S7) Functional Anatomy and Disorders of the Ear Flashcards
What is the ear?
The ear is the organ of hearing and balance (equilibrium)
Different pathologies can involve the three different areas of the ear.
Identify these
- External ear
- Middle ear
- Inner ear
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/421/671/a_image_thumb.png?1510002456)
Identify 6 signs/symptoms of ear disease
- Otalgia (ear pain)
- Tinnitus (ear ringing)
- Discharge
- Vertigo
- Hearing loss (conductive vs sensorineural)
- Facial nerve palsy
Within which bone of the skull do we find the parts of the ear?
Temporal bone
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/421/977/a_image_thumb.jpg?1510002561)
Identify the four components of the temporal bone
- Squamous part
- Petromastoid part
- Tympanic plate
- Styloid process
![](https://s3.amazonaws.com/brainscape-prod/system/cm/226/167/330/a_image_thumb.png?1511891245)
What is referred pain?
Referred pain is pain felt in a part of the body other than its actual source
What is the significance of otalgia?
- Otalgia can sometimes be referred pain
- Due to the diverse sensory innervation of the ear, sources outside of the ear that share similar nerve innervation may present with otalgia e.g. laryngeal cancers
State the components and function of the external ear
- Components: pinna, external auditory meatus, lateral surface of tympanic membrane
- Function: collects, transmits and focuses sound waves onto the tympanic membrane
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/422/407/a_image_thumb.png?1510002970)
What does the pinna of the external ear consist of?
The pinna consist of cartilage, skin and fatty tissue
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/422/559/a_image_thumb.jpg?1510003068)
Label the following surface features of the external ear:
- Helix
- Antihelix
- Concha
- Tragus
- External auditory meatus
- Lobule
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/503/922/q_image_thumb.jpg?1510074656)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/503/922/a_image_thumb.gif?1510074660)
Identify 4 causes of pinna abnormalities
- Congenital
- Inflammatory
- Infective
- Traumatic
When do pinna haematomas occur?
- Secondary to blunt injury to the pinna
- Common in contact sports
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/422/993/a_image_thumb.png?1510003416)
How do pinna haematomas occur?
- Accumulation of blood between cartilage and perichondrium
- Deprives the cartilage of its blood supply
- Causes pressure necrosis of tissue
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/153/a_image_thumb.png?1510003472)
How are pinna haematomas treated?
- Prompt drainage
- Measures to prevent re‐accumulation and re‐apposition of two layers
What happens to untreated/poorly treated pinna haematomas?
Untreated or poorly treated leads to fibrosis and new asymmetrical cartilage development → ‘cauliflower deformity’ of the ear
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/277/a_image_thumb.jpeg?1510003613)
How long is the external acoustic meatus?
2.5 cm
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/448/a_image_thumb.jpg?1510003664)
Describe the structure of the external acoustic meatus (ear canal)
- Consists of a a cartilaginous (outer 1/3) and bony part (inner 2/3)
- Skin-lined cul-de-sac
- Sigmoid shape
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/739/a_image_thumb.jpg?1510004136)
Describe the anatomical location of the external acoustic meatus
- Free outer border provides an attachment for external ear cartilage
- Medially, it fuses with the petrous part of the temporal bone
![](https://s3.amazonaws.com/brainscape-prod/system/cm/226/167/439/a_image_thumb.png?1511891590)
Identify 4 functions of the external acoustic meatus
- Arrangement of hairs and production of wax (cartilaginous part)
- Prevent objects entering deeper into ear canal
- Aids in desquamation and skin migration out of canal
- Skin lining secretes cerumen to protect meatal skin
What are the components of ear wax?
- Discarded cells of meatal skin
- Cerumen (modified sebum)
Describe the structure, location and function of the tympanic membrane
- Structure: fibrous structure, translucent
- Location: apex points medially
- Function: allows visualisation of some structures within the ear (malleus)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/226/168/674/a_image_thumb.png?1511892295)
Identify two common conditions involving external acoustic meatus
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/518/a_image_thumb.png?1510003802)
Identify two common conditions affecting the tympanic membrane
![](https://s3.amazonaws.com/brainscape-prod/system/cm/224/423/710/a_image_thumb.png?1510003851)
Where are the middle and inner ear found?
The petrous part of the temporal bone contains the middle and inner ear
![](https://s3.amazonaws.com/brainscape-prod/system/cm/226/167/854/a_image_thumb.jpg?1511891730)
Describe the anatomical relations of the petrous part of the temporal bone
Upper surface forms part of the floor of the middle and posterior cranial fossae:
- Internal acoustic meatus pierces the part forming the posterior cranial fossa
- ICA and carotid canal are found in its inferior surface (irregular)