The External Ear - Revision history

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	[[Category:Sensory organs\|Ear]]		[[Category:Sensory organs\|Ear]]
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← Older revision		Revision as of 17:32, 16 January 2025
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	The cranial surface of the auricula presents elevations which correspond to the depressions on its lateral surface and after which they are named, ''e. g'' '''eminentia conchae, eminentia triangularis''' etc.		The cranial surface of the auricula presents elevations which correspond to the depressions on its lateral surface and after which they are named, ''e. g'' '''eminentia conchae, eminentia triangularis''' etc.

			[[File:Gray904.png\|thumb\|FIG. 904– The auricula. Lateral surface. (''Picture From the Classic Gray's Anatomy'')]]
	~~<center>http~~:~~//www~~.~~wikimd.org/images/gray/large/image904.gif </center>~~


	FIG. 904– The auricula. Lateral surface. (''Picture From the Classic Gray's Anatomy'')
	==== '''Structure''' ====		==== '''Structure''' ====
	The auricula is composed of a thin plate of yellow [[fibrocartilage]], covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the external [[acoustic meatus]] by fibrous tissue.		The auricula is composed of a thin plate of yellow [[fibrocartilage]], covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the external [[acoustic meatus]] by fibrous tissue.
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	The '''[[skin]]''' is thin, closely adherent to the [[cartilage]], and covered with fine hairs furnished with [[sebaceous glands]], which are most numerous in the [[concha]] and [[scaphoid fossa]]. On the [[tragus]] and [[antitragus]] the hairs are strong and numerous. The skin of the auricula is continuous with that lining the external acoustic meatus.		The '''[[skin]]''' is thin, closely adherent to the [[cartilage]], and covered with fine hairs furnished with [[sebaceous glands]], which are most numerous in the [[concha]] and [[scaphoid fossa]]. On the [[tragus]] and [[antitragus]] the hairs are strong and numerous. The skin of the auricula is continuous with that lining the external acoustic meatus.

			[[File:Gray905.png\|thumb\|FIG. 905– Cranial surface of cartilage of right auricula. (''Picture From the Classic Gray's Anatomy'')]]
	~~<center>http~~:~~//www~~.~~wikimd.org/images/gray/large/image905.gif </center>~~


	FIG. 905– Cranial surface of cartilage of right auricula. (''Picture From the Classic Gray's Anatomy'')
	The '''cartilage of the auricula''' (''cartilago auriculae; cartilage of the pinna'') (Figs. 905, 906) consists of a single piece; it gives form to this part of the ear, and upon its surface are found the eminences and depressions above described. It is absent from the [[lobule]]; it is deficient, also, between the [[tragus]] and beginning of the [[helix]], the gap being filled up by dense fibrous tissue. At the front part of the [[auricula]], where the helix bends upward, is a small projection of cartilage, called the ''spina helicis'' while in the lower part of the helix the cartilage is prolonged downward as a tail-like process, the '''cauda helicis''' this is separated from the [[antihelix]] by a [[fissure]], the '''fissura antitragohelicina''' The cranial aspect of the cartilage exhibits a transverse furrow, the '''sulcus antihelicis transversus''' which corresponds with the inferior [[crus]] of the antihelix and separates the eminentia conchae from the eminentia triangularis. The eminentia conchae is crossed by a vertical ridge (''ponticulus''), which gives attachment to the Auricularis posterior muscle. In the cartilage of the auricula are two fissures, one behind the crus helicis and another in the tragus.		The '''cartilage of the auricula''' (''cartilago auriculae; cartilage of the pinna'') (Figs. 905, 906) consists of a single piece; it gives form to this part of the ear, and upon its surface are found the eminences and depressions above described. It is absent from the [[lobule]]; it is deficient, also, between the [[tragus]] and beginning of the [[helix]], the gap being filled up by dense fibrous tissue. At the front part of the [[auricula]], where the helix bends upward, is a small projection of cartilage, called the ''spina helicis'' while in the lower part of the helix the cartilage is prolonged downward as a tail-like process, the '''cauda helicis''' this is separated from the [[antihelix]] by a [[fissure]], the '''fissura antitragohelicina''' The cranial aspect of the cartilage exhibits a transverse furrow, the '''sulcus antihelicis transversus''' which corresponds with the inferior [[crus]] of the antihelix and separates the eminentia conchae from the eminentia triangularis. The eminentia conchae is crossed by a vertical ridge (''ponticulus''), which gives attachment to the Auricularis posterior muscle. In the cartilage of the auricula are two fissures, one behind the crus helicis and another in the tragus.

