Posterior Belly of the Digastric Muscle

Original Article

OriginalOriginal Research Research ArchArch Clin Clin Exp Exp Surg Surg 2015;4:79-82 2015;X:X-X Archives of Clinical doi:10.5455/aces.20140702071204 1 Experimental Surgery doi:NA 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 IncreasedPosterior belly of of theLangerhans digastric muscle: Cells An important in Smokeless landmark 11 12 Central corneal thickness in children with type 1 diabetes mellitus 12 for various head and neck surgeries 13 Tobacco-Associatedand the effect of metabolic Oral control Mucosal on corneal Lesions thickness 13 14 Vrinda Hari Ankolekar, Anne D. Souza, Rohini Alva, Antony Sylvan D. Souza, Mamatha Hosapatna 14 15 Emine Cinici 15

16 ABSTRACT 16 ABSTRACT 17 Objectives: The digastric muscle1 is an important landmark in head2 and neck surgeries. Important neurovascular1 structures 17 18 ÉricasuchObjective: as Dorigatti the Tospinal research accessory de whether Ávila and central, hypoglossal Rafael corneal Scaf nerves thickness de (HNs), Molon (CCT) internal of, Melainechildren jugular veinwith de (IJV)Type Almeida and1 diabetes internal Lawall mellitus carotid (T1D)artery, Renata islie different deep Bianco 18 1 1 19 Consolarotofrom the healthy posterior children, Albertobelly of at digastric same Consolaro age (PBD); group the and study whether relating metabolic to it deserves control special has an mention effect inon anatomical corneal thickness. literature. Therefore, 19 20 theMaterials present and study methods: aims to describe The children the PBD with in T1D relation who to applied the essential to our anatomicaloutpatient department landmarks. with the aim of controlling for 20 Materialspossible diabetes and Methods: complications This study and was who carried had no out diabetic using 10retinopathy cadavers werepreserved prospectively in 10% formalin. evaluated. The The midpoint healthy of IJVchildren in 21 thefrom neck the samewas identified age group as who the appliedpoint between to our outpatientthe angle settingof the formandible eye control and midclavicular and who had point. no systemic The anatomical or eye disease landmarks were 21 22 consideredincluded in thefor measuringcontrol group. the Theparameters CCT of wereall children tip of thewas mastoid measured process with ultrasonic(TMP), loop pachymeter of HN, midpoint with topical of IJV, anesthesia. bifurcation 22 1 23 ofFindings: common While carotid the artery corneal (CCA) thickness and the for midpoint healthy of children PBD. Various was 554.25±42.85 parameters (500were –measured 678 µ), the using average the digital corneal calipers. thickness 23 Bauru Dental School Abstract University of São Paulo 24 Results:for diabetic The children length wasof PBD 567.38±33.28 was 3.77 ± 1.08(487 cm– 628 on rightµ). A andsignificant 3.15 ± 0.05difference cm on leftwas sidedetected indicating for average slightly longercorneal belly thickness on 24 the(Z=-2.040 right. The p=0.041). extended No length relation did was not detectedvary much between on both the the central sides, whichcornea were thickness 6.7 ± 1.23and thecm onduration right and of diabetes 6.7 ± 0.75 (t=1.418 cm. Bauru–SP, Brazil 25 Thep=0.168),Objective: HN crossed average ToPBD HbA1C evaluate 2.72 ± level 0.8 the cm (t=1.261p=0.218), changesanterior to inthe the TMP hyperglycemia number on right side,of Langerhans(t=0.228 while on p=0.821) left side Cells itand was (LC) hypoglycemia situated observed 2.1 ± attack0.57 in cmthe number an epithelium- 25 of 2 26 terior(t=-0.332smokeless to TMP. p=0.743). The tobacco distance (SLT-induced) between the midpoint lesions. of PBD and of IJV was 6.58 ± 0.99 cm on right side, whereas it was 6.1 26 Araraquara Dental School 27 ±Result: 0.96 cm CCT on leftis increased side. The indistance the patients between compared the midpoint to the PBD control and groupbifurcation even of before CCA wasDM 3.04has developed± 0.61 cm ona retinopathy.right and 27 São Paulo State University 2.78Methods: ± 0.74 cm Microscopicon left side. sections from biopsies carried out in the buccal mucosa of twenty patients, who were 28 A relation of this increase with period of diabetes, HbA1C level and hypoglycemia attack number could not be detected. 