The foramina of the facial region

The foramina identified dorsally in the facial part of the skull of Chinkara were, the infraorbital, supraorbital and lacrimal foramina and rostrally maxillary, sphenopalatine and caudal palatine foramina, these rostral foramina were placed in the pterygopalatine fossa (Fig. 6).

The infra-orbital foramen was small, oval shaped, located in maxilla bone dorsally and oriented rostrally at the level of 2nd cheek tooth (Fig. 6). The supraorbital foramen was positioned in the frontal bone in the supraorbital groove of the medial brim of the orbit (Fig. 6). The supra-orbital foramen penetrated the root of the zygomatic process and opened into the orbit. The ethmoidal foramen was positioned completely in the frontal bone and was located through the coincidence of the orbital ramus of frontal bone and presphenoid wing of the spheniod bone. The diameter of ethmoidal foramen was smaller than optic foramen and orbitorotundum. The orbit through ethmoidal foramen, optic foramen and foramen orbitorotundum linked with the cranial cavity. The round foramen and orbital fissure unite to form foramen orbitorotundum. The minor palatine foramens were present completely on the horizontal process of the palatine bone while the major palatine foramina were located on the intersection of horizontal plate of palatine bone and the palatine process of maxilla (Fig. 7).

The bones of the cranial region

The bony region of the cranium of Chinkara was comprised of sphenoid, occipital, ethmoid, parietal, interparietal, temporal and frontal bone (Figs. 6, 7, 8). The occipital bone consisted of two occipital condyles and formed the ventral part of the nuchal surface (Fig. 8) and nuchal crest. The temporal bone also contributed in the formation of the nuchal crest, lateral to the paramastoid process (Fig. 9). The paramastoid processes were thin, prismatic shaped and had projected ventrally (Figs. 6, 7, 8). The ethmoid bone was wedged between the nasal and cranial cavity. the ethmoid bone was sutured with the presphenoid caudally, with vomer and palatine rostro-ventrally and with the frontal bones dorso-rostrally (Figs. 6, 7). The parietal bone enters into the formation of the roof of the cranial cavity and its dorsal part formed the extension of the frontal sinus.

Orbit

The orbits were oval in shape, complete, formed by the zygomatic, frontal, and lacrimal bone and placed rostro-laterally; the highest share in the development of the bony orbit was predominantly by the frontal bones tailed by the zygomatic and the lacrimal. The orbital rim was nearly circular in shape (Figs. 6, 9).

The foramina of the cranial region

The foramina of the cranial region of the skull of the Chinkara were the internal acoustic meatus, external acoustic meatus, hypoglossal canal, transverse canal foramen, sphenorbital fissure, carotid canal, foramen magnum, stylomastoid foramen, foramen ovale, foramen rotundum and jugular foramen, and the caudal and the rostral foramina that molded to form pterygoid canal. The foramen magnum (foramen occipital magnum) was large and roughly oval in shaped (Figs. 7, 8). The oval foramen was present in the sphenoid bone. The ventral surface (Figs. 7, 9) of the skull had foramen oval and present entirely in the sphenoid bone.

Gross morphology of the mandible

In the present study, it was observed that the mandibular symphysis (Fig. 10) remained unossified in adult Chinkara. Slightly lateral curvedness was noted in the distal portion of the ramus (pars molaris) of the mandible of Chinkara. It was noted that the rostral (incisive) region of the body of mandible remains elevated from the ground surface in Chinkara. The alveolar border (limbus alveolaris) of the incisive part had three alveoli for incisor teeth and one for canine on each side in adult Chinkara (Fig. 11). The molar region of the body had alveoli for six cheek teeth (three premolar and three molar teeth) and for each cheek teeth two alveoli were observed except last cheek teeth had three alveoli in Chinkara (Fig. 10). On lateral surface (Fig. 11) merely one mental foramen (foramen mentale) caudal to the base of the incisor tooth, was notified. The mandibular tuberosity (Fig. 11) was observed on the lateral surface slightly caudal and distal to last molar teeth in Chinkara. In adult Chinkara, the ventral border of the body of the mandible was thick, smooth and convex in length (Fig. 11). The caudal and perpendicular part of the mandible (ramus), was the non-tooth bearer part (Fig. 10). The dorsal articular surface (caudal extremity) was comprised of the coronoid process and the condylar process with the paramount notch. The coronoid process of the ramus forms the highest point of the bone (Fig. 11).