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	In man, these muscles possess very little action: the Auricularis anterior draws the auricula forward and upward; the Auricularis superior slightly raises it; and the Auricularis posterior draws it backward.		In man, these muscles possess very little action: the Auricularis anterior draws the auricula forward and upward; the Auricularis superior slightly raises it; and the Auricularis posterior draws it backward.

	~~<center>http~~:~~//www~~.~~wikimd.org/images/gray/large/image906.gif </center>~~		[[File:Gray906.png\|thumb\|FIG. 906– The muscles of the auricula. (''Picture From the Classic Gray's Anatomy'')]]

	FIG. 906– The muscles of the auricula. (''Picture From the Classic Gray's Anatomy'')

	===== The ''intrinsic'' muscles =====		===== The ''intrinsic'' muscles =====
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	The '''[[sensory nerves]]''' are: the great [[auricular]], from the [[cervical plexus]]; the auricular branch of the [[vagus]]; the auriculotemporal branch of the [[mandibular nerve]]; and the lesser occipital from the cervical plexus.		The '''[[sensory nerves]]''' are: the great [[auricular]], from the [[cervical plexus]]; the auricular branch of the [[vagus]]; the auriculotemporal branch of the [[mandibular nerve]]; and the lesser occipital from the cervical plexus.

	~~<center>http~~:~~//www~~.~~wikimd.org/images/gray/large/image907.gif </center>~~		[[File:Gray907.png\|thumb\|left\|FIG. 907– External and middle ear, opened from the front. Right side. (''Picture From the Classic Gray's Anatomy'')]]

	FIG. 907– External and middle ear, opened from the front. Right side. (''Picture From the Classic Gray's Anatomy'')

	=== The '''External Acoustic Meatus''' ===		=== The '''External Acoustic Meatus''' ===
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	The '''osseous portion''' (''meatus acusticus externus osseus'') is about 16 mm. in length, and is narrower than the cartilaginous portion. It is directed inward and a little forward, forming in its course a slight curve the convexity of which is upward and backward. Its inner end is smaller than the outer, and sloped, the anterior wall projecting beyond the posterior for about 4 mm.; it is marked, except at its upper part, by a narrow groove, the '''[[tympanic sulcus]]''' in which the circumference of the [[tympanic membrane]] is attached. Its outer end is [[dilated]] and rough in the greater part of its circumference, for the attachment of the cartilage of the auricula. The front and lower parts of the [[osseous]] portion are formed by a curved plate of bone, the tympanic part of the temporal, which, in the fetus, exists as a separate ring ('''annulus tympanicus''') incomplete at its upper part (page 146).		The '''osseous portion''' (''meatus acusticus externus osseus'') is about 16 mm. in length, and is narrower than the cartilaginous portion. It is directed inward and a little forward, forming in its course a slight curve the convexity of which is upward and backward. Its inner end is smaller than the outer, and sloped, the anterior wall projecting beyond the posterior for about 4 mm.; it is marked, except at its upper part, by a narrow groove, the '''[[tympanic sulcus]]''' in which the circumference of the [[tympanic membrane]] is attached. Its outer end is [[dilated]] and rough in the greater part of its circumference, for the attachment of the cartilage of the auricula. The front and lower parts of the [[osseous]] portion are formed by a curved plate of bone, the tympanic part of the temporal, which, in the fetus, exists as a separate ring ('''annulus tympanicus''') incomplete at its upper part (page 146).

	~~<center>http~~:~~//www~~.~~wikimd.org/images/gray/large/image908.gif </center>~~		[[File:Gray908.png\|thumb\|FIG. 908– Horizontal section through left ear; upper half of section. (''Picture From the Classic Gray's Anatomy'')]]

	FIG. 908– Horizontal section through left ear; upper half of section. (''Picture From the Classic Gray's Anatomy'')

	The '''[[skin]]''' lining the meatus is very thin; adheres closely to the cartilaginous and osseous portions of the tube, and covers the outer surface of the [[tympanic membrane]]. After [[maceration]], the thin pouch of [[epidermis]], when withdrawn, preserves the form of the [[meatus]]. In the thick [[subcutaneous]] tissue of the cartilaginous part of the meatus are numerous [[ceruminous glands]], which secrete the ear-wax; their structure resembles that of the [[sudoriferous glands]].		The '''[[skin]]''' lining the meatus is very thin; adheres closely to the cartilaginous and osseous portions of the tube, and covers the outer surface of the [[tympanic membrane]]. After [[maceration]], the thin pouch of [[epidermis]], when withdrawn, preserves the form of the [[meatus]]. In the thick [[subcutaneous]] tissue of the cartilaginous part of the meatus are numerous [[ceruminous glands]], which secrete the ear-wax; their structure resembles that of the [[sudoriferous glands]].

