Iulian Komarnitki et al. Pterygoid hamulus, morphometry Anthropological Review • Vol. 82(4), 389–395 (2019) Functional morphometry of the pterygoid hamulus. A comparative study of modern and medieval populations Iulian Komarnitki1,2, Hanna Mankowska-Pliszka1, Ewa Ungier1, Dawid Dziedzic1, Michal Grzegorczyk1, Agnieszka Tomczyk3, Bogdan Ciszek1 1Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Poland 2Clinical Department of Cranio-Maxillofacial Surgery, Military Institute of Medicine, Warsaw, Poland 3Łódź University of Technology, Faculty of Technical Physics, Computer Science and Applied Mathematics, Poland ABSTRACT: The pterygoid hamulus (PH) is located in the infratemporal fossa and is part of the pterygoid process of the sphenoid bone. Its location on the cranial base and the multitude of anatomical structures whose attachments lie on the surface of the pterygoid hamulus make it of high functional and topographic significance. Due to insufficient literature on the PH morphometry, we decided to study this issue using modern and archaeological material. In total, 99 observations were subjected to quantitative and qual- itative analysis (50 - from modern times and 49 - from medieval times). On the basis of the statistical analysis, statistically significant differences in the length of PH were found with respect to age and sex. Statistically significant differences in the PH width were also noticed with respect to sex and the period of origin. The results obtained may help better understand the development mechanism of the pterygoid hamulus bursitis. KEY WORDS: pterygoid hamulus, cone-beam computer tomography, archeological material Introduction tachments lie on the surface of the pter- ygoid hamulus make it of high functional The pterygoid hamulus (PH) is an osse- and topographic significance. In the mac- ous structure located in the lower seg- roscopic structure of PH the base, the ment of the medial pterygoid plate of the body, the neck and the head can be distin- sphenoid bone (Rusu et al. 2013). The guished, as well as the lateral and medial location on the cranial base and the mul- surfaces. On the lateral surface there is a titude of anatomical structures whose at- shallow groove (Sulcus hamuli pterygoidei) Original Research Article Received: October 10, 2019; Revised: November 23, 2019; Accepted: November 25, 2019 DOI: 10.2478/anre-2019-0029 © 2019 Polish Anthropological Society 390 Iulian Komarnitki et al. which is covered with cartilage tissue. constrictor muscle. The hamulus muscle Around this place the tensor veli palatini bundles running in this zone attach to muscle winds (Figure 1). the pterygoid hamulus. These bundles It is with this muscle that the ptery- are connected with the palatopharyngeal goid hamulus is most frequently associ- sphincter muscle and the pterygoman- ated (Misuria 1976). However, there are dibular part of the superior pharyngeal a lot of other structures which are con- constrictor muscle (Sumida et al. 2017). nected with this tiny osseous process. According to scanty scientific reports on These include the pterygopharyngeal the development of PH, in children it part of the sphincter muscle of the upper has an identical macroscopic structure pharynx, the pterygomandibular raphe, with that in adults but with proportion- the buccinator muscle, and the medi- ally smaller dimensions (Putz and Kroy- al pterygoid muscle (Putz and Kroyer er 1999). The ossification centres of the 1999). According to some researchers, medial pterygoid plate of the sphenoid the pharyngobasilar fascia (Takezawa bone develop independently of the chon- and Kageyama 2012) and the palatine drocranium. Although the main part of aponeurosis (Iwanaga et al. 2017) at- the medial pterygoid plate of the sphe- tach to PH in 51%. There is a number of noid bone ossifies on the membranous reports in literature which indicate that base, the pterygoid hamulus, however, PH plays an important role in the topog- turns into cartilage before ossification raphy of the so-called transition zone (Fawcett 1905). between the palatopharyngeal sphinc- The histological structure of PH re- ter muscle and the superior pharyngeal minds a sandwich consisting of a thicker medial plate and a thinner lateral one. The plates are connected diagonally with the help of the osseous trabeculae running there. In the histological exam- ination it was found that the course of collagen fibers in the medial plate has a more obtuse angle of inclination in rela- tion to the vertical axis than in the lat- eral plate. The authors believe that PH has a stable structure in both adults and children (Putz and Kroyer 1999). Due to insufficient literature concerning mor- phometry, we decided to study this issue on modern and archaeological material. Material and methods