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You are watching: Which bones form the hard palate

StatPearls . Sweetheart Island (FL): StatPearls Publishing; 2021 Jan-.


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Introduction

Proper palate development in the occurring fetus is important for practical phonation and also feeding after ~ birth. The palate develops the roof that the mouth and also separates the dental cavity native the sleep cavity. The palate undergoes facility morphological alters during embryogenesis to accomplish its final kind and divides into an anterior immobile hard bony segment and a posterior mobile soft palate the does no contain bone. The superior facet of the palate forms the floor of the sleep cavities and also has a lining of ciliated pseudostratified columnar epithelium (respiratory epithelium). The inferior facet of the palate develops the roof of the dental cavity and also is lined v stratified squamous epithelium (oral mucosa) that includes secretory salivary glands. The difficult palate comprises around two-thirds that the full palate surface area, and also its basic bony structure is composed of the palatine processes of the maxilla and the horizontal bowl of the palatine bones. The soft palate is made up of muscle fibers covered by a rubber membrane, specifically 5 muscles which have actually a functional function in breathing and swallowing: 


Levator veli palatini muscle: elevates the soft palate and is affiliated in swallowing.
Musculus uvulae muscle: functions to shorten the uvula.
Palatoglossus muscle: traction the soft palate in the direction of the tongue and is associated in swallowing.

Structure and also Function

Hard Palate

The hard palate comprises the anterior two-thirds that the palate and also is one immobile hard bony segment whose underlying bony structure consists of the palatine procedures of the maxilla and the horizontal plates of the palatine bones. Positioned anteriorly, the palatine procedures of the maxilla consist of most of the tough palate and also cover the area between the two sides of the maxillary dental arch. The palatine processes of the maxilla fulfill the 2 horizontal plates of the palatine skeletal posteriorly, which fuse down the midline. The hard palate officially separates the dental cavity native the sleep cavities, creating the floor that the sleep cavity and the roof the the oral cavity. The difficult palate is covered superiorly through ciliated pseudostratified columnar epithelium (respiratory mucosa) and also inferiorly through stratified squamous epithelium (oral mucosa). Anteriorly, the tough palate has irregular ridges or rugae, called rugae palatinae, ~ above the mucous membrane the facilitates the passage of food posteriorly towards the pharynx. The difficult palate consists of three foramina/canals that serve as passageways for an important neurovascular structures that it is provided the dental cavity. These important landmarks include the incisive canal, the better palatine foramen, and also the lesser palatine foramen. The incisive canal is located at the anterior midline of the maxilla, straight posterior come the main maxillary incisor teeth, and also contains the nasopalatine nerve and also the diminish palatine artery. The better palatine foramen is situated in the posterior hard palate medial come the 3rd molar tooth and also is traversed by the higher palatine vessels and nerve. The lesser palatine foramen is situated posterior come the greater palatine foramen top top the base of the pyramidal procedure and is traversed through the lesser palatine nerve. Structurally, the hard palate gives a strictly floor to the sleep cavity that stays clear of changes in pressure within the mouth from closing turn off nasal passages. Historically, babies with a slot palate might not suckle and often died from malnutrition; this is due to the fact that infants cannot efficiently create negative sucking press without a properly created hard palate. The difficult palate is also essential for phonation and contains rugae that assist in mastication and also digestion.<1><2>

Soft Palate

The soft palate renders up the posterior 3rd of the palate and is a posterior continuation of the difficult palate. The soft palate consists of muscle fibers and connective tissue spanned by a mucus membrane consisting of a stratified squamous epithelium with secretory salivary glands. Unequal the hard palate, the soft palate is really flexible and does not contain any kind of bony structures. The soft palate offer to elevate the nasopharynx, successfully closing the interaction from the oropharynx to the nasopharynx. The soft palate is comprised of five muscles that play vital roles in breathing, phonation, and also swallowing.

Anteriorly, the soft palate is consistent with the difficult palate and the palatine aponeurosis. Posteriorly, the soft palate ends together a midline projection dubbed the uvula that projects right into the dental cavity. The soft palate develops the roof the the oropharyngeal isthmus, an area connecting the pharynx and also oral cavity. Two arches bind the soft palate to the tongue and pharynx, the palatoglossal arches, and also palatopharyngeal arches, respectively. The palatine tonsils show up between these arcs in the tonsillar fossa of the oropharynx.

