NURS305 Chapter Notes - Chapter 16: Weber Test, Sensorineural Hearing Loss, Conductive Hearing Loss
Document Summary
Starts to develop 6th week gestation - identifiable by 12th week (ears and kidneys develop at same time) Guides sound waves into meatus of external auditory canal - chamber that transitions from firm cartilage to bone and ends at tm. Thing, sensitive layer of skin covers external auditory canal (s shape) Tm is oblique, multilayered (3 layers), translucent, pearly grey barrier. Adheres through concave shape to the malleus near the centre. Outer rim (annulus) is thicker and more fibrous. Most of the tm is called the pars tensa is stretched tightly and easy to see through. Pars flaccida (small portion of tm above short process of malleus) is relaxed and opaque. Hairs and glands that secrete cerumen line the canal. Malleus, incus, stapes (ossicles of middle ear) conduct sound waves to inner ear. Acts as a volume dampened to protect the inner ear. Cochlear window (round window) - connects middle ear and inner ear.