HEAD
OSCE
Station 5
External Ear
Identify the different anatomical parts of the external ear on the image.
View answer
What is the blood supply to the external ear?
The arterial supply is derived mainly from the posterior auricular and superficial temporal arteries, both branches of the external carotid artery.
What is the nerve supply of the external ear?
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- Posteromedial, posteriorlateral and inferior auricle - supplied by the greater auricular nerve (a branch of the cervical plexus C2 and C3).
- Anteriosuperior and anteromedial aspects of the auricle - supplied auriculotemporal nerve (branch of the mandibular division of the trigeminal nerve CN V3)
- External acoustic meatus - supplied by branches of the auriculotemporal and vagus nerves (auricular branch of the vagus nerve, also known as Arnold's nerve).
- Middle section of the ear to include the helix and the antihelix - supplied by the lesser occipital nerve.
What is the clinical significance of the auricular branch of the vagus nerve (Arnolds nerve)?
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- Otalgia from laryngeal cancer.
- Cough and rarely syncope caused by stimulation during microsuctioning of the ear.
Describe the pathology of ‘cauliflower ear’ deformity.
Blunt injury to the external ear can cause a collection of blood between the perichondrium and auricular cartilage (pinna haematoma). If this condition is not treated expeditiously both abscess formation and cartilage necrosis may ensue. This process causes the outer ear to become permanently misshapen and swollen leading to a ‘cauliflower ear’. This is common following contact sports injury.
What benign conditions can affect the pinna?
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- Perichondritis
- Erysipelas
- Herpes zoster
- Allergic/contact dermatitis
- Eczema
- Psoriasis
- Chondrodermatitis nodularis
Name two cutaneous malignancies that can affect the pinna secondary to sun exposure.
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- SCC
- BCC
Describe why poorly diabetic patients and elderly patients presenting with deep ear pain should be thoroughly investigated.
Malignant otits externa is a rare non-neoplastic progressive infection of the external ear canal characterised by osteomyelitis, which can spread to the lateral skull base and cause multiple cranial nerve palsies.
What is the most common causative organism of malignant otitis externa?
Malignant otitis externa is usually caused by Pseudomonas aeruginosa and Staphylococcus aureus.
What complications can arise due to malignant otitis externa?
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Complications of malignant otitis externa include:
- Cranial nerve palsies: VII, IX, X, XI, XII
- Cavernous sinus thrombosis
- Meningitis
What is the likely long-term complication of an untreated haematoma of the pinna?
"Untreated pinna haematoma may lead to the development of a deformed ear, so
called “cauliflower ear”. The blood / blood clot (or pus in case of an abscess formation) separates the perichondrium from the cartilage causing a lack of blood
supply and cartilage necrosis. Fibrous tissue forms in the overlying skin."