# Morphological and Applied Anatomical Studies on the Head Region of Local Mizo Pig (Zovawk) of Mizoram/ Estudios Morfologicos y Anatomicos Aplicados en la Cabeza de Cerdo Local Mizo (Zovawk) de Mizoram.

INTRODUCTIONPiggery plays an important role in the rural economy of North East (NE) India. Among all the livestock, pig is one of the most valued and popular as almost 100 % tribal population in the region are pork eaters (Mayengbam et al., 2012).

North eastern region has the highest population and concentration of pig per household than any other state or region of the country. The total pig population of Mizoram is around 1,17,675 (Livestock Census, 2007) whereas the Zovawk population of Mizoram is about 43,000 (Livestock Census). Zovawk is newly identified breed of pig of Mizoram approved by breed registration committee of Indian Council of Agricultural Research (ICAR), New Delhi.

The head is a very important region for animals. It is the location of vital organs viz., brain, eyes, nose, tongue, ear and mouth. Also, the health of an animal can be deduced from the functional state of any of these organs.. Additionally, a unique head aspect of the anatomy of any animal is the skull typology of that animal with usefulness in providing a database on the bone features. The regional anatomy of the head is therefore, very useful tool that will aid the regional anesthesia (Olopade & Onwuka, 2003).

For instance, Choudhary & Singh (2015a & b) determined the applied landmarks on the head region of the Indian blackbuck and their application to clinical maneuvers around the head. The results obtained after morphometry of the skull will be of clinical importance and used in regional nerve blocks of the supra-orbital, infra-orbital, mental nerves and mandibular nerves which are useful during surgical operations in head region and dental extraction. The application of local anesthetic agent is easier for the maxillary and mandibular nerve blocks through the injection of local anesthetic agent via the infra-orbital foramen and mental foramen respectively.

Regional nerve block is used for all painful procedures including dental removals via buccotomy, rasping of maxillary and mandibular molar teeth in case of sharp teeth, treatment of upper eyelid entropion, alar fold resection and in some cases of sinus surgery. It is useful in minimizing the dose of sedative and general anesthetics. The present work was carried out because there is no comprehensive data on the head region of Zovawk and its clinical implications during regional anesthesia.

MATERIAL AND METHOD

The present study was conducted on the head region of ten Zovawk pigs of either sex. The samples for the study were collected from local slaughter houses near to the college campus. The collected head samples of the Zovawk pig were macerated using the maceration technique given by Choudhary etal. (2015).

This study was designed to provide maximum number of biometrical parameters of skull and some valuable information on clinically important parameters of Zovawk. The following measurements were taken for different bones of the skull and were summarized in Tables I and II.

Skull parameters (Figs. 1 and 2).

a) Length (Lsk): Distance between the highest points of the parietal bone to the middle of the rostral margin of the incisive bone.

b) Width (Wsk): Distance between two zygomatic arches.

c) Skull/cephalic index (SI): Skull width/ Skull length X 100 (Miller et al, 1964).

d) Skull base length (LBsk): Distance between the midpoints of the dorsal margin of the foramen magnum to the level of the middle point of the rostral margin of the incisive bone.

e) Height of the skull with mandible (Hskm): Distance between the lines drawn between caudal margins of mandible to the middle point of the nuchal crest.

Cranial parameters (Fig. 1).

a) Cranial length (Lcr): Distance from the central point of the fronto-nasal suture to the middle point of the nuchal crest.

b) Cranial width (Wcr): Maximum distance between the highest points of the parietal bone.

c) Cranial index (Icr): Cranial width/ Cranial length X 100 (Miller et al, 1964).

d) Cranial height (Hcr): Distance between the central points of the ventral rim of the foramen magnum to the middle point of the nuchal crest.

e) Capacity of the cranial cavity: All the foramina of the cranial cavity were plugged with cotton. The cavity was then filled with mustard grains through the foramen magnum up to its brim. The mustard was then emptied into a measuring cylinder to get the capacity. This technique was already described by the Choudhary and Singh (2015a & b).

