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Otorhinolaryngology
Ear
Maria Magdalena Bujnowska-Fedak
Department of Family Medicine, Wroclaw Medical University
Basic anatomy and physiology
of the external and middle ear
The ear can be divided into three main parts:
–– external (outer) ear,
–– middle ear (tympanic cavity),
–– internal ear (labyrinth) (Fig. 1).
Fig. 1. Anatomical model of
the ear
External auditory canal (external acoustic meatus)
External auditory canal is about 4 cm in length if measured from the tragus; from
the bottom of the concha its length is about 2.5 cm. It is composed of two portions
– an external part which is cartilaginous and inner part which is formed of bone. The
cartilaginous part starts with aperture of the concha and represents one third length
of ear canal. It is covered with the skin, containing hair and sebaceous glands, which
discharge creates earwax (cerumen). Bone part (osseous portion) of the auditory
canal is created by the tympanic, squamosal or mastoid part of the temporal bone.
At the inner end of the ear canal is the narrow tympanic groove (tympanic sulcus),
in which the circumference of the tympanic membrane with fibro-cartilage ring is
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attached. From the front and bottom line the external auditory canal is adjacent to the
parotid gland. Rear wall of the duct is bordered with mastoid air cells. This facilitates
the transition of inflammation from the tympanic cavity to the mastoid antrum. The
skin on bony parts of the canal is thin, tightly adherent to the periosteum, there is
usually no hair or sebaceous glands.
External auditory canal to its course resembles the letter S with its concavity facing downwards and forwards. The tympanic membrane, which closes the inner end
of the meatus, is obliquely directed; in consequence of this the floor and anterior wall
of the meatus are longer than the roof and posterior wall. The arteries supplying the
meatus are branches from the posterior auricular, internal maxillary, and temporal.
The nerves are chiefly derived from the auriculotemporal branch of the mandibular
nerve and the auricular branch of the vagus.
Normal eardrum is thin, pearl-gray and semi-transparent. It is covered with a thin
layer of fat that comes from the wax, causing the shining of the drum. Sometimes,
if it is sufficiently transparent, some middle ear structures, such as the long crus of
the incus (crus longum) and the entrance to the Eustachian tube can be seen. The
longest diameter of the tympanic membrane is downward and forward, and measures
from 9 to 10 mm; its shortest diameter measures from 8 to 9 mm. The eardrum in the
newborn and the infant is almost round, in adults has an oval shape.
The greater part of eardrum circumference is thickened, and forms a fibrocartilaginous ring (annulus fibrosus) which is fixed in the tympanic sulcus at the inner
end of the meatus. There are a larger part of the tympanic membrane called pars
tensa, embedded in the tympanic sulcus and the smaller, upper, somewhat triangular
part of the membrane called pars flaccida (lax and thin). Boundaries between these
parts are two folds of the tympanic membrane named the anterior and posterior malleolar folds, which are prolonged to the lateral process of the malleus. The handle
(manubrium) of the malleus is firmly attached to the medial surface of the membrane
and is presented as a bright stripe (stria mallearis) on the drum. The central place of
the attachment the membrane to the malleus is concave and called the umbo. From
the umbo forward and downward runs cone-shaped light reflex, caused by the setting
of this part of the membrane at a right angle to the light illuminating it (Figs. 2, 3).
Eustachian (auditory) tube
OTORHINOLARYNGOLOGY
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The Eustachian tube connects the nasopharynx to the tympanic cavity. Its length
is about 36 mm, and its direction is downward, forward, and medialward. Tympanic
opening of the auditory tube is on the front wall of the tympanic cavity and the pharyngeal opening lies on the side wall of the nasopharynx on a level with the inferior
nasal turbinate. The upper third of the Eustachian tube is bony, with the lower two
thirds cartilaginous. The Eustachian tube is to equalize the air pressure (barofunction) between the middle ear spaces and the environment. The tube compensates for
variations occurring during atmospheric pressure changes, and also due to air absorption through the mucous membrane of the middle ear air cells. By the Eustachian
tube open, the pathological contents (mucus, pus, blood) can escape from nasopharyngeal or vice versa. The diameter of the tube is not uniform throughout, being
greatest at the pharyngeal orifice, least at the junction of the bony and cartilaginous
portions, and again increased toward the tympanic cavity; the narrowest part of the
tube is termed the isthmus. The mucous membrane of the tube is covered with ciliated epithelium and is thin in the osseous portion, while in the cartilaginous portion it
contains many mucous glands and near the pharyngeal orifice a considerable amount
of adenoid tissue, which has been named the tube tonsil. In the child the tube is more
horizontal and relatively wider and shorter than in the adult.