The soft palate has 5 muscles that room innervated by the pharyngeal plexus the CN X, other than for the tensor veli palatini muscle, i m sorry receives innervation indigenous a branch the the trigeminal nerve called the medial pterygoid nerve. The muscles that make up the soft palate encompass the palatoglossus, palatopharyngeus, tensor veli palatini, musculus uvulae, and also levator veli palatini muscles. The tensor veli palatini muscle attaches to the palatine aponeurosis indigenous its beginning at the medial pterygoid plate of the sphenoid. The tensor veli palatini muscle attributes to it s too dirty the soft palate throughout swallowing, preventing the entrance of food into the nasopharynx. The levator veli palatini muscle emerges from the eustachian tube and also the petrous temporal bone prior to attaching come the palatine aponeurosis, this muscle attributes to elevate the soft palate throughout swallowing to avoid the entry of food into the nasopharynx. The palatoglossus muscle occurs from the palatine aponeurosis and travels inferiorly, anteriorly, and laterally to affix into the side of the tongue—the palatoglossus muscle attributes to traction the soft palate in the direction of the tongue and initiates the act of swallowing. The palatopharyngeus muscle increase from the hard palate and the palatine aponeurosis and attaches to the exceptional border that the thyroid cartilage. The palatopharyngeus muscle tenses the soft palate and draws the pharynx superiorly and also anteriorly during the plot of swallowing. The palatopharyngeus muscle close the door the laryngeal airway during swallowing to stop the aspiration the food. The musculus uvulae muscle derives from the palatine aponeurosis and the posterior sleep spine and also attaches to the mucous membrane the the uvula. The musculus uvulae muscle attributes to shorten the uvula. Ipsilateral convulsion of the musculus uvulae muscle draws increase the uvula ~ above the exact same side.

During the action of swallowing, the levator veli palatini muscle elevates the soft palate, approximating it v the posterior pharyngeal wall surface and totally blocking off the airway and nasal passages. Together a result, the soft palate develops a vacuum in the dental cavity, maintaining food native entering the respiratory tract tract. Breathing end briefly during swallowing; this is since of the physics closure the the airway by elevation of the soft palate. During a sneeze, the soft palate protects the nasal passage by diverting some secretions come the dental cavity. The soft palate dram a function in the gag reflex, poignant the finish of the soft palate or uvula evokes the gag reflex in the majority of people.<3><4><5>


Embryology

Early in embryonic development, the nasal cavity runs repeatedly with the dental cavity, together there is no anatomic structure separating these two cavities. Together embryonic breakthrough progresses, palate formation ensues, official separating the oral and also nasal cavities from one another. Proper palate advance requires the development of a primary palate in the sixth week that development, and also the development of a second palate in between the sixth and eighth main of development. The primary palate has the alveolar arch. The second palate is composed of the hard and also soft palate. The external human face develops between the fourth and also sixth main of embryonic development. The major palate develops around the exact same time as the outside face, specifically the 6th week that development, together a an outcome of the blend of the medial nasal and also maxillary processes. Subsequently, in between the sixth and twelfth main of embryonic development, the secondary palate creates as the an outcome of the combination between palatal processes farming from the medial walls of the maxillary processes. During second palate formation, the palatal shelves expand medially and also fuse remarkable to the tongue. Together the palatal shelves increase medially, the arising mandible proceeds to grow, permitting for the tongue to get out of the way of the cultivation palatal shelves. By the nine week of development, the palatal shelves fuse as well as with the major palate anteriorly to kind the definitive palate.<6><7><8>


Blood Supply and also Lymphatics

The greater palatine arteries operation anteriorly, from the greater palatine foramen to supply the palate. The better palatine arteries serve as the primary arterial supply to the palate. Anastomosis in between the ascending palatine artery and the lesser palatine artery offers collateral supply to the palate. The higher palatine and lesser palatine arteries are branches that the maxillary artery, which occurs from the external carotid artery. The ascending palatine artery is a branch the the face artery, which also arises native the external carotid artery. The palate’s venous drainage directs in the direction of the pterygoid venous plexus. The lymph vessels of the soft palate drain into the sub-digastric and/or lateral pharyngeal nodes.<9><10><11>


