Anatomy of the Human Temporal Bone

Details

• Personal Author:
  Bohne BA ; Militchin V
• Description:
  The temporal bone contains the organs for hearing (i.e., organ of Corti) and the detection of gravity, linear and rotational motion (i.e., maculae of the utricule and saccule, cristae of the superior, lateral and posterior semicircular canals). The senses of hearing and balance involve the peripheral auditory and vestibular structures and the central nervous system. This atlas covers the anatomy of the peripheral auditory and vestibular systems only. The peripheral auditory system consists of the external, middle and inner ears (p 3). The peripheral vestibular system consists of five separate sensory organs (pp 47-49). A portion of the external ear and all of the middle and inner ears as well as the vestibular sense organs are housed within the temporal bone. The vestibulocochlear nerve (8 cranial) traverses the internal auditory meatus (pp 4, 7, 15, 42) to synapse on sensory cells. The central processes of the vestibulocochlear neurons synapse in the central nervous system. The end organ for hearing consists of the coiled organ of Corti (p 50) that averages about 32 mm in length. Sensory (hair) cells are located in the organ of Corti (p 31). There are approximately 100 inner hair cells and 400 outer hair cells per mm length of the organ of Corti. Primary auditory neurons, called spiral ganglion neurons, are located in Rosenthal's canal (pp 29, 30), a spiral channel at the periphery of the modiolus. The bipolar SGNs send their peripheral processes to synapse on the hair cells in the sensory epithelia while their central processes traverse the modiolus, exit the temporal bone via the internal auditory meatus and synapse in the cochlear nuclei of the brainstem. Hearing is a very important sense for oral communication, language acquisition, employment and the enjoyment of some of life's greatest pleasures such as music, the sounds of nature and the voices of loved ones. A variety of conditions and disease processes in the peripheral auditory system result in mild to profound hearing loss. Some hearing losses are treatable or correctable to a variable degree with medication, surgery, a cochlear implant or a hearing aid; other losses are permanent. Disease entities of the external ear include: absence of the pinna or external auditorymeatus, infections, earwax accumulation in the external auditory canal, or tumors. Disease entities of the middle ear include: tympanic membrane perforation, damage to or loss of one of the middle ear ossicles, otosclerosis, fluid or infection in the middle ear space, or malfunction of the Eustachian tube. Disease entities of the inner ear include: congenital malformations, loss of sensory cells and nerve fibers (i.e., sensorineural hearing loss), cochlear otosclerosis, Meniere's disease, acoustic neuroma, or sudden hearing loss. Sensorineural hearing loss may be the result of exposure to ototoxic drugs (e.g.,aminoglycoside antibiotics, platinum compounds, diuretics), noise, or radiation, the process of aging (presbycusis) or viral infections. The end organs for gravity and motion detection consist of five separate sensory organs: the macula of the utricule (pp 47 and 50) and macula of the saccule, both housed in the vestibule and three cristae, one in the ampullated end of the superior, lateral (or horizontal) and posterior semicircular canals (pp 48-50). Detection of motion and the position of the head in space depend upon the peripheral vestibular organs and central vestibular pathways. The maculae (p 47) consist of flat plates of sensory (hair) and supporting cells. Nerve fibers enter the maculae from beneath the epithelium to innervate the hair cells. The maculaeare covered by an extracellular otolithic membrane in which are embedded a number of microscopic stones composed of calcium carbonate and protein (i.e., otoconia). These organs are sensitive to linear acceleration and give one the sense of head position in space. The cristae (pp 48-49) are crests of connective tissue covered with a single layer of sensory and supporting cells. Nerve fibers enter the cristae through the connective tissue to innervate the hair cells. Stereocilia on the hair cells project into an extracellular gelatinous material called the cupula. Motion of endolymph in response to angular acceleration deflects the cupula and stimulates the hair cells. Most of the photomicrographs in this atlas were taken with a dissection microscope at low magnification in order to demonstrate the gross anatomy of the auditory and vestibular systems and their relation to one another. Higher magnifications are needed to identify individual cells in the sensory end organs in these systems. [Description provided by NIOSH]
• Subjects:
  Anatomy Ear Hearing Loss Hearing Loss, Noise-Induced Occupational Health Safety Sense Organs
• Keywords:
  Auditory System Ear Disorders Ears Hearing Loss
• Publisher:
  Washington University School of Medicine
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Report
• Place as Subject:
  Missouri ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-52
• NIOSHTIC Number:
  nn:20055537
• Citation:
  St. Louis, MO: Washington University School of Medicine, 2012 Nov; :1-52
• Federal Fiscal Year:
  2013
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Anatomy of the human temporal bone
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4d4f0ddaa55003a314f1d5edb7c910b69e96b4b96336b99464d204d8524d8eb05952c4ddbf652a9669792f70f4dfa66579d884a52b0987b58ed1493fc5799ec2
• Download URL:
  https://stacks.cdc.gov/view/cdc/213367/cdc_213367_DS1.pdf
• File Type:
  [PDF - 3.39 MB ]