Global Veterinaria 9 (6): 691-695, 2012ISSN 1992-6197© IDOSI Publications, 2012DOI: 10.5829/idosi.gv.2012.9.6.66187

Corresponding Author: Behzad Mobini, Department of Basic Sciences, College of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, Shahrekord - Iran.Tel: +98-311-7754770, Fax: +98-381-3361060.

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Topographical and Morphological Anatomy of the Guttural Pouches of the Domestic Donkey (Equus asinus)

Seyed Morteza Ghazi, Behzad Mobini and Mohammad Reza Afsharzadeh1 2 2

School of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, Shahrekord - Iran1

Department of Basic Sciences, College of Veterinary Medicine, 2

Islamic Azad University, Shahrekord Branch, Shahrekord - Iran

Abstract: Guttural pouches are paired filled with air, located ventral to the atlas. The donkeys possessed large,symmetrical guttural pouches incompletely divided into medial and lateral compartments by the stylohyoidbone. The left and right guttural pouches have almost the same capacity. In this study, topographic andmorphologic anatomy of the left and right guttural pouches was carried out in the heads of male and femalehealthy donkeys. Results of the transverse and median sections of the heads revealed that the gutturalpouches of donkey were much smaller than those of the horse. All the anatomical structures related to theguttural pouches of donkey resemble those in the horse with differences in the pharyngeal recess whichwas deeper and larger in donkey. The lateral walls of each guttural pouch contain the five cranial nerves(VII, IX, X, XI and XII), the cranial cervical ganglion, the cranial sympathetic trunk, the cranial laryngeal andpharyngeal nerves and the linguofacial trunk, maxillary vein, the internal carotid and branches of the externalcarotid arteries. The volumes of the guttural pouches in the males were larger than females. The length, widthand depths of the lateral compartment in right side were more than left guttural pouch, while these values formedial compartments were reversed. The retropharyngeal lymph node which located under the floor of gutturalpouch was found in both sexes.

Key words: Anatomy % Donkey (Equus asinus) % Guttural Pouch % Morphologic % Topographic

INTRODUCTION Because of their localization and relationship with

The guttural pouches are large paired auditory tube are of veterinary importance in perissodactyls [3, 6, 7].diverticuli present in the horse as well as in other The diseases of the guttural pouch such as emphysema,mammals [1, 2], such as horse, donkey, tapir [3, 4]. mycosis, tympany, neoplasia, cysts and muscle rupturesThe pouches are symmetrically extended from the can result in erosion of the carotid artery and precipitatepharynx to the atlanto-occipital joint in both sides fatal hemorrhages [11, 12], or make the pouch susceptible[5-8]. The right and left guttural pouches met each to serious clinical conditions [5].other at the median part to form a thin membranous Although, some advanced studies give adequateseptum. Moreover, each pouch incompletely divided detail on the topographic and morphologic anatomy ofinto medial and lateral compartments by the stylohyoid the guttural pouch of the horse [4, 7, 9, 13, 14], to ourbone [5]. knowledge there are limited reports in the literature

The physiological function, if any, of guttural pertaining to the topographic and morphologic anatomypouches is unknown, but recently it has been proposed of the guttural pouch of the donkey [15]. Therefore,that they might have an important function of brain this study was undertaken to investigate more preciselycooling [3, 5, 9] and also intimately involved in the the anatomical features of the guttural pouches of thephysiology of swallowing [4, 10]. donkey bilaterally.

several cranial nerves and blood vessels, the pouches

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MATERIALS AND METHODS Oto and Haziroglu [19] and Manglai et al. [7]

Four healthy adult donkeys for teaching purpose in of hard tissue (sphenoid bone and occipital bone) andthe Department of Anatomy, College of Veterinary except for the region connected to the stylohyoid bone,Medicine, Shahrekord Islamic Azad University, the other walls were in contact with soft tissue such asShahrekord, Iran, were used in this study (2 each sex). pharynx, esophagus and many muscles. Similar findingsEuthanization were made by using 20 of Acepromazine were observed in this study.ml

(2%; Alfason, Woerden, Holland) as a sedative and 250 The results of topographic anatomy showed thatml

of Magnesium sulfate (29.1%, Sahand, Tabriz, Iran). the pharyngeal recess in the donkey was deep and large.The guidelines of the ethical committee of Shahrekord This finding agrees with those reported by Alsafy et al.Azad University were strictly followed during the [15] and Lindsay and Clayton [22]. It has been shown toprocedure. All the heads were cut off transversely at the have a close physical relation with the medial laminae andlevel of the sixth cervical vertebra. Transverse section of septum of the auditory tube diverticula. It is equallythe donkey’s head passed at the level of the medial likely, therefore, that the excursions of the recess reflectcanthus of the eyes, whereas median section passed pressure changes within the auditory diverticula and thatlongitudinally on the head. The volume, the maximum the asymmetric movements of its wall are due to differinglength, width and depth of the right and left pouches pressures in the two diverticula [22].were measured in both sexes. The specimens were The internal carotid artery, the linguofacial trunk,submerged in 10% formalin and dissection was performed the cranial cervical ganglion, the cranial sympatheticcarefully on the anatomical structures related to the trunk, the cranial laryngeal and pharyngeal nerves, asguttural pouches. Definitions of the anatomical structures well as the facial nerve, glossopharyngeal N., vagus N.,were based on the atlases regarding equine anatomy accessory N., hypoglossal N., branches of the external[16, 17, 18]. All steps were photographed by digital camera carotid and maxillary vein were present in the lateral walls(Sony, Cyber-shot, DSC-H10). of the guttural pouches (Figs. 2-4). These results are in

