Morphologic characteristics of palatopharyngeal Title muscle Author(s) Okuda, S; Abe, S; Kim, HJ; Agematsu, H; Mitarashi, Alternative S; Tamatsu, Y; Ide, Y Journal Dysphagia, 23(3): 258-266 URL http://hdl.handle.net/10130/1073 Right Posted at the Institutional Resources for Unique Collection and Academic Archives at Tokyo Dental College, Available from http://ir.tdc.ac.jp/ Editorial Manager(tm) for Dysphagia Manuscript Draft Manuscript Number: DYSP193R2 Title: Morphologic Characteristics of Palatopharyngeal Muscle Article Type: Original Article Keywords: Palatopharyngeal muscle, palatal muscles, soft palate, swallowing, pharynx, levator muscle of palatine velum, tensor muscle of palatine velum Corresponding Author: Dr. Shinichi Abe, DDS, Ph,D. Corresponding Author's Institution: Tokyo Dental College First Author: Shinpei Okuda, DDS Order of Authors: Shinpei Okuda, DDS; Shinichi Abe, DDS, Ph,D.; Hee-Jin Kim, DDS, Ph,D.; Hiroko Agematsu, BH, PhD; Satoshi Mitarashi, DDS, PhD; Yuichi Tamatsu, DDS, PhD; Yoshinobu Ide, DDS, PhD Manuscript (must not contain author information) 1 2 3 4 5 6 7 Morphologic Characteristics of Palatopharyngeal Muscle 8 9 10 11 Abstract 12 13 In an effort to clarify the morphologic characteristics of the 14 15 palatopharyngeal muscle, we examined the origin, insertion and positional 16 17 relationship with other muscles. The origin of the palatopharyngeal muscle 18 19 was both the oral and nasal sides of the soft palate, being also attached to 20 21 both the palatal aponeurosis and soft palate median. However, in some cases, 22 23 the muscle originated on the nasal side. When the palatopharyngeal muscle 24 25 26 originated from both the oral and nasal sides, it traveled through its 27 28 insertion via the levator muscle of the palatine velum. This insertion was 29 30 seen in a wide area and could be divided into three parts; the pharynx 31 32 anterior, central and posterior walls. In the central pharyngeal wall, 33 34 insertion into the pharyngeal aponeurosis, inferior constrictor pharyngeal 35 36 muscle and esophagus were observed. The present results suggest that the 37 38 palatopharyngeal muscle has a close positional relationship with the levator 39 40 and tensor muscles of the palatine velum, the pharyngeal constrictor 41 42 muscles and the esophagus. 43 44 45 46 Key Words: Palatopharyngeal muscle, palatal muscles, soft palate, 47 48 swallowing, pharynx, levator muscle of palatine velum, tensor muscle of 49 50 palatine velum 51 52 53 54 55 56 57 58 59 60 61 62 63 1 64 65 1 2 3 4 5 6 7 I. Introduction 8 9 Swallowing results from the carefully coordinated movement of 10 11 muscle groups in various many organs, including the oral cavity, soft palate, 12 13 pharynx and esophagus. To better understand swallowing function, it is 14 15 important to understand the morphologic characteristics of the muscle 16 17 groups linking the oral cavity, pharynx and esophagus. 18 19 In current reports on the morphologic characteristics of the muscles 20 21 from the pharynx through esophagus, variations in pharyngeal constrictor 22 23 muscles have been noted. Many of these reports are related to the continuity 24 25 1, 2) 26 of the buccal muscle and pharyngeal raphe variations . Bosma et al. 27 28 reported that pharyngeal raphe tissue at the junction of hypopharynx and 29 3) 30 upper esophagus is replaced with loose connective tissue . Hollinshed also 31 32 reported that the upper esophageal aponeurosis is attached to cricoid 33 34 cartilage 4). These reports clearly indicate a close morphologic relationship 35 36 between the oral cavity, pharynx and esophagus. However, the relationships 37 38 between these organs and the soft palate largely remain unknown. 39 40 With regard to the morphologic characteristics of the muscle groups 41 42 comprising the soft palate, Kuehn et al. 5,6) reported muscle bundle 43 44 arrangements from a functional perspective. However, the relationship at 45 46 the insertion site of the pharynx has not yet been elucidated. Furthermore, 47 48 although there are histopathological reports on the bundle arrangements for 49 50 the muscle groups comprising the soft palate 5,6), no studies have focused on 51 52 the muscle bundles facing the important palatopharyngeal muscle insertion. 53 54 55 Although functional coordination between the soft palate and 56 57 pharynx is necessary during swallowing, swallowing disturbance has been 58 59 reported due to shifts in the timing of muscle motions 7,8). Therefore, detailed 60 61 62 63 2 64 65 1 2 3 4 5 6 7 morphologic observation of running directions and insertion conditions of the 8 9 palatopharyngeal muscle fibers from the soft palate through the pharynx is 10 11 essential for understanding swallowing function. We thus performed 12 13 morphologic observation of the palatopharyngeal muscle fibers with regard 14 15 to running, origin and insertion attachment patterns, and relationships with 16 17 surrounding muscles. 18 19 20 21 II. Materials and methods 22 23 1. Observation materials 24 25 26 A total of twenty Japanese adult cadavers (10 males and 10 females; age 27 28 range, 49-90 years) fixed with neutral buffered 10% formalin solution and 29 30 provided for anatomical practice to the Department of Anatomy at Tokyo 31 32 Dental College were used. Medical records of the cadavers were not available. 33 34 However, on gross inspection, oropharyngeal structures appeared to be 35 36 normal. 37 38 2. Dissection of palatopharyngeal muscle 39 40 After performing sagittal section of the head and neck, the masseter 41 42 muscle, zygomatic arch, part of the mandibular ramus, temporal muscle, 43 44 lateral pterygoid muscle and medial pterygoid muscle were removed. 45 46 Cervical vertebrae localized in the posterior pharynx were also removed. 47 48 With regarding to the soft palate, the palatoglossal muscle was removed and 49 50 the palatopharyngeal muscle was exposed for observation from the oral and 51 52 nasal sides. 53 54 55 3. Observation region 56 57 1) Origin of palatopharyngeal muscle 58 59 We investigated the presence of the palatopharyngeal muscle origin 60 61 62 63 3 64 65 1 2 3 4 5 6 7 through the oral and nasal directions. The locus relationship between the 8 9 palatopharyngeal muscle and the levator muscle of palatine velum was also 10 11 observed through the oral and nasal directions. Classification was performed 12 13 based on the oral side locus relationship, followed by observation of the nasal 14 15 side locus relationship of each part. 16 17 2) Insertion of palatopharyngeal muscle 18 19 Confluence of the palatopharyngeal muscle with the salpingopharyngeus 20 21 muscle is already known 9). Moreover, some reports have considered the 22 23 salpingopharyngeus muscle to be part of the palatopharyngeal muscle 10). 24 25 11) 26 This makes distinction of the two muscles difficult . Therefore, we excluded 27 28 cases having a salpingopharyngeus muscle. 29 30 As insertion of the palatopharyngeal muscle covers a large area of the 31 32 hypopharynx, morphologic observation was performed by dividing the 33 34 palatopharyngeal muscle into 3 regions; anterior, posterior and central. 35 36 37 38 III. Results 39 40 1) Origin of palatopharyngeal muscle 41 42 (1) Observation from oral side 43 44 Two regions of the palatopharyngeal muscle origin were seen on the oral 45 46 side. Origin from the posterior of the palatine aponeurosis (Oral Tendineus 47 48 (OT); 20 out of 20 cases) was observed, and origin with interlacing fibers at 49 50 the median portion of the soft palate from the contralateral 51 52 palatopharyngeal muscle were seen (Oral Median (OM); 20 out of 20 cases). 53 54 55 On the oral side, OT and OM were seen in all cases (Fig. 1). 56 57 (2) Observation from nasal side 58 59 Two regions of the palatopharyngeal muscle origin were seen on the nasal 60 61 62 63 4 64 65 1 2 3 4 5 6 7 side. Origin from the posterior of the palatine aponeurosis (Nasal Tendineus 8 9 (NT); 14 out of 20 cases) and at the median portion of the soft palate, and 10 11 origin with interlacing fibers from the contralateral palatopharyngeal 12 13 muscle (Nasal Median (NM); 17 out of 20 cases) were observed. 14 15 NT did was not seen the posterior palatine aponeurosis area. Rather, it 16 17 was observed in a narrow area of the palatine aponeurosis medial to the 18 19 vertical section of the levator muscle of the palatine velum (vertical muscle 20 21 bundles running from the temporal bone to the soft palate) (Fig. 2). Moreover, 22 23 insertion from the posterior palatine aponeurosis near the hamulus 24 25 26 pterygoideus lateral to the vertical section of the levator muscle of palatine 27 28 velum was observed (Fig. 3) 29 30 2) Positional relationship with levator muscle of palatine velum 31 32 (1) Observation from oral side 33 34 The palatopharyngeal muscle at the oral side (MOP) originated at the 35 36 posterior (OT) and median (OM) parts of the palatine aponeurosis. From the 37 38 positional relationship of MOP with the levator muscle of the palatine velum, 39 40 two types were observed: 41 42 Type 1: MOP running through the anterior part of the oral side of the 43 44 levator muscle of the palatine velum (17 out of 20 cases). 45 46 Type 2: MOP covering all the levator muscle of the palatine velum on the 47 48 oral side (3 out of 20 cases) (Fig. 4). 49 50 (2) Observation from nasal side 51 52 The palatopharyngeal muscle at the nasal side (MNP) originated at 53 54 55 the posterior (NT) and median (NM) palatine aponeurosis.