Unit 2 Support & Motion Vocabulary

Hematopoesis

Blood cell formation

Cartilage

Flexible connective tissue found throughout the body

Ligament

Short bands of tough but flexible dense connective tissue that connect two bones and stabilize joints

Tendon

Cords of dense connective tissue that connect muscles to bones

Joint (articulation)

Junction between 2 or more bones that includes the cartilage, ligaments and tendons needed to allow movement and flexibility in the body

Intervertebral discs

Cushioning pads that absorb shock and protect against tension or torsion between the vertebrae of the vertebral column

Sutures

Interlocking immovable joints in the skull

Sesamoid bones

A special type of short bone, shaped like a sesame seed, that is embedded within tendons to provide support and stability with little movement

Osteon

The basic structural unit of compact bone; long cylinders that act as tiny weight-bearing pillars in the bone

Lamellae

Groups of hollow tubes that make up osteons and are filled with tiny salts and collagen fibers to help the bone resist torsion stress

Central canal (Haversian canal)

Runs through the middle of each osteon and contains small blood vessels for nourishing the bone and nerve fibers for signaling

Trabeculae

Tiny bone struts in spongy bone that help it to resist stress; where bone marrow is

Lacunae

Gaps in the lamellae that house osteocytes

Osteocyte

Type of bone cell housed in the lacunae that maintains healthy bone structure

Osteoblast

Type of bone cell used to build and construct bones by calcifying bone as it forms

Osteoclast

Type of bone cell that is critical in the regeneration of bone through bone remodeling

Ossification

The process of bone tissue formation (osteogenesis)

Fracture

Break in a bone

Synarthrosis

Type of joint that is non-moving

Amphiarthrosis

Type of joint that is slightly moving

Diarthrosis

Type of joint that is freely moving

Suture

Type of immovable fibrous joint that holds the bones in the skull together

Syndesmosis

Type of immovable fibrous joint that is only held together by ligaments

Gomphosis

Type of fibrous joint that acts like a peg in a socket

Synchondrosis

Type of cartilaginous joint where a bar or plate of hyaline cartilage unites the bones, yielding them immovable

Symphysis

Type of cartilaginous joint where fibrocartilage units the bones, making them slightly movable (but more like shock absorbers)

Gliding

When one flat bone surface glides or slips over another (back and forth or side to side)

Flexion

Bending in a way that decreases the angle of the joint so the articulating bones get closer

Extension

Bending in a way that increases the angle of the joint so the articulating bones get further away

Hyperextension

Bending that goes beyond the anatomical position

Rotation

Turning of a bone around its own long axis

Supination/Pronation

Turn/twist forward; turn/twist backward

Abduction

Moving the limb away from the median plane

Adduction

Moving the limb toward from the median plane

Opposition

Action of touching thumb to each fingertip

Circumduction

Moving limb in a circle

Elevation/Depression

Lifting (and then lowering) a body part superiorly

Protraction/Retraction

Non-angular anterior (toward the front of the body) and posterior (toward the back of the body) movements

Dorsiflexion/Plantar flexion

Bending the foot at the ankle towards the body and away from the body