RESULTS AND DISCUSSION The total mean volume of the guttural pouches in

The current study demonstrated that donkeys females (185 ml). This may be due to the bray mechanism.possessed relative large symmetric guttural pouches It is believed that a remarkable large size of pharyngealwhich extended from the pharynx to the atlanto-occipital recess plays a role in braying [22].joint in both sides [5-8, 15, 19]. The capacity of the right and left guttural pouch in

Manglai et al. [7] described the opening of auditory male donkeys were respectively 164 ml and 227 ml,tube as a funnel form canal. On the contrary, Oto and whereas in the females were 190 and 180 ml, respectively.Haziroglu [19] emphasized that the entrance of the The different values for the capacity of the right and leftpharyngeal part of the pouches was like a triangle shape guttural pouches may be due to the deviation of the headorifice. In this study, it clearly observed parallel data to to the right or left during euthanization. Since declinationOto and Haziroglu [19]. of the head to the right or left reduces the volume of the

Each pouch incompletely divided into medial and right or left guttural pouches, accordingly.lateral compartments by the stylohyoid bone. They lie Although, Lepage [21] has stated that the capacitybetween the base of the skull (basilar part of the occipital of guttural pouches in horses were generally ranged fromand sphenoid bones) and atlas dorsally, the pharynx, 300 to 600 ml, but Manglai et al. [7] reported that theretropharyngeal lymph node and commencement of the capacity of guttural pouches in adult horses were 472 cm .esophagus ventrally, the parotid and mandibular salivary In comparison of the capacity of guttural pouches inglands, caudal belly of the digastric and pterygoideus horses with donkey, It was determined that the donkeysmedialis muscles, laterally. In the medial plane, the left possessed smaller guttural pouches than horses.and right sacs were separated from each other by the The average length, width and depths of the lateralrectus capitis ventralis and longus capitis muscles (Fig. 1). compartments of the right guttural pouches (24.65 cm,These results are in agreement with those recorded 5.10 cm 2.85 cm, respectively) were more than those inpreviously [3, 5, 15, 16, 19-21]. left side (23.45 cm, 5.05 cm and 2.35 cm, respectively),

described that the dorsal side of the pouches consisted

agreement with those recorded previously [5, 7, 15, 19, 23].

the male donkeys was more (195 ml) than that in the

3

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Fig. 1: The topography of the guttural pouch (G.P) and close structures in the donkey. Medial view, right lateralcompartment (R.L.C), right medial compartment (R.M.C), left medial compartment (L.M.C) left lateral compartment(L.L.C), pharynx (P), larynx (L), basisphenoid bone (B.S), basilar part of occipital bone (B.O), rectus capitisventralis muscle (R.C.V), atlas (A), pterygoideus medialis muscle (P.M), pharyngeal orifice of auditory tube(P.O.A.T), spinal cord (S.C), nasopharynx (N.P), pharyngeal recess (P.R), stylohyoid bone (S), sphenoidal sinus(S.S), soft palate (S.P), frontal sinus (F.S)

Fig. 2: Median section of the head of a donkey. basisphenoid bone (B.S), internal carotid a. (I.C.A), retropharyngeallymph node (R.P.L.N), linguofacial trunk (L.T), hypoglossal nerve (H.G.N), guttural pouch (G.P)

Fig. 3: Median section of the head of the donkey passes at the level of the middle of the nuchal crest, atlas and axisbones. Stylopharyngeus caudalis muscle (S.C.M), occipitohyoideus muscle (O.H.M), hypoglossal nerve (H.G.N),maxillary vein (M.V), pharyngeal nerve (P.N), pharynx (P)

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Fig. 4: The guttural pouch and its related structures in the donkey. Medial view, hypoglossal nerve (H.G.N),glossopharyngeal nerve (G.P.N), accessory nerve (A.N), vagus nerve (V.N), maxillary vein (M.V)

while these values in the medial compartments of the left 4. Sasaki, M., Y. Hayashi, H. Koie, Y. Yamaya,guttural pouches (30.40 cm, 5.55 cm and 2.05 cm, J. Kimura, D. Manglai, S. Kawashima, H. Endo andrespectively) were more than those in right side (29.20 cm, M. Yamamoto, 1999. CT examination of the guttural5.25 cm and 2.10 cm, respectively). pouch (auditory tube diverticulum) in Przewalski’s

Oto and Haziroglu [19] and Carmalt [5] reported that horse (equus przewalskii). Journal of Veterinarythe medial compartment was larger than the lateral part. Medical Science, 61: 1019-1022.On the contrary, Manglai et al. [7] emphasized that the 5. Carmalt, J., 2002. Guttural pouch diseases in thelateral compartment was wider and medial part was horse. Large Animal Veterinary Rounds, Vol 2,narrow. We clearly observed that the medial compartment Issue 2, EriÕim: [http:// www.drounds.ca/ crus/was a little bigger than that of the lateral part. laveng_0202.pdf], EriÕim tarihi: 15.09.2009.

CONCLUSIONS Organ. In: Veterinary Anatomy of the Domestic

The results of topographic and morphologic Schattauer, Stuttgart, pp: 577-579.anatomy demonstrated that the guttural pouches of 7. Manglai, D., R. Wada, H. Endo, M. Kurohmaru,donkey were relatively smaller than horse. All the T. Yoshihara, M. Sasaki, M. Oikawa and Y. Hayashi,anatomical structures related to the guttural pouches 2000. Macroscopic anatomy of the auditory tuberesemble those in the horse with differences in the diverticulum (guttural pouch) in the thoroughbredpharyngeal recess which was deeper and larger in equine - a slicon mold approach. Okajimas Foliadonkey. The volume of the guttural pouch in the males Anatomica Japonica, 76: 335-346.was more than females. 8. Sisson, S., 1975. Sisson and Grossman’s The

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