Maxilla (Upper Jaw Bone): Anatomy, Function, Articulations & Common Problems

The Upper jaw is the paired bone that forms your upper jaw, sitting at the center of the face between the nose and the mouth. Beyond anchoring the upper teeth, this facial bone shapes the floor of the eye sockets, the walls of the nasal cavity, and the roof of the mouth, which is why an injury or infection affecting the Upper jaw rarely stays confined to one area.

This guide walks through the Upper jaw bone’s structure, its role in everyday functions like chewing and breathing, and what happens clinically when it’s fractured, infected, or corrected surgically.

Upper jaw at a Glance

Feature	Detail
Location	Midface, between the nose and mouth
Number of bones	Paired, fused at the interupper jaw suture
Processes	4 – alveolar, frontal, zygomatic, palatine
Bones it articulates with	9, including the opposite Upper jaw
Sinus	Upper jaw: maxillary sinus, the largest paranasal sinus
Main sensory nerve	Upper jaw: division of the trigeminal nerve (CN V2)
Teeth supported	8 permanent teeth per Upper jaw, 16 total
Movement	Fixed; does not articulate directly with the mandible

Where Is the Upper Jaw Located?

The Upper jaw sits in the middle third of the face, between the nose and the mouth. It’s a paired bone – left and right halves fused at a midline suture – and together the two upper jaws form most of the upper jaw while contributing to the orbital floors, the lateral walls and floor of the nasal cavity, the anterior hard palate, and the sockets that hold the upper teeth.

What Does the Upper Jaw Do?

The Upper jaw’s core functions center on chewing, facial structure, and airway support:

• Anchors the upper teeth via the alveolar process, giving the mandible a fixed surface to bite against
• Contributes to the hard palate, separating the mouth from the nasal cavity
• Contributes substantially to the floor of the orbit, supporting the eye from below
• Forms part of the lateral wall and floor of the nasal cavity
• Houses the Upper jawry sinus, the largest of the paranasal sinuses
• Helps transmit chewing forces upward through the frontal and zygomatic processes into the rest of the skull, distributing load away from the jaw joint

Because the Upper jaw itself doesn’t move, it gives the mandible something stable to work against every time you bite, chew, or speak.

Upper jaw Anatomy: One Body, Four Processes

The Upper jaw is a paired, pyramidal bone made up of a central body and four bony processes: alveolar, frontal, zygomatic, and palatine. Picture the body as a hollow structure with four arms reaching outward to connect with neighboring facial bones.

The Four Surfaces of the Upper Jaw Body

Surface	Faces	Notable Landmark
Anterior (facial)	Outward, toward the face	Infraorbital foramen, canine fossa
Posterior (infratemporal)	Backward, into the infratemporal fossa	Upper jawry tuberosity
Superior (orbital)	Upward, into the eye socket	Contributes most of the orbital floor
Medial (nasal)	Inward, into the nasal cavity	Upper jawry hiatus, opening into the sinus

The Four Processes

• Alveolar process – contains the dental sockets for the upper teeth; each Upper jaw normally supports eight permanent teeth in the adult dentition, for 16 upper teeth total.
• Frontal process – rises upward to articulate with the frontal bone.
• Zygomatic process – extends laterally to articulate with the cheekbone.
• Palatine process – extends medially and, together with its counterpart, forms most of the hard palate.