Orbital parameters (Fig. 4).

a) Orbital length (Ho): Maximum height of the orbit.

b) Orbital height (Lo): The perpendicular distance between the supraorbital and infraorbital margins of the orbit.

c) Orbital depth (Do): Distance between optic foramen and center of the orbital rim.

d) Inter-orbital width (Wio): Minimum distance between the upper edges of the orbits measured across the tip of the skull.

e) Orbital circumference length (Co): Maximum circumference of the orbit, along the rim. One imaginary line was drawn to join the two edges of the incomplete margins of the orbit.

Maxilla parameters (Fig. 3).

a) Length of maxilla (Lma): Maximum length of the maxilla.

b) Height of maxilla (Hma): Maximum width of the maxilla

c) Distance between infraorbital foramen (Diof): Maximum distance between two intraorbital foramen.

d) Diameter of infraorbital foramina (Diof): Maximum distance between the two edges of infraorbital foramina.

Premaxilla parameters (Fig. 3).

a) Length of premaxilla (Lpm): Maximum length of premaxilla.

b) Height of premaxilla (Hpm): Maximum height of premaxilla.

Lacrimal parameters (Fig. 3).

a) Length of lacrimal (Lla): Distance from the fronto-lacrimal suture to the junction between the lacrimal and maxilla bones.

b) Height of lacrimal (Hla): Distance from the fronto-lacrimal suture to the junction between the lacrimal and malar bones

Zygomatic parameters (Fig. 7).

a) Length of zygomatic (Lzy): Maximum length of zygomatic.

b) Height of zygomatic (Hzy): Maximum height of zygomatic.

Nasal parameters (Fig. 1).

a) Length of nasal bone (Lna): Distance from the central point of the fronto-nasal suture to the rostral end of the internasal suture.

b) Width across nasal bone (Wna): Maximum distance across the nasal bones or maximum distance between the naso-maxillary sutures.

c) Nasal Index (Ina)=Nasal width/ Nasal length X 100.

Palatine parameters (Fig. 2).

a) Length of palate (Lpa): Distance measured from the rostral mid sutured line of incisive bone to the caudal nasal spine of the palatine bone.

b) Width of palate (Wpa): Maximum distance at the horizontal plate of palatine bone behind the last molar tooth.

Occipital parameters (Fig. 5).

a) Width of occipital (Woc): Maximum distance between external margins of two paracondylar processes

b) Height of occipital (Hoc): Distance from base of the occipital condyle to the starting point of sagittal crest

c) Intercondylar width (Wic): Width between the lateral ends of the occipital condyles.

d) Interparacondylar width (Wipc): Width between the lateral ends of the paracondylar process.

e) Height of foramen magnum (Hfm): The distance between the midpoints of the dorsal ventral rims of the foramen magnum.

f) Width of foramen magnum (Wfm): The maximum distance between the two occipital condyles.

g) Foramen magnum index (Ifm): Foramen magnum height/Foramen magnum width X 100.

h) Area of foramen magnum (Afm): Calculated by using the formula- [approximately equal to]* 22/7* WH, where W= width and H = height of the foramen magnum.

i) Circumference of foramen magnum (Cfm): Length of the entire rim of the foramen magnum.

Parietal parameters:

a) Height of parietal (Hpa): Maximum height of parietal bone.

b) Width of parietal (Wpa): Maximum width of parietal bone.

Frontal parameters (Fig. 1).

a) Length of frontal (Lfr): Maximum length between parito-frontal suture and fronto-nasal suture.

b) Width of frontal (Wfr): Maximum length between two lateral edges of frontal bone.

c) Distance between supraorbital foramen (Dsof): Distance between two supraorbital foramen of frontal bone.

d) Distance between supraorbital foramen to rim of the orbit (Sofrio): Maximum straight distance between the supraorbital foramen and the edge of the orbital margin.