Tympanic membrane (eardrum) and tympanic cavity
The middle ear or tympanic cavity is an irregular, laterally compressed space
within the temporal bone. It is filled with air, which is conveyed to it from the nasal
part of the pharynx through the auditory tube. It contains a chain of movable bones,
which connect its lateral to its medial wall, and serve to convey the vibrations
communicated to the tympanic membrane across the cavity to the internal ear. The
tympanic cavity is bounded laterally by the tympanic membrane; medially, by the
lateral wall of the internal ear; it communicates, behind, with the tympanic antrum
and through it with the mastoid air cells, and in front with the auditory tube.
Fig. 2. Diagrammatic representation of the ear
Fig. 3. Normal tympanic membrane
The eardrum is a lateral membranous wall of the tympanic cavity. The membrane
consists of three layers – an outer epithelial layer, a middle fibrous layer, and an inner mucosal layer. The fibrous stratum consists of two layers: a radiate stratum, the
fibers of which diverge from the manubrium of the malleus, and a circular stratum,
the fibers of which are plentiful around the circumference but sparse and scattered
near the center of the membrane.
Vascularization of the tympanic membrane is derived mainly from the external auditory canal. The arteries of the tympanic membrane come from the deep auricular branch
of the internal maxillary, which ramifies beneath the cutaneous stratum; and from the
stylomastoid branch of the posterior auricular, and tympanic branch of the internal maxillary, which are distributed on the mucous surface. The membrane receives its chief
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nerve supply from the auriculotemporal branch of the mandibular; the auricular branch
of the vagus, and the tympanic branch of the glossopharyngeal also supply it.
–– the handle, which contains the power for the light source,
–– the head, which contains the light bulb and magnifying lens,
–– the cone, which is inserted into the ear canal.
Most otoscopes have a small air vent connection that allows the doctor to puff air
in to the canal. Observing how much the eardrum moves with air pressure assesses
its mobility, which varies depending on the pressure within the middle ear. This
technique is called insufflation.
Normally the air pressure within the middle ear is the same as that in the outer ear.
This allows the eardrum to lie in its middle position and respond to sound vibration
most efficiently. If the Eustachian tube is blocked, air cannot get to the middle ear to
equalize the pressure on the eardrum. This can impair hearing or, if the pressure difference is enough to stretch the eardrum, cause pain. It is possible to get some idea of
whether the Eustachian tube is blocked by asking the patient to gently blow out while
pinching a nose and closing lips. This is called Valsalva’s manoeuvre, and the normal
finding is that the eardrum moves slightly during it. When the Eustachian tube is
blocked, the eardrum cannot move.
Otoscopy examination and practical tips
References
1. Gray’s Anatomy of the Human Body. X. The Organs of the Senses and the Common
Integument. Available at URL: http://education.yahoo.com/reference/gray/subjects/subject/228 [cited 28.10.2010].
2. Netter FH.: Atlas of Human Anatomy. Saunders 2010.
3. Otoscopy. Anatomy. Available at URL: http://medweb.cf.ac.uk/otoscopy/anatomy.htm
[cited 28.10.2010].
4. Podstawy otoskopii. Med. Prakt. 1992, 11 (22), 49–55 (przedruk za zezwoleniem Welch
Allyn Inc.).
5. Sanna M., Russo A., de Donato G.: Color atlas of otoscopy; from diagnosis to surgery.
Thieme, New York 2002.
6. Steciwko A. (ed.): Vademecum umiejętności praktycznych lekarza rodzinnego. Akademia Medyczna we Wrocławiu, Wrocław 2007.
7. Steciwko A. (ed.): Umiejętności diagnostyczne i terapeutyczne w praktyce lekarza rodzinnego. Akademia Medyczna we Wrocławiu, Wrocław 2003.
8. Zalesska-Kręcicka M., Kręcicki T.: Zarys otolaryngologii. Wydawnictwo Lekarskie
PZWL, Warszawa 1998.