Key Anatomical Landmarks of the Upper Jaw

Landmark	Location	Function or Relationship	Clinical Importance
Infraorbital foramen	Anterior surface, below the orbital rim	Exit point for the infraorbital nerve and vessels	Landmark for infraorbital nerve blocks; numbness signals nerve injury
Infraorbital groove and canal	Orbital surface	Carries the infraorbital nerve and vessels	Frequently disrupted in orbital floor and Le Fort II fractures
Canine fossa	Anterior surface, lateral to the incisive fossa	Shallow depression over the canine root region	Surgical access landmark, such as the Caldwell–Luc approach
Canine eminence	Anterior surface	Bony convexity near the canine root	Surface landmark on imaging and clinical exam
Incisive fossa	Anterior surface, above the incisors	Adjacent to nasalis muscle attachment	Reference point in anterior upper jaw surgery
Anterior nasal spine	Medial-anterior junction	Forms part of the piriform aperture	Landmark in rhinoplasty and nasal trauma assessment
Incisive canal and foramen	Midline, hard palate	Passage for the nasopalatine nerve and vessels	Site of nasopalatine nerve block
Upper jawry tuberosity	Behind the last molar	Attachment for part of the medial pterygoid muscle	Landmark for posterior superior alveolar nerve block
Upper jawry hiatus	Medial surface	Communicates with the Upper jawry sinus	Relevant to sinus drainage and sinus surgery
ZygomaticoUpper jawry suture	Zygomatic process/zygomatic bone junction	Structural link to the cheekbone	Common fracture line in midface trauma

Read More: Maxilla

Nine Bones, One Central Connector

Each Upper jaw articulates with nine surrounding bones, including its opposite twin at the midline. This extensive connectivity is a major reason trauma to the Upper jaw rarely stays isolated to a single site.

The Upper jaw connects to the frontal, nasal, lacrimal, ethmoid, zygomatic, and palatine bones, along with the inferior nasal concha, the vomer, and the opposite Upper jaw. Notably absent from this list is the mandible – despite both being informally called “jaws,” the Upper jaw and mandible never articulate directly with one another; they interact only through the teeth and surrounding soft tissue.

The Upper jawry Sinus: Development and Anatomy

Within the body of the Upper jaw lies the Upper jawry sinus, the largest of the four paranasal sinuses and the first to begin developing before birth. Sinus development generally begins in the middle of pregnancy, with a small, fluid-filled cavity present at birth that gradually aerates over the following months. Growth then continues in phases tied to overall facial development: rapid expansion during the first few years of life, further extension through the childhood years, and a final growth spurt as the permanent premolars and molars erupt, pushing the sinus floor closer to the nasal cavity floor. Full adult sinus dimensions are generally reached by the late teens, though some growth can continue slightly longer in certain individuals.

Because the sinus floor often sits close to the roots of the upper premolars and molars – sometimes separated by only a thin shelf of bone – dental infections can occasionally spread into the sinus, a pattern known as odontogenic sinusitis. More often, sinus infections arise from nasal inflammation and blocked drainage rather than dental disease, so a dental cause is worth considering specifically when symptoms are one-sided or linked to known tooth problems that don’t resolve with standard sinus treatment.

Nerve and Blood Supply of the Upper Jaw

Sensory innervation of the Upper jaw, upper teeth, and palate comes from branches of the upper jaw division of the trigeminal nerve, also called CN V2:

• Infraorbital nerve – supplies the lower eyelid, side of the nose, and upper lip
• Superior alveolar nerves (anterior, middle, and posterior) – supply the upper teeth and gums
• Greater palatine and nasopalatine nerves – supply the hard palate

Blood supply comes primarily from branches of the Upper jawry artery running alongside these nerves, which is one reason numbness and localized bleeding often occur together after Upper jawry trauma or dental procedures.

How the Upper jaw Develops

The Upper jaw forms through intramembranous ossification – bone laid down directly without a cartilage template – arising from the Upper jawry prominence of the first pharyngeal arch during early embryonic life.

Cleft lip and cleft palate arise from distinct developmental failures and shouldn’t be treated as the same condition:

• Cleft lip results from failure of fusion where the merged medial nasal prominences meet the upper jaw prominences, a process normally completed by the end of the sixth week of gestation. Failure can extend into the nostril, alveolus, and primary palate.
• Cleft palate results from failure of the palatal shelves – projections of the upper jaw prominences – to elevate above the tongue, meet at the midline, and fuse, a process normally completed between roughly the ninth and twelfth week of gestation.

Because these are separate fusion events, a cleft lip and cleft palate can occur independently or together depending on which specific step fails. Confirmed cases are typically managed through multidisciplinary craniofacial care involving staged surgery, orthodontics, and speech therapy.