The study was carried out on the basis of the images of cone-beam computer to- mography (CBCT) and excavation mate- Fig. 1. Pterygoid hamulus preparation (left side) a. Tensor veli palatini muscle. rial. The CBCT images were taken using b. Pterygoid hamulus. a Toshiba PCH6500 camera at the Clin- Pterygoid hamulus, morphometry 391 ical Department of Cranio-Maxillofacial curacy of 0.1 mm. Precise determination Surgery, Military Institute of Medicine of the location of the measurements, it in Warsaw, Poland. The cross-sectional was possible to compare the results read analysis was performed with the help of with the help of electronic caliper and the Ez3D Plus software. The measure- obtained in computed tomography. In ments of the hamulus process: width addition, observations of dental alveoli were taken at the widest point above the obliteration were noted. column of hamuli and the height from In total, 99 observations were sub- basis hamuli to caput hamuli. jected to quantitative and qualitative The craniometric material came from analysis. The sample group consisted of the Millennium excavations of Professor 46 females and 53 males of which 15 fe- Wierciński deposited at the Museum of males and 22 males from the age group of the Department of Descriptive and Clin- up to 30 years old without juveniles, 20 ical Anatomy of the Medical University females and 17 males aged 30–60 years, of Warsaw. The material included 50 and 11 females and 14 males 60–90 years skulls classified in terms of sex, females old. The subgroup from the medieval (F) and males (M) in four age groups: period (49 observations) included 15 fe- Juvenis (14–18/20 years) Adultus (20–40 males and 34 males, while from modern years) Maturus (40–60 years) and Seni- times (50 observations) 31 females and lis (over 60 years). The four age groups 19 males. Thirty seven observations came were then combined in three, (1) up to from people aged up to 30 (including 30 30 years old with exclusion of juveniles; from the Middle Ages and 7 from modern (2) 30–60 years old, and (3) 60–90 years times), 37 from pep- aged 30–60 (includ- old. In order to optimize the results, both ing 11 from the Middle Ages and 26 from off, direct and radiographic measure- modern times), and 25 - aged 60–90 (in- ments were carried out by two research- cluding 8 from the Middle Ages and 17 ers and repeated three times. Skulls with from modern times) (Table 1 and 2). a well-preserved pterygoid process were The statistical analysis was per- selected and left-sided measurements of formed using the statistical package R heights and widths were performed with version 3.4.3. Statistica 2017 for proce- the help of a slide-compass with an ac- dure. The Scheirer-Ray-Hare test was ap- Table 1. Group distribution according to age and sex in modern and medieval populations Variable Category N Females, n (%) N Males, n (%) Age group (years) (0,30] 15 (32.6%) 22 (41.5%) (30,60] 46 20 (43.5%) 53 17 (32.1%) (60,90] 11 (23.9%) 14 (26.4%) Time period Medieval times 15 (32.6%) 34 (64.2%) 46 53 Modern times 31 (67.4%) 19 (35.8%) Table 2. Age of individuals in modern and medieval populations Variable Level Medieval times Modern times age group, n(%) (0,30] 30 (61.2%) 7 (14.0%) (30,60] 49 11 (22.4%) 50 26 (52.0%) (60,90] 8 (16.3%) 17 (34.0%) 392 Iulian Komarnitki et al. plied. The calculations were made at the ences were stated between the females significance level of α=0.05 taking into in age groups 0–30 and 60–90 years old, consideration the Benjamini-Hochberg the average value respectively 5.3±1.1 procedure. mm, 8.4±1.8 mm (p<0.001), and in age groups 30–60 and 60–90 years old, the Results average value respectively 6.7±2.1 mm, 8.4±1.8 mm (p=0.047). The subgroup Length of the pterygoid process of males did not show differences re- garding the pterygoid process length in The analysis of the pterygoid process age groups (Figure 2). An interesting ob- length was conducted with respect to the servation was the absence of significant following factors: age, sex and period of differences in the length of the ptery- origin of the observation. goid hamulus for modern and historical Statistically significant differences populations. were revealed with respect to age. The average lengths in the age subgroups Width of the pterygoid process 0–30, 30–60, 60–90 years old were 5.7±0.9 mm, 6.7±2.1 mm, 7.3±2.2 mm The analysis of the pterygoid process respectively (p=0.008). width was conducted with respect to the The interaction between the age and age factor, sex and period of origin of sex factors turned out to be statistically the observation. Statistically significant significant. Group comparisons showed differences were shown in the division differences in the length of the pterygoid with regard to sex and period of origin.