Zygomatic process

Zygomatic process
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Zygomatic process Definition

It is a slender protrusion of the temporal bone that serves to strengthen the Zygomatic arch.

Zygomatic process Etymology

Picture of Zygomatic process

Picture 1 – Zygomatic process

The word “Zygomatic” comes from the Greek term “Zygon” which means “Yoke” due to its similarity with a yoke set on oxen. The term “process” comes from the fusion of two Latin words “pro” standing for “forward” and “cessus” for gone. It is an archaic word that may be traced back to the compositions of Celsus, an early anatomist.

Zygomatic process Names

This outgrowth is known by various other names like:

  • Processus zygomaticus
  • Temporal zygomatic process
  • Processus zygomaticus ossis temporalis

In Latin, it is known as “Processus zygomaticus ossis temporalis”.

Zygomatic process Description

This is a thin, arch-shaped protrusion that arises from two roots on the anterolateral face of the squamous temporal bone. The anterior end of the arch arises in a media position from the articular tubercle. Its posterior root develops above the external acoustic meatus as a ridge. Its anterior root originates medially from the articular tubercle. The posterior root extends as the superior and the anterior root proceeds as the inferior margin of the protrusion.

The anterior root of the bony outgrowth makes a rough, toothed suture that joins the zygomatic bone. The temporalis fascia gets its site of attachment at the superior border of the protrusion. The inferior border and medial surface provide adhesion for the masseter muscle.

The zygomatic bone, in many cases, does not lead to the development of the inferior orbital fissure. This may be due to:

  • Articulation of the greater sphenoid wing with the maxilla
  • Interference of a wormian bone

The maxilla may be straightaway attached to the zygomatic temporal bone process by a dorsal extension of the maxillary zygomatic process. The maxillary process may unite with the lacrimal hamulus.

Zygomatic process Function

Being an attachment site for muscles, especially those involved in mastication, it serves to strengthen the zygomatic arch.

Zygomatic Process of Maxilla

It is a rough, pyramidal protuberance that laterally projects to create with the zygomatic bone a non-smooth articular surface. It has three surfaces – facial, orbital and infratemporal. Its apex is medial and base lateral. It is referred to as “Processus zygomaticus maxillae” in the Latin language.

It forms an anterior surface section in the front. It is concave at the back and forms a section of the infratemporal fossa. It is rough at the top and jagged, which helps it articulate with the zygomatic bone. At the bottom, it exhibits the prominent arched border. This acts as a division between the infratemporal and anterior surfaces.

Zygomatic Process of Frontal Bone

It is the zygomatic process section that comprises of the frontal bone. It extends in a lateral and inferior manner from the frontal bone. It is a thick lateral outgrowth of the supraorbital margin. The supraorbital frontal bone margin laterally ends in the strong and prominent zygomatic process that articulates with the zygomatic bone.

Fracture of the Zygomatic process of temporal bone

Depressed fractures of distal zygomatic process section of temporal bone typically cause malocclusion, difficulties in eating and atrophy of masticatory muscles. In the early stages, however, such fractures cause little or no symptoms. As a result, these often go undiagnosed. With passing time, osseous callus develops and leads to reduced movement of the jaw. Diagnosis can help identify clinical signs like:

  • Atrophy of masticatory muscles
  • Decreased movement of the jaw
  • Malocclusion
  • Perceptible hard inflammation in TMJ area

The differential diagnosis aims at distinguishing the fracture from other similar problems like:

  • Canine masticatory myopathy
  • Degenerative joint disease (DJD) of TMJ
  • Infection of TMJ
  • Mandibular neuropraxia
  • Neoplasia of TMJ
  • TMJ (Temporomandibular joint) fracture

The problem can be treated by surgical excision of caudodistal zygomatic process. It generally has a good prognosis.

Zygoma fracture

Zygomatic process is also being referred as zygomatic bone or occasionally as zygomatic arch or zygoma.  Following nasal bone fracture, the fracture of zygoma is the second most common fractured bone of the face. Road traffic accidents are identified to be the leading cause of zygomatic arch and zygomatic bone fractures, while sports and assault are other known ones.