Table I.- Measurements (cm, Mean±SD) of skull parameters of adult Chinkara based on sex.

Table II.- Measurements (cm, Mean±SD) of orbital and foramen magnum parameters of the skull of male and female adult Chinkara.

Orbit height (Lo), Orbit length (WO), Orbital index (OI), Orbital depth (Do), Interorbital interval at different points: i) at rostral extent. (IORE) ii) at central extent (IOCE) iii) at caudal extent (IOCDE). Height of the Foramen Magnum (FMH), Width of the Foramen Magnum (FMW), Index of foramen magnum (FMI), Thickness of the Occipital Condyle (OCT), Width of the Intercondylar bones (ICW), Width of the Interparacondylar bones (IPCW), Length of the Paracondylar Process (PCPL).

Table III.- Measurements (cm, Mean±SD) of the facial bones of the skull of male and female adult Chinkara (n=20).

Length (Lma), Width (Wma), Length (Lpm), Width (Wpm), Length (Lla), Width (Wla), length (Lna), width (Wna), length (Lpa) ,Width (Wpa).

Descriptive studies

Various skull and mandibular parameters of both adult male and female Chinkara calculated were tabulated in Tables I, II, III and IV. Measurements of the facial bones of the skull of male and female adult Chinkara were tabulated in Table III. The measured parameters did not show statistically significant differences (p>0.05) between male and female adult Chinkara except palatine bone. Various orbital parameters have been summarized in Table II. Descriptive statistics of the measured orbital parameters did not show statistically significant differences (p>0.05) between male and female adult Chinkara except Orbital Index (OI), Orbital depth (Do) and the Interorbital interval at the caudal extent (IOCDE). Foramen magnum parameters measured for male and female adult Chinkara were tabulated in Table II. The average mandibular values obtained in the current study were presented in Table IV. Mean values of the mandibular parameters except b and h were significantly (p< 0.5) higher in male than female Chinkara.

Table IV.- Measurements (cm, Mean±SD) of the mandible of adult Chinkara (n=20).

Lateral alveolar root to the mental foramen (a), mental foramen to the caudal mandibular border (b) Mandibular length (c) Mandibular foramen to base of mandible (d) Caudal border of mandible to below mandibular foramen (e) Condyloid fossa to the height of the mandible (f) Maximum mandibular height (g) Condyloid fossa to the base of the mandible (h).

Discussion

Literature on the gross morphological and osteometric descriptions of the skull of the Chinkara was not available. Morphological and morphometrical studies of the skeletal elements are used for assessment of animals’ age, identification of species, genetic and forensic exploration. In mammals, the skull is highly conservative, informative and adaptive structures, symbolized the most influential tool for biogeographic, phylogenetic and systematic studies afore the molecular investigations (Loy, 2007). In animals, specific parts of the skeletal system are often implied as reflective catalogues to define bodily proportions, physiological growth and confrontation to seasonal variations in food availability (Zanneśe et al., 2006b). Different researchers described the shape of the skull in different animals. In this research, the skull of adult Chinkara was elongated in shape analogous shape was narrated (Sarma, 2006) in kagani goat, (Ramswarup, 2011) in chital and (Choudhary et al., 2015) in blackbuck. While, in camels (Shahid and Kausar, 2005) reported that the skull was pentagonal in outline.

