1. Obstruction or stoppage of a passage or an opening.
2. A method of regional anesthesia to stop the passage of sensory impulses in a nerve, a nerve trunk, the dorsal root of a spinal nerve, or the spinal cord, depriving a patient of sensation in the area involved.
SEE: anesthesia
3. To obstruct a passage or opening.
4. Hardened, preserved tissue, prepared for thin slicing and mounting on a slide to make it suitable for microscopic viewing.
5. Any device that prevents hazardous or unwanted movement of a body part.

air block

Leakage of air from the respiratory passageways and its accumulation in connective tissues of the lungs, forming an obstruction to the normal flow of air.

alveolar-capillary block

An outdated term for impaired pulmonary diffusing capacity.

atrioventricular block

ABBR: A-V block A condition in which the depolarization impulse is delayed or blocked at the atrioventricular (A-V) node or a more distal site, as in the A-V bundle or bundle branches. A-V block can be partial or complete. There are several degrees: First-degree block is due to prolonged A-V conduction; electrocardiograms show a characteristic prolonged P-R interval. Second-degree blocks are intermittent, i.e., some, but not all A-V impulses are transmitted to the ventricles. Third-degree block, also known as complete A-V block, is present when no atrial impulses are conducted to the ventricles.
A-V block may be caused by age-related degenerative changes; drugs such as digoxin, beta blockers, and calcium channel blockers; hyperkalemia; hypokalemia; increased vagus nerve activity; local hypoxia; and scarring from myocardial infarction.

bed block

A block made of sturdy material, such as wood, to elevate one end of a bed relative to the other. Bed blocks may be used in the home, e.g., to treat people with gastroesophageal reflux disease. Most beds in health care institutions are built with devices that separately raise or lower the feet, legs, trunk, or head.

bite block

1. A wedge of sturdy material used to maintain space between the two jaws.
2. A film holder held between the teeth for stable retention of the film packet during dental radiology.

bundle branch block

SEE: bundle branch block

Bunnell block

SEE: Bunnell block

complete atrioventricular block

Third-degree atrioventricular block.
SEE: atrioventricular block

continuous peripheral nerve block

The placement of a catheter near a nerve to allow administration of an analgesic.
SYN: SEE: perineural local anesthetic infusion

digital block

Injection of a regional anesthetic into the proximal portion of a finger or toe.

ear block

Blockage of the auditory tube to the middle ear. It may result from trauma, infection, or an accumulation of cerumen.
SEE: aerotitis; SEE: otitis media

epidural block

SEE: epidural anesthesia

field block

Regional anesthesia in which a limited operative area is walled off by an anesthetic.

first-degree atrioventricular block

Delayed conduction through or from the atrioventricular node, marked on the electrocardiogram by a prolonged P-R interval. Usually no treatment is necessary.
SYN: SEE: first-degree heart block

heart block

SEE: bundle branch block; SEE: heart block

infranodal block

The Mobitz II variety of second-degree heart block.
SEE: second-degree heart block

interpleural block

SEE: Interpleural analgesia.

mandibular block

Regional anesthesia of the lower face and mandibular tissues by infiltration of the mandibular division of the trigeminal nerve.

maxillary block

SEE: Second division block.

nerve block

The induction of regional anesthesia by preventing sensory nerve impulses from reaching the central nervous system. This is usually done by injecting an anesthetic solution (such as lidocaine) into a peripheral nerve or by electrically stimulating the nerve.
Descriptive text is not available for this imageComplications of peripheral nerve blocks occur in about 1% of patients and include anesthetic toxicity, hematoma, or injury to the injected nerve.

neuromuscular block

A disturbance in the transmission of impulses from a motor endplate to a muscle. It may be caused by an excess or deficiency of acetylcholine or by drugs that inhibit or destroy acetylcholine.
SYN: SEE: neural blockade

paravertebral block

Infiltration of the stellate ganglion with a local anesthetic.

perineural block

SEE: Perineural analgesia.

saddle block

SEE: saddle block anesthesia

second division block

Regional anesthesia of the upper face and maxillary tissues by infiltration of the maxillary division of the trigeminal nerve.
SYN: SEE: maxillary block

sinoatrial block

SEE: 1. Sinoatrial heart block.
2. Heart block in which there is interference in the passage of impulses between the sinus node and the atria.

spinal block

Blockage in the flow of cerebrospinal fluid within the spinal canal.

subarachnoid block

SEE: Spinal anesthesia.

van Lint block

SEE: van Lint block

ventricular block

Interference in the flow of cerebrospinal fluid between the ventricles or from the ventricles through the foramina to the subarachnoid space.