Eustachian tube

Examples of Eustachian tube in the following topics:

• Otitis Media

  • It occurs in the area between the tympanic membrane and the inner ear, also effecting a duct known as the eustachian tube.
  • A major risk factor for developing otitis media is Eustachian tube dysfunction, which leads to the ineffective clearing of bacteria from the middle ear.

• Pharynx

  • The Eustachian tubes, which connect the middle ear to the pharynx, open into the nasopharynx.
  • The opening and closing of the Eustachian tubes serves to equalize the barometric pressure in the middle ear with that of the ambient atmosphere.
  • On the lateral walls of the nasopharynx are the pharyngeal ostia of the auditory tube, triangular shaped openings bound from behind by a firm prominence, the torus tubarius or cushion.
  • This binding is formed by a cartilaginous tube-like opening.
  • Behind the ostia of the auditory tube is a deep recess known as the pharyngeal recess (or fossa of Rosenmüller).

• Tonsils

  • Tubal tonsils: a pair of tonsils that are located in the wall of the nasopharynx near the entrances to each eustachian tubes.

• Pharynx

  • The nasopharynx connects to the eustachian tubes of the middle ear, which allows the nasopharynx to help balance pressure within the ear.
  • The lateral walls of the nasopharynx are made of the pharyngeal ostia (bone) of the auditory tube, and supported by the torus tubarus, a mound of cartilage tissue from the auditory tube.
  • Two folds arise from the cartilaginous opening of the auditory tube.
  • Behind the bone of the auditory tube is a deep recess, the pharyngeal recess.

• Withdrawing Blood

  • A blood collection tube is a sterile glass or plastic tube with a closure.
  • Translucent-topped tubes contain a weaker vacuum in the same sized tube, and will gather less blood.
  • With the vacuum tube system, the needle pierces the top of the sample tube and will potentially come into contact with the additives in the tube.
  • Vacuum tubes for blood collection have colored tops which define the additives to the tube.
  • The gold tube contains a clot activator and gel for serum separation, the green tube contains heparin for clinical chemistry, and the red tube contains a clot activator.

• Cathode Rays

  • Cathode rays are electron beams or streams of electrons that were observed for the first time in Crookes tubes (vacuum tubes).
  • The early cold cathode vacuum tubes, called Crookes tubes, used a high electrical potential between the anode and the cathode to ionize the residual gas in the tube.
  • These were called Crookes tubes.
  • But at the anode (positive) end of the tube, the glass of the tube itself began to glow.
  • A Crookes tube is a rarefied tube evacuated to a pressure below 10−6 atm.

• Embryonic Development

  • The spinal cord derives from the neural tube in two processes: primary and secondary neurulation.
  • The neural folds pinch in towards the midline of the embryo and fuse together to form the neural tube.
  • For a short time, the neural tube is open both cranially and caudally.
  • At the dorsal end of the neural tube, BMPs are responsible for neuronal patterning.
  • Shh secreted from the floor plate creates a gradient along the ventral neural tube.

• Establishing Body Axes during Development

  • The neural tube develops in two ways: primary neurulation and secondary neurulation.
  • Mammalian neural tubes close in the head in the opposite order that they close in the trunk.
  • In the trunk, overlying ectoderm closes, the neural tube closes and neural crest cells migrate.
  • For a short time, the neural tube is open both cranially and caudally.
  • (Neural tube is in green. )

• Female Duct System

  • The fallopian tubes, or oviducts, connect the ovaries to the uterus.
  • The fallopian tubes, also known as oviducts, uterine tubes, and salpinges (singular salpinx) are two very fine tubes lined with ciliated epithelia, leading from the ovaries of female mammals into the uterus, via the utero-tubal junction.
  • The different segments of the fallopian tube are (lateral to medial):
  • the ampullary region that represents the major portion of the lateral tube
  • the isthmus which is the narrower part of the tube that links to the uterus

• Neurulation

  • Following gastrulation, the neurulation process develops the neural tube in the ectoderm, above the notochord of the mesoderm.
  • Neurulation is the formation of the neural tube from the ectoderm of the embryo.
  • By the end of the fourth week of gestation, the open ends of the neural tube (the neuropores) close off.
  • It is the process by which the neural tube at lower levels and caudal to the mid-sacral region is formed.
  • Clinical Example: Spina bifida is a developmental congential disorder caused by the incomplete closing of the neural tube during neurulation.