Mandible parameters (Figs. 7 and 8).

a) Lateral alveolar root to mental foramen (A): From the mental foramen to the lateral extent of the alveolar root of lower incisor.

b) Mental foramen to the caudal mandibular margin (B): From the level of the mental foramen to the extreme caudal margin of the mandible.

c) Mandibular length (C): From the level of the cranial extremity of the alveolar root of the incisor to the level of the caudal margin of the mandible.

d) Maximum mandibular height (D): From the basal level of the mandible to the highest level of the coronoid process.

e) Mandibular foramen to base of mandible (E): Vertical line from the ventral limit of the mandibular foramen to the base of the mandible.

f) Caudal margin of mandible to below mandibular foramen (F): length from the caudal most margin of the mandible to the vertical line produced by a description of the measurement of the mandibular foramen to the base of the mandible.

g) Condyloid fossa to the base of the mandible (G).

h) Caudal margin of mandible to the level of mandibular foramen (H).

i) Mandibular foramen to mandibular angle (I): Shortest distance from the mandibular foramen to the extreme caudal margin of the angle of the mandible.

These parameters of the skull and mandible were measured and subjected to routine statistical analysis (Snedecor & Cochran, 1994). The photographs of the skull of Zovawk were taken by the Nikon D3200 digital SLR camera and labeled with Adobe Photoshop 7 and CS6 extended version 13.0.1.

RESULTS AND DISCUSSION

The skull of Zovawk was divided into frontal, lateral, nuchal and basal surfaces for the convenience of description as reported in Pygmy hog (Kalita et al., 2015). The frontal surface of the skull was formed by the frontal, parietal, nasal, parts of the maxilla and premaxilla (incisive) bone as reported in Kagani goats (Sarma, 2006), chital (Kumawat et al., 2014), Pygmy hog (Kalita et al.) and blackbuck (Choudhary & Singh, 2016b). The basal surface of the skull which formed the osseous hard palate was almost completely enclosed by the alveolar processes of the maxilla and incisive bones. The horizontal plate of the palatine bone also contributes quite considerably to the formation of the palate as reported in Pygmy hog (Kalita et al.). The nuchal surface of the skull of Zovawk was formed in the middle by the squamous and the lateral parts of the occipital bone as reported in Pygmy hog (Kalita et al.) and blackbuck (Choudhary & Singh, 2016b). The lateral surface of the skull was formed by the temporal, zygomatic, maxilla, premaxilla and some part of frontal as reported in blackbuck (Choudhary & Singh, 2016b).

The measurements demonstrated that the skull was elongated in shape as also reported in Kagani goat (Sarma, 2006), chital (Kumawat et al.) and blackbuck (Choudhary & Singh, 2016a).

The skull of the Zovawk was dolichocephalic according to the cephalic index as reported in chital (Kumawat et al.), blackbuck (Choudhary & Singh, 2016a) and Indian wild pig (Choudhary et al., 2017); however, it was brachycephalic in tiger (Joshi, 2004) and mesaticephalic in dog (Miller et al., 1964).

The skull index or cephalic index of Zovawk was 53.56[+ or -]0.11, whereas it was 38.23[[+ or -] or -]0.85 in donkey (Zhu et al., 2014), 46.12[+ or -]0.12 cm in blackbuck (Choudhary and Singh, 2015b), 46.51[+ or -]0.29 cm in dromedary camel (Choudhary et al., 2016) and 70.56[+ or -]0.22 in Indian wild pig (Choudhary et al., 2017).

