NBCE Part I key terms

The standard reference posture in which a person stands upright, faces forward, has arms at the sides with palms turned forward, and feet flat and parallel. All anatomical directions and descriptions are based on this posture.

A freely movable joint where two or more bones meet inside a capsule lined by synovial membrane. The capsule contains lubricating synovial fluid and usually articulating cartilage, allowing smooth motion with low friction.

Sheets or bands of connective tissue made mainly of collagen that surround, separate, and connect muscles, organs, and other structures. Fascia helps transmit force, provide support, and allow tissues to glide.

A strong cord of dense regular connective tissue that attaches a muscle to bone. Tendons transmit the pulling force of muscle contraction to produce or control movement at a joint.

A fibrocartilage pad between adjacent vertebral bodies that cushions load and allows limited spinal motion. Each disc has a tough outer ring and a soft inner core.

The soft, gel-like central region of an intervertebral disc. It contains water-binding proteoglycans, distributes compressive forces, and can herniate through a torn outer ring.

The tough, layered outer ring of an intervertebral disc, made of concentric fibrocartilage lamellae. It contains the soft inner core and resists shear and tensile forces during spinal movement.

A synovial joint formed between the superior and inferior articular processes of adjacent vertebrae. Facet joints guide and limit spinal motion and can become painful or arthritic.

A yellow elastic ligament connecting the laminae of adjacent vertebrae. It helps maintain posture, limits excessive flexion, and protects the spinal cord by covering the posterior aspect of the vertebral canal.

The body's ability to keep internal conditions such as temperature, pH, and blood glucose within stable ranges despite external changes. It relies on feedback systems that detect and correct deviations.

A rapid, self-propagating change in electrical potential across a cell membrane. In nerve and muscle cells, ion channels open and close in sequence to produce a brief reversal of resting voltage.

The movement of water across a semipermeable membrane from an area of lower solute concentration to one of higher solute concentration. It helps regulate cell volume and fluid balance.

A single motor neuron together with all the skeletal muscle fibers it innervates. Activating the neuron causes all of its fibers to contract together, and units are recruited by size.

The basic contractile unit of a muscle fiber, extending between two Z lines. It contains overlapping actin and myosin filaments whose sliding produces muscle shortening.

A scale from 0 to 14 that expresses the hydrogen ion concentration of a solution. Lower values mean more acidity; higher values mean more alkalinity; 7 is neutral at standard conditions.

A solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid, that resists large pH changes when acid or base is added.

A chemical bond formed when two atoms share one or more pairs of electrons. Covalent bonds are strong and hold together the atoms within biological molecules such as proteins and DNA.

A protein, or sometimes RNA, that speeds up a biochemical reaction by lowering its activation energy without being consumed. Enzymes are usually specific for particular substrates and conditions.

The body's local response to injury or infection, marked by redness, heat, swelling, pain, and sometimes loss of function. It involves blood vessel changes and movement of immune cells into tissue.

Cell death caused by injury, infection, or inadequate blood supply. Unlike apoptosis, necrosis usually triggers inflammation and releases cell contents that damage surrounding tissue.

Programmed cell death that removes unwanted, damaged, or infected cells in an orderly way. The cell shrinks and fragments into bodies that are cleared without provoking much inflammation.

Inadequate blood flow to a tissue, causing a shortage of oxygen and nutrients. Persistent ischemia can injure cells, impair organ function, and progress to infarction or necrosis.

The degree of disease-causing ability of a microorganism. Virulence depends on factors such as toxins, adhesion molecules, and the ability to evade or damage host defenses.

A process that destroys or removes all forms of microbial life, including bacterial spores, from an object or medium. It is stricter than disinfection, which may leave some organisms viable.

The time between exposure to an infectious agent and the appearance of the first symptoms or signs of illness. It varies with the organism and the route of transmission.

Indirect protection of a population from an infectious disease when a sufficient proportion of people are immune. Transmission slows because susceptible people are less likely to contact infectious individuals.

Listening to sounds produced by the body, usually with a stethoscope, to assess the heart, lungs, blood vessels, and abdomen. It helps identify normal and abnormal murmurs, breath sounds, and bowel sounds.

Tapping a body surface with the fingers or a small instrument to produce sounds that reveal the density and position of underlying structures. It is used mainly in chest and abdominal examinations.

Standard measurements of body temperature, pulse rate, respiratory rate, and blood pressure. They provide quick information about a person's basic physiological status and response to illness or treatment.

Examining the body by touch to assess texture, temperature, moisture, tenderness, swelling, and organ position. It is a basic physical diagnosis technique used in many body regions.

The area of skin supplied by sensory fibers from a single spinal nerve root. Dermatome maps help localize nerve root lesions and are tested during neurological examination.

The group of skeletal muscles supplied by motor fibers from a single spinal nerve root. Testing myotomes by resisted movement helps identify which nerve root may be affected.

A disorder of a spinal nerve root, often caused by disc herniation or foraminal narrowing. It produces pain, numbness, tingling, or weakness in the pattern of the affected root.

A cervical nerve root compression test in which the examiner extends, side-bends, and rotates the patient's head toward the symptomatic side and applies gentle downward axial compression. It may reproduce radiating arm pain.

A test for lumbosacral nerve root irritation in which the supine patient's straight leg is slowly lifted. Pain radiating below the knee in a dermatomal pattern suggests nerve root involvement.

Damage to motor pathways within the brain or spinal cord above the anterior horn cell. It typically causes increased tone, hyperreflexia, spasticity, and a positive Babinski sign.

Damage to the anterior horn cell, its axon, or a peripheral nerve. It typically causes weakness, decreased tone, muscle wasting, fasciculations, and reduced or absent reflexes.

A neurological sign elicited by stroking the sole of the foot. In adults, extension of the big toe and fanning of the other toes suggests an upper motor neuron lesion.