While assessing the patients with zygomaticomaxillary complex (ZMC) or zygomatic arch or following points must be considered:

  • Limited jaw movement or alteration in biting: an  indication of zygomatic arch, maxilla, or mandible injury
  • Troubled vision: an indication of a globe or orbital injury
  • Sensory disruption in the upper gum and cheek region: an indication of infraorbital nerve injury
  • Peripheral area damage:  a possible indication of a head or cervical injury

Zygoma Investigational procedures:

X rays

Basic x-ray of the skull is common for diagnosing ZMC or zygomatic arch fractures.  Standard x-ray views include facial, occipitomental and submento-vertical. While interpretation can be challenging, the following points should be checked:

  • An ‘elephant’s trunk’ – observation of maxillary line medially and zygomatic line laterally
  • The sinus outline – look out for any fluid level or opacification in the maxillary sinus
  • The orbital outline – an orbital floor fracture is seen as the droplet sign which depicts prolapse of soft tissue into the maxillary sinus
  • The coronoid processes:  should be bilaterally equidistant from the maxillary line

Spiral facial CT scan is an effective method that allows accurate diagnosis of the zygomatic arch and ZMC fractures. However, it is the second line of an investigation ordered usually by maxillofacial practitioners or when other injuries, like cervical spine injury, do not allow for routine facial analysis by x-rays.

CT also reveals any prevalent intracranial injury. The fracture is represented by displacement along medial, posterior, and inferior positions. Displacement of malar complex fractures may lead to increased orbital volume because of orbital floor blowout or angulation of the zygomaticosphenoid suture. Planning a surgery also requires a CT scan of facial series.

Magnetic Resonance Imaging (MRI)

Although currently CT scan is being widely used for evaluating orbital fractures, MRI could also be a potential alternative.

Ultrasound

Ultrasound is beneficial for providing a good view of the frontal sinus’s anterior wall and zygomatic arch, especially during limiting radiation exposure.

Focused ocular ultrasound (FOUS) has also been found to highly effective in diagnosing followed by excluding both ocular and orbital injuries.

Zygoma Management

ZMC fracture

Most of the ZMC fractures are manageable until there is a decrease in the local swelling and examination by a maxillofacial surgeon.

Any indication of eye trauma like diplopia or decreased vision warrants immediate examination by maxillofacial surgeon or ophthalmologist, while infraorbital suspicion does not necessitate one.

General advice to patients in case of a fracture is as follows:

  • Usage of ice packs to the affected area to alleviate swelling
  • Avoidance of blowing of the nose or holding the nose while sneezing as it may result in surgical emphysema.
  • Regular usage of analgesia
  • Follow any other advice related to general head injury

Although there is a there is an existence of a rare risk of developing orbital cellulitis, there is lack of evidence that suggests regular administration of antibiotics in ZMC fracture.

Zygomatic arch fracture

Unlike ZMC fractures, the vast majority of zygomatic arch fractures do not require urgent surgery. However, restriction of movement of mouth resulted from trapping mandibular condyle or temporalis muscle necessitates immediate examination from a maxillofacial surgeon.

Good prognosis in ZMC and zygomatic arch fractures is indicated by:

  • An absence of any deformity
  • Joining of bones
  • Complete mandibular movement

Prevention of ZMC and zygomatic arch fractures

  • Wearing seat belts are of great importance in lowering injuries resulting from road traffic accidents.
  • Consumption of alcohol is the leading cause of facial injuries and assaults.  Several remedial measures suggested in such cases include usage of plastic glasses and bottles in licensed premises, regular targeted policing and regulation of the alcohol prices. Also, minimum price per unit policy, and modifying supply and marketing are found to be helpful.
  • Usage of appropriate protective gears during sports may aid in reducing injuries associated with sports. However, more research and evidence is needed.

Zygomatic process Pictures

Here are some useful Zygomatic process photos that will help you get an exact idea about the physical appearance of this bony projection. You may use these Zygomatic process images for your reference.

Image of Zygomatic process

Picture 2 – Zygomatic process Image

Photo of Zygomatic process

Picture 3 – Zygomatic process Photo

References:

http://www.vetstream.com/canis/Content/Disease/dis00902

http://www.enotes.com/topic/Zygomatic_process_of_maxilla

Last updated on November 14th, 2018 at 8:01 pm

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