In the present study, the supraorbital foramina distance, infraorbital foramina distance, skull length, skull width, cranial length and nasal length of the Zovawk were 3.49[+ or -]0.01 cm, 6.55[+ or -]0.01 cm, 28.26[+ or -]0.03 cm, 15.11[+ or -]0.26 cm, 13.17[+ or -]0.04 cm and 13.79[+ or -]0.02 cm, respectively. Choudhary et al. (2015) reported that the supraorbital foramina distance, infraorbital foramina distance, skull length, skull width, cranial length and nasal length for the Indian wild pig were 4.56[+ or -]0.056 cm, 6.54[+ or -]0.063 cm, 32.55[+ or -]0.40 cm, 22.90[+ or -]0.24 cm, 18.27[+ or -]0.17cm and 14.93[+ or -]0.13 cm, respectively. However, the supraorbital foramina distance, infraorbital foramina distance, skull length, cranial length and nasal length were 18.3 cm, 6.43 cm, 46.2 cm, 32.5 cm and 13.3 cm, respectively in the Iranian one-humped camels (Monfared, 2013a). Zhu et al. also reported skull length, skull width and cranial length in donkey were 44.307[+ or -]5.35 cm, 16.90[+ or -]1.76 cm and 20.782[+ or -]2.22 cm, respectively. Choudhary et al. (2016) mentioned that the supraorbital foramina distance, infraorbital foramina distance, skull length, skull width, cranial length and nasal length for the dromedary camels were 6.35[+ or -]0.047 cm, 8.41[+ or -]0.076 cm, 48.75[+ or -]0.244 cm, 22.66[+ or -]0.108 cm, 32.73[+ or -]0.484 cm and 16.89[+ or -]0.283 cm, respectively. While according to Sarma (2006) in kagani goats; the mean lengths of the skulls were 24.72[+ or -]0.93 cm, with the width and cephalic index of 10.40[+ or -]0.61 cm and 41.95[+ or -]0.97 cm, respectively; whereas the skull length was 20.06[+ or -]1.71 cm in Mehraban sheep (Karimi et al., 2011) and 46.2 cm in Iranian native camels (Monfared, 2013b). Zhu et al. noted skull length and width 443.07[+ or -]53.57 mm and 169.09[+ or -]17.64 mm in donkey. The mean skull length of the lion, dog and cat was 39.75[+ or -]1.04, 20.02[+ or -]1.36 and 8.4[+ or -]1.5 cm, while the skull width was 28[+ or -]2.16, 10.04[+ or -]0.56 and 6.8[+ or -]1.4 cm respectively (Saber & Gummow, 2015). The mean cranial length of the lion's, dog's and cat's skulls were 18.86[+ or -]4.77, 5.96[+ or -]0.63 and 3.4[+ or -]0.4 cm, respectively (Saber & Gummow).

The height of the skull with mandible (Hskm) in the present study was 24.55[+ or -]0.13. The cranial width of the Zovawk was 8.45[+ or -]0.04; however, it was 11.85[+ or -]1.98, 5.13[+ or -]0.34 and 4.1[+ or -]0.2 cm respectively in lion's, dog's and cat's skulls (Saber & Gummow). The cranial index was 64.16[+ or -]0.07 in Zovawk; however, cranial index was 52.76[+ or -]1.13 in Mehraban sheep (Karimi et al.).

The orbital margins were found to be incomplete in Zovawk as also reported in tiger (Taluja et al., 2000), Pygmy hog (Kalita et al.) and Indian Wild pig (Choudhary et al., 2016). Whereas, the orbits were circular in blackbuck (Choudhary & Singh, 2015a) and elliptical in Mehraban sheep (Karimi et al.). The orbital margins were formed by frontal, lacrimal and zygomatic bone. The maximum contribution in the formation of the orbit was from frontal bone followed by the zygomatic and lacrimal bone. The interorbital distance in the present study was 7.81[+ or -]0.07 cm.

Various orbital parameters showed bilateral variation among the orbits of both the sides. The orbital height (4.16[+ or -]0.01 cm) was more in left than right orbit (4.08[+ or -]0.01 cm), however the height of right orbit was more than left one in Kagani goats (Sarma, 2006).

The orbital depth and orbital circumference was 2.32[+ or -]0.01 and 12.85[+ or -]0.04 cm in the present study. Similarly, orbital depth and circumference have been recorded more in the left orbit (4.66[+ or -]0.004 and 13.49[+ or -]0.009 cm, respectively) than the right one (4.61[+ or -]0.003 and 13.09[+ or -]0.01 cm, respectively) in blackbuck (Choudhary & Singh, 2015c).

