The document summarizes the gross anatomy of the ear, which has three main parts - the external, middle, and inner ear. The external ear collects and transmits sound waves through the external acoustic meatus to the middle ear. The middle ear contains the auditory ossicles and transmits vibrations through the oval window to the inner ear for hearing and balance. It is separated from the external ear by the tympanic membrane and surrounded by six bony walls. The inner ear is concerned with hearing and balance.

1. GROSS ANATOMY OF THE ‘EAR’

2. EAR
Parts:
• It has 3 parts;
 1st part ……………external ear
 2nd part….................middle ear
 3rd part……………..inner ear
• The external and middle ear are mainly concerned with the
transference of sound to the internal ear
• internal ear is for hearing and balancing (equilibrum)
External ear
• has 2 parts;
 The Auricle (pinna) which projects from the lateral side of the head
 the External acoustic meatus (ear canal) which is a canal leading
inwards

6. AURICLE

8. Auricle (pinna)
• is on the side of the head and assists in capturing sound
• It consists of cartilage covered with skin and arranged in a pattern of
various elevations and depressions
• The large outside rim of the auricle is the helix
• It ends inferiorly at the fleshy lobule (ear lobe)
• The lobule is the only part of the auricle not supported by cartilage
• It is consists of fibrous tissue, fat, and blood vessels
• It is easily pierced for taking small blood samples and inserting
earrings
• The hollow center of the auricle is the concha of auricle
• at the depth of the concha is the opening of the external acoustic
meatus
• Just anterior to the opening of the external acoustic meatus, in front of
the concha, is an elevation called the tragus

9. • Opposite the tragus, and above the fleshy lobule, is another elevation
(the antitragus)
• A smaller curved rim, parallel and anterior to the helix is the
antihelix
• The antihelix divides above into 2 legs or crura
• In between these crura is a depression called the triangular fossa
• A curved depression lies between the helix and antihelix and it is
called the scapha/scaphoid fossa
Muscles
Include;
 Intrinsic muscles
 Extrinsic muscle
intrinsic muscles
• pass between the cartilaginous parts of the auricle and may change
the shape of the auricle

10. They include:
• Helicis major
• Helicis minor
• Tragicus
• Antitragicus
• Transverse muscle
• Oblique muscle
extrinsic muscles
• pass from the scalp or skull to the auricle and may also play a role in
positioning of the auricle
• anterior auricular muscle
• Superior auricular muscle
• posterior auricular muscle
Both groups of muscles are innervated by the facial nerve [VII]
Arterial supply
• posterior auricular artery
• superficial temporal artery
Venous drainage
• through vessels following the arteries

13. Innervation
superficial surfaces supplied by;
• great auricular nerve
• auriculotemporal branch of the mandibular nerve [V3] (anterior
superior portion)
• lesser occipital nerve (posterior superior portion)
deeper parts are supplied by;
• facial nerve [VII]
• vagus nerve [X] (the auricular branch)
Lymphatic drainage : drain
• anteriorly into parotid nodes
• posteriorly into mastoid nodes
• possibly into the upper deep cervical nodes

15. External acoustic meatus
• extends from the deepest part of the concha to the tympanic
membrane (eardrum)
• a distance of approximately 1 inch (2.5 cm)
• Its walls consist of cartilage and bone
• The lateral 1/3 is formed from cartilaginous extensions from some
of the auricular cartilages
• the medial 2/3 is a bony tunnel in the temporal bone
• Throughout its length the external acoustic meatus is covered with
skin
• some of this skin contains hairs and modified sweat glands
producing cerumen (earwax)
• cerumen protects the skin of the ear canal, assists in cleaning and
lubrication,
and
also
provides
some
protection
from bacteria, fungi, insects and water

17. Clinical anatomy
• Excess production of cerumen can press against the eardrum and/or
occlude (block) the external auditory canal or hearing aids,
potentially hindering hearing
•
•
•
•
•
•
Tympanic membrane (ear drum)
is a membrane that separates the external acoustic meatus from the
middle ear
is a thin, oval semi-transparent membrane
approximately 1 cm in diameter
it is covered with thin skin externally and with mucous membrane of
the middle ear internally
When viewed through an otoscope, the tympanic membrane appears
concave toward the external acoustic meatus with a shallow, conelike central depression
the peak of this cone like depression is called the umbo of the
tympanic membrane