The shape and location of the infra-orbital foramen and supraorbital foramen described in this study as in accordance to the observations (Parmar and Shrivastava, 2003) in chital and (Choudhary et al., 2015) in blackbuck, and (Bharti, 2016) in blue bull; whereas this study opposes the reports of (Nickel et al., 1973), in dog (Smuts and Bezuidenhout, 1987) in camel.

The orbital shape of an animal defines the degree of visual field and the amount of shield gave to the eye and its contiguous tissue (Dyce et al., 2002). The gross morphology of the orbits of adult Chinkara was parallel to the reports of Sharma (2006) in Kagani goat and Choudhary et al. (2015) in blackbuck, while, contradiction to the current study was seen in reports of Taluja et al. (2000) in tiger, Getty (1975) in horse, Karimi et al. (2011) in Mehraban sheep and Prince et al. (1960) in dogs.

The size, shape and location of the foramina identified in the facial region of the skull of Chinkara were analogous to reports of Parmar and Shrivastava (2003) and Choudhary et al. (2015) in blackbuck and Bharti (2016) in chital deer, but these conclusions were in disagreement with the findings of Smuts and Bezuidenhout (1987) in camel, and Joshi (2004) in tiger.

Craniometric dimensions are used for the identification of species and finding of intraspecies variations (Yalçin and Kaya, 2009; Karimi et al., 2011; Sheremetyeva and Sheremetyev, 2008). The measured parameters of the facial bones of the skull did not show statistically significant differences (p>0.05) between male and female adult Chinkara except Palatine bone, which was in accordance with the findings in most of the craniometric dimensions in the Pyrenean chamois (Garcia-Gonzalez and Barandalla, 2002), in adult camels (Yahaya et al., 2012) and the goats found in the middle regions of Nigeria (Samuel et al., 2013), in which no marked sexual dimorphism was observed in most of the skull indices measured. In the present research, the skull length, skull width, and cephalic index were measured. Getty (1975) classical anatomist and Dyce et al. (2002) did not cite the measurements, they described the skull bones just morphologically in domestic animals, while, Yahaya et al. (2012) and Monfared (2013) cited that in camel. Cephalic/ skull index is an essential parameter in forensic medicine, anthropology and gender determinations (Lakshmi et al., 2015). Cephalic/skull index calculated in the current study in male and female adult Chinkara was 35.26±0.05 and 39.49±0.09, respectively, however, higher value of the skull index 66.05±0.05, 52.76±1.13 and 59.00±0.11 cm were reported in blue bull (Bharti, 2016), in Mehraban sheep (Karimi et al., 2011) and in blackbuck (Choudhary et al., 2015), respectively. The low skull index in the current investigation indicated the shape of the Chinkara skull was dolichocephalic, these findings were in line with the findings (Ramswarup, 2011) in chital, (Choudhary et al., 2015) in blackbuck and (Bharti, 2016) in blue bull, contrary to the current study, it was reported brachycephalic (Joshi, 2004) in tiger and mesaticephalic (Lieve et al., 2003) in dog. The cephalic/skull index described in this study, was on the basis of international anatomical description, depending upon this index, types of head shapes are: dolichocephalic (<75), mesaticephalic (75 to 83) and brachycephalic( > 83). The current study was in agreement to the reports of (Aragon et al., 1998) who reported that animals feed on woody shrubberies have shorter and broader crania than animals that feed mostly on herbaceous plants.

In the current study, no bilateral variations were found in orbital parameters. These findings were consistent with the study of Olopade et al. (2011) in Nigerian local pig, however, in contrast to the studies of Choudhary et al. (2015) in blackbuck and Sarma (2006) in Kagani goat who notified bilateral variations in orbital parameters. Black buck and Chinkara are related wild ungulates, the difference observed in orbital parameters are highly important during practical approach. In the current study, mean of the right and left of all the orbital parameters was used as a measurement value in all statistical calculations, since no statistically significant difference (p>0.05) was found between the osteometric values. The orbital parameters had clinical importance is to ascertain the topographic anatomy, in order to perform surgical procedures in the area of the head, e.g. ophthalamectomy, dehorning and eyelid droopy (Allouch, 2008). A higher orbital index from the current study was reported in Blue bull (Bharti, 2016) and in tiger (Taluja et al., 2000), which was 111.93±0.38 and 155, respectively. However, lower orbital index of 21.46±0.68 cm described by Karimi et al. (2011) in Mehraban sheep.

