Ear Anatomy

Question 1

Name the 3 main regions/divisions of the ear

Answer 1

1. External ear
2. Middle ear
3. Internal ear

Question 2

What does the lobule of the auricle contain?

Answer 2

Fibrous tissue
Fat
Blood vessels

Question 3

The auricle is connected to the 1. ____________ by the 2. ______________

Answer 3

1. Temporal bone

2. Extrinsic muscles and ligaments

Question 4

What extrinsic muscles and ligaments connects the auricle to the temporal bone?

Answer 4

Extrinsic muscles - orbicularis ant/post/sup

Extrinsic ligaments - ant and post extrinsic ligaments

Question 5

What is the length of the external auditory canal?

Answer 5

2.5 cm long from the concha

4 cm long from the Travis

Question 6

This structure is semi-transparent and serves as a partition between EAC and the middle ear

Answer 6

Tympanic membrane

Question 7

Rim of the auricle

Answer 7

Helix

Question 8

Innervation of auricle

Answer 8

Mnemonic - A FLAG

Auriculotemporal nerve
Facial nerve
Lesser occipital nerve
Auricular branch of vagus nerve
Greater auricular nerve

Question 9

Which part of the auricle is innervated by the great auricular nerve?

Answer 9

Posterior upper lateral 2/3 of the surface of the auricle (helix, antihelix, and lobule)

Question 10

The lesser occipital nerve innervates what structures of the auricle?

Answer 10

Upper part of the cranial surface of the auricle

Question 11

Innervation of the concha and posterior part of the eminitia

Answer 11

Auricular branch of the vagus nerve

Question 12

This nerve gives off a branch that supplies the tragus, helical crus, and the adjacent part of the helix

Answer 12

V3 - branch: auriculotemporal nerve

Question 13

What structures of the auricle is innervated by the facial nerve?

Answer 13

Depression and eminence of concha

Question 14

Lymphatic drainage of the auricle

Answer 14

1. Nodes at the mastoid tip (post aspect)
2. Pre-auricular nodes (tragus and upper part of auricle)
3. Superficial cervical lymph nodes (remainder of the auricle) - drains to the upper deep cervical lymph nodes

Question 15

What are the supporting structures of the external auditory meatus?

Answer 15

Cartilage (lateral 1/3)
Temporal bone (medial 2/3)

Question 16

What are the protective mechanisms found within the EAC?

Answer 16

Hair and cerumen - prevents dust and foreign objects from entering the ear

Question 17

Arterial supply of the EAM

Answer 17

1. Outer portion - post auricular artery and superficial temporal artery
2. Inner portion - deep auricular branch of the maxillary artery

Question 18

Venous drainage of EAM

Answer 18

Associated veins. Drains into EJV, maxillary vein, and the pterygoid plexus

Question 19

Lymphatic drainage of the EAM

Answer 19

Those associated with the auricle

Mnemonic - NPS

Nodes at the mastoid tip
Preauricular nodes
Superficial cervical lymph nodes

Question 20

EAM Innervation

Answer 20

Anterior wall and roof - auriculotemporal nerve (V3) (major innervation)

Posterior wall and floor - auricular branch of the vagus nerve (minor innervation)

Question 21

Tympanic membrane (TM) innervation

Answer 21

Mnemonic - 2AT

Auriculotemporal nerve - pain
Auricular branch of the vagus nerve
Tympanic branch of glossopharyngeal nerve

Question 22

TM arterial supply

Answer 22

Stylomastoid branch of post auricular and deep auricular artery

Ant tympanic branches of the maxillary artery

Question 23

TM venous drainage

Answer 23

Superficial surface - EJV

Deep surface - transverse sinus and dural veins

Question 24

TM lymphatic drainage

Answer 24

Parotid or upper deep cervical lymph nodes

Question 25

Where is the middle ear located?

Answer 25

Petronius portion of the temporal bone

Question 26

Partitions of the middle ear

Answer 26

Tympanic membrane Bony partition (oval and round window)

Question 27

Middle ear function

Answer 27

Main function is to transmit vibrations from the TM to the inner ear via the auditory ossicles

Question 28

Divisions of the middle ear

Answer 28

Tympanic cavity and epitympanic recess

Question 29

The malleus and incus partially extend upwards to this space

Answer 29

Epitympanic recess

Question 30

Space superior to the tympanic cavity which lies next to the mastoid air cells

Answer 30

Epitympanic recess

Question 31

Borders of the middle ear

Answer 31

Roof - formed from the thin bone from the petrous part of the temporal bone (separates middle ear and middle cranial fossa) Floor - a.k.a jugular wall, consists of a thin layer of bone. Separates middle ear from the IJV Lateral wall - tympanic membrane and lateral wall of the epitympanic recess Medial wall - lateral wall of inner ear (contains a prominent bulge produced by the facial nerve as it travels nearby Ant wall - a thin bony plate with 2 openings for the auditory tube and the tensor tympani muscle (separates middle ear from the ICA) Post wall - bony partition between tympanic cavity and the mastoid cells (superiority there is a hole that communicates the 2 areas known as the aditus to the mastoid antrum)

Question 32

Bones of the middle ear

Answer 32

Mnemonic - MIS Malleus Incus Stapes

Question 33

Collection of air-filled spaces in the mastoid process of the temporal bone located behind the epitympanic recess

Answer 33

Mastoid air cells

Question 34

Cavity within mastoid air cells are contained

Answer 34

Mastoid antrum

Question 35

Structure that communicates ME and mastoid antrum

Answer 35

Aditus to mastoid antrum

Question 36

Role/function of mastoid air cells

Answer 36

Acts as a buffer system of air - releases air into the ME when pressure is too low

Question 37

Describe the acoustic reflex

Answer 37

It is the contraction of ME muscles in response to loud noises which inhibits the transmission of vibrations by auditory ossicles and therefore decreases the transmission of sound to the inner ear

Question 38

Name the 2 muscles of the ME

Answer 38

Tensor tympani | Stapedius

Question 39

Origin, insertion, innervation and action of tensor tympani muscle

Answer 39

Origin - auditory tube Insertion -handle of malleus Innervation - tensor tympani branch of V3 Action - contraction pulls the handle of malleus medially

Question 40

Origin, insertion, innervation, and action of stapedius muscle

Answer 40

Origin - walls of pyramidal eminence Insertion - stapes Innervation - facial nerve Action - controls the amplitude of waves to the inner ear