T. Ozgur

A study of the course of the internal carotid artery in the parapharyngeal space and its clinical importance

The differences in the course and shape of the internal carotid artery (ICA) in the parapharyngeal space were investigated to determine the possible risks for serious hemorrhage during tonsillectomy, drainage of peritonsillar abscess, soft palate injuries, adenoidectomy and velopharyngeoplasty. The course of the ICA was studied in the parapharyngeal spaces of 50 adult cadavers. From each specimen, circumferential sections were obtained and they stained with hematoxylin–eosin and Verhoeff’s elastic staining. The cervical course of the ICA showed no curvature in 70 cases; but in 25 cases it had a medial curve, and five cases showed kinking out of a total 100 dissected carotid sheaths. In two cases, kinking of the ICA was related to the pharyngeal wall. The histological examination of all kinking specimens demonstrated depletion and decreasing muscle tissue in tunica media and an increase was observed in vasa vasorum numbers in the tunica adventitia of ICA. The dissections and integrity losses were seen in tunica media and tunica adventitia. The vessel wall of histological structure change were detected in kinking specimens and lays the groundwork for the vessel wall to get easily harmed or torn either directly or indirectly by decreasing the elasticity and soundness of the wall. The transposition of the ICA artery in submucous position becomes important for otorhinolaryngologists when its aberrant course causes a widening in the retropharyngeal or parapharyngeal tissues and an impression on the pharyngeal wall. Curving and kinking of the ICA can constitue a risk factor for acute hemorrhage in routine surgical procedures, which are performed by inexperienced surgeons.

The superior orbital fissure and its contents

Topographic landmarks for the superior orbital fissure are useful for general orientation and approach to the middle fossa, cavernous sinus and orbit. In this study, the microsurgical anatomy and morphometry of the superior orbital fissure and its related structures were examined in 57 disarticulated sphenoid bones, 102 skull bases and 58 adult cadaveric heads. The superior orbital fissure was observed in nine different shapes based on the classification of Sharma et al. (1988), and the most frequently observed was Type VI. The distance from the superomedial to the superolateral edge was measured as 17.3 ± 3.4 mm on the right side and 16.9 ± 2.9 mm on the left side, and from the superolateral to the inferior edge as 20.8 ± 3.9 mm on the right side and 20.1 ± 3.8 mm on the left side. The distance from the superomedial to the inferior edge of the fissure was measured as 9.5 ± 2.2 mm on the right side and 9 ± 2.4 mm on the left side. No right-left differences were observed for these measurements. Measurements regarding the relationship of the oculomotor, trochlear and abducent nerves, the ophthalmic branch of the trigeminal nerve and the superior orbital vein were performed and topographic aspects of the superior orbital fissure region were described.

Anatomical and surgical aspects of the lobes of the thyroid glands.

Variation in the descent of the thyroid gland and during fetal life and regression of the thyroglossal duct is associated with many variations in form of the mature gland. The shape and morphometric details of gland, its extension as the pyramidal lobe (PYR-L) and attachments of the levator glandulae thyroidea were studied in 40 cadavers. We categorized the shape of the thyroid into 12 types. The most frequent type was PYR-L with 22.5% which started from the left lobe and moved across by intercrossing the larynx. Horseshoe-shaped gland and the gland with separate lobes were the most frequently observed glandular shapes, with 17.5 and 20%, respectively. The incidences of the PYR-L and the levator glandulae thyroideae were 60 and 17.5%, respectively. The pyramidal lobe branched off more frequently from the left part of the isthmus (14 specimens) than from the right (5 specimens) or the midline (2 cases). Knowledge about the glandular landmarks and anatomic measurements around the thyroid will be helpful for the surgeon to constitute a simplification of the topographic anatomy, plan and decide on a safe approach to the thyroid gland, and to avoid postoperative complications.

