EAR

EAR

• The ear is the organ of hearing and, in mammals, balance.
• The ear has three main parts; the outer, middle, and the inner ear.
• The outer ear consists of the pinna and the auditory canal.

• The middle ear is filled with ear and contains 3 tiny bones called ossicles: the anvil, hammer and stirrup.

• the inner ear contains the semicircular canals and the cochlea.

• since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone.
• The middle ear includes the tympanic cavity and the 3 ossicles.
• The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enables balance and eye tracking when moving; the urticle and saccule, which enable balance when stationary; and the cochlea, which enables hearing.
• The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation.
• The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.
• The ear may be affected by disease, including infection and traumatic damage.
• disease of the ear may lead to hearing loss, tinnitus and balance disorder such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear.
• The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations.

BLOOD SUPPLY-

• The blood supply of the ear differs according to each part of the ear.
• The outer ear is supplied by a number of arteries.
• The posterior auricular artery provides the majority of the blood supply.
• The anterior auricular arteries provide some supply to the outer rim of the ear and scalp behind it.
• The posterior auricular artery is a direct branch of the external carotid artery, and the anterior auricular arteries are branches from the superficial temporal artery.
• The occipital artery also plays a role.
• The middle ear is supplied by the mastoid branch of either the occipital or posterior auricular arteries and the deep auricular artery, a branch of the maxillary artery.
• Other arteries which are present but play a smaller role include branches of the middle meningeal artery, ascending pharyngeal artery, internal carotid artery, and the artery of the pterygoid canal.
• The inner ear is supplied by the anterior tympanic branch of the maxillary artery, the stylomastoid branch of the posterior auricular artery, the posterior branch of middle meningeal artery; and the labyrinthine artery, arising from either the anterior inferior cerebellar artery of the basilar artery.