The cranial cavity of Zovawk was oval in outline as reported in blackbuck (Choudhary and Singh, 2016a). The capacity of cranial cavity was 101.16[+ or -]0.51 cm3 in the Zovawk, while it was 113[+ or -]0.84 cm3 in Kagani goat (Sarma, 2006), 130.86[+ or -]11.55 cm3 in Mehraban sheep (Karimi et al.) and 107.83[+ or -]0.86 cm3 in blackbuck (Choudhary & Singh, 2016a). The mean cranial capacity of the lion, dog and cat was 207.4[+ or -]24.49, 86.4[+ or -]11.87 and 20.8[+ or -]1.95 cm3 respectively (Saber & Gummow).

The height and width of the occipital bone was found to be 10.89[+ or -]0.01 cm and 7.97[+ or -]0.01 cm, respectively; whereas same occipital parameter was 5.21[+ or -]0.01 cm and 5.76[+ or -]0.008 cm, respectively in blackbuck (Choudhary & Singh, 2015b).

The intercondylar and interparacondylar width was 5.07[+ or -]0.02 cm and 5.75[+ or -]0.01 cm, respectively in Zovawk; whereas it was 4.62[+ or -]0.01 cm and 5.29[+ or -]0.01 cm, respectively in blackbuck (Choudhary & Singh, 2015b).

The foramen magnum was large and roughly oval in shape as also reported by Kumawat et al. in chital and Choudhary & Singh (2016b) in blackbuck.

The height, width, circumference and area of the foramen magnum in the Zovawk was 1.56[+ or -]0.01 cm, 1.87[+ or -]0.01 cm, 5.78[+ or -]0.06 cm and 2.29[+ or -]0.04 cm2, respectively; whereas the same parameters were 1.74[+ or -]0.008 cm, 2.03[+ or -]0.006 cm, 8.22[+ or -]0.01 cm and 2.77[+ or -]0.006 cm2, respectively in blackbuck (Choudhary & Singh, 2015b). Sarma (2006) also reported that the height, width, circumference and area of the foramen magnum in Kagani goat was 3.08[+ or -]0.35 cm, 3.12[+ or -]0.36 cm, 12.30[+ or -]0.28 cm and 2.53[+ or -]0.58 cm2, respectively. Yahaya et al. (2012), noted a mean foramen magnum height and width of 4.04[+ or -]0.15 and 3.70[+ or -]0.16 cm, and 3.65[+ or -]0.27 and 3.45 [+ or -] 0.21 cm in males and females of one humped camel.

The foramen magnum index was 83.42[+ or -]0.03 in the present study, which was 98.71[+ or -]0.03 in blackbuck (Choudhary & Singh, 2015b), 109.30[+ or -]4.44 and 107.37[+ or -]6.33 in males and females of one humped camel (Yahaya et al., 2012).

The length and width of the frontal bone in the Zovawk was 14.76[+ or -]0.02 cm and 10.47[+ or -]0.02 cm, respectively, whereas length and width of the frontal bone was 7.75[+ or -]0.01 cm and 4.81[+ or -]0.008 cm, respectively in blackbuck (Choudhary & Singh, 2015b).

The supraorbital foramina were small in Zovawk; whereas the supraorbital foramina was very large opening with larger in right side (1.02[+ or -]0.00 cm) than the left one (0.84[+ or -]0.00 cm) in blackbuck (Choudhary & Singh, 2015b). The distance between supraorbital foramina to rim of orbit was 2.09[+ or -]0.002 cm in present study.

The length and width of the maxilla bone was 10.16[+ or -]0.04 cm and 5.42[+ or -]0.01 cm, respectively in Zovawk, however it was 9.29[+ or -]0.005 cm and 4.83[+ or -]0.008 cm in blackbuck (Choudhary & Singh, 2015b). The diameter of the infraorbital foramen in the present study was 0.895[+ or -]0.00 cm.

The length and width of the premaxilla was 10.68[+ or -]0.01 cm and 3.70[+ or -]0.05 cm, respectively, however it was 7.23[+ or -]0.007 cm and 1.00[+ or -]0.001 cm in blackbuck (Choudhary & Singh, 2015b).