18. • The lower end of the handle of malleus is attached to the umbo of
tympanic membrane
• Superior to the handle of the malleus is a small elevation called the
lateral process of the malleus
• the part of the tympanic membrane superior to the lateral process of
the malleus is thin and is called the flaccid part /pars flaccida
• the remaining part of the membrane is thick and is called the tense
part /pars tensa
• The pars flaccida lacks the radial and circular fibers present in the
remaining part of the membrane
• in the anterior-inferior quadrant of the membrane is a bright
triangular reflection of light called the cone of light
• This region is usually visible when examining the tympanic membrane
with an otoscope

23. innervation
• external surface of the tympanic membrane is supplied;
 the auriculotemporal nerve (a branch of CN V3 ) {main contribution}
 a small auricular branch of the vagus (CN X)
• The internal surface of the tympanic membrane is supplied by the
glossopharyngeal nerve (CN IX)
Clinical anatomy
External Ear Injury
• Bleeding within the auricle resulting from trauma may produce an
auricular hematoma
Acute Otitis Externa
• Otitis externa is an inflammation of the external acoustic meatus
• The infection often develops in swimmers who do not dry their meatus
after swimming and/or use ear drops
• it may also be the result of a bacterial infection of the skin lining the
meatus

24. Middle Ear
• is the narrow air-filled chamber in the petrous part of the temporal
bone
• It has a cavity called tympanic cavity
parts
• The cavity has 2 parts:
 tympanic cavity proper
 epitympanic recess
 Tympanic cavity proper is the space directly internal to the tympanic
membrane
 while the space superior to the membrane is called the epitympanic
recess
 The middle ear communicates with the mastoid area/ mastoid antrum
posteriorly
 It communicates anteriorly with the nasopharynx via the
pharyngotympanic tube

25. contents of the middle ear:
 Auditory ossicles (malleus, incus, and stapes)
 Stapedius and tensor tympani muscles
 Chorda tympani nerve, a branch of CN VII
 Tympanic plexus of nerves
Walls of the Tympanic Cavity
• The middle ear is shaped like a narrow box with concave sides
• It has 6 walls, which include;
I. Tegmental wall (roof)
II. Jugular wall (floor)
III. membranous wall (lateral wall)
IV. labyrinthine wall (medial wall)
V. carotid wall (anterior wall)
VI. Mastoid wall (posterior wall)

28. Tegmental wall (roof):
• is formed by a thin plate of bone called the tegmen tympani
• This bone separates the tympanic cavity from the middle cranial fossa
jugular wall (floor)
• is formed by a layer of bone that separates the tympanic cavity from
the internal jugular vein
• Near the medial border of the floor is a small aperture, through which
the tympanic branch from the glossopharyngeal nerve [IX] enters
the middle ear
Membranous wall (lateral wall)
• is formed mostly by the tympanic membrane and superiorly by the
bony wall of the epitympanic recess
labyrinthine wall (medial wall)
• separates the tympanic cavity from the internal ear
• also the lateral wall of the internal ear

29. • features on this wall include;
 promontory of the labyrinthine wall: a round bulge produced by the
basal coil of the cochlea
 Oval window
 Round window
carotid wall (anterior wall):
•
separates the tympanic cavity from the carotid canal
•
superiorly, it has the opening of the ;
 pharyngotympanic tube
 canal for the tensor tympani
mastoid (posterior) wall
•
has an opening called the aditus to the mastoid antrum
•
The aditus to the mastoid antrum connects the tympanic cavity
(epitympanic recess) to the mastoid air cells (sinus)
Note: The mastoid antrum is a cavity continuous with collections of airfilled spaces (the mastoid cells), throughout the mastoid part of the
temporal bone

31. Other features on the mastoid wall are:
 the pyramidal eminence, a small elevation through which the
tendon of the stapedius muscle enters the middle ear
 the opening through which the chorda tympani nerve, a branch of
the facial nerve [VII], enters the middle ear
Clinical anatomy
Mastoiditis:
Infection within the mastoid antrum and mastoid cells