Anatomy of the ear

Anatomy of the ear:
1. External ear which consist of auricle and external auditory canal .
The auricle has a framework of cartilage except the lobule, the skin is closely adherent to perichonderium at the anterior surface of the auricle.

The length of external auditory canal about 2.5 cm, the outer 1\3 is cartilage but inner 2\3 is bony.
Nerve supply
• V, VII, IX, and X cranial Ns.
• Lesser occipital n. c1.
• Greater auricular n. c2-c3.
Lymphatics
• pre and post auricular lymph nodes.
• Upper superficial cervical lymph nodes.
2. Middle ear cleft: consists of
Eustachian tube pass from anterior wall of tympanic cavity to the nasopharynx
the length of the tube about 3.7 cm
the lateral 1\3 is bony and the medial 2\3 is cartilaginous with membrane.
Tympanic cavity this is biconcave disc shaped cavity , antero-posterior diameter 1.3 cm , height 1.5, the width is 2mm of the centre .
Tympanic membrane have 3 layers:
• Outer epithelial layer.
• Middle fibrous layer.