The Anatomy of the Palatine Bone

Making up a portion of the nasal cavity and palate, the palatine bone is a paired, L-shaped facial bone. It forms a part of the underside of the skull, and lies between the maxilla bone (the fixed, upper bone of the jaw) and the sphenoid bone (whose wings help form the base of the eye sockets and base of the skull). Most often, these bones are clinically implicated as housing the incredibly sensitive greater and lesser palatine nerves, which need to be numbed during the extraction of molars and premolars in dentistry.

Anatomy

The palatine bone has a horizontal and vertical plate as well as a pyramidal process (or pyramid-shaped portion). The horizontal plate makes up the roof of the mouth, and the rear portion of the oral cavity, just behind the nasal cavity; its front end is serrated and its back end is smoother.

The two palatine bones sit next to each other, giving rise to the posterior nasal spine towards the back of this plate. This part also includes the greater palatine foramen, a space that contains the greater palatine nerve as well as its necessary blood vessels.

The perpendicular plate of the palatine bone makes up a portion of the sidewall of the nasal cavity at the point where it joins the sphenoid bone and pterygoid process (essential for jaw and mouth movement). This plate also gives rise to the orbital process, which makes up a part of the orbit—the socket where the eye sits.

Here, the palatine canal, which runs between the sidewall of the palatine bone and the adjacent maxilla bone, is also observed. This portion also includes a sphenopalatine notch on the upper border that connects with the sphenoid bone.

Finally, the pyramidal process arises at the juncture between the horizontal and perpendicular plates. Here, the lesser palatine canals arise, which house a range of important nerves and arteries.

Location

The location of the palatine bone is best understood through its borders and articulations.

Its horizontal plate is just behind the maxilla bone of the upper jaw, while lying in front of the soft palate (the soft tissue at the roof of the mouth). The end of this bone’s perpendicular plate closest to the back of the head articulates with the pterygoid process of the sphenoid bone.

On the upper border, this bone helps form the base of the orbital process. The two paired palatine bones join together down the middle of the upper mouth at the median palatine suture.

Anatomical Variations

The most commonly seen anatomical variation in the palatine bone has to do with the positioning of the greater palatine foramen, an opening towards the rear side that allows the descending and greater palatine nerves to pass through.

One study found that in approximately 73% of cases, this opening was located opposite the third upper molar tooth. It also noted a positioning opposite the second molar about 7% of the time, and in between the second and third molar roughly 16% of the time.

Function

Primarily, the palatine bone serves a structural function, with its shape helping carve out important structures within the head and defining the lower wall of the inside of cranium. This bone helps form the nasal and oral cavities, the roof of the mouth, and the lower portion of the eye sockets (orbits).

As noted above, they also house the greater palatine fossa, openings that allow the palatine nerves to pass through. In this sense, palatine bones help house primary pain-signaling pathways for the mouth and teeth.

Associated Conditions

There are several conditions related to the palatine bone.

In Dentistry

Clinically speaking, this bone is most often considered in dentistry as the greater and lesser palatine nerves, known to be extremely sensitive. When dentists need to extract the upper molars and premolars, these nerves have to be anesthetized (numbed).

Sites of injection need to be carefully monitored—they typically are about 1 centimeter (cm) from the gingival margin (the “height” of the gums)—as there’s a risk of the syringe penetrating the greater palatine foramen. In fact, there are clinical guidelines in place to prevent this from happening and dentists and specialists, in particular, need to be versed in the variant anatomy of this bone.

Fractures

In addition, accidents or falls can lead to fracture of the palatine bone. These "palatal fractures" are relatively rare and occur most often in adult men. They present a difficult challenge for doctors because of the position of the bone in the face.

Doctors classify six major types based on the location of the bone break—anterior and posterior alveolar, sagittal, para sagittal, para alveolar, complex, and transverse fractures—and this issue often accompanies Le Fort fracture of the maxillary bone. Not only can surrounding structures be affected, leading to pain and swelling, but these issues can also lead to malocclusion or misalignment of the teeth.

Torus Palatinus

Furthermore, in rare instances, doctors have observed torus palatinus, which is the development of mostly benign, painless outgrowths from the palatine bone. These tend to arise in the mid-plate of the palate, and can occur bilaterally or just one side.

Though usually asymptomatic, and often never noticed by patients, some cases do lead to pain, ulcers in the mouth, disrupted chewing, and impaired speech. This condition arises most often in adults in their 30s.

Treatment

Palatal fractures are detected using medical imaging methods, usually CT scans paired with X-ray. This allows doctors to assess the scope and location of the issue.

Treatment varies based on the severity and location of the fracture, and there are two surgeries that most often take it on: open reduction and internal fixation (ORIF) or intermaxillary fixation (IMF). In both cases, the idea here is that surgeons access the fractured bone, correct any alignment problems, and use splints, orthodontic braces, arch bars, or other methods to set in place.

Pain and inflammation need to be managed following this surgery, with the length of recovery depending on how severe the fracture is.

In cases where torus palatinus becomes symptomatic, or if it disrupts chewing and speech ability, doctors employ surgery to alter the shape of the palatine bone and remove the growth. Typically, this involves an incision in the middle of the palate to allow surgeons to get at the problem. In recovery, which usually takes three to four weeks, pain and inflammation are managed with prescription drugs.