Prab at 04:05, 29 August 2023

2023-08-29T04:05:08Z

New page

[[Anatomy]] > [[Gray's Anatomy| Gray's Anatomy of the Human Body]] > X. The Organs of the Senses and the Common Integument > 1d. 1. The External Ear

[[Henry Gray]] (1821–1865). Anatomy of the Human Body. 1918.

== '''The External Ear''' ==
The '''external ear''' consists of the expanded portion named the '''[[auricula]]''' or '''[[pinna]]''' and the '''external acoustic meatus''' The former projects from the side of the head and serves to collect the vibrations of the air by which sound is produced; the latter leads inward from the bottom of the auricula and conducts the vibrations to the [[tympanic cavity]].

=== The '''Auricula''' or '''Pinna''' ===
The '''Auricula''' or '''Pinna''' (Fig. 904) is of an [[ovoid]] form, with its larger end directed upward. Its lateral surface is irregularly [[concave]], directed slightly forward, and presents numerous eminences and depressions to which names have been assigned. The prominent rim of the auricula is called the '''[[helix]]''' where the helix turns downward behind, a small [[tubercle]], the '''auricular tubercle of Darwin''' is frequently seen; this tubercle is very evident about the sixth month of fetal life when the whole auricula has a close resemblance to that of some of the adult monkeys.

Another curved prominence, parallel with and in front of the helix, is called the '''[[antihelix]]''' this divides above into two crura, between which is a triangular depression, the '''fossa triangularis''' The narrow-curved depression between the helix and the antihelix is called the '''[[scapha]]''' the antihelix describes a curve around a deep, capacious cavity, the '''[[concha]]''' which is partially divided into two parts by the '''[[crus]]''' or commencement of the helix; the upper part is termed the '''cymba conchae''' the lower part the '''cavum conchae'''

In front of the concha, and projecting backward over the [[meatus]], is a small pointed eminence, the '''[[tragus]]''' so called from its being generally covered on its under surface with a tuft of hair, resembling a goat’s beard. Opposite the tragus, and separated from it by the '''intertragic notch''' is a small tubercle, the '''[[antitragus]]''' Below this is the '''[[lobule]]''' composed of tough areolar and adipose tissues, and wanting the firmness and elasticity of the rest of the auricula.
The cranial surface of the auricula presents elevations which correspond to the depressions on its lateral surface and after which they are named, ''e. g'' '''eminentia conchae, eminentia triangularis''' etc.

<center>http://www.wikimd.org/images/gray/large/image904.gif </center>

FIG. 904– The auricula. Lateral surface. (''Picture From the Classic Gray's Anatomy'')
==== '''Structure''' ====
The auricula is composed of a thin plate of yellow [[fibrocartilage]], covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the external [[acoustic meatus]] by fibrous tissue.

The '''[[skin]]''' is thin, closely adherent to the [[cartilage]], and covered with fine hairs furnished with [[sebaceous glands]], which are most numerous in the [[concha]] and [[scaphoid fossa]]. On the [[tragus]] and [[antitragus]] the hairs are strong and numerous. The skin of the auricula is continuous with that lining the external acoustic meatus.

<center>http://www.wikimd.org/images/gray/large/image905.gif </center>

FIG. 905– Cranial surface of cartilage of right auricula. (''Picture From the Classic Gray's Anatomy'')
The '''cartilage of the auricula''' (''cartilago auriculae; cartilage of the pinna'') (Figs. 905, 906) consists of a single piece; it gives form to this part of the ear, and upon its surface are found the eminences and depressions above described. It is absent from the [[lobule]]; it is deficient, also, between the [[tragus]] and beginning of the [[helix]], the gap being filled up by dense fibrous tissue. At the front part of the [[auricula]], where the helix bends upward, is a small projection of cartilage, called the ''spina helicis'' while in the lower part of the helix the cartilage is prolonged downward as a tail-like process, the '''cauda helicis''' this is separated from the [[antihelix]] by a [[fissure]], the '''fissura antitragohelicina''' The cranial aspect of the cartilage exhibits a transverse furrow, the '''sulcus antihelicis transversus''' which corresponds with the inferior [[crus]] of the antihelix and separates the eminentia conchae from the eminentia triangularis. The eminentia conchae is crossed by a vertical ridge (''ponticulus''), which gives attachment to the Auricularis posterior muscle. In the cartilage of the auricula are two fissures, one behind the crus helicis and another in the tragus.

