External Ear- Pinna / Auricle

EXTERNAL EAR- Pinna / Auricle


AURICLE OR PINNA

  • The entire pinna (except its lobule and outer part of external acoustic canal) is made up of a framework of a single piece of yellow elastic cartilage
  • There is no cartilage between the tragus and crus of the helix – incisura terminalis
  • An incision made in this area will not cut through the cartilage – used for endaural approach in surgery of external auditory canal and mastoid.
  • Skin over the pinna is closely adherent to the perichondrium on the lateral surface while it is loosely attached on the medial surface.
  • Incisura terminalis is the area between the tragus and crus of helix

NERVE SUPPLY OF PINNA

Greater auricular nerve(C2C3)

  • Major part of the skin of Pinna is supplied by Greater Auricular nerve.
  • The great auricular supplies the whole of the cranial (medial /back) surface of auricle  and the posterior part of lateral (front) surface (helix, anthelix, and lobule).

Lesser occipital nerve(C2)

  • Auriculotemporal nerve (mandibular branch of 5th nerve)
  • Auricular branch of Vagus (Arnold’s N)
  • Facial nerve

DEVELOPMENT OF PINNA

  • Ear pinna develops from Ecdoderm.
  • Pinna is formed at birth.
  • The auricle starts to develop when 6 hillocks appear around the first pharyngeal groove(cleft), which lies between the first and the second branchial arches.
  • First branchial cleft is the precursor of external auditory canal.
  • Around the sixth week of embryonic life, a series of six tubercles appear around the first branchial cleft.
  • They progressively coalesce to form the auricle/Pinna. Branchial clefts are ectodermal in origin.

LYMPHATIC DRAINAGE OF PINNA

  • Concha, Tragus, Fossa triangularis-  Pre auricular and parotid nodes
  • Lobule and antitragus  –  Infra-auricular nodes
  • Helix and anti-helix   – Post auricular nodes, deep jugular and spinal accessory nodes

CLINICAL SIGNIFICANCE

  • Keratocanthoma-Flesh-colored, dome-shaped, on the  ear lobe with  central keratin-filled crater and surrounded by  proliferating squamous epithelium. This  lesion  regresses over/  the  next month   and   then   disappears.
  • Malignant Otitis externa-Ear pain and drainage in an elderly diabetic patient must raise concern about malignant external otitis.It is associated with tenderness in the pinna and  swelling and inflammation of the external auditory meatus.This infection is almost always caused by P. aeruginosa.
  • Ramsay Hunt Syndrome-A clinical condition characterised by a facial palsy and often associated with facial pain and the appearance of vesicles on the canal and pinna.Vertigo and sensor neural hearing loss (VIIIth nerve) may occur.
  • Boil can occur on Pinna.
  • Acute mastoiditis is characterized by Clouding of Mastoid Air cells,Deafness and Outward and downward deviation of the pinna.
  • Darwin’s tubercle (or auricular tubercle) is a congenital earcondition which often presents as a thickening on the helix at the junction of the upper and middle thirds.
  • Boxer’s ear is Hematoma of Auricle
    • It is the collection of blood between the auricular cartilage and its perichondrium.
    • It is often the result of blunt trauma seen in boxers, wrestlers and rugby players, so called Boxer’s ear.
    • Extravasated blood may clot and then organize resulting in typical deformity of cauliflower ear.

Exam Important

  • The entire pinna (except its lobule and outer part of external acoustic canal) is made up of a framework of a single piece of yellow elastic cartilage
  • Pinna develops from the cleft of  1st and 2nd pharyngeal arch
  • Ear pinna develops from Ectoderm
  • Skin over the pinna is closely adherent to the perichondrium on the lateral surface while it is loosely attached on the medial surface.
  • Greater auricular nerve(C2C3)-Supplies Major Part of Pinna
  • Sensory nerve supply of pinna is Mandibular nerve

Cauliflower ear (boxer’s ear, wrestler’s ear)

  1. Is an acquired deformity of the outer ear.
  2. In this injury, the ear can shrivel up and fold in on itself and appear pale, giving it a cauliflower-like appearance, hence the term cauliflower ear.
  3. Wrestlers, boxers and martial artists in particular are susceptible to this type of injury.
  4. When the ear is struck and a blood clot develops under the skin, or the skin is sheared from the cartilage, the connection of the skin to the cartilage is disrupted.

 

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