Anatomy and Physiology of the Velopharyngeal Mechanism Jamie L. Perry, Ph.D.1 ABSTRACT Understanding the normal anatomy and physiology of the velopharyngeal mechanism is the first step in providing appropriate diagnosis and treatment for children born with cleft lip and palate. The velopharyngeal mechanism consists of a muscular valve that extends from the posterior surface of the hard palate (roof of mouth) to the posterior pharyngeal wall and includes the velum (soft palate), lateral pharyngeal walls (sides of the throat), and the posterior pharyngeal wall (back wall of the throat). The function of the velopharyngeal mechanism is to create a tight seal between the velum and pharyngeal walls to separate the oral and nasal cavities for various purposes, including speech. Velopharyngeal closure is accomplished through the contraction of several velopharyngeal muscles including the levator veli palatini, musculus uvulae, superior pharyngeal con- strictor, palatopharyngeus, palatoglossus, and salpingopharyngeus. The tensor veli palatini is thought to be responsible for eustachian tube function. KEYWORDS: Anatomy, physiology, velopharyngeal muscles, cleft palate anatomy Downloaded by: SASLHA. Copyrighted material. Learning Outcomes: As a result of this activity, the reader will be able to (1) list the major muscles of the velopharyngeal mechanism and discuss their functions; (2) list the sensory and motor innervation patterns for the muscles of the velopharyngeal mechanism; and (3) discuss the variations in velopharyngeal anatomy found in an unrepaired cleft palate. Understanding the normal anatomy and and treatment for children born with cleft lip physiology of the velopharyngeal mechanism is and palate. Most of the diagnostic and therapy the first step in providing appropriate diagnosis approaches are based on a strong foundation of 1Department of Communication Sciences and Disorders, Guest Editor, Ann W. Kummer, Ph.D., CCC-SLP, Illinois State University, Normal, Illinois. ASHA-F. Address for correspondence and reprint requests: Jamie Semin Speech Lang 2011;32:83–92. Copyright # L. Perry, Ph.D., Department of Communication Sciences 2011 by Thieme Medical Publishers, Inc., 333 Seventh and Disorders, Illinois State University, 208 Rachel Avenue, New York, NY 10001, USA. Tel: +1(212) 584- Cooper, Normal, IL 61790 (e-mail: [email protected]). 4662. Communication Disorders Related to Cleft Palate, DOI: http://dx.doi.org/10.1055/s-0031-1277712. Craniofacial Anomalies, and Velopharyngeal Dysfunction; ISSN 0734-0478. 83 84 SEMINARS IN SPEECH AND LANGUAGE/VOLUME 32, NUMBER 2 2011 the underlying anatomy. In addition, this pop- resonance image (MRI) of the velopharyngeal ulation continually presents with changes in the mechanism at rest and during speech produc- anatomy and physiology as the head and neck tion. The orifice or gap behind the velum is anatomy develops across childhood and called the ‘‘velopharyngeal port.’’ This is the through adolescence. Being able to identify distance that the velum and pharyngeal walls the important structures and know how these must overcome to have complete closure, such relate to normal and abnormal speech produc- as during speech and swallowing. Histological tion is a critical part of our ongoing evaluation studies show that the velum consists of a for such individuals. Although cleft palate mixture of tendinous, muscular, adipose, con- anatomy includes facial, oral, nasal, and phar- nective, and glandular tissue along the velar yngeal anatomy, the focus for this article is on length.3,4 The anterior two-thirds of the velum the structures and muscles related to the nor- appears to be consistent in its composition mal velopharyngeal mechanism as these struc- compared with the posterior one-third, which tures and muscles have the greatest impact on shows greater variability across individuals. speech and resonance. The purpose of this This demonstrates the importance of the ante- article is to provide an overview of normal rior two-thirds in providing the functional anatomy and physiology of the velopharyngeal components to the velum during velopharyng- mechanism and to provide a brief discussion of eal closure.5 how the anatomy is altered when there is a cleft palate. Function The function of the velopharyngeal mechanism VELOPHARYNGEAL MECHANISM is to create a tight seal between the velum and pharyngeal walls to separate the oral and nasal Orientation cavities. During speech, normal velopharyngeal The velopharyngeal mechanism consists of a closure is necessary to be able to produce oral muscular valve that extends from the posterior speech phonemes. Only three sounds in the surface of the hard palate (roof of mouth) to the English language, /m/, /n/, /ng/, are produced posterior pharyngeal