Ear: External Ear

Question 1

Parts

Answer 1

1. Auricle
2. External auditory meatus
3. Tympanic membrane (ear drum)

Question 2

Auricle

Answer 2

1. Single yellow elastic cartilage covered with skin
2. Lower part (lobule) formed of fibrofatty tissue

Question 3

External auditory meatus: shape

Answer 3

S shaped tube (24 mm long)

Question 4

External auditory meatus: extent

Answer 4

Extending from auricle to the tympanic membrane

Question 5

External auditory meatus: parts

Answer 5

1. Lateral 1/3 cartilaginous
2. Medial 2/3 bony
   With a constriction between the 2 parts

Question 6

External auditory meatus: isthmus

Answer 6

Narrowest site lying about 5mm from tympanic membrane

Question 7

External auditory meatus: nerve supply

Answer 7

1. Auriculotemporal nerve
2. Auricular branch of vagus

Question 8

External auditory meatus: function

Answer 8

1. Sound collection
2. Tympanic membrane protection

Question 9

Tympanic membrane

Answer 9

Oval, thin, and semi translucent membrane stretched obliquely at external auditory meatus medial end

Question 10

Tympanic membrane: parts

Answer 10

2 parts
1. Pars tensa (major part)
2. Pars flaccida (small triangular part)

Question 11

Tympanic membrane: surfaces

Answer 11

1. Outer
2. Inner

Question 12

Tympanic membrane: outer surface

Answer 12

Concave, shows triangular cone of light in its anteroinferior part

Question 13

Tympanic membrane: inner surface

Answer 13

Convex, point of maximum convexity is called umbo

Question 14

Tympanic membrane: layers (3)

Answer 14

1. Outer (skin)
2. Intermediate (fibrous): absent in pars flaccida
3. Inner (middle ear mucosa)

Question 15

Nerve supply

Answer 15

Outer surface:
1. Auriculotemporal nerve
2. Auricular branch vagus nerve
Inner surface:
1. Tympanic plexus of nerves (mainly from Glossopharyngeal nerve)

Question 16

Blood supply

Answer 16

Outer surface:
1. Deep auricular artery (maxillary artery)
Inner surface:
1. Anterior tympanic artery (maxillary artery)
2. Posterior tympanic artery
3. Stylomastoid artery