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.

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.

Examination of the heads of the lateral pterygoid muscle on the temporomandibular joint.

The lateral pterygoid muscles (LPMs) function as a unit during precise mandibular positioning movements that occur during such activities as speech, singing, or playing musical instruments. The LPM has been the focus of an attempt to explain problems associated with the temporomandibular joint and anterior displacement of the meniscus of the joint. The aim of the study was to define the general morphology, describing the position and shape of the heads of the LPMs. In the course of dissection, the heads of the LPMs were noted, as well as the pattern, position of the origin and insertion, and course under 2.5x loupe magnification in 25 adult male human cadavers. The LPM has the general form of an irregular pyramid that narrows progressively toward the front. As a result of the macroscopic examination, the LPM was found to originate, with 3 heads as the superior LPM (SLPM), the inferior LPM (ILPM), and inner LPM. It was realized that the ILPM width was 3 times more than that of the SLPM. The SLPM ending fibers of LPM had a more tendinous structure compared with the ILPM ending fibers. The SLPM and ILPM were observed as being adhered mostly to the pterygoid fovea. The study has shown that the muscle has atypical penniform structure made up of 8 tendinous layers that were particularly well developed. It is an indisputable fact that the success in surgical strategy and planning mainly relies on the surgeon's knowledge of the variable origins and insertions of the LPM.

Anatomic variations of popliteal artery that may be a reason for entrapment.

PURPOSE: The aim of this study was to demonstrate some anatomic variations of popliteal artery and its surrounding structures that may be important especially for popliteal artery entrapment (PAE) syndrome. METHODS: A cadaveric study in 46 lower limbs was performed to improve the understanding of anatomy of the popliteal artery and its relations with surrounding structures. RESULTS: The popliteal artery was lateral to the popliteal vein in four specimens (8.7%) and deep to popliteal vein in three specimens (6.5%). An aberrant accessory head of gastrocnemius was present in three specimens (6.5%). The popliteal artery and vein were tethered at the adductor magnus hiatus very tightly in one specimen (2.2%). An aberrant medial arterial course around normal medial head of gastrocnemius muscle was seen in one specimen (2.2%). CONCLUSIONS: Various anomalous anatomic relationships between muscle and arteries in the popliteal fossa results in arterial compression. We believe that a review of the anatomic variations of the popliteal artery and its surrounding structures will be beneficial for the surgical approaches in PAE.

Branching patterns of the popliteal artery and its clinical importance.

PURPOSE: The aim of this study was to evaluate the popliteal artery branching patterns and related measurements. METHODS: A cadaveric study in forty lower limbs was performed to improve the understanding of anatomy of the popliteal artery and its main branches. RESULTS: Normal branching of the popliteal artery was present in 36 specimens (90%). High origin of the anterior tibial artery was seen in two specimens (5%). The bifurcation was at the level of proximal border of popliteus, but the posterior tibial artery originated directly from the popliteal artery in one specimen (2.5%). Trifurcation pattern with no trunk was observed in one specimen (2.5%). CONCLUSIONS: We believe that a review of the anatomic characteristics of the popliteal artery and its branches will be beneficial for the surgical approaches and the choice of suitable arterial graft sites.

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.

Clinically relevant variations of the superior thyroid artery: an anatomic guide for surgical neck dissection.

The superior thyroid artery (STA) is the dominant arterial supply of the thyroid gland, upper larynx and the neck region. The knowledge of variations in possible patterns of origin, courses, and branching pattern of the STA is also important for surgical procedures in the neck region, such as emergency cricothyroidotomy, radical neck dissection, catheterization, reconstruction of aneurysm and carotid endarterectomy. The surgical anatomy of the STA was studied in 20 adult Anatolian preserved cadavers between the age of 40 and 70 years. The outer diameter of the STA origin was observed to be 3.53 +/- 1.17 mm. The location of the origin of the STA according to the carotid bifurcation was evaluated as above (25%), below (35%) and at the same level (40%). The distribution patterns of the STA were classified into six types depending on the branching pattern. The outer diameter of the infrahyoid branch, superior laryngeal artery, sternocleidomastoid artery and cricothyroid branch at their origins were observed to be 1.13 +/- 0.14, 1.42 +/- 0.47, 1.54 +/- 0.96 and 1.30 +/- 0.41 mm, respectively. Typical and variant glandular branching patterns were observed in 85 and 15% of the specimens, respectively. The outer diameters of anterior, anteromedial, anterolateral and posterior glandular branches were measured as 2.05 +/- 0.46, 1.41 +/- 0.43, 1.51 +/- 0.41 and 1.73 +/- 0.53 mm, respectively. It is necessary to understand the surgical anatomy of the STA to carry out successful radical neck dissection and to minimize postoperative complications in a bloodless surgical field.