Nerves

Excluding the tensor veli palatini muscle, every one of the palatal muscles are innervated by yarn from the pharyngeal plexus obtained from the vagus nerve. The tensor veli palatini muscle receives its innervation indigenous the medial pterygoid nerve, a branch the the trigeminal nerve. The sensory innervation of the palate originates from the maxillary branch of the trigeminal nerve. The maxillary division of the trigeminal nerve offers rise to numerous sensory branches that innervate the middle section of the face, including the nasopalatine, better palatine, lesser palatine, remarkable alveolar, center meningeal, infraorbital, zygomatic, worse palpebral, superior labial, and also pharyngeal nerves. The greater palatine nerve arises from its canal v the greater palatine foramen and also courses anteriorly in the roof of the palate, innervating the gingivae and also mucosa the the tough palate while connecting with the nasopalatine nerve anteriorly. The lesser palatine nerve runs alongside, the higher palatine nerve, occurring from the lesser palatine foramen to carry out sensory innervation to the tonsils, uvula, and also soft palate.<12>


Muscles

The soft palate has five muscles that get innervation through the pharyngeal plexus that the vagus nerve, except for the tensor veli palatini muscle, i beg your pardon is innervated through a branch of the trigeminal nerve called the medial pterygoid nerve. The muscle that comprise the soft palate incorporate the palatoglossus, palatopharyngeus, tensor veli palatini, musculus uvulae, and levator veli palatini muscles.

The tensor veli palatini muscle attaches to the palatine aponeurosis from its origin at the medial pterygoid plate of the sphenoid. The tensor veli palatini muscle functions to it is too dirty the soft palate during swallowing, avoiding the entry of food right into the nasopharynx.

The levator veli palatini muscle increase from the eustachian tube and also the petrous temporal bone prior to attaching to the palatine aponeurosis, this muscle attributes to elevate the soft palate during swallowing to stop the entrance of food right into the nasopharynx.

The palatoglossus muscle occurs from the palatine aponeurosis. It travels inferiorly, anteriorly, and also laterally to attach into the side of the tongue—the palatoglossus muscle features to pull the soft palate in the direction of the tongue and initiates the act of swallowing.

The palatopharyngeus muscle emerges from the difficult palate and the palatine aponeurosis and also attaches come the exceptional border the the thyroid cartilage. The palatopharyngeus muscle tenses the soft palate and draws the pharynx superiorly and anteriorly throughout the act of swallowing.

The palatopharyngeus muscle close the door the laryngeal airway during swallowing to avoid the aspiration that food.

The musculus uvulae muscle derives indigenous the palatine aponeurosis and also the posterior nasal spine and attaches to the mucous membrane of the uvula. The musculus uvulae muscle attributes to shorten the uvula. Ipsilateral convulsion of the musculus uvulae muscle draws increase the uvula top top the same side.


Physiologic Variants

Studies have actually demonstrated the the structural and obstructive patterns of the pharynx and palate vary among the basic population. The is crucial to identify these phenotypic variations and understand just how they create the shape and also collapsibility that the retropalatal airway. Understanding phenotypic variations in palatal anatomy room imperative in the diagnosis and also treatment of sleep apnea.

The soft palate has both distal and also proximal segment separated by a structure called the palatal genu. The palatal genu almost right the border in between the aponeurotic and muscular materials of the soft palate. The size of both the distal and proximal soft palate might vary amongst individuals, possibly predisposing particular individuals to sleep apnea. A distal palatal segment length greater than fifteen millimeters has actually been presented to rise the risk of sleep apnea dramatically and also correlates through poorer palatopharyngoplasty outcomes.

The configuration of the soft palate and also the position of the palatal genu is strongly associated to the length of the levator veli palatini muscle. The levator veli palatini muscle comprises fourty percent that the soft palate length in between the tough palate and also the base of the uvula. The proximal soft palatal segment maintains a variable edge from the tough palate, termed the alpha angle, which is determined by the length and position that the levator veli palatini muscle.

Studies have defined three palatal airway phenotypes based on the measure up of the alpha angle; oblique, intermediate, and also vertical. In people with intermediate and also oblique palatal phenotypes, the angle between the proximal soft palate and also hard palate is less acutely downwards, enabling for the soft palate to maintain a position more parallel come the tough palate. The prayer of patients through oblique and also intermediate phenotypes commonly collapse circularly. In people who display a vertical palatal phenotype, the angle in between the proximal soft palate and also hard palate is much more acutely downward, enabling for the soft palate to preserve a position an ext parallel to the posterior pharyngeal wall, fairly than the difficult palate. Airway collapse occurs in an anterior-posterior fashion in this patients.<13>


Surgical Considerations

Surgical techniques including the palate are quickly evolving to boost the quality of life for patients further. Palate surgical procedure is typically indicated for patients with significant obstructive sleep apnea, slit palate repair, and cancer resection.