This study was novel in Chinkara, sexual dimorphism based on craniometric data was not yet reported in the literature. The measured anatomical standards were of clinical importance and aid in regional nerve blocks of mental and infraorbital nerves and hence it was ascertained in the current study to adopt the same approach to access cranial nerves in both sexes of adult Chinkara. Good information about the location of the foramen and the infraorbital nerve can offer a harmless clinical procedure, such as a surgical procedure, the practice of intra and extra oral anesthesia (Mozsary and Middleton, 1983; Lawrence and Poole, 1992; Zide and Swift, 1998). These conclusions in this study were of great clinical implication in relation to the infra-orbital nerve block. The injection of a local anesthetic agent through the infra-orbital foramen leads to the analgesia of the incisor, canine and the first two premolar teeth (Hall et al., 2000). This data will corroborate to the regional anesthesia of the areas innervated by the infra-orbital nerve in the adult Chinkara.

The data created from above mentioned parameters were not reported already, in this species, which had great clinical significance and may be used as a landmark for tracing the infra-orbital nerve, mental nerve and mandibular nerve desirable for its desensitization during any type of procedures at the level of the foramen.

In addition to species comparison, many researchers underlined the usefulness of foramen magnum diameter in differentiation of sex within the species (Göçmez et al., 2014; İlgüy, 2014; Simoens, 1994; Uthmanet et al., 2012) which is of high significance in forensic investigations. Among the seven parameters measured in the current investigations of the foramen magnum OCT, ICW, IPCW, and PCPL were significantly higher (p>0.05) in male than female Chinkara. These measurements may be used for sexual dimorphisum in Chinkara, along with other skull parameters identified in the current study. The height and width of the foramen magnum of the adult Chinkara measured in the current study were lower than shown in blackbuck (Choudhary et al., 2015) and in blue bull (Bharti, 2016). From this study, it may be proposed a divergence in morphology, like other measurements, the foramen magnum height and width showed variation from the other related wild ungulates.

In our study, mean values of the mandibular parameters except b and h were significantly (p< 0.5) higher in male Chinkara than female Chinkara. Similar to foramen magnum parameters, sexual dimorphisum was more evident in mandibular parameters. Sexual dimorphisum in closely related animals viz Black Buck, Chital, Hog deer, Urial and Blue Bull were still not specified. However, mandibular parameters studied in our study were lower than reported in blackbuck (Choudhary et al., 2015), in blue bull (Bharti, 2016) and in Iranian native cattle (Monfared, 2013).

Conclusions

No previous information on gross morphological and osteometric data on the skull and mandible of Chinkara deer were available, so the current study provides primary baseline data, we therefore consider that the data presented above will form vital standard for use by clinician working on wild animals and baseline for further research work and a good initiation for further interdisciplinary professional and scientific researchers (anatomists, archeozoologists, biologists, hunters, forensic scientists). The overall gross morphological and osteometric data obtained data showed similarities with others domestic mammals, but also several peculiarities in the Chinkara head osteology. Furthermore, in this research, osteometrical data derived was from modern populations are helpful as can be compared with ancient animal populations in archaeo-zoological assessments. However, this study describes an important preliminary step, more data regarding different age group and in different environmental condition and to include other species of game and protected mammals should be assembled; these will prove valuable in other research studies on deer metrics.

Acknowledgements

The authors are thankful to the Chief Conservator Wildlife and Conservator (WL), Wildlife Department, Khyber Pakhtunkhwa and the Divisional Forest Officer, Peshawar Wildlife Division, for providing essential facilities for the present research.

Satetment of conflict of interest

The authors have declared no conflict of interest.

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