The length and width of palatine bone was 15.47[+ or -]0.04 cm and 5.07[+ or -]0.01 cm, respectively, whereas length and width of palatine bone was 6.04[+ or -]0.046 cm and 3.23[+ or -]0.022 cm, respectively in blackbuck (Choudhary & Singh, 2015b). The length of the palatine suture in the present study was 14.04[+ or -]0.02 cm.

The length and width of the nasal bone was 13.79[+ or -]0.02 cm and 4.95[+ or -]0.02 cm, respectively, however it was 5.69[+ or -]0.01 cm and 1.29[+ or -]0.01 cm, respectively in blackbuck (Choudhary & Singh, 2015b). The length of the nasal suture was 13.19[+ or -]0.03 cm in present study. The nasal index for the Zovawk was 35.91[+ or -]0.03.

The length and width of the lacrimal bone was 4.83[+ or -]0.01 cm and 2.31[+ or -]0.01 cm, respectively, whereas the length and width of the lacrimal bone was 4.36[+ or -]0.01 cm and 1.71[+ or -]0.01 cm. The lacrimal bone was situated on the lateral aspect of the skull and involved in the formation of the anterior margin of the orbit. There were three lacrimal foramina in the present study, two were situated at anterior margin and one was situated posteriorly in the orbital cavity.

The length and width of the zygomatic bone was 8.26[+ or -]0.02 cm and 4.26[+ or -]0.01 cm, respectively in Zovawk.

The distance from the process of alveolar socket of canine tooth to the infraorbital canal and from the latter to the root of the fourth upper premolar alveolar tooth directly ventral to it was 4.77[+ or -]0.04 cm and 1.20[+ or -]0.01 cm, respectively in Zovawk, while it was 5.40[+ or -]0.048 cm and 3.57[+ or -]0.069 cm, respectively in Indian wild pig (Choudhary et al., 2017). However, the distance from the facial tuberosity to the infraorbital canal and from the latter to the root of the alveolar tooth directly ventral to it was 1.6-1.8 cm and 1.3-1.6 cm in west African dwarfs goats (Olopade & Onwuka, 2005); 2.06[+ or -]0.14 cm and 1.13[+ or -]0.11 cm in Gwembe Valley dwarf goat (Pares-Casanova et al, 2014); 2.8 cm and 2.5 cm in Iranian native cattle (Monfared, 2013b); 2.37[+ or -]0.009 cm and 0.72[+ or -]0.008 cm in blackbuck (Choudhary & Singh, 2015b); 2.19[+ or -]0.068 cm and 3.21[+ or -]0.078 cm, respectively in dromedary camel (Choudhary et al., 2016) and 1.85[+ or -]0.14 cm and 1.75[+ or -]0.19 cm in black Bengal goat (Uddin et al, 2009).

The data are of clinical importance as a guide for tracking the infra-orbital nerve, and necessary for its desensitization during the manipulations in the skin of the upper lip, nostril and face at the level of the foramen. The injection of local anesthetic agents within the canal via the infra-orbital foramen will also lead to analgesia of the incisor, canine and first two premolar teeth (Choudhary et al., 2015).

The distance between the lateral end of the alveolus of the third incisor tooth to the mental foramen was 3.57[+ or -]0.04 cm in Zovawk, which is an important landmark for achieving the location of the mental nerve for the regional nerve block in Indian wild pig, while the same measurement was 1.6[+ or -]0.22 cm in west African dwarf goat (Olopade & Onwuka, 2005), 2.0[+ or -]0.30 cm in red sokoto (Maradi) goat (Olopade & Onwuka, 2007), 4.74 cm in Iranian one-humped camels (Monfared, 2013a), 2.45[+ or -]0.008 in blackbuck (Choudhary etal., 2015), 9.22[+ or -]0.059 cm in dromedary camel (Choudhary et al., 2016) and 3.00[+ or -]0.028 cm in Indian wild pig (Choudhary et al., 2017).