The '''ligaments of the auricula''' (''ligamenti auricularia'' [''Valsalva'']; ''ligaments of the pinna'') consist of two sets:

(1) '''[[extrinsic]]''' connecting it to the side of the head;

(2) '''[[intrinsic]]''' connecting various parts of its cartilage together.

The '''extrinsic ligaments''' are two in number, anterior and posterior. The ''[[anterior]] ligament'' extends from the [[tragus]] and [[spina helicis]] to the root of the [[zygomatic process]] of the [[temporal bone]]. The ''[[posterior]] ligament'' passes from the posterior surface of the [[concha]] to the outer surface of the [[mastoid process]].

The chief '''intrinsic ligaments''' are:

(''''a'''') a strong fibrous band, stretching from the [[tragus]] to the commencement of the [[helix]], completing the [[meatus]] in front, and partly encircling the boundary of the [[concha]]; and

(''''b'''') a band between the [[antihelix]] and the cauda helicis. Other less important bands are found on the cranial surface of the [[pinna]].

==== The '''muscles of the auricula''' ====
The '''muscles of the auricula''' (Fig. 906) consist of two sets:

(1) the '''[[extrinsic]]''' which connect it with the [[skull]] and [[scalp]] and move the auricula as a whole; and

(2) the '''[[intrinsic]]''' which extend from one part of the auricle to another.

===== The '''extrinsic muscles''' =====
The '''extrinsic muscles''' are the Auriculares anterior, superior, and posterior.

The ''Auricularis anterior'' (''Attrahens aurem''), the smallest of the three, is thin, fan-shaped, and its fibers are pale and indistinct. It ''arises'' from the lateral edge of the galea aponeurotica, and its fibers converge to be inserted into a projection on the front of the [[helix]].

The ''Auricularis superior'' (''Attolens aurem''), the largest of the three, is thin and fan-shaped. Its fibers ''arise'' from the galea aponeurotica, and converge to be inserted by a thin, flattened [[tendon]] into the upper part of the cranial surface of the auricula.

The ''Auricularis posterior'' (''Retrahens aurem'') consists of two or three fleshy [[fasciculi]], which ''arise'' from the mastoid portion of the [[temporal bone]] by short [[aponeurotic]] fibers. They are inserted into the lower part of the cranial surface of the [[concha]].

===== ''Actions'' =====
In man, these muscles possess very little action: the Auricularis anterior draws the auricula forward and upward; the Auricularis superior slightly raises it; and the Auricularis posterior draws it backward.

<center>http://www.wikimd.org/images/gray/large/image906.gif </center>

FIG. 906– The muscles of the auricula. (''Picture From the Classic Gray's Anatomy'')

===== The ''intrinsic'' muscles =====
The ''intrinsic'' muscles are the:
Helicis major.

Antitragicus.

Helicis minor.

Transversus auriculae.

Tragicus.

Obliquus auriculae.

The ''Helicis major'' is a narrow vertical band situated upon the anterior margin of the [[helix]].
It ''arises'' below, from the spina helicis, and is inserted into the [[anterior]] border of the helix, just where it is about to curve backward.

The ''Helicis minor'' is an oblique [[fasciculus]], covering the crus helicis.

The ''Tragicus'' is a short, flattened vertical band on the lateral surface of the [[tragus]].

The ''Antitragicus arises'' from the outer part of the [[antitragus]], and is inserted into the cauda helicis and [[antihelix]].

The ''Transversus auriculae'' is placed on the cranial surface of the [[pinna]]. It consists of scattered fibers, partly tendinous and partly muscular, extending from the eminentia [[conchae]] to the prominence corresponding with the [[scapha]].

The ''Obliquus auriculae'' also on the cranial surface, consists of a few fibers extending from the upper and back part of the [[concha]] to the convexity immediately above it.

==== ''Nerves'' ====
The Auriculares [[anterior]] and [[superior]] and the [[intrinsic muscles]] on the lateral surface are supplied by the temporal branch of the facial nerve, the Auricularis posterior and the [[intrinsic]] muscles on the cranial surface by the posterior auricular branch of the same nerve.