Otoscopy (ear examination)
OTORHINOLARYNGOLOGY
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Otoscopy examination is one of the methods used by the physician to determine
the causes of ailments of the ear and nasopharyngeal cavity. It is necessary to use for
this purpose an adequate otoscope, which gives good lighting, image magnification
and to assess the mobility of the tympanic membrane through the formation of pressure. Using otoscope it is possible to carefully examine the external auditory canal,
and especially the tympanic membrane (Fig. 1).
Otoscope used correctly is one of the most useful diagnostic tools to show
evidence that ear disease is the cause of the ailment of the patient.
An otoscope consists of three parts:
Fig. 1. Otoscope with
insufflation opportunity
1. The otoscopy should start from a healthy ear. Such an order will reduce patient anxiety, and the examination will enable comparison between the healthy
and ill ear (Figs. 2, 3).
2. Sit in a comfortable for you position.
3. View the external ear and the skin in the retro auricular (mastoid) area. Gentle
palpate to determine whether there is a pain.
4. Carefully watch the entrance to the ear canal, looking for dirtiness: wax, pus
or blood, affecting the course of the inspection.
5. Illumination is paramount. Most modern otoscopes have a very bright bulb
that is adequate for the job.
6. Check batteries. It is essential that the batteries are in good condition as a dim
light makes examination very difficult.
7. Use the biggest earpiece that you can fit into the ear canal. Small earpieces
may be easy to use but the amount of visual information you get is very limited.
8. Straighten the ear canal, which has a natural curve, makes it easy to insert the
speculum and to see the eardrum. In adults, this is done by pulling the pinna
upwards and backwards, in children – by pulling the outer ear backwards and
downwards or horizontally.
9. Otoscope is introduced into the place where the cartilaginous part of the ear
canal passes in the osseous portion. Introduction speculum out of this place is
painful. Introduction speculum sometimes causes a cough reflex and congestion of the ear canal.
10. Keep hands and speculum properly, do not cross arms, otoscope should be
directed obliquely forward.
11. During otoscopy a physical contact with the head of the examined patient
should be maintained to prevent injury to the ear canal and eardrum with unexpected movements of the patient. At the same time hold the otoscope at the
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you should put a light source
on the left side. It is important
that the light source, the eye
of the investigator and the ear
of the patient were situated at
the same height. Eye of the
investigator should be close to
the tested object, because if the
eye is distant from the central
hole in the mirror, watching the
edges of the hole is very probable.
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Fig. 4. Frontal speculum (mirror)
Ear examination – medical history
OTORHINOLARYNGOLOGY
Fig. 2. Ear examination
Fig. 3. Otoscopy on
the fantom
end near the head (eyepiece), this way movement of your hand and arm is not
translated into as much of the tip of the otoscope in the ear canal which may
cause discomfort.
12. Wax is not normally present in the inner third of the ear canal. Its presence there
may indicate inappropriate use of cotton tips/hygienic sticks to clean the ears.
13. Due to the limited field of vision, even with the largest speculum, there is
usually a need to change its position and angle to carefully inspect the entire
external auditory canal and the tympanic membrane.
14. During the otoscopy with the use of a frontal speculum (mirror), correct use
of light (Fig. 4). The light source should be located slightly behind and to the
right of the investigator. In this light setting it is possible to examine with the
right eye. When the right eye is weaker, you can examine the left eye, but then
The classic symptoms of ear disease are:
–– pain (otalgia),
–– hearing loss,
–– discharge (otorrhoea),
–– tinnitus,
–– vertigo.
Other relevant features in the history:
–– long history of middle ear disease,
–– otoxic drugs (antibiotics, diuretics, cytotoxics),
–– previous mastoid or middle ear surgery,
–– head injury,
–– systemic disease (e.g., multiple sclerosis, cardiovascular disease),
–– exposure to noise at work or recreation (shooting),
–– history of atopy and allergy (in children),
–– family history of deafness.
Examination of the external auditory canal
Abnormal findings may include:
–– a dry, flaky lining suggestive of eczema. The usual symptom is itching,
–– an inflamed, swollen, narrowed canal, possibly with a discharge indicating
infection (otitis externa). The usual symptoms include itch, local discomfort,
a discharge and often an unpleasant smell from the ear,
–– wax obscuring the eardrum,
–– a foreign body in the ear, such as: cotton, folded paper, toys, stones, beads,
crayons, seeds, insects and others.
Examination of the tympanic membrane
In a normal tympanic membrane one should be able to identify the following:
–– colour and shape (pearl-gray, semitransparent, circular),