28 Araraquara-SP, Brazil Conclusion: As the PBD muscle is an important surgical landmark, the present study adds to the existing knowledge about 29 Keychronic words: users Central of cornealsmokeless thickness, tobacco type 1(SLT), diabetes were mellitus utilized. For the control group, twenty non-SLT users of SLT29 it. The present study has also included few newer landmarks, which were not given importance in the previous studies. Received: February 05, 2012 30 with normal mucosa were selected. The sections were studied with routine coloring and were immunostained30 Key words: Carotid arteries, hypoglossal nerve, internal jugular vein, posterior belly of digastric muscle Accepted: February 29, 2012 31 Introductionfor S-100, CD1a, Ki-67 and p63. These data were statisticallyorescence[5], analyzed fragility bythat the is Student’sraised with t-test the todecrease investigate 31 the Arch Clin Exp Surg 2012;X: X-X AQ132 DMdifferences may lead in to the some expression ischemic conditionsof immune such markers as inin normalcorneal sensitivity,mucosa and recurrent in SLT-induced epithelial leukoplakia erosions, lesions.32 DOI: 10.5455/aces.20120229052919 Introduction structures, such as the spinal accessory and hypoglos- 33 coronaryResults: artery There disease, was peripheral a significant artery differencedisease and in theepithelial immunolabeling edema, desensitization of all markers and neurotrophic between normal ul- 33mucosa 34 retinopathy.The digastric It is characterized muscle is an byimportant a hyperglycemia landmark that in salcers. nerves Following (HNs), argoninternal laser jugular iridotomy vein (IJV), and andintraocular com- 34 Corresponding author and SLT-induced lesions (p<0.001). The leukoplakia lesions in chronic SLT users demonstrated a significant 35 headmay causeand neck microvascular surgeries. It hasand/or two belliesmacrovascular with separate com - monsurgery, carotid endothelial artery (CCA) dysfunction are intimately and persistentrelated to thestro - 35 Érica Dorigatti de Avila Departamento de Estomatologia 36 embryologicalplicationsincrease over in origins time.the number Although and innervations. of Langerhansdiabetic Theretinopathy cells digastric and is in posteriorthemal absence edema belly; wereof thusepithelial the studies other dysplasia. aboutcorneal them disorders deserve that spe -we 36 muscle is located in the anterior region of the neck, and cial attention in anatomical literature [3]. Radical su- da Faculdade de Odontologia de 37 its mostConclusion: common complication The increase and in theneovascular number glauof these- werecells foundrepresents in DM the patients[6,initial stage 7]. of leukoplakia.It was noticed in 37 Bauru its bellies are the limits of the submandibular (digas- prahyoid neck dissections are often required to remove 38 coma,Key refractive words: Smokelesschanges[1] tobacco, and various leukoplakic corneal lesions, dis- cancer,many langerhans publications[8-16] cells, chewing that central tobacco. corneal thickness 38 Universidade de São Paulo (USP) 39 tric),orders submental, may be also and seen. carotid These triangles. include The dysfunction posterior in metastatic(CCT) is lymph increased nodes in inadult the diabetescarcinoma mellitus involving patients. the 39 Avenida Alameda Octávio 40 bellythe corneal of the digastricendothelium, (PBD) desensitization[2], muscle originates stromalat the floorHowever, of the this mouth. increase In such was dissections, not observed PBD in serves some as of 40 Pinheiro Brizola, 9-75, 17012-901 41 mastoidand subbasalIntroduction process, nerve and abnormalities[3], runs down and forward low endothelial toward a theuseful studies,contact landmark [17-19]. with[4]. In Any thethe interventional studies oral thatmucosa were surgery done and or on creates 41 a Bauru–SP, Brasil the hyoid bone [1,2]. The important neurovascular radiological procedure in this region requires precise [email protected] 42 density and hexagonality[4], increased corneal autoflu- the childrenmore with alkaline T1D, it environment, was detected that its in generalproducts 42 may Among tobacco users, there is a false be- 43 Author affiliations : Department of Anatomy, Kasturba Medical College, Manipal, Karnataka, India 43 CorrespondenceAuthor affiliations :: MamathaDepartment Hosapatna, of Ophthalmology, Department Erzurum of Anatomy, District Kasturba Training Medical and Research College, Hospital,even Manipal, Erzurum, Karnataka,be more Turkey India. e-mail:aggressive [email protected] to tissue [5]. The 44 ReceivedCorrespondencelief that / Accepted SLT :: MayEmine is 29, safeCINICI, 2014 / DepartmentJulybecause 02, 2014 of Ophthalmology, it is not Erzurum burned, District Training and Research Hospital, Erzurum, Turkey 44 e-mail: [email protected] 45 Receivedwhich / Accepted leads : October many 28, 2014 people / December to 04, 2014quit cigarettes percentage of SLT users is lower compared45 and start using SLT [1]. However, SLT con- to cigarette users; however, usage is increasing tains higher concentrations of nicotine than among young individuals and it is therefore a cigarettes and, in addition, nearly 30 carci- significant and disturbing danger [6,7]. nogenic substances, such as tobacco-specific Initial studies on the effects of SLT on the N-nitrosamines (TSNA), which is formed oral mucosa demonstrated the formation of during the aging process of the tobacco, [2-4] white lesions induced by chronic exposure to and which presents high carcinogenic poten- tobacco, characterized by epithelial thicken- tial. Moreover, because the tobacco has direct ing, increased vascularization, collagen altera- 80 Ankolekar VH et al. knowledge of the anatomy of this region. In addition, some clinicians recommend palpation of the PDB in cases of temperomandibular disorders [5]. During the surgery, the PBD is the most easily identifiable landmark for facial nerve dissection during parotidectomy, with a consistent anatomical relationship with the facial nerve trunk [6]. Numerous studies pertaining to the anterior belly of the muscle are available, whereas studies on the PBD are limited. Therefore, the goal of the present study was to add to the existing knowledge about this region. Materials and Methods This study was carried out in the Department of

Anatomy, Kasturba Medical College (Manipal, India) Figure 1. Parameters measured in the PBD muscle. PBD: Posterior using 10 cadavers (20 sides of the neck) preserved in belly of the digastric muscle, HB: Hyoid bone, TMP: Tip of the mastoid process, HN: Hypoglossal nerve, a: Length of the PBD, b: Extended 10% formalin. The sternocleidomastoid muscle was re- length of the PBD. tracted to visualize the PBD from the tip of the mastoid process (TMP). The midpoint of the IJV in the neck was identified as the point between the angle of the mandible and the midclavicular point. This parameter was considered in the study because of the close relationship of the IJV to the jugulo-digastric and jugulo- omohyoid group of lymph nodes, which are commonly resected during radical neck dissection. Since there are no bony landmarks around the HN, anatomical landmarks such as the PBD, internal carotid artery, and IJV are used in surgeries involving this nerve [7]. Because the hyoid bone is an important landmark in this region, attachment of the intermediate tendon of the digastric at the junction of the body with the greater cornu of the hyoid bone was performed as a novel technique to Figure 2. Relationship between the PBD and essential anatomical extend the length of the PBD. landmarks. PBD: Posterior belly of the digastric muscle, HN: Hypoglossal nerve, CCA: Common carotid artery, IJV: Internal jugular vein, a: The anatomical landmarks considered for measur- Distance between the tip of the mastoid process to crossing of the HN, ing the parameters were the TMP, the loop of the HN, b: Distance between midpoint of IJV to midpoint of PBD, c: Distance between bifurcation of CCA to midpoint of PBD, Yellow line: Midpoint of the midpoint of the IJV, bifurcation of the CCA and IJV (i.e., midpoint between angle of mandible and midclavicular point). the midpoint of the PBD. The measured parameters are shown in Figures 1 and 2 and were as follows: (1) cornu of the hyoid bone. The distances were measured Length of the PBD (length of the fleshy part of the mus- using digital calipers, and statistical analysis of the data cle); (2) Extended length of the PBD measured from was carried out using SPSS version 16. the TMP to the junction of the body and greater cornu Results of the hyoid bone; (3) Midpoint of the IJV to midpoint The length of the PBD was 3.77 ± 1.08 cm on the of the PBD; (4) Bifurcation of the CCA to midpoint right and 3.15 ± 0.05 cm on the left, indicating a slightly of the PBD; and (5) TMP to the posterior end of the longer belly on the right side. The extended length did HN loop. The midpoint of the PBD is the midpoint be- not vary much on both sides, with measurements of 6.7 tween the TMP to the junction of the body and greater ± 1.23 cm and 6.7 ± 0.75 cm on the right and left sides, Archives of Clinical and Experimental Surgery Year 2015 | Volume 4 | Issue 2 | 79-82 An anatomical study on the posterior belly of the digastric muscle 81 respectively. The HN crossed the PBD 2.72 ± 0.8 cm ence points during operations [9]. anterior to the