The Tympanic Membrane and its Landmarks

The middle ear begins with the TM. This is the most important structure for the clinician diagnostically, because its appearance, and what can be seen through it, are by and large the only anatomic clues to what goes on inside (Figs. 3.3 and 3.4). The most visible landmark beneath the TM is the manubrium, or handle, of the malleus, the lower portion of this first ossicle. The upper portion of the manubrium has a visible prominence, seen near the top of the TM, called the short process. The bottom end of the handle, at the

16 3 Useful Anatomy and Function

16 3 Useful Anatomy and Function

Scar Tympanic Membrane

Fig. 3.3 Normal tympanic membrane of right ear:

1. Pars flaccida; 2. Short process of the malleus; 3. Handle (manubrium) of the malleus; 4. Umbo; 5. Supratubal recess; 6. Eustachian tube orifice (just to the right of the light reflex); 7. Hypotympanic air cells; 8. Stapedius tendon; c. Chorda tympani; I. Incus; P. Promontory; o. Oval window; R. Round window; T. Tensor tympani; A. Annulus. (Source: Sanna M, Russo A, DeDonato G. Color Atlas of Otoscopy. Stuttgart: Thieme; 1999)

Fig. 3.3 Normal tympanic membrane of right ear:

1. Pars flaccida; 2. Short process of the malleus; 3. Handle (manubrium) of the malleus; 4. Umbo; 5. Supratubal recess; 6. Eustachian tube orifice (just to the right of the light reflex); 7. Hypotympanic air cells; 8. Stapedius tendon; c. Chorda tympani; I. Incus; P. Promontory; o. Oval window; R. Round window; T. Tensor tympani; A. Annulus. (Source: Sanna M, Russo A, DeDonato G. Color Atlas of Otoscopy. Stuttgart: Thieme; 1999)

center of the TM, ends in the umbo, the "apex" of the drum (the TM is actually somewhat conical in shape, from the periphery toward the center). Thus, the umbo, the deepest central depression, has a circular appearance.

The examining light usually reflects back most brightly from the TM in a triangular shape, located anteroinferiorly to the umbo, the light reflex. When a TM is dulled by acute or chronic infection, or thickening for other reasons, the light reflex may be decreased or absent, but this is not an infallible diagnostic criterion. A light reflex can still be seen in many abnormal middle ears, especially those with clear fluid effusions.

Most of the TM (the pars tensa) has three layers: outer squamous epithelium, middle fibrous tissue, and inner cuboidal epithelium. Above the short process of the malleus is a variable and irregular small portion of the drum called the pars flaccida, which contains no fibrous middle layer, only an outer squamous and inner mucosal layer. The pars flaccida is clinically significant as a site for possible cholesteatoma formation. The same applies for the marginal posterosuperior portion of the pars tensa, which may also be

The Middle Ear 17

Tympanic Membrane Landmarks
Fig. 3.4 Structures of the right ear after removal of the tympanic membrane: f. Facial nerve bulge; j. incudostapedial joint. See also key to Fig. 3.3. (Source: Sanna M, Russo A, DeDonato G. Color Atlas of Otoscopy. Stuttgart: Thieme; 1999)

deficient in the middle fibrous layer in some disease states. Cholesteatoma, a squamous ingrowth, is discussed in more detail later.

Posterosuperiorly, the long process of the incus is frequently visible, deep to the drum, as it inserts into the stapes head. Going backward, the stapedius tendon may be seen as well. The vertical long process of the incus and the horizontal stapedius tendon can often be seen as a faint white backward-tilted "V." Overlying and above them, just adjacent to the margin of the drum, the white band of the chorda tympani nerve may also be seen through the drum. This arises from the facial nerve (cranial nerve VII) and courses forward between the malleus and incus to eventually innervate the anterior tongue, receiving taste sensation. Not well seen through the TM, the stapes, the smallest bone in the body, transmits sound from the incus into the oval window via its footplate. It is shaped like a stirrup and is directed medially toward the inner ear. The round window niche and the bony bulge of the promontory are structures of the medial wall of the middle ear. The visibility of all these landmarks varies with individual anatomy and scarring of the drum.

The periphery of the pars tensa, bordering the innermost external canal, contains a dense white fibrous ring called the annulus. Variably present is

18 3 Useful Anatomy and Function the vascular strip of vessels, not visible in Figure 3.3, but very prominent in Figure 5.5. This is seen on the upper drum just posterior to the manubrium, giving off vessels that course down the TM just behind the manubrium, as well as posteriorly, running along the peripheral annulus. These vessels may become bright red and inflamed in the early stages of acute otitis media. However, they may also be somewhat prominent in the normal individual.

Was this article helpful?

+1 0
Mole Removal

Mole Removal

Moles, warts, and other unsightly irregularities of the skin can be bothersome and even embarrassing. They can be removed naturally... Removing Warts and Moles Naturally! If you have moles, warts, and other skin irregularities that you cannot cover up affecting the way you look, you can have them removed. Doctors can be extremely expensive. Learn the natural ways you can remove these irregularities in the comfort of your own home.

Get My Free Ebook


Responses

  • emily
    What does it mean by loss of tm landmarks?
    3 years ago
  • shishay
    What are the five land marks of the middle ear?
    3 years ago
  • jessica
    What is the main landmark of the normal ear drum?
    2 years ago
  • Elfstan Bunce
    Where is the shorter process of malleus on tympanic membrane?
    2 years ago
  • J BAECKER
    What are the major landmarks of the tympanic membrane?
    2 years ago
  • alexander
    What all can be seen in normal tympanic membrane ?
    2 years ago
  • ASMARINA
    What is visible through the tympanic membrane?
    1 year ago
  • Karin
    What does loss of landmark mean?
    1 year ago
  • diana
    What does TM normal landmarks and mobility in ears mean?
    1 year ago
  • celedor
    What landmarks can you see with an otosocpe?
    1 year ago
  • otto
    What does "loss of landmarks" mean on ear exam?
    11 months ago
  • MIKA ELORANTA
    What landmark is lost with bulging tympanic membrane?
    10 months ago
  • lukas schmitt
    How to chart normal tympanic membrane with some fluid behind ears?
    10 months ago
  • ali
    What structure is visible with otoscope when look at tympanic membrane?
    8 months ago
  • sasha
    How to chart clear tympanic membrane?
    7 months ago
  • philipp
    What does poor landmarks in ear men?
    5 months ago
  • Maxima
    Which middle ear bone is most visible?
    5 months ago
  • lemlem semhar
    When you look at the tympanic membrane with an otoscope, what normal landmark is present?
    4 months ago
  • jonas
    What landmarks do i need to chart in assessemnt of tympanic membrane?
    4 months ago
  • Bertoldo
    What does it mean when you TM light relfex is in the center?
    3 months ago
  • tesmi
    What the most landmark for eardrum?
    2 months ago
  • kaisa
    What does abnormal appearance of the tm and eam mean?
    1 month ago
  • kristen perez
    Which parts of the inner ear can be visualized with assesing the tympanic membrane with an otoscope?
    1 month ago
  • virpi
    What does red manubrium of malleus?
    1 month ago
  • KALERVO
    Which bone is visible on otoscope?
    1 month ago

Post a comment