The '''[[arteries]] of the auricula''' are the posterior auricular from the external [[carotid]], the anterior [[auricular]] from the superficial [[temporal]], and a branch from the [[occipital]]

The '''[[veins]]''' accompany the corresponding arteries. ''[[26]]''

The '''[[sensory nerves]]''' are: the great [[auricular]], from the [[cervical plexus]]; the auricular branch of the [[vagus]]; the auriculotemporal branch of the [[mandibular nerve]]; and the lesser occipital from the cervical plexus.

<center>http://www.wikimd.org/images/gray/large/image907.gif </center>

FIG. 907– External and middle ear, opened from the front. Right side. (''Picture From the Classic Gray's Anatomy'')

=== The '''External Acoustic Meatus''' ===
(''meatus acusticus externus; external auditory canal or meatus'') extends from the bottom of the [[concha]] to the [[tympanic membrane]] (Figs. 907, 908). It is about 4 cm. in length if measured from the [[tragus]]; from the bottom of the concha its length is about 2.5 cm. It forms an S-shaped curve, and is directed at first inward, forward, and slightly upward (''pars externa''); it then passes inward and backward (''pars media''), and lastly is carried inward, forward, and slightly downward (''pars interna''). It is an oval cylindrical canal, the greatest diameter being directed downward and backward at the external orifice, but nearly horizontally at the inner end. It presents two constrictions, one near the inner end of the [[cartilaginous]] portion, and another, the '''[[isthmus]]''' in the [[osseous]] portion, about 2 cm. from the bottom of the concha. The [[tympanic membrane]], which closes the inner end of the [[meatus]], is obliquely directed; in consequence of this the floor and anterior wall of the meatus are longer than the roof and posterior wall.

The external acoustic meatus is formed partly by cartilage and membrane, and partly by bone, and is lined by skin.

==== The '''cartilaginous portion''' ====
The '''cartilaginous portion''' (''meatus acusticus externus cartilagineus'') is about 8 mm. in length; it is continuous with the cartilage of the [[auricula]], and firmly attached to the circumference of the [[auditory process]] of the [[temporal bone]]. The cartilage is deficient at the upper and back part of the [[meatus]], its place being supplied by fibrous membrane; two or three deep fissures are present in the anterior part of the cartilage.

==== The '''osseous portion''' ====
The '''osseous portion''' (''meatus acusticus externus osseus'') is about 16 mm. in length, and is narrower than the cartilaginous portion. It is directed inward and a little forward, forming in its course a slight curve the convexity of which is upward and backward. Its inner end is smaller than the outer, and sloped, the anterior wall projecting beyond the posterior for about 4 mm.; it is marked, except at its upper part, by a narrow groove, the '''[[tympanic sulcus]]''' in which the circumference of the [[tympanic membrane]] is attached. Its outer end is [[dilated]] and rough in the greater part of its circumference, for the attachment of the cartilage of the auricula. The front and lower parts of the [[osseous]] portion are formed by a curved plate of bone, the tympanic part of the temporal, which, in the fetus, exists as a separate ring ('''annulus tympanicus''') incomplete at its upper part (page 146).

<center>http://www.wikimd.org/images/gray/large/image908.gif </center>

FIG. 908– Horizontal section through left ear; upper half of section. (''Picture From the Classic Gray's Anatomy'')

The '''[[skin]]''' lining the meatus is very thin; adheres closely to the cartilaginous and osseous portions of the tube, and covers the outer surface of the [[tympanic membrane]]. After [[maceration]], the thin pouch of [[epidermis]], when withdrawn, preserves the form of the [[meatus]]. In the thick [[subcutaneous]] tissue of the cartilaginous part of the meatus are numerous [[ceruminous glands]], which secrete the ear-wax; their structure resembles that of the [[sudoriferous glands]].

==== '''Relations of the Meatus''' ====
In front of the [[osseous]] part is the [[condyle]] of the [[mandible]], which however, is frequently separated from the cartilaginous part by a portion of the [[parotid gland]]. The movements of the jaw influence to some extent the [[lumen]] of this latter portion. Behind the osseous part are the [[mastoid]] air cells, separated from the [[meatus]] by a thin layer of bone.

The '''[[arteries]]''' supplying the meatus are branches from the posterior [[auricular]], internal [[maxillary]], and [[temporal]].

The '''[[nerves]]''' are chiefly derived from the [[auriculotemporal]] branch of the [[mandibular nerve]] and the [[auricular]] branch of the [[vagus]].
{{Auditory and vestibular anatomy}}
{{Human regional anatomy}}
[[Category:Auditory system]]
[[Category:Human head and neck]]
[[Category:Sensory organs|Ear]]
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