Ear bones

Another well-established area of mechanical finite-element analysis is in the motion of the structures of the human middle ear (Figure 9.3). Of particular interest are comparisons between the vibration pattern of the eardrum, and the mode of vibration of the middle-ear bones under normal and diseased conditions. Serious middle-ear infections and blows to the head can cause partial or complete detachment of the bones, and can restrict their motion. Draining of the middle ear, to remove these products, is usually achieved by cutting a hole in the eardrum. This invariably results in the formation of scar tissue. Finite-element models of the dynamic motion of the eardrum can help in the determination of the best ways of achieving drainage without affecting significantly the motion of the eardrum. Finite-element models can also be used to optimise prostheses when replacement of the middle-ear bones is necessary. 

According to the Centers for Disease Control and Prevention (CDC), 60% of all human infections are caused by biofilms. To broaden the potential of antimiaobial peptoids, the Barron and Spormann groups investigated the potential of selected peptoids against Pseudomonas aeruginosa biofilms. Pseudomonas aeruginosa is known to cause 200 000 hospital-acquired infections annually in the United States alone. This opportunistic bacterium can cause a variety of infections such as wound and ear, bone, urinary tract, and... 

Highly mineralized bone (petrosal bones of some non-human mammals) has little organic material (8% in the horse petrosal to 3% in the tympanic bulla) [3]. (Almost certainly human ear bones will be somewhere near or in this region, though they seem not to have been studied.)... 

The inner ear consists of the cochlea and the labyrinth, organs for hearing and balance respectively, with the eighth cranial nerve. This nerve has an auditory and a vestibular portion. The inner ear is filled with liquid. When sound waves strike the eardrum, between the external canal and the middle ear, this causes movements of the ear bones (hammer, anvil and stirmp). These movements are transferred into vibrations of the liquid in the inner ear, where the hair cells convert the movements to nerve impulses. The signals are sent to the brain through the auditory nerve. 

In order to obtain a bioactive material with a lower elastic modulus and ductility, Bonfield prepared a hydroxyapatite-polyethylene composite [50]. Hydroxyapatite powders can be dispersed in a polyethylene matrix up to 45 vol% without losing any ductility of the polymer. The resultant composite shows a Young s modulus value of about 3 GPa, an ultimate tensile strength of 22-26 MPa, and a fracture toughness, Kjc, of 2.9 MPa m [51]. This composite is already used clinically as an artificial middle ear bone, etc. 

The bioceramic material, Bioxitan, developed by Hanoi University of Technology has been used for bone reconstruction since 2005. It is normally used for reconstruction of the ear bones because of difficulty in making the complex parts from bioceramic materials. 

Figure 9.3. The human ear is divided into three main parts. The outer ear collects sound and directs it down the ear canal towards the eardrum. The size of the eardrum, comhined with the lever action of the three hones of the middle ear, ensures the efficient conduction of sound from the ear canal, which is filled with air, to the inner ear, which is filled with a liquid. Very small muscles, not shown here, are cormected to these bones to protect the ear from very lond sounds. The inner ear consists of two parts. Only the cochlea is shown, which is the part of the human ear that is responsible for converting sound into electrical signals in the auditory nerve. The other part of the inner ear, the vestibular organ, is involved in balance.

Tophi Chalky deposits of sodium urate occurring in gout. Tophi form most often around joints in cartilage, bone, bursae, and subcutaneous tissue and in the external ear, producing a chronic, foreign-body inflammatory response. If untreated, tophi can lead to joint deformity or destruction. 

Black-eared kite, Milvus migrans lineatus Japan premoult (April) vs. postmoult Bone 0.08 DW vs. 0.07 DW 112... 

Otitis media is inflammation or infection of the middle ear and is not usually associated with back pain. Osteoporosis is a condition occurring mostly in postmenopausal women and is characterised by brittle bones caused by reduced bone mass. It is presented with pain. If it occurs in the vertebral structure the condition may be associated with chronic back pain. Pregnancy may be associated with back pain because of an increase in weight and the increased strain. 

Otitis media inflammation or infection of the middle ear Paget s disease non-metabolic disease of the bones Paraesthesia numbness and tingling sensation Parkinson s disease progressive degenerative neurological disease characterised by tremors and muscle rigidity Periodontitis inflammation of the periodontium Peripheral neuropathies disorders of the peripheral nervous system... 

Leahy M, Ray-Coquard 1, Verweij J, Le Cesne A, Duffaud F, Hogendoom PC, Fowst C, de Balincourt C, di Paola ED, van Glabbeke M, Judson 1, Blay JY. (2007) European Organisation for research and treatment of cancer soft tissue and bone sarcoma group. Ear J Cancer 43 308-315. 

Teflon was introduced to the public in 1960 when the first Teflon-coated muffin pans and frying pans were sold. Like many new materials, problems were encountered. Bonding to the surfaces was uncertain at first. Eventually the bonding problem was solved. Teflon is now used for many other applications including acting as a biomedical material in artificial corneas, substitute bones for nose, skull, hip, nose, and knees ear parts, heart valves, tendons, sutures, dentures, and artificial tracheas. It has also been used in the nose cones and heat shield for space vehicles and for their fuel tanks. 

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