Cleft palate repair, termed palatoplasty, should be performed between six come twelve month of period to optimize feeding and speech advancement without interrupting normal maxillofacial growth. There space three types of palatoplasty techniques: one form is because that soft palate repair, the second type is for difficult palate repair, and the third involves the surgical schedule. Soft palate repair techniques are radical muscle dissection, intravelar veloplasty, main pharyngeal flap, and twin opposing Z-plasty techniques. The difficult palate repair methods consist of the von Langenbeck, Veau-Wardill-Kilner V-Y, vomer flap, and also alveolar extension palatoplasty techniques. The surgical schedule/protocol based methods are totality in one, Malek’s, and also modified schedule through palatoplasty before lip repair. The goal of surgical procedure is to reapproximate or realign the palatal muscles. Upon completion of the surgery, this can assist expedite the breakthrough of typical speech and sound. Further, cleft palate repair with repositioning of muscle can also improve the functioning of the eustachian tube and also hearing. Once a surgeon repositions the palatal muscles correctly, this maneuver have the right to improve center ear ventilation and decrease illustration of otitis media and also hearing defects.

The most typical surgical procedure provided to treat obstructive sleep apnea is dubbed uvulopalatopharyngoplasty (UPPP) and involves the repositioning and/or removed of organization at the soft palate, uvula, and throat wall surfaces to rise airway size and decrease tissue collapse.

Soft palate implants, or the column procedure, is a minimally invasive procedure that has actually demonstrated to assist with mild come moderate cases of sleep apnea. The pillar procedure calls for the placement of 3 rods make of polyester right into the soft palate. This polyester rods incite an inflammatory reaction in ~ the surrounding soft tissue, which results in a stiffening the the soft palate. This inflammation reaction outcomes in a stiffer soft palate the is much less apt to make contact with the posterior pharyngeal wall surface as the muscles relax during the deep stages of sleep.

Surgical resection is the treatment for cancer the the tough palate. Expansion into neighboring bone is common, and frequently warrants removed of surrounding bone. If the tumor is small, the excision may be closed ~ surgery. If the tumor is large, a prosthetic maker can offer to covering the opening in the palate as the excised area cannot be closed.<1><3><13><14>


Clinical Significance

Tumors of the palate, both benign and malignant, many often existing asymptomatically or are associated with a short level the discomfort.  The illustration of benign and malignant lesions of the palate is additionally quite similar, making that of utmost prestige that the clinician be able to differentiate between them. Malignant squamous epithelial neoplasms such as verrucous carcinoma, carcinoma the the maxillary sinus, and also squamous cabinet carcinoma may show up in the difficult palate. Carcinoma that the maxillary sinus is regularly asymptomatic because that a long time and usually presents at an progressed stage. This tumor is associated with the elderly and is most typically diagnosed once the tumor expands to fill the sinus and also produces a bulge of the alveolar ridge or palatal area on physical examination. Squamous cell carcinomas constitute much more than ninety percent that all oral cancers. Non-squamous cabinet carcinomas of the oral cavity are rare. Risk components for squamous cabinet carcinoma the the palate incorporate alcohol, tobacco, and also HPV infection. Major squamous cell carcinoma that the soft palate is painful, causes dysphagia, and portends a lot worse prognosis than tumors located an ext anteriorly. Verrucous carcinoma is a form of squamous cabinet carcinoma that hardly ever metastasizes, behaves indolently, and demonstrates a white papillary clinical appearance. The most typical locations for verrucous carcinoma space the alveolar ridge and also hard palate, and it is linked with elderly patients that wear complete denture prosthesis. Tumors of the palate deserve to follow the palatine nerves v the greater and lesser palatine foramen and also extend right into surrounding bone, nerves, and also soft tissue. Up to seventy percent the squamous cell carcinomas the the tough palate extends past the tough palate into neighboring structures. Radiographically, malignant tumors of the palate may show evidence the bone destruction and also sometimes expose a radioopacity created by the neoplastic mass.<15>

