ANATOMY and PHYSIOLOGY of ENT-

ORGANS

The ear

The ear is divided into three large parts:

The external ear The middle ear The inner ear

The outer earThe outer ear comprises the pinna and the

external auditory rneatus. The outer part of this is cartilaginous. The deep part is bony.

The cartilaginous meatus contains hair follicles and glands which secrete wax. The hair follicles extend only for a short distance into the ear and are not found in the deeper parts of the external meatus. The external meatus varies in size and form with growth.

The topography of meatus: The middle cranial fossa is above. The mastoid bone is behind.The joint of the lower jaw is in frontThe parotid gland is below

 

The Middle Ear

The tympanum

The Eustachian tube

The mastoid antrum and cells

The tympanic membraneThe tympanic membrane consists of

three layers — an outer epithelial layer, a middle layer of yellow elastic fibrous tissue and an inner layer of mucous.

The drum membrane is divided into two parts, the pars tensa (1) and the pars flaccida (2). In the pars flaccida the fibrous layer is absent. This area constitutes only the small uppermost part of the eardrum and is sometimes difficult to see. It is frequently referred to as the attic part of the eardrum; chronic perforations in this area are potentially dangerous, as will be seen later.

The Landmarks of the Eardrum

The most prominent landmark is the handle of the malleus, seen as a white streak running down to the ap proximate centre of the drum. At its upper end is a small projection known as the short process.

In the drum membrane are two folds stretching anteriorly and posteriorly from the short process. They are known as the anterior and posterior mallear folds and the part of the drum above this level constitutes the pars flaccida.

1. The umbilicus of eardrum2. The Handle of the malleus3. The posterior fold4. The short process of the malleus5. The anterior fold6. The light reflex.

The Tympanum The middle ear can be divided

into three portions. The uppermost portion is the attic, the middle portion the mesotympanum, and the lowest portion the hypotympanum. The attic is that partof the middle ear above the level of the mallear folds. It is divided into a number of small pockets by the contained ossicles, their ligaments and mucosal folds. Chronic infection may localize in these spaces. It should be noted that the middle ear extends beyond the limits of the drum.

The Ossicles of the Middle Ear

The middle ear is an air-containing space and contains three ossicles: the malleus, incus and stapes.

The handle of the malleus is firmly embedded in the middle layer of the drum. The stapes footplate occupies the oval window of inner ear

The malleus The incus The stapes The eardrum

The Topography of Tympanum

The middle cranial fossa – is above

The mastoid bone (the biggest cell is known as antrum or cave) – is behind

The inner carotid - is in front ofThe jugular vein – is belowThe eardrum – is the lateral wallThe medial wall is the wall of the

inner ear with two windows: oval window (connects with the stapes) and round window (closed by the membrane of scala tympany)

 

The Eustachian tube

The Eustachian tube connects the tympanum and the nasopharynx. It is closed in adults and opened by swallowing.

Functions: Barometric (to maintain the

pressure of air inside the middle ear and mastoid system approximately equal to the external atmospheric pressure)

To drain the secret from the middle ear to the nasopharynx

To protect the middle ear from nasopharyngeal infection (due to respiratory epithelium)

The characteristic of the Eustachian tube in children

1.     The Eustachian tube is short, straight and wide. It opens in nasopharynx much below in compare with adults.

2. The Eustachian tube is open all time.

3. The respiratory epithelium covered the tube is underdeveloped in newborn.

The characteristic of the middle ear in newborn

1.     There are remainders of the embryonic mixoid tissue in tympanum until 3 years old.

2. There is no full ossification of the tympanum walls. So that there are places of contact between mucous membrane of middle ear and dura mater of the brain.

The characteristic of the middle ear in newborn

The eardrum is more thick than the eardrum in adult. And the angle between the eardrum and the meatus is more sharp so it is much more difficult to look carefully the babies eardrum.

1 – eardrum in adult 2 – eardrum in newborn

The characteristic of the mastoid bone in newborn

There is only one air cell of the mastoid bone in newborn – antrum or the cave. So a newborn can’t suffer from mastoiditis but antritis is a frequent pathology of this age.

NOSE and PARANASAL SINUSES

The external nose

The external nose is supported by bone and cartilage.

The bony part is formed mainly by the nasal bones on each side, and the frontal process of the maxillary bone.

The cartilaginous portion is formed by several cartilages which support and give shape to the lower part of the nose and nasal tip.