Upper Jaw Fracture: Understanding the Le Fort System

Facial trauma involving the Upper jaw is commonly classified using the Le Fort system, developed from cadaver studies more than a century ago and still the reference framework today.

What are the three types of Le Fort fractures? Le Fort I is a horizontal fracture separating the hard palate and upper teeth from the rest of the midface. Le Fort II is a pyramid-shaped fracture running through the nose, Upper jaw, and orbital floor. Le Fort III completely separates the entire facial skeleton from the skull base. By definition, all three types involve the pterygoid plates at the back of the upper jaw.

Type	Fracture Pattern	Structures Involved
Le Fort I	Horizontal	Alveolar ridge, upper jaw sinus walls, pterygoid plates
Le Fort II	Pyramidal	Nasal bridge, lacrimal bones, orbital floor and rim, pterygoid plates
Le Fort III	Transverse	Orbital walls, zygomatic arch, naso-orbito-ethmoid complex, pterygoid plates

Real-world facial trauma often produces mixed patterns that don’t map neatly onto a single Le Fort type, which is why CT imaging – rather than physical exam alone – is the standard tool for diagnosing complex midface fractures and planning treatment.

Warning signs of a possible upper jaw fracture include a change in bite alignment, facial swelling or asymmetry, numbness across the cheek or upper lip, nosebleeds, and, in more serious cases, double vision, restricted eye movement, or difficulty breathing. Any of these symptoms following facial trauma calls for prompt evaluation by an oral and maxillofacial surgeon rather than self-assessment at home. Not every facial fracture requires surgery – some non-displaced fractures heal without it – but true Le Fort fractures typically need surgical fixation because they disrupt the structural buttresses that hold the face together.

Clinical Significance Across Specialties

The Upper jaw sits at the intersection of several fields of care:

• Dentistry – the alveolar process and its bone density directly affect extractions, implants, and orthodontic treatment.
• ENT and radiology – the Upper jawry sinus and its drainage pathway are central to sinus disease diagnosis and treatment.
• Oral and maxillofacial surgery – Le Fort fractures, orthognathic correction, and cleft repair are managed here.
• Orthodontics – Palatal width, growth pattern, and suture maturity influence bite alignment and the timing of expansion treatment.

Correcting a Narrow Upper Jaw in Adults

A narrow upper jaw can be corrected at any age, but the approach depends heavily on how mature the midpalatal suture is:

• Conventional tooth-borne expansion works well in growing children and some younger adults, though it faces more resistance once the suture matures.
• Mini-screw-assisted expansion (MARPE) anchors expansion forces directly to bone using palatal mini-implants, offering a non-surgical option for some adults with a still-responsive suture, though results vary by case and the evidence base remains limited.
• Surgically assisted expansion (SARPE) combines a small surgical release with expansion hardware and remains a common choice for adults with more complete sutural fusion.
• Full orthognathic surgery is reserved for skeletal discrepancies that go beyond transverse width alone.

Because outcomes vary so much by anatomy and suture maturity, the right approach should be determined by an orthodontist or oral and maxillofacial surgeon on a case-by-case basis rather than assumed from age alone.

Upper jaw vs. Mandible: Key Differences

Point of Comparison	Upper jaw	Mandible
Movement	Fixed	Mobile, via the temporomandibular joint
Bone count	Two bones fused at midline	One continuous bone
Sinus present	Yes – Upper jawry sinus	No
Direct joint with each other	No	No
Typical fracture pattern	Le Fort types I–III	Angle, body, condyle, symphysis
Ossification	Intramembranous	Intramembranous, guided by Meckel’s cartilage

The Bottom Line

The Upper jaw is far more than “the upper jaw” – it’s a load-bearing hub connecting the eye sockets, nasal cavity, palate, and cheekbones into one working structure. That connectivity is exactly why trauma, infection, or developmental anomalies affecting this facial bone tend to involve more than one specialist, and why understanding its anatomy provides useful context whether you’re studying for an anatomy exam, recovering from facial trauma, or researching a dental procedure.

Frequently Asked Questions