supplying branches to the incisors and to the posterior teeth. This observation differs clearly from the classical description that the anterior superior alveolar artery, a branch of the infraorbital artery, supplies the anterior maxillary segment and its incisors as seen in the postnatal life.

The vidian artery: normal and pathologic anatomy.

Arising as a branch of either the distal maxillary artery or the petrous portion of the internal carotid artery, the vidian artery (artery of the pterygoid canal) participates in two complex vascular networks through its anastomoses in the pterygopalatine fossa and oropharyngeal mucosa. The vidian artery may become a major source of blood supply to a variety of deep facial and paracavernous lesions. The embryology, anatomy, and pathology of this vessel are described and implications of its anastomotic patterns in therapeutic embolization procedures are discussed.