The nasal cavity

The nasal cavity is divided by the nasal septum into two parts which have similar anatomical structure but may be asymmetrical

The septum of nasal cavity

The septum is a structure composed partly of cartilage and partly of a bone.

The septum is covered by perichondrium where there is a cartilage, with periosteum where there is a bone, and outside this with mucous membrane.

Septum of nasal cavity

Nasal septum deviation is the frequent reason of nasal obstruction.

Septum of nasal cavity

The lower and anterior area of nasal septum is known as Epistaxis zone or Kisselbach zone. This area from which bleeding commonly occurs in patients due to situation of arteries. area,

The Lateral Wall of Nasal Cavity

On the lateral wall there is a system of ridges known as turbinates, each of which overhangs a groove known as a meatus:

1 – inferior2 – middle 3 – superiorThe inferior turbinates forms a

bone by itself, the others are the parts of ethmoid bone.

Underlying the mucous membrane there is erectile tissue with many venous blood vessels.

The Meatuses of the Nose

The meatuses of the nose are of importance, since they are the drainage channels of the air sinuses. The appearance of pus in one of the meatuses is of diagnostic importance in infections of the air sinuses opening into particular meatus.

The Meatuses of the Nose

1 – inferior nasal meatus

2 – common nasal meatus

3 – middle nasal meatus

4 – nasal septum5 – middle turbinate6 – inferior turbinate

The Nasal Functions

1.   Olfaction. 2.   Filtration. 3.   Humidification and

warming of the air passing to the lung.

4. Vocal resonance. Aesthetic function.

The Nasal Functions

The functions depend upon the mucous membrane with its underlying tissues. In certain areas such as the turbinates this is a complicated structure of ciliary mucous membrane, glands, blood spaces and connective tissues based upon bone, and is under the control of the autonomic nervous system. In this way the turbinates act as a valve mechanism, enlarging or narrowing the air channels and so determining the direction of the air stream

Ciliary Action

Ciliary action is the means by which the mucous membrane cleanses itself and removes unwanted material. By the movement of the cilia a constant streaming of mucus is produced from the nostrils to the pharynx. Any interference with normal action causes unpleasant symptoms. Post-nasal 'drip', or 'catarrh', which is so often a cause of complaint, is an expression of the inability of the ciliary mechanism to deal with thickened mucus, which slowly finds its way into the pharynx, where it accumulates. The conditions necessary for efficient ciliary action are mucus of the correct consistency and adequate aeration.

Filtration and Humidification Filtration is effected by the

adhesion to the mucous film of dust, bacteria and other particles. These are removed by ciliary action into the pharynx and swallowed with the secretions.

Humidification. The moistening and warming of the air passing to the lungs is one of the chief functions. Air reaches the lungs at about 30°C and at 75-95% relative humidity. When, during cold weather, the air in a room is heated, the humidity may fall. To increase this humidity to the level necessary for comfort may cause a severe strain on the nasal mechanism.

Olfaction Discharge

Olfaction as a function may be influenced in various ways. For example, obstruction from inflammation changes may prevent air reaching the olfactory area.

Sometimes toxic or infective conditions or head injury damage the nerve endings and destroy or alter the sense of smell.

So if the patient has smell loss he suffer from:

- Respiratory hyposmia or- Essential hyposmia.

Vocal Resonance Discharge

In case of nasal obstruction the vocal resonance nasal function is disturbed. And the voice of patient obtains the nasal intonations or twang.

There are two kinds of twang:1. Closed Twang (due to

nasal obstruction)

2. Opened Twang (due to pathological associated between nasal and oral cavities (cleft palate, palate paralyses)

Deformities of the Nose

Nose is the center of face. The form of the external nose influence on the appreciation of the appearance

Paranasal sinuses

There are eight air sinuses situated around and near the nasal cavity (4 pairs):1. Maxillary sinuses2. Frontal sinuses3. Ethmoidal sinuses (is divided into anterior and posterior)4. Sphenoidal sinuses.

Paranasal Sinuses Functions

Vocal-resonance. They are like thermos bottle

defend our brain against over high and low temperature.

They are protect the brain and the eyes at the time of head injury (like air pillow of the car).

They are the strong barrier that prevent vitally important structures (cranial cavity and orbita) from the spreading of the infection

Paranasal Sinuses

The anterior group(maxillary, frontal and anterior

ethmoidal cells) drains into the

middle meatus The posterior group

(posterior ethmoidal cells and sphenoidal sinus) drains into the

superior meatus Into the inferior meatus

drains the naso-lacrimal duct

Paranasal Sinuses

It should be noted that, while the inferior and middle meatuses are open at both ends, the superior meatus is clothed at the anterior end. This means that pus from the posterior group of sinuses will not be seen on anterior rhinoscopy.

