TMD and the EAR and EYE Connection

TMD and the EAR and EYE Connection

To fully appreciate the TMD and the EAR and EYE connection, it would benefit to look at their commonality in nerve innervations.

The Trigeminal Nerve (V): It is further subdivided into three branches:

1.      Ophthalmic Division (V1): It is the upper division of the Trigeminal nerve system. It has three major branches:

a.       Lacrimal nerve cries sensory information from the lateral part of the upper eyelid, conjunctiva, and lacrimal gland.

b.      Frontal

c.       Nasociliary

2.      Maxillary Division (V2): It is the middle division of the Trigeminal nerve and gives general sensory to the nerve branches to the zygomatic, infraorbital areas (branching further off to the outer nasal, upper lip areas), upper teeth, eye, palatal, posterior nasal areas, pharyngeal area and the meningies.

3.      Mandibular Division (V3): It is the lower division of the Trigeminal nerve and gives sensory the buccal, tongue, lower teeth, frontal ear and acoustic areas, the temporomandibular joint areas and meningies.

a.       It also caries motor branches to medial pterygoid (further to Tensor Veli Palatini and Tensor Tympani), lateral pterygoid, masseter, deep temporal, front area of the digastric and mylohyoid muscles.

The Facial Nerve (VII): Innervates muscles of the nose, buccinators, rhisorius, obicularis oris, muscles of lower lip and chin, platysma, and posterior area of the digastric.

There are three types of Pain:

1.      Vascular------- 10%

2.      Neurologic---- 10%

3.      Muscular------ 90%

The primary etiology of muscle pain is due to sustained muscle contraction resulting in vascular entrapment. Blood flow is impaired, oxygen is depleted and anaerobic metabolism starts.

The EAR Connection:

Eustachian Tube dysfunction: The Eustachian tube is the connection between the middle ear and the pharynx. It has three functions which are the aeration (equalizing pressure), clearance, and protection of the middle ear. Pressure equalization being its main option is regulated by three muscles including the Tensor Veli Palatini (TVP).

Patients suffering form TMJD often complain of a hearing loss, fullness isn the ears, and hypersensitivity to sound (hyperacusis). The TVP is innervated by the V3 division of the trigeminal nerve (motor branch) and lies in close anatomical proximity to the medial pterygoid. When there is pain occurring from primary pain source such as the temporalis, masseters, and medial pterygoid muscles, the effects spread to other muscles that share the same nerve supply. Dysfunction in muscles causes excitation and resulting in unnecessary sustained contraction of a muscle. In the case of the TVP muscle this sustained contraction causes the lumen of the Eustachian tube to remain patent at rest and pressure build up. This will give rise to the complaint of fullness and pressure in the ear and hollow sounding voice, but no changes in hearing. The closeness of the TVP to the medial Pt muscle is of great importance. Any chronic contraction of the medial Pt can impair normal function of the TVP. This in turn will prevent normal dilation of the Eustachian tube resulting in an inability to equalize the middle and outer ear pressure. Patients may complain of ear pain in a rapidly descending airplane and when scuba diving.

Displaced Condyle (retruded) and Mandibular-Malleolar Ligament (MML): A change in vertical dimension affects condylar position within the glenoid fossa. Teeth dictate the relationship of the lower jaw (mandible) to the upper jaw (maxilla) when teeth are in contact. A deep bite/over closure will translate the condyles back within the glenoid fossa resulting in compression of the retrodiscal tissue. The patient’s impression is pain in the ear (otalgia). The MML also plays a role in ear complaints. This ligament connects the neck and anterior process of the Malleous (hammer shaped bone in the middle ear, part of the ear ossicles) to a part of the capsule, the disc, and sphenomandibular ligament (ligament between the sphenoid bone and the mandible) through the small channel known as the petrotympanic fissure. A change in mandibular posture can affect the tension of the MML which in turn affects the movement of the ear ossicles. Many patients will complain of pressure and/or ringing in the ears when moving the lower jaw forward. The petrotympanic fissure is a communication from the middle ear to the glenoid fossa (the cavity where the joint is) and it is locate behind the condyle. In addition the fissure also contains the anterior tympanic artery which supplies the tympanic membrane (ear drum) and chorda tympani (branch of the Facial nerve VII). It also contains lymph channels. A posterior displacement of the condyle results in an increase in Tinnitus and Vertigo.

There is a mechanism that protects the inner ear form excessive sound. This protection is achieved by certain intratympanic muscles. Among them the tensor tympani muscle which is also supplied by a segment of the trigeminal nerve. Again when there is deep somatic and visceral pain occurring from a primary pain source such as the muscles of mastication, the effects spread to other divisions of the same neural segment. The action of tensor tympani is to pull on the tympanic membrane to increase its tension to reduce the movement of the ossicles when loud sound is present, hence protection of the middle ear. A dysfunction in this muscle will result in sensitivity to loud noise.

The EYE Connection

Patients suffering from craniomandibular dysfunction often complain of pain behind the eyes. The back portion of the orbital bony complex contains the greater and lesser wing of the sphenoid bone. The bones where the lateral and medial pterygoid muscles insert lie just below them namely medial and lateral pterygoid plates. Chronic contracture of these muscles could result in the torquing action of the sphenoids. Another recent finding that also could lead to retro-orbital pain is the Spenomandibular muscle. It originates from maxillar portion of the sphenoid bone and inserts into the internal oblique line of the mandible.