Minor salient gland carcinomas represent much less than five percent of oral cavity cancers, and also around sixty percent of castle arise on the tough palate. Both malignant and benign salivary gland tumors of the palate appear as well-circumscribed, smooth, dome-shaped, non-moveable swellings that demonstrate a slow growth pattern.<16>

Pleomorphic adenoma is the most typical benign outstanding gland neoplasm uncovered within the palate. The most frequently discovered malignant salient gland tumors of the palate in descending order are adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, and mucoepidermoid carcinoma.<17><18>

Melanoma is a malignant tumor the melanocytes many often associated with cancer that the skin. Melanoma may develop anywhere melanocytes exist and also have the potential to kind from melanocytes located within the palate. Oral melanoma is extremely rare, accounting for much less than one percent of all oral malignancies. The most typical site for dental melanoma is the tough palate, which accounts for approximately forty percent of cases. Oral melanoma many commonly appears on the maxillary alveolus or hard palate and tends to have a lot worse prognosis 보다 cutaneous melanoma. Initially, melanoma lesions appear flat and also later become fixed and nodular in appearance. Melanomas often appear as light/dark brown lesions.<15>

The most usual locations that extranodal lymphoma in the head and also neck room the soft palate and also posterior tough palate. ~ above examination, lymphomas typically show up as a non-ulcerated, non-tender diffusive mass.

Sarcomas room malignant tumors of non-epithelial-tissue origin that might arise all over in the person body, consisting of the palate. Sarcoma that the palate appears as ulcerated masses in the middle-aged or young patient.<15> 

Cleft palate and lip room the most common congenital orofacial deformities in the world. Cleft palate to represent the 3rd most frequently emerging congenital deformity after ~ clubfoot and cleft lip. Cleft lip and also palate show a multifactorial inheritance pattern. They are the an outcome of a combination of genetic predispositions and also in-utero exposure come teratogens choose nicotine, alcohol, antiepileptics, and folate antagonists. Slot palate outcomes in significant facial deformities, feeding difficulties, nasal regurgitation that milk, coughing/choking during feeds, obstacles with phonation, dentition defects, and predisposes patients to recurrent illustration of otitis media v effusion. Slot palate occurs in a range of chromosomal abnormalities favor the Pierre-Robin sequence, Patau syndrome (trisomy 13), and also Edward syndrome (trisomy 18). Embryologically, a cleft palate occurs because of a partial or complete failure of blend of the palatine prominences by the 9th week that development. Slot palate may be unilateral or bilateral and complete or incomplete. There space three species of slot palate: submucosal cleft palate, incomplete cleft palate, and also a finish cleft palate. In the submucosal cleft palate, the palatine mucosa remains intact, yet an basic bony palatal or muscular defect is present. Incomplete slit palate describes clefting of the secondary palate exclusively, while complete cleft palate describes clefting that the entire soft palate, tough palate, and also uvula. Slit palate repair, termed palatoplasty, have to be performed in between six come twelve month of age to optimize feeding and speech advancement without interrupting typical maxillofacial growth.

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Repeated bouts of upper airway obstruction reason obstructive sleep apnea during the deep stages of sleep together a result of the narrowing/collapse of the respiratory tract passages. Patients with obstructive sleep apnea tend to it is in overweight with linked peripharyngeal fat infiltration and/or increased size of the tongue and also soft palate. This anatomic abnormalities predispose patient to obstructive sleep apnea because they diminish the cross-sectional area that the top airway. An raised neck circumference coincides to boosted peripharyngeal fat infiltration, specifically lining the airway and at the basic of the tongue. Neck circumference must be measured as soon as obstructive sleep apnea is suspected. A neck circumference higher than seventeen inch in men and greater than sixteen inches in women increases the risk for obstructive sleep apnea. One regional airway aspect thought to it is in a causative certified dealer of obstructive sleep apnea is an elongated soft palate. A distal palatal segment length better than fifteen millimeter has presented to increase the risk of sleep apnea dramatically. Initial treatment of sleep apnea is primarily nonsurgical and consists of optimistic airway press therapy, most generally in the type of CPAP. Historically, numerous of the surgical techniques used to correct sleep apnea in adult were sub-optimal, and palatopharyngoplasty techniques have advanced from primarily excisional methods to those the reposition and also reconstruct the palate. Examples of these an ext advanced surgical techniques encompass the growth sphincter-pharyngoplasty, lateral pharyngoplasty, relocation pharyngoplasty, and also uvulopalatopharyngoplasty (UPPP).<1><5>