Paranasal Sinuses in Children

There is only well developed ethmoidal sinus in newborn. The other sinuses are underdeveloped.

The development of maxillary sinus comes to the end to 4-5 years of life.

The frontal sinus has the longest period of development – until to 11-13 years of life

The Pharynx

The pharynx comprises three parts — the nasopharynx, the oropharynx and the hypopharynx.

The Pharynx

The nasopharynx is situated above to a line at the level of the soft palate .

The oropharynx is situated below this line and extends to the level of the tip of the epiglottis.

the hypopharynx commences at the level of the tip of the epiglottis and extends to the level of the cricoids' cartilage

The Pharynx

It has 7 holes to connect with neighboring organs:

1. Two choanae (with nasal cavity).

2. Two holes of auditory tube (with tympanic cavities).

3. Throat (with oral cavities).

4. Aperture of larynx. 5. Aperture of esophagus.

The NasopharynxAt the junction of the roof and

the posterior wall is situated the aggregation of lymphoid tissue called adenoids or pharyngeal tonsil. Anteriorly the nasopharynx is in continuation with the posterior choanae of the nose, with the posterior ends of the three turbinates on each side and the posterior edge of the nasal septum in the midline On the lateral wall there are the openings of the Eustachian tubes Behind these are the aggregation of lymphoid tissue called tonsil of torus tubaris

The Nasopharynx

The pharyngeal tonsil often becomes overlarge in children of 5-6 years old. It may block choanae and cause nasal obstruction.

The Oropharynx

Nasopharynx and oropharynx are separated by the strong mobile, membranous-muscular soft palate. The uvula hangs from the soft palate in the midline. From the palate stretch down on each side two folds of mucous membrane and muscle to meet the side of the tongue. These are the pillars of the fauces; they are known as an anterior and posterior palatine arches.

The Oropharynx

Between the palatine arches there are the faucial tonsils, while below the tonsils, into the base of the tongue, are masses of lymphoid tissue which are called the lingual tonsil

The Oropharynx

On the posterior wall of the oropharynx are many little aggregations of lymphoid tissue which are liable, in certain conditions, to enlarge and become inflamed.

The Lymphoid Circus Of Pharynx

It consist of 6 tonsils (3 – in nasopharynx, 3 – in oropharynx)

The two faucial (or palatine) tonsils The two tonsils of torus tubaris The one pharyngeal tonsil (adenoids) The one lingual tonsil

The Hypopharynx

This is the part of the pharynx which lies level with the larynx. Between the base of tongue and front of the epiglottis are found two spaces which are known as the valleculae. They are divided in the midline by the glosso-epiglottic ligament and bounded posteriorly by the pharyngo-epiglottic ligaments. These are folds of mucous membrane which are attached to the posterior part of the base of the epiglottis. Behind these ligaments commence the pyrifarm fossae — one on each side.

The Hypopharynx

These are folds of mucous membrane which are attached to the posterior part of the base of the epiglottis. Behind these ligaments commence the pyrifarm fossae — one on each side.

The Larynx

The larynx consists of a cartilaginous framework which is bound together by ligaments and covered with muscle and mucous membrane. The cartilages of the larynx are usually spoken of as 'paired' and 'unpaired' cartilages

The Larynx

The paired cartilages:1. the arytenoid cartilages; 2. the wedge-shaped

cartilages;3. the corniculate

cartilages.

The unpaired cartilages 4. The thyroid cartilage 5. the cricoid cartilage 6. The epiglottis

The Larynx

In the interior of the larynx two folds of mucous membrane are stretched from front to back. They are rounded and pink in colour, and are called the false cords. Inferior to them is an opening into the space known as the ventricle. The lower lip of the ventricle is formed by a muscular bundle which is the true vocal cord

The Larynx

Seen from above, the cord looks narrow and white.

The spaces of larynx

The vestibulum of laryngis (above the false cords). The middle space (between false and vocal cords). The subglottic space (below the vocal cords) - which is the

narrowest part of the larynx

The view in laryngoscopy

1 – the arytenoid cartilage 2 – the arytenoid-epiglottis

ligament 3 – the pyrifarm fossae 4 – the ventricle of larynx 5 – the epiglottis 6 – the vocal cords