TMP on the right side, whereas on the The distance from the midpoint of the IJV to the left side it was situated 2.1 ± 0.57 cm anterior to the PBD was 6.58 ± 0.99 cm on the right side and 6.1 ± TMP. The distance between the midpoint of the PBD 0.96 cm on the left side. The study done by Hinsley et and of the IJV was 6.58 ± 0.99 cm on the right side and al. found that transition of the spinal accessory nerve 6.1 ± 0.96 cm on the left side. The distance between the from the lateral to medial occurred high in the neck and midpoint of the PBD and bifurcation of CCA was 3.04 deep in the PBD. Dissections at or above the level of ± 0.61 cm on the right and 2.78 ± 0.74 cm on the left the digastric muscle, where operating deep to the IJV side. There was no significant difference between the may place it at risk to nerve injury. Therefore, it is nec- values of the right and left sides. essary to recognize the morphometric anatomy of the Discussion digastric muscle in order to avoid complications to the Since 1847, there have been descriptions of ana- IJV and spinal accessory nerve during therapeutic pro- tomical variations in the digastric muscle as pointed cedures [10]. The distance from the bifurcation of the out by Bergman et al. [3]. In temporomandibular dis- CCA to the midpoint of the PBD was 3.04 ± 0.61 cm orders, palpation of the PBD is a mandatory procedure. and 2.78 ± 0.74 cm on the right and left sides, respec- An anomalous posterior belly may lead to perplexing tively. Considering the complicated anatomy of the situations while diagnosing these disorders [5]. In this cervical and submandibular regions, the use of only study, the length of the PBD was 3.77 ± 1.08 cm on the one surgical landmark is not recommended. The PBD right side and 3.15 ± 0.05 cm on the left side. In a study represents a good landmark during the submandibular by Shin et al., the length of the PBD was 6.22 ± 0.60 cm dissection to identify the HN, facial nerve, and spinal and 5.29 ± 0.72 cm on the right and left sides, respec- accessory nerves [11-13]. tively. It was also noted that the length of the PBD was A limitation of this study was that it was difficult to longer in females than in males [7]. trace the facial and spinal accessory nerves in relation There is very limited literature available on the ex- to the PBD. The present study is a preliminary attempt tended length of the PBD. The extended length was to determine the anatomy of the PBD with respect to measured from the TMP to the junction of the body important surgical landmarks. Using these novel pa- and greater cornu of the hyoid bone, and was 6.7 ± rameters, further studies should be done using fresh 1.23 cm on the right side and 6.75 ± 0.75 cm on the specimens. left side. These parameters may help radical suprahyoid Conclusions neck procedures designed to remove metastatic lymph Since the PBD is an important surgical landmark, nodes in carcinoma involving floor mouth. In such the present study adds to the existing knowledge about dissections, PBD serves as a useful landmark [8]. The it. The present study also included a few novel land- present morphometric study of PBD is relevant to the marks that were not focused on in previous studies. interpretation of radiological and surgical explorative Conflict of interest statement procedures. The authors have no conflicts of interest to declare. In the present study, the HN crossed the PBD 2.72 References ± 0.8 cm anterior to the TMP on the right side, whereas 1. Ziólkowski M, Marek J, Klak A. The human digas- it was situated 2.1 ± 0.57 cm anterior to the TMP on tric muscle in the fetal period. Folia Morphol (War- the left side. Shin et al. found that the HN appeared un- sz) 1984;43:243-9. der the PBD, and the crossing point corresponded to 2. Larsson SG, Lufkin RB. Anomalies of digastric about 65.5% of the whole length of the PBD from the muscles: CT and MR demonstration. J Comput digastric groove [7]. These parameters may be given Assist Tomogr 1987;11:422-5. consideration in surgical procedures in the neck region, 3. Bergmann RA, Afifi AK, Miyauchi R. Muscular sys- especially in relation to submandibular gland resection, tem: Alphabetical listing of muscles: D. Available since this muscle and its tendon are anatomical refer- from: http://www.anatomyatlases.org/Anatomic- www.acesjournal.org Archives of Clinical and Experimental Surgery 82 Ankolekar VH et al.

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Archives of Clinical and Experimental Surgery Year 2015 | Volume 4 | Issue 2 | 79-82