Assessment of Origin Characteristics of the Front Branches of the External Carotid Artery

The neck region has a great vital value; its variations and known micrometric values are accepted as important orientation points during intervention. Micrometric values of the front branches of the external carotid artery and their relations to the surrounding structures and metric data pertaining to origin locations of the superior thyroid (STA), lingual (LA), and facial (FA) arteries were evaluated in 40 samples. As regards the evaluation of the branching types of the external carotid artery, the cases where the STA, LA, and FA originated as separate branches were 90%, linguofacial trunk cases were 7.5%, and thyrolingual trunk cases were 2.5%. The diameters of the STA, LA, and FA at their origins were observed to be 3.53 ± 1.17, 3.06 ± 0.65, and 3.35 ± 0.68 mm, respectively. The distances from the origin of the STA to the carotid bifurcation of 3.29 ± 4.27 mm, origin of the STA to that of the LA of 10.45 ± 5.16 mm, and origin of the STA to that of the FA of 18.20 ± 8.81 mm were found. The current findings may have serious implications for radiologic examinations, exploration of the neck, thyroid and parathyroid surgery, tracheotomy, and surgery of the larynx, pharynx, upper esophagus, pterygopalatine, and infratemporal fossa.

An unreported anatomical finding: unusual insertions of the stylohyoid and digastric muscles

The presence of a unusual appearance of the stylohyoid and digastric muscles may lead to a confusion in some pathological cases, during the radiological examination and aesthetic facial surgery. These differences may cause pharyngeal pain and foreign body sensation in the throat. During the dissection, unusual insertions, origin, insertion, shape and bilaterality were investigated in 28 cadavers’ heads. In a total of 56, the presence of unusual insertions which belong to the stylohyoid muscle were observed in 22 sides (39.3%), and atypical fibers which belong to the digastric muscle were observed in 39 sides (69.6%). Bilaterality of the presence of atypical appearance was observed for stylohyoid and digastric muscles, in 10 (35.7%) and 19 (67.8%) specimens, respectively. In 12 heads (42.9%), atypical fibers, the stylohyoid and the digastric coexisted. These fibers which were shaped like a circular spiral were realized to have the shape of an arch or circle in front of the hyoid bone. The posterior bellies of the digastric muscle, the mylohyoid and the remaining suprahyoid muscles of both sides were normal. The unusual insertion of the stylohyoid muscles which cover the hyoid bone as a collar was not described in the classification of the previous studies. These fibers may give an variant mobility to the hyoid and they occur depending on the differences in the stylohyoid chains. Although the styloid process was in normal size, unusual insertions of the stylohyoid muscle that cover the hyoid as a belt or collar may give symptoms similar to those of the stylohyoid syndrome.

Neuro-arterial relations in the region of the optic canal.

In this paper, we present the results of our investigations on the neuro-arterial relations in the region of the optic canal. A thorough knowledge of the microanatomic features of the ophthalmic artery, optic canal and optic nerve is very important for surgeons approaching lesions of this area. We aimed to extend our present knowledge of the origin of the ophthalmic artery and microsurgical anatomy of the optic canal with exposure of the optic nerve. The optic canal walls and width and height of the orbital and cranial apertures, and thickness of the bony roof of the optic canal were measured on the right and left sides of 57 sphenoid bones, 102 skull bases and 58 fixed adult cadaver heads. The ophthalmic artery originated from the rostromedial circumference of the internal carotid artery in 51.8%, from the medial circumference in 26.2% and the laterobasal circumference in 22% of the specimens. The outer diameter of the ophthalmic artery at its origin was 1.81 ± 0.36 mm on the right and 1.75 ± 0.37 mm on the left side.

Bilateral Quadrification of the Anterior Digastric Muscles With Variations of the Median Accessory Digastric Muscles

During dissection of the submental region, the anterior bellies of the right and left digastric muscles were found to have four separate insertions. Two median accessory digastric muscles were located medially to anterior bellies of the digastrics and inferiorly to the mylohyoid and deep in the platysma. The four accessory muscles of the anterior bellies of the digastric muscles originated from the digastric fossa and inserted into the hyoid bone. Two median accessory digastric muscles were located between the anterior bellies of the digastric muscle and inserted into the hyoid bone as well. These muscle fibers formed a muscular floor for the oral cavity similar to the second mylohyoid muscle. When the muscle heads were analyzed, the anterior belly of the digastric muscle appeared to have six heads. These six heads were united by an intermediate rounded tendon, which was attached to the hyoid bone. This finding of a bilateral quadrification of the anterior digastric muscles with variations in the median accessory digastric muscles has not previously been reported. Anatomic variations of the anterior bellies of the digastric muscles can be easily confused on computed tomographic scans and magnetic resonance imaging. The possible occurrence of such anomalies should be kept in mind during surgical procedures involving the submental region.