Key Points The eustachian tube is involved in pressure equalization, mucociliary clearance, and middle ear protection. The principal dilator of the eustachian tube is the tensor veli palatini muscle. Anatomic changes in the tube with growth and development include increased…
Key Points The labyrinth develops from the otic placode, which invaginates to become the otic pit and then pinches off to form the otic cyst, or otic vesicle. The vertical canals are oriented at 45 degrees with regard to the…
Key Points The external ear funnels acoustic signals into the ear and plays an important role in sound localization. The middle ear matches the impedance between the air-filled external environment and the fluid-filled inner ear. The inner ear has two…
Key Points The neuroanatomy of the central and peripheral auditory systems reflects their function: to extract specific information from the complex waveforms of speech, music, and environmental sounds. The cochlea is organized tonotopically, with low frequencies processed at the apex…
Key Points The temporal bone consists of four embryologically distinct components: these are squamous, mastoid, petrous, and tympanic . The temporal line is located approximately 5 mm inferior to the lowest level of the middle fossa floor. The mastoid antrum is…
Key Points Graves disease is an autoimmune disorder associated with hypermetabolism, enlargement of the thyroid gland, and exophthalmos. In Graves ophthalmopathy (GO), retrobulbar fibroblasts secrete glycosaminoglycans, causing engorgement of the extraocular muscles and orbital fat and increasing the volume of…
Key Points Surgical robots have evolved from being rudimentary scope holders to currently sophisticated and precise telerobotic systems, with “wristed” technology and true three-dimensional visualization. Adoption of robotic surgery has gained the most widespread adoption for upper aerodigestive tract early…
Key Points Most patients diagnosed with primary hyperparathyroidism are asymptomatic or are only mildly symptomatic, compared with the classic descriptions of patients with hyperparathyroidism. Calcium levels are regulated by the actions of parathyroid hormone (PTH), vitamin D, and calcitonin on…
Key Points The incidence of thyroid cancer is increasing. Although some of this increase may be attributable to improved detection, other factors may also be affecting the biology and incidence of thyroid cancer. Women are three times more likely than…
Key Points Thyroxine (T 4 ) and triiodothyronine (T 3 ), produced by the thyroid gland, are iodinated derivatives of tyrosine. Most circulating thyroid hormones are bound to one of several plasma proteins, the most important of which is thyroxine-binding…