In the anterior aspect of the mandibular canal, injection can be made through the mental foramen to desensitize mental aspect of the mandibular nerve. This will ensure the loss of sensation of the lower incisors, premolar and lower lip on that side (Hall et al., 2000). The distance from the mental foramen to the caudal mandibular margin was 18.47[+ or -]0.01 cm in Zovawk. However, the distance from the mental foramen to the caudal mandibular margin was 13.43[+ or -]0.081 cm in Iranian one-humped camels (Monfared, 2013a,b) and 32.12[+ or -]0.165 cm in dromedary camel (Choudhary et al., 2016) and 29.33[+ or -]0.374 cm in Indian wild pig (Choudhary et al., 2017).

The length and height of the mandible were 25.02[+ or -]0.09 cm and 10.54[+ or -]0.07 cm, respectively in Zovawk, however the length and height of the mandible were 12.00[+ or -]1.89 cm and 6.90[+ or -]1.09 cm in west African dwarfs goats of Nigeria (Olopade & Onwuka, 2005), 27.4 cm and 15.88 cm in Iranian native cattle (Monfared, 2013b); 39.9 cm and 9.92 cm in Iranian one-humped camels (Monfared, 2013a); 16.53[+ or -]0.128 cm and 10.69[+ or -]0.024 cm in blackbuck (Choudhary et al., 2015); 42.98[+ or -]0.624 cm and 22.58[+ or -]0.287 cm, respectively in dromedary camel (Choudhary et al., 2016) and 33.25[+ or -]0.30 cm and 16.88[+ or -]0.124 cm in Indian wild pig (Choudhary et al., 2017).

The distances between condyloid fossa to the base of the mandible was 10.51[+ or -]0.02 cm in Zovawk; whereas, it was 7.57[+ or -]0.024 cm in blackbuck (Choudhary & Singh, 2015a), 18.38[+ or -]0.15 cm in dromedary camel (Choudhary et al., 2016) and 15.96[+ or -]0.14 cm in Indian wild pig (Choudhary et al, 2017).

The distance between the vertical line drawn downward from the caudal margin of mandible (E) and the vertical line drawn from the mandibular foramina downwards (G) was (F) 4.45[+ or -]0.03 cm, while same distance was observed to be 1.85[+ or -]0.011 cm in blackbuck (Choudhary and Singh, 2015a) and 7.04[+ or -]0.05 cm in Indian wild pig (Choudhary et al., 2017).

The distances from the mandibular foramen to the base of the mandible, caudal margin of mandible to the level of mandibular foramen and the mandibular foramen to the margin of mandibular angle were 4.56[+ or -]0.01 cm, 3.81[+ or -]0.00 cm and 4.84[+ or -]0.002 cm, respectively in Zovawk; however, the distances from the mandibular foramen to the base of the mandible, caudal margin of mandible to the level of mandibular foramen and the mandibular foramen to the margin of mandibular angle were 4.18[+ or -]0.014 cm, 1.36[+ or -]0.010 cm and 3.07[+ or -]0.006 cm, respectively in blackbuck (Choudhary & Singh, 2015a), 8.84[+ or -]0.085 cm, 5.88[+ or -]0.055 cm and 8.29[+ or -]0.079 cm, respectively in dromedary camel (Choudhary et al., 2016) and 7.44[+ or -]0.069 cm, 7.04[+ or -]0.05 cm and 7.13[+ or -]0.082 cm, respectively in Indian wild pig (Choudhary et al., 2017). Equivalent figures for West African dwarfs goats of Nigeria were 1.57[+ or -]0.44 cm, 2.58[+ or -]0.34 cm, respectively, for the caudal margin of mandible to below mandibular foramen and the mandibular foramen to the base of the mandible (Olopade & Onwuka, 2005).

In horse and dogs the distance between the mandibular foramen and the base of the mandible was 3 cm and 1.5 to 2 cm, respectively (Hall et al.). The anesthetic agents must be injected on the medial side of the mandible, thereby; a successful nerve block produces anesthesia of the lower jaw with its teeth and the lower lip. These data are necessary for achieving the regional anesthesia of the mandibular nerve and also have clinical importance for desensitization of all the teeth in lower jaw.