Anatomic evaluation of the carotid artery bifurcation in cadavers: implications for open and endovascular therapy.

Knowledge of carotid bifurcation (CB), common carotid artery (CCA) and its branches and their recognition during diagnostic imaging are also important for vascular surgical procedures in the region, such as carotid endarterectomy or radical neck dissection, catheterization and aneurysms. The surgical anatomy of the carotid arteries was studied in 20 cadavers. Micrometric values of the CB and its relation with surrounding structures, measurements belonging to the external carotid artery (ECA) and internal carotid artery (ICA), and metric data, such as lower face including the greater horn, laryngeal prominence have been evaluated by making linear measures. The diameter of the CCA at the CB under 2 cm and CB diameter was measured as 8.1 +/- 2.24 mm and 12.79 +/- 2.87 mm, respectively. Evaluating data related to the ICA and the ECA in samples, the aspect was measured the ICA and the ECA in the CB discrimination point as 21.52 +/- 20.53 degrees . In the most location of the ECA origin according to the ICA has been determined as medial position in 35 specimens. The origin of the superior thyroid artery (STA) was found to be at the same level with the CB in 40% and below it in 25% specimens. This study has provided measured objective criteria for the arterial features of the neck region, which are crucial during surgery. The origins of the branches of the CCA act as key landmarks for adequate and appropriate placement of the cross-clamp on the carotid arteries.

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.

The cause of the difference in the submental region: aberrant muscle bundles of the anterior belly of the digastric muscle.

The aberrant bundles' presence in the anterior belly of the digastric muscle is important in terms of causing asymmetry in the submental region, getting confused with some pathologic cases, radiologic examination, and aesthetic facial surgery. To provide data, aberrant bundles in the submental region were investigated in 30 cadaver heads. During the dissection of the submental region, origin, insertion, shape, and bilaterality of the anterior bellies of the digastric muscles and the aberrant bundles were investigated. The 20 heads with aberrant bundles were classified into two types based on the muscle arrangement: digastric fossa type and crossover type. The aberrant bundles, which did not cross the median line, were classified as being of the digastric fossa type, whereas those that crossed the line were of the crossover type. Fifteen of the heads contained bundles of the unilateral type and five heads contained the crossover type. In three heads, digastric fossa and crossover types coexisted. In this study, a wide range for incidence in the submental region was observed of variations. Some cases were not described in the classification of the previous studies of this muscle. It is also possible that the incidences may vary as a result of the ethnic differences of the populations studied. Bilaterality was frequently observed in this study. Anatomic variations of the anterior bellies of the digastric muscle can easily be confused with the pathologic conditions in ultrasonography, computed tomography, and magnetic resonance imaging; therefore, it is necessary to recognize that variants of the anterior belly of the digastric muscle occur to avoid confusion when diagnosis shows abnormal lesions in the floor of the mouth and submental region. Additionally, the possible occurrence of such anomalies should be remembered during the surgical procedures involving the submental region.

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 constitute a risk factor for acute hemorrhage in routine surgical procedures, which are performed by inexperienced surgeons.

Morphologic features of the acetabulum.

INTRODUCTION: The embryology and development of the hip joint are complex. The acetabulum is not always of the same shape, width, or depth. Minor anatomical abnormalities in the acetabular shape, joint congruences are frequent. Controversies still exist on the importance of these variations and help to prevent problems following in surgical procedures such as acetabular reconstruction and femoracetabular impingement. MATERIAL AND METHODS: The aim of this study is to provide the location of the unusual facets, the acetabular point, and the anterior ridge of the acetabulum based on a morphological study of human pelvic bones. Morphologic features of the acetabulum, particularly determination of unusual facets, were studied in 226 human coxal bones. RESULTS: In adult coxal bones the acetabular fossa has an irregular clover-leaf shape, the superior lobe being smaller than the anterior and the posterior lobes. Measured lunate surface area varied between 14.5 and 30.5 cm2. A smooth unusual facet was found anteroinferior to the lunate surface in 62 acetabulums. Measured along the long axis, its size varied between 11 and 17 mm. Three different shapes of the unusual facet were as follows: oval (32.26%), piriform (45.16%), and elongated (22.58%). The prevalence of the piriform facet shape was higher in males. In 59.68% of the bones it extended to the superior ramus of the pubis, and in the remaining 40.32% it was limited within the acetabular margin. It is postulated that this facet could be a consequence of a particular posture, which results in traction of the ligaments attached to this area. Four distinct configurations were identified relative to the anterior acetabular ridge. The majority 98 (43.36%) were curved; 64 (28.33%) were angular; 37 (16.37%) were irregular; and 27 (11.94%) were straight. CONCLUSION: There have been no reports on details such as unusual facets, acetabular point, and anterior ridge of the acetabulum in a single research. These findings will be of help in planning reorientation procedures, using spikes, screws, and press-fitting for fixation.