Anatomy of Ear

Anatomy of External Ear

In Anatomy of External Ear consist of mainly 3 structures i.e.:

1. Auricle or pinna,
2. External acoustic canal
3. Tympanic membrane

External Acoustic Canal of Ear

It extends from the bottom of the concha to the tympanic membrane also measures about 24 mm along its posterior wall. It is not a straight tube because its outer part is directing upwards, backwards and medially while its inner part is directing downwards, forwards and medially. Therefore, to see the tympanic membrane of the ear, the pinna has to pull upwards, backwards and laterally so as to bring the two parts in alignment.

The canal is dividing into two parts:

1. Cartilaginous and
2. Bony.

CARTILAGINOUS PART

It forms outer one-third (8 mm) of the canal. Cartilage is a continuation of the cartilage which forms the framework of the pinna. It has two deficiencies—the “fissures of Santorini” in this part of the cartilage and through them the parotid or superficial mastoid infections can appear either in the canal or vice versa. The skin covering the cartilaginous canal is thick and contains ceruminous and pilosebaceous glands which secrete wax. Hair is only confined to the outer canal and therefore furuncles (staphylococcal infection of hair follicles) are seen only in the outer onethird of the canal.

BONY PART

It forms inner two-thirds (16 mm). Skin lining the bony canal is thin and continuous over the tympanic membrane. It is devoid of hair also ceruminous glands. Especially, 6 mm lateral to tympanic membrane, the bony meatus presents a narrowing called isthmus. Generally, Foreign bodies, lodged medial to the isthmus, get impacted, and are difficult to remove. Anteroinferior part of the deep meatus, beyond the isthmus, presents a recess called anterior recess, which acts as a cesspool for discharge and debris in cases of external and middle ear infections (Figure 1.2). Anteroinferior part of the bony canal may present a deficiency (foramen of Huschke) in children up to the age of four or sometimes in adults, permitting infections to and from the parotid.

Tympanic Membrane of Ear

It forms the partition between the external acoustic canal also the middle ear.

Tympanic Membrane obliquely set and as a result, its posterosuperior part is more lateral than its anteroinferior part.  It is 9–10 mm tall, 8–9 mm wide and 0.1 mm thick. Tympanic membrane can divide into two parts i.e.:

1. Firstly, PARS TENSA

2. Secondly, PARS FLACCIDA (SHRAPNELL’S MEMBRANE)

A. PARS TENSA

It forms most of tympanic membrane. Its periphery thicken to form a fibrocartilaginous ring called annulus tympanicus, which fits in the tympanic sulcus. Moreover, The central part of pars tensa is tenting inwards at the level of the tip of malleus and is called umbo. A bright cone of light seen radiating from the tip of malleus to the periphery in the anteroinferior quadrant

B. PARS FLACCIDA (SHRAPNELL’S MEMBRANE)

This situate above the lateral process of malleus between the notch of Rivinus and the anterior and posterior malleal folds (earlier called malleolar folds). It is not so taut and may appear slightly pinkish. Various landmarks seen on the lateral surface of tympanic membrane are shown in Figure 1.4.

LAYERS OF TYMPANIC MEMBRANE

Tympanic membrane consists of three layers i.e.:

Outer epithelial layer

which is continuous with the skin lining the meatus.

Inner mucosal layer,

which is continuous with the mucosa of the middle ear.

Middle fibrous layer

which encloses the handle of malleus and has three types of fibres—the radial, circular also
parabolic (Figure 1.5).

Fibrous layer in the pars flaccida is thin and not organized into various fibres as in pars tensa.

Relation of External Acoustic Meatus

• Superiorly: Middle cranial fossa Triangular fossa Helix Spine of helix Tail of helix Antitragus
• Posteriorly: Mastoid air cells and the facial nerve
• Inferiorly: Parotid gland
• Anteriorly: Temporomandibular joint
  Posterosuperior part of deeper canal near the tympanic membrane is related to the mastoid antrum. “Sagging” of this area may be noticed in acute mastoiditis.

Nerve Supply of Ear

1. Greater auricular nearve (C_2,3) supplies most of the
medial surface of pinna and only posterior part of the
lateral surface (Figure 1.6).
2. Lesser occipital (C2)supplies upper part of medial surface.

Terminology

Auricle (Pinna): The external, visible part of the ear.

External Auditory Canal: The tube leading from the auricle to the eardrum.

Tympanic Membrane (Eardrum): A thin membrane that vibrates in response to sound waves.

Ossicles: The three tiny bones in the middle ear (malleus, incus, stapes) that transmit vibrations.

Oval Window: Membrane-covered opening that connects the middle ear to the inner ear.

Cochlea: Spiral-shaped structure in the inner ear that contains fluid and hair cells that convert vibrations into nerve impulses.

Vestibular System: Structures in the inner ear responsible for balance (semicircular canals, vestibule).

Eustachian Tube: Connects the middle ear to the back of the throat, equalizing pressure.

Auditory Nerve: Transmits nerve impulses from the cochlea to the brain

Reference

1. Gray’s Anatomy for Students

   • Drake, R. L., Vogl, A. W., & Mitchell, A. W. M.
   • (2019).
   • Elsevier.

2. Clinically Oriented Anatomy

   • Moore, K. L., Dalley, A. F., & Agur, A. M. R.
   • (2018).
   • Lippincott Williams & Wilkins.

3. Human Anatomy & Physiology

   • Marieb, E. N., & Hoehn, K.
   • (2019).
   • Pearson.

4. Thieme Atlas of Anatomy: Head and Neuroanatomy

   • Schünke, M., Schulte, E., Schumacher, U., Voll, M., & Wesker, K.
   • (2015).
   • Thieme.

5. Color Atlas of Human Anatomy, Vol. 3: Nervous System and Sensory Organs

   • Kahle, W., & Frotscher, M.
   • (2010).
   • Thieme.

Also Search As

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2. Focus on Function:

Since homeopathy emphasizes how things work, try searches like:

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3. Condition-Specific Searches:

If looking for information on how homeopathy views ear problems in relation to anatomy, try:

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4. Homeopathic Resources:

Websites of homeopathic organizations: National Center for Homeopathy, North American Society of Homeopaths, etc.

Homeopathic journals: Search within journals like The American Homeopath, Homeopathy, etc.

Homeopathic practitioners’ blogs and websites: Many practitioners share articles on their sites.

5. Expand Beyond "Anatomy":

"Materia medica of the ear": This refers to the homeopathic remedies associated with ear conditions, which often link to anatomical areas.

"Ear constitution homeopathy": This explores how a person’s overall constitution might relate to their ear health.

Other Ways 

Visual Learners:

Anatomical atlases: Books like Thieme Atlas of Anatomy or Color Atlas of Human Anatomy provide detailed illustrations and labeled diagrams. 

Online image searches: Search for "anatomy of the ear diagram" or "ear structure" on Google Images, Bing Images, or specialized medical image databases.

Interactive anatomy websites: Explore websites like BioDigital Human or Visible Body, which offer 3D models and interactive tools to visualize ear structures. 

Videos: Search for "anatomy of the ear animation" or "ear dissection" on YouTube or educational platforms like Khan Academy. 

Anatomy textbooks: Standard textbooks like Gray’s Anatomy for Students or Clinically Oriented Anatomy provide comprehensive information on ear anatomy.

Encyclopedias and dictionaries: Resources like the Encyclopedia Britannica or medical dictionaries can offer concise explanations of ear structures and functions.

Scholarly articles: Search databases like PubMed or Google Scholar for research articles on specific aspects of ear anatomy (e.g., "cochlear anatomy," "tympanic membrane structure").

 Hands-On Learning:

Dissections: If you have access to a lab setting, a supervised ear dissection can provide a unique and in-depth understanding of its anatomy.

Models: Physical models of the ear can be helpful for visualizing the spatial relationships between different structures.

 Auditory Learners:

Lectures and podcasts: Listen to lectures by anatomy professors or podcasts on ear anatomy and function.

Audiobooks: Some anatomy textbooks are available in audiobook format, allowing you to learn while listening. 

Combined Approaches:

Interactive learning platforms: Many online platforms combine visuals, text, and interactive elements for a comprehensive learning experience.