CONCLUSIONS

The morphometric measurements of the skull and applied anatomy of the head region of the Zovawk provide an important baseline data for further research in the field of applied anatomy. Furthermore, these results are of clinical importance that will aid the regional anesthesia of the various nerves around the head, especially during the treatment of head injury, dental extraction and mandibular fractures in Zovawk pigs.

REFERENCES

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Corresponding author:

Dr. O.P. Choudhary

Assistant Professor

Department of Veterinary Anatomy and Histology

College of Veterinary Sciences and Animal Husbandry

Central Agricultural University

Selesih, Aizawl

Mizoram

INDIA

Email: dr.om.choudhary@gmail.com

Received: 10-06-2018

Accepted: 26-11-2018

Om Prakash Choudhary (1); Pranab Chandra Kalita (1); Bedanga Konwar (2); Probal Jyoti Doley (1); Girin Kalita (3) & Arup Kalita (1)

(1) Department of Veterinary Anatomy and Histology, College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram- 796015, India.

(2) Department of Veterinary Surgery, College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram796015, India.

(3) Department of Livestock Production and Management, College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram- 796015, India.

Caption: Fig. 1. Measurement of the skull of local Mizo pig (dorsal view) showing skull length (Lsk), skull width (Wsk), length of frontal (Lfr), width of frontal (Wfr), distance between two supraorbital foramina (Dsof), distance between supraorbital foramina to rim of orbit (Sof-rio) length of nasal (Lna) and width of nasal (Wna) and cranial width (Wcr).

Caption: Fig. 2. Measurements of the skull of local Mizo pig (ventral view) showing width of foramen magnum (Wfm), base length of skull (LBsk), width of skull (Wsk), length of palatine (Lpa), width of palatine (Wpa) and incisor, canine, premolar, molar teeth (I1-3,C1,PM1-4,M3).

Caption: Fig. 3. Measurements of the skull of local Mizo pig (lateral view) showing length of premaxilla (Lpm), height of premaxilla (Hpm), length of maxilla (Lma), height of maxilla (Hma), length of zygomatic (Lzy), height of zygomatic (Hzy), length of lacrimal (Lla), height of lacrimal (Hla), height of the skull with mandible (Hskm), length of skull (Lsk), nasal bone (Na), frontal bone (Fr), palatine (Pa), occipital bone (Oc) and temporal bone (Te).

Caption: Fig. 4. Measurements of the orbit of local Mizo pig showing Height of orbit (Ho), length of orbit (Lo), depth of orbit (Do), circumference of orbit (Co), frontal (Fr), lacrimal (La) and zygomatic bone (Zy).

Caption: Fig. 5. Measurements of the skull of local Mizo pig (nuchal view) showing height of occipital (Hoc), width of occipital (Woc), intercondylar width (Wic) and interparacondylar width (Wipc), skull height (Hsk), skull width (Wsk), height and width of foramen magnum (Hfm & Wfm).

Caption: Fig. 6. Measurements of the skull of local Mizo pig (lateral view) skull length (Lsk), cranial length (Lcr), nasal length (Lna), height of cranium (Hcr), infraorbital foramen (iof), distance from infraorbital canal to root of 4th premolar tooth (A), distance from infraorbital canal to root of canine tooth (B), distance from infraorbital canal to orbital rim (C).

Caption: Fig. 7. Measurements of the mandible (lateral view) of local Mizo pig showing distance from lateral alveolar root to mental foramen (A), mental foramen to the caudal mandibular margin (B), mandibular length (C) and mandibular height (D).

Caption: Fig. 8. Measurements of the mandible (medial view) of local Mizo pig showing mandibular height (D), distance from mandibular foramen to base of mandible (E), caudal margin of mandible to below mandibular foramen (F), condyloid fossa to the base of the mandible (G), caudal margin of mandible to the level of mandibular foramen (H), mandibular foramen (mf).