Applied Anatomy

External auditory meatus
  • The external acoustic meatus is narrow at the medial end of its cartilaginous portion. This constriction is called the isthmus . Foreign bodies e.g. beans inserted in the meatus usually become lodged in this isthmus.

  • Because of its sigmoid shape, instruments are most steadily inserted into the EAM by pulling the auricle posterior superiorly. This pulling straightens the EAM.

  • The lateral third is lined by skin, while the medial 2/3 is lined by stratified squamous epithelium. Both are tightly adherent to the cartilage and bone. Therefore pimples in the EAM are painful.

  • The EAM has ceruminous glands, which produce waxy material (cerumen). This prevents maceration or softening of the EAM.

  • Cleaning of the EAM stimulates the vagus nerve and may cause bradycardia and / or vomiting.

Tympanic membrane
  • Perforation of the tympanic membrane may result from foreign bodies, excessive pressure, or infection. Deafening may occur.

  • Skull fractures, may be accompanied by meningeal tear and perforation of tympanic membrane. In this case, severe bleeding and/or escape of CSF through the ruptured membrane, and external auditory meatus (CSF otorrhea ) occur.

  • Sometimes, a fracture may involve the bony part of the external auditory meatus, and cause bleeding and/or loss of CSF via external auditory meatus, even when the tympanic membrane is intact.

  • When the tympanic membrane, has to be incised e.g. to drain pus from the tympanic cavity; the incision is made postero inferiorly . This is because the superior part is more vascular, and the chorda tympani nerve and ear ossicles may be damaged.

  • Inflammation in the tympanic cavity is called otitis media. It (the infection) may spread to the mastoid antrum, or through meningitis and/ or cerebritis and even a brain abcess. Through veins, the infection may also reach the superior petrosal, sigmoid, and the other venous sinuses.

  • Ear ache, may be referred from distant sites from distant sites e.g.:

    • The oral cavity-tongue, dental abcess e.t.c, via the Mandibular nerve

    • Pharynx, including palatine tonsils via the glossopharyngeal nerve.

    • Larynx, via the vagus nerve.

Earache due to otitis media is not worsened by movements of tragus in adults (it may be in infants and children). However, because the cartilage in the tragus is continous with that in the external acoustic meatus; the pain of otitis externa is made much worse by movement of tragus.

  • The auditory tube forms a route through which infections may pass from the nasopharynx to the tympanic cavity, especially in babies.

Swelling of its mucous membrane easily blocks the auditory tube. When this happens, residual air in the tympanic cavity is usually absorbed into the mucosal blood vessels. This results in lowering of pressure in the tympanic cavity; retraction of the tympanic membrane, and interference with its movement. This affects hearing. Fluid may exude into the tympanic cavity (serous otitis).


Outstanding Auricle / Bat Ear

These are unduly prominent ears. This feature becomes less prominent with development of  mastoid process. In marked cases. Plastic surgery is performed.

Congenital Aural Fistulae

This is an opening usually found in the helix or tragus. It leads to a fine blind canal. It is a remnant of the 1st branchial cleft. It may block and lead to a cyst or abscess. Treated by excision

Hematoma of auricle

Results from injury. Blood accumulates under the perichondrium forming a swelling on the lateral or anterior surface of the auricle. Considerable pain  is experienced. Inflammation may result in destruction of cartilage and finally swelling of the auricle

Otitis Externa

  • A diffuse inflammation of the external auditory meatus. Most common mode of infection is by scratching / poking the ears with contaminated fingers/ objects. Common also with ill fitting hearing aids

  • Because of tight adherence of skin to the cartilage/ bone, the condition is very painful
    A sense of heat is felt owing to the increased vascularity Soon thee walls of the meatus begin to weep, giving some relief to the pain

Impacted wax

Ear wax is sufficiently fluid to be removed at each washing. Accumulation is precipitated by:

  • Undue narrowness of the passage
  • Presence of infection in the meatus
  • Excessive or abnormally thick secretion
  • Presence of foreign body
  • Abnormal body/ cartilaginous growth causing blockage
  • Irregular/ inappropriate cleaning of ears.

Foreign bodies in the ear

  • These are usually introduced by patients themselves especially children. They include:
  • Inanimate objects such as beans and peas which swell with moisture  or beads, buttons and shells which do not swell with moisture.
  • Care must be taken when attempting removal as this may push them deeper. They may be harmless and remain there for years if the ear drum is not damaged.
  • On the other hand, they may block the meatus and cause deafness or trigger inflammation. Some get badly infected.
  • Animate foreign bodies include insects and maggots.
  • Meatal Atresia and Stenosis
  • Usually congenital but can be caused by chronic inflammation


Tympanic membrane

Traumatic rupture may be caused by:

  1. Accidentaly pushing in objects
  2. When attempting to clean
  3. Fall on side of head
  4. Slapping
  5. Unskillful attempts to remove foreign bodies
  6. A kiss on the ear
  7. Forceful and careless syringing


Middle Ear

Otitis media refers to inflammation of the middle ear. Infection frequently spreads to middle ear from the pharynx through auditory tube. From the middle ear the infection can spread in various directions:

  1. To the mastoid process to cause mastoiditis
  2. To cranial cavity and cause meningitis, encephalitis and brain abscess
  3. To the jugular vein leading to venous thrombosis
  4. To the inner ear and cause labyrinthitis
  5. To bone and cause osteomyelitis
  6. Pharyngeal abscess secondary to otitis media may develop in two ways:

    Directly from tympanic auditory tube
    Indirectly through mastoid air cells or from an extradural abscess – the pus first forming in the suboccipital regiona deep to digastric muscle
    Caries of the ossicles: Caries and necrosis of the ossicles may occur in chronic otitis media



Plast reconstruction of middle ear to overcome conduction deafness resulting from complications of otitis media


This is an ear ache. It can occur when ear is healthy. Because the ear is supplied by twigs from fifth, seventh, nineth and tenth cranial nerves, painful stimuli from the ear cause pain to be experienced in the ear for example:

    • Disease of lower molars
    • Throat diseases like tonsilits
    • Diseases in the posterior cranial fossa
    • Affections of sphenoidal sinuses
    • Geniculate ganglionitis


Injury to laryngeal nerves

Caused  by

  • Surgery such as thyroidectomy
  • Compression by tumors
  • Compression from goitre

Leads to:

  • Weakening or paralysis of laryngeal muscles with consequent impaired voice production
  • Anaesthesia of laryngeal mucosa, impairing protective reflexes. Foreign bodies may then easily enter the larynx

Cancer of larynx

  • Common in smokers
  • Presents with persistent hoarseness often associated with ear ache and dysphagia


  • Removal of larynx may be performed in severe cases of laryngeal cancer
  • Vocal rehabilitation is then accomplished by the use of electrolarynx, a tracheo-esophagel prosthesis or esophageal speech (regurgitation of inspired airs)

Age changes in the larynx

1) At puberty in boys because of testosterione the larynx enlarges due to :

  • Enlargement of allcartilages
  • Doubling of anteroposterior diameter doubles
  • lengthening and thickening of Vocal folds

This growth accounts for pubertal voice changes

2) In old age say after 60 yrs, the large cartilages even ligaments may ossify. This may explain the voice changes occurring in old age/

Fractures of laryngeal skeleton

  • These may occur in traffic accidents or sports
  • Produce submucous hemorrhage and edema, respiratory obstruction, hoarseness and temporary inability to speak.


Acute inflammation due to viral or bacterial infection or allergy may cause mucosal edema severe enough to cause dysphagia or aphonia (loss of voice)


The Larynx and the Ear