Describe the blood supply, nerve supply and lymphatic drainage of the ear.

Arterial and Venous Supply

• The blood supply of the ear follows its embryological division into three parts, and the inner ear is supplied quite separately from the other two — which has major clinical consequences
• The auricle is supplied by the posterior auricular and superficial temporal arteries, both from the external carotid, with a contribution from the occipital artery. It has a rich anastomosis, which is why auricular lacerations heal well and need minimal debridement, and why even a nearly avulsed pinna may survive on a small pedicle
• The external canal is supplied by the deep auricular branch of the maxillary artery, with the posterior auricular and superficial temporal arteries

Nerve Supply and Lymphatic Drainage

• The sensory supply IS shared among four cranial and two cervical nerves.
• Trigeminal (V3) — the auriculotemporal nerve, supplying the tragus, anterior canal and anterior drum. Refers pain from the teeth, temporomandibular joint, tongue and oral cavity
• Facial (VII) — a small sensory area over the concha and postauricular skin.
• Glossopharyngeal (IX) — jacobson’S nerve, forming the tympanic plexus on the promontory and supplying the middle ear and inner surface of the drum. Refers pain from the tonsil, oropharynx and base of tongue — which is why otalgia is universal after tonsillectomy and why a tonsillar carcinoma presents with earache
• Vagus (X) — ARNOLD’S nerve, the auricular branch, supplying the posterior canal and concha. Refers pain from the larynx, hypopharynx and oesophagus, and produces the cough and vomiting reflex on instrumenting the ear
• C2 and C3 — the great auricular and lesser occipital nerves, supplying the lower and posterior pinna. Refer pain from the cervical spine
• The clinical rule that follows IS absolute: otalgia with a normal ear must be investigated as referred pain — and in an adult smoker over 40 with persistent unilateral otalgia and a normal ear, a malignancy of the tonsil, tongue base, hypopharynx or larynx must be excluded by endoscopy. Many such tumours present in exactly this way
• Other causes of referred otalgia — dental disease and impacted third molars; temporomandibular joint dysfunction, which is very common; tonsillitis and quinsy; cervical spondylosis; and neuralgias
• Secretomotor fibres reach the parotid from the tympanic plexus via the lesser petrosal nerve and the otic ganglion