Anatomy and physiology of the ear

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Anatomy and physiology of the ear

Lecture 15/4/2015

Anatomy and physiology of the ear

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Anatomy is the study of the structure of living organisms. The study of the form and gross structure of the various parts of the human body

Physiology the science of the functioning of the living organisms and their component parts

Anterior describing or relating to the front portion of the body, describing the front part of any organ

Superior situated in the upper most in the body in relation to another structure or surface

Inferior lower in the body in relation to another structure or surface

Terminology

Anatomy and physiology of the ear

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Lateral situated at, or relating to the side of an organ

Dorsal related or situated at or close to the back of the body or to the posterior part of the organ

Posterior situated at or near the back of the body Afferent designated nerves or neurons that

convey impulses from the sense organs and another receptors to the brain or spinal cord

Efferent designated nerves or neurons that convey impulses from the brain or spinal cord to the muscles, glands or other effectors

Terminology

Anatomy and physiology of the ear

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The auditory system is divided into- Peripheral component

Overview of the anatomy and physiology of the auditory system

Anatomy and physiology of the ear

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Located in the most part of the temporal bone, its made of

1. The outer ear- Pinna- External auditory meatus (ear canal)- Tympanic membrane (ear drum)2. The middle ear- The tympanic cavity (ossicles and their

associated muscles, tendons and ligaments- Eustachian tube

Peripheral auditory system

Anatomy and physiology of the ear

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3. Inner ear- begins at the oval window, sensory organ of hearing and balance

- Cochlea is the hearing part of the inner ear- Semisircular canals, utricle and saccule are

the balance part of the inner ear

4. The auditory nerve (acoustic, VIII cranial nerve)

Peripheral auditory system

Anatomy and physiology of the ear

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Central componentDeals with processing of auditory information as it is carried up to the brain

Anatomy and physiology of the ear

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Sound impulses pass through the auditory tract where it goes through a number of energy transformation from

Acoustical: in the air into the external ear Mechanical: tympanic membrane and the

ossicles hydraulic : cochlear fluid ( perilymph and

endolymph) Chemical: inner and outer hair cells electrical: auditory nerveUntil they are received by the brain

Sound transmission

Anatomy and physiology of the ear

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Air conduction (AC) the course of sounds that are conducted from the outer, middle and finally to the inner ear

Bone conduction (BC) the course of sounds that are conducted to the inner ear by way of bones of the skull

The human hearing pathways

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1. Conductive hearing loss (CHL) impaired AC and normal BC. Abnormalities of the outer and/or middle ear causes hearing loss

2. Sensorineural hearing loss (SNHL) impaired AC and impaired BC (sound is perceived of the same loudness) damage of the coclea or the neural structures

3. Mixed hearing loss (MHL) impaired AC and impaired BC with air-bone-gap.

Types of hearing loss

Anatomy and physiology of the ear

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The temporal bone

Anatomy and physiology of the ear

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The right and the left temporal bones are two of the 22 bones of the skull

The temporal bone forms he inferior portion of the side of the skull

Temporal bone

Anatomy and physiology of the ear

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Is divided into five anatomical divisions1. The squamous2. Mastoid3. Petrous4. Tympanic portion5. Styloid process

Temporal bone