Volkmann's canal

Examples of Volkmann's canal in the following topics:

• Supply of Blood and Nerves to Bone

  • Blood is supplied to mature compact bone through the Haversian canal.
  • Haversian canals are formed when individual lamellae form concentric rings around larger longitudinal canals (approx. 50 µm in diameter) within the bone tissue.
  • A Haversian canal generally contains one or two capillaries and nerve fibers.
  • Volkmann's canals are channels that assist with blood and nerve supply from the periosteum to the Haversian canal.
  • The Haversian canals surround blood vessels and nerve cells throughout the bone.

• Canals

• Transportation: Roads, Canals, and Railroads

  • In 1808, a government-sponsored Report on the Subject of Public Roads and Canals suggested that the federal government should fund the construction of interstate turnpikes and canals.
  • Among the most important of these canals was the Erie Canal.
  • The success of the Erie Canal led to a proliferation of smaller canal routes in the region.
  • Most of the canal work was done by Irish immigrants who had previously worked on the Erie Canal.
  • The Illinois and Michigan Canal was an important canal in the nineteenth century, but was rendered obsolete when new railroads replaced it.

• Impacted Cerumen

  • Earwax, or cerumen, is a yellowish waxy substance secreted in the ear canal which can affect hearing if produced excessively.
  • Earwax, also known by the medical term cerumen, is a yellowish waxy substance secreted in the ear canal of humans and other mammals.
  • Excessive earwax may impede the passage of sound in the ear canal, causing conductive hearing loss.
  • Cerumen is produced in the outer third of the cartilaginous portion of the human ear canal.
  • A curette method is more likely to be used by otolaryngologists when the ear canal is partially occluded and the material is not adhering to the skin of the ear canal.

• Root Canal Therapy

  • This set of procedures is commonly referred to as a "root canal" .
  • This procedure is known as root canal therapy.
  • The alternatives to root canal therapy include no treatment, tooth extraction, or the 3Mix-MP procedure.
  • Recent studies indicate that substances commonly used to clean the root canal space incompletely sterilize the canal.
  • However, a properly restored tooth following root canal therapy yields long-term success rates near 97%.

• Balance and Determining Equilibrium

  • Head position is sensed by the utricle and saccule, whereas head movement is sensed by the semicircular canals.
  • The semicircular canals are three ring-like extensions of the vestibule.
  • The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically.
  • Rotational movement of the head is encoded by the hair cells in the base of the semicircular canals.
  • The movement of two canals within a plane results in information about the direction in which the head is moving, and activation of all six canals can give a very precise indication of head movement in three dimensions.

• Invertebrate Digestive Systems

  • Invertebrate digestive systems include a gastrovascular cavity with one opening or an alimentary canal with a true mouth and anus.
  • The alimentary canal is a more advanced digestive system than a gastrovascular cavity and carries out extracellular digestion.
  • Most other invertebrates like segmented worms (earthworms), arthropods (grasshoppers), and arachnids (spiders) have alimentary canals .
  • (b) An alimentary canal has two openings: a mouth for ingesting food and an anus for eliminating waste, as shown in this nematode.
  • Invertebrates like grasshoppers have alimentary canals with specialized compartments for digestion.

• Ventricles

  • This system is continuous with the central canal of the spinal cord.
  • The structures of the ventricular system are embryologically derived from the center of the neural tube (the neural canal).
  • As the future brain stem aspect of the primitive neural tube develops, the neural canal expands dorsally and laterally, creating the fourth ventricle.  
  • The cerebral aqueduct is formed from the part of the neural canal that does not expand and remains the same at the level of the midbrain superior to the fourth ventricle.
  • The fourth ventricle narrows at the obex, where the fourth ventricle narrows to become the central canal in the caudal medulla.

• Audition: Hearing, the Ear, and Sound Localization

  • It includes the pinna, the ear canal, and the most superficial layer of the ear drum, the tympanic membrane.
  • The sound waves enter the ear canal, which amplifies the sound into the ear drum.
  • Within the cochlea there are three fluid-filled spaces: the tympanic canal, the vestibular canal, and the middle canal.
  • Fluid movement within these canals stimulates hair cells of the organ of Corti, a ribbon of sensory cells along the cochlea.
  • Hearing begins with pressure waves hitting the auditory canal and ends when the brain perceives sounds.

• The Vestibular System

  • The fluid-filled semicircular canals are tubular loops set at oblique angles, arranged in three spatial planes.
  • The base of each canal has a swelling that contains a cluster of hair cells.
  • One canal lies horizontally, while the other two lie at about 45 degree angles to the horizontal axis.
  • Upon cessation of acceleration or deceleration, the movement of the fluid within the canals slows or stops.
  • Note that the canals are not sensitive to velocity itself, but to changes in velocity.