TMD and the EAR
and EYE Connection
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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.