wall.1 The mechanism with an open velopharyngeal port. includes the velum (soft palate), lateral phar- The velum extends from the posterior yngeal walls (sides of the throat), and the nasal spine of the hard palate to the uvula. posterior pharyngeal wall (back wall of the During nasal breathing, the oral surface is Downloaded by: SASLHA. Copyrighted material. throat).2 Fig. 1 shows a midsagittal magnetic down and rests against the back of the tongue Figure 1 Midsagittal magnetic resonance imaging of velopharyngeal mechanism at rest (A) and during speech production (B). The white arrow is pointing at the velar eminence during elevation. PPW, posterior pharyngeal wall. ANATOMY AND PHYSIOLOGY OF THE VELOPHARYNGEAL MECHANISM/PERRY 85 (Fig. 1A). During production of oral speech to contraction of the inferior fibers of the sounds, the velum is elevated and retracted to superior constrictor muscle.6 It can best be make complete contact against the posterior viewed on the lateral view of videofluoroscopy pharyngeal wall. As seen in Fig. 1B, when the but can also be seen with nasopharyngoscopy velum elevates it creates a ‘‘knee’’ or eminence when there is a large velopharyngeal opening. as it bends against the posterior pharyngeal wall It can even be viewed through an intraoral (white arrow on Fig. 1B). This creates a tight examination in some cases. Passavant’s ridge seal to redirect the sound and airflow into the is seen in children with a repaired cleft palate mouth instead of the nasal cavity. and also in individuals with normal anatomy. Closure of the velopharyngeal mechanism The existence of a Passavant’s ridge does not is primarily accomplished by retraction and mean that contact is achieved against this ridge. elevation of the velum. Movement of the phar- In most cases, the ridge is too low to assist with yngeal walls, however, also contributes to ve- velopharyngeal closure. lopharyngeal closure. Lateral pharyngeal wall Three basic types of closure have been movement toward the midline and anterior identified across individuals with normal movement of the posterior pharyngeal wall speech and also those with repaired cleft palate. help to create a sphincterlike closure pattern. Closure patterns include coronal, where the Some individuals may create velar contact closure occurs primarily due to the action of against an enlarged adenoid pad. This is more the velum, with less contribution of the lateral commonly observed in children before adenoid pharyngeal walls; circular, where all structures involution occurs during adolescence. Fig. 2 come together as ‘‘purse string’’; and sagittal, demonstrates a midsagittal MRI of this ad- where lateral pharyngeal wall movement is the enoid-to-velar contact in a 4-year-old child major component of closure.2,7 Passavant’s with normal anatomy. ridge is commonly seen with the circular pat- Some individuals have what is called a tern of closure. Closure pattern is best observed ‘‘Passavant’s ridge.’’ When a Passavant’s ridge through nasopharyngoscopy, which provides a is present, it appears as a shelflike structure that view from the top or nasal surface of the velum. bulges forward during speech and then disap- Fig. 3 demonstrates a coronal closure pattern pears at rest. Passavant’s ridge is felt to be due observed in an adult male in which the major movement is an upward and backward move- ment of the velum accompanied by a secondary component of lateral pharyngeal wall move- Downloaded by: SASLHA. Copyrighted material. ment. This is the most common pattern of closure observed in individuals with normal anatomy. NORMAL VELOPHARYNGEAL MUSCULATURE There are several velopharyngeal muscles, in- cluding the levator veli palatini, musculus uvu- lae, tensor veli palatini, superior pharyngeal constrictor, palatopharyngeus, palatoglossus, and salpingopharyngeus. These muscles are described below. Levator Veli Palatini Figure 2 Midsagittal magnetic resonance ima- The paired levator veli palatini muscle is the ging of a 4-year-old child with an enlarged adenoid most important muscle for normal velophar- pad (white arrow). yngeal closure.8 This muscle originates at the 86 SEMINARS IN SPEECH AND LANGUAGE/VOLUME 32, NUMBER 2 2011 Figure 3 Nasopharyngoscopy demonstrating the velum, lateral pharyngeal walls (LPW), posterior pharyngeal wall (PPW) in the open (left image) and closed position (right image). Note the upward and backward movement of the velum and the medial movement of the lateral pharyngeal walls. base of the skull on each side, specifically the the levator veli palatini muscle from its origin petrous portion of the temporal bone. Accord- to insertion (Fig. 5). ing to Huang et al,8 part of the muscle may The function of the levator veli palatini originate at the junction of the cartilaginous