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The pinna consists of the '''auricular [[Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilage]]''', and skin which allows for flexibility and elasticity. The auricular cartilage is flared distally into a flattened cone shape, covered by skin on both sides - more tightly on the medial or concave side than the convex side.  The [[Hair - Anatomy & Physiology|hair]] covering on the convex side is usually similar to the rest of the body but the hair covering on the concave or medial aspect is variable.  There are also irregularities on the concave surface with ridges and prominences, the '''medial and lateral crus of the helix''' on the medial aspect of the opening of the external ear canal, opposite the rectangular '''tragus''' on the lateral aspect.

The pinna consists of the '''auricular [[Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilage]]''', and skin which allows for flexibility and elasticity. The auricular cartilage is flared distally into a flattened cone shape, covered by skin on both sides - more tightly on the medial or concave side than the convex side.  The [[Hair - Anatomy & Physiology|hair]] covering on the convex side is usually similar to the rest of the body but the hair covering on the concave or medial aspect is variable.  There are also irregularities on the concave surface with ridges and prominences, the '''medial and lateral crus of the helix''' on the medial aspect of the opening of the external ear canal, opposite the rectangular '''tragus''' on the lateral aspect.

Proximally, the auricular cartilage is rolled into a funnel shape, known as the '''concha'''.  The '''scutiform''' cartilage lies rostromedially in the lower ear canal and provides support.  The '''annular''' cartilage lies between the proximal horizontal ear canal and the bony '''acoustic process''' of the [[Skull and Facial Muscles - Anatomy & Physiology#Temporal Bone (os temporale)|typmanic bulla]], connected by ligaments.  The vertical ear canal lies in a rostroventral orientation before bending medially to become the horizontal canal.

Proximally, the auricular cartilage is rolled into a funnel shape, known as the '''concha'''.  The '''scutiform''' cartilage lies rostromedially in the lower ear canal and provides support.  The '''annular''' cartilage lies between the proximal horizontal ear canal and the bony '''acoustic process''' of the [[Skull and Facial Muscles - Anatomy & Physiology#Temporal Bone (os temporale)|tympanic bulla]], connected by ligaments.  The vertical ear canal lies in a rostroventral orientation before bending medially to become the horizontal canal.

The cartilage and bony process of the external ear and the tympanic membrane are covered by skin.  The skin of the normal ear has a thin stratified keratinising epidermis and a thin dermis containing adnexal structures – [[Hair - Anatomy & Physiology|hair follicles]], [[Skin - Anatomy & Physiology#Glands|sebaceous and apocrine glands]].  The density of hair follicles on the concave pinna is variable, as is the density and distribution of hair follicles in the ear canal itself.  Some species are devoid of hair in the lower (proximal) ear canal (eg horse); hair follicle density in the dog is variable – usually simple but in some breeds compound hair follicles.

The cartilage and bony process of the external ear and the tympanic membrane are covered by skin.  The skin of the normal ear has a thin stratified keratinising epidermis and a thin dermis containing adnexal structures – [[Hair - Anatomy & Physiology|hair follicles]], [[Skin - Anatomy & Physiology#Glands|sebaceous and apocrine glands]].  The density of hair follicles on the concave pinna is variable, as is the density and distribution of hair follicles in the ear canal itself.  Some species are devoid of hair in the lower (proximal) ear canal (eg horse); hair follicle density in the dog is variable – usually simple but in some breeds compound hair follicles.

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[[image: Canine Auricular Cartilages.jpg|thumb|250px|right|The auricular cartilages of the left canine ear. Image by Rachael Wallace]]

[[image: Canine Auricular Cartilages.jpg|thumb|250px|right|The auricular cartilages of the left canine ear. Image by Rachael Wallace]]

===Microclimate of the Ear Canal===

===Microclimate of the Ear Canal===

The epithelial cells in the [[Skin - Anatomy & Physiology#Epidermis|stratum granulosum]] of the tympanic membrane migrate centripetally, and this migration comprises the natural cleaning mechanism keeping the tympanum free of debris.  The upward/distal migration of epithelial cells clears desquamated cells, secretions, debris and microbes. The more aqueous secretions of the ceruminous glands, present proximally, allow easier upward migration, whereas the higher lipid content of the distal secretions offers better barrier protection.

The epithelial cells in the [[Skin - Anatomy & Physiology#Epidermis|stratum granulosum]] of the tympanic membrane migrate centripetally, and this migration comprises the natural cleaning mechanism keeping the tympanum free of debris.  The upward/distal migration of epithelial cells clears desquamated cells, secretions, debris and microbes. The more aqueous secretions of the ceruminous glands, present proximally, allow easier upward migration, whereas the higher lipid content of the distal secretions offers better barrier protection.

===Structures surrounding the Ear===

===Structures Surrounding the Ear===

In the tissues medial to the ear canal lie the auricular and superficial temporal arteries.  Laterally is the '''parotid salivary gland''' and also a branch of the [[Cranial Nerves - Anatomy & Physiology|facial nerve]], external maxillary vein and branches of the external carotid artery.  The facial nerve exits the skull through the stylomastoid foramen behind the osseous bulla; it passes below the rostroventral aspect of the horizontal ear canal.  The '''auriculo-temporal''' branch of the mandibular portion of the [[Cranial Nerves - Anatomy & Physiology|trigeminal nerve]] (CN V) and branches of the facial nerve pass rostral to the vertical ear canal.

In the tissues medial to the ear canal lie the auricular and superficial temporal arteries.  Laterally is the '''parotid salivary gland''' and also a branch of the [[Cranial Nerves - Anatomy & Physiology|facial nerve]], external maxillary vein and branches of the external carotid artery.  The facial nerve exits the skull through the stylomastoid foramen behind the osseous bulla; it passes below the rostroventral aspect of the horizontal ear canal.  The '''auriculo-temporal''' branch of the mandibular portion of the [[Cranial Nerves - Anatomy & Physiology|trigeminal nerve]] (CN V) and branches of the facial nerve pass rostral to the vertical ear canal.

Sensory innervation to the outer ear:

Sensory innervation to the outer ear:

*Ce2 (second cervical spinal nerve) to medial pinna

*Ce2 (second cervical spinal nerve) to medial pinna

*Auriculopalpebral branch of trigeminal nerve ([[Cranial Nerves - Anatomy & Physiology|CN V]]) to most of the lateral pinna

*Auriculopalpebral branch of facial nerve ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) to most of the lateral pinna

*Facial ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) and vagus nerves ([[Cranial Nerves - Anatomy & Physiology|CN X]]) via small auricular branches to pinna

*Facial ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) and vagus nerves ([[Cranial Nerves - Anatomy & Physiology|CN X]]) via small auricular branches to pinna

{{Learning

{{Learning

|flashcards = [[Ear flashcards - Anatomy & Physiology|Ear Flashcards]]

|flashcards = [[Ear flashcards - Anatomy & Physiology|Ear Flashcards]]

}}

}}

 

 

[[Category:Special Senses - Anatomy & Physiology]]

[[Category:Special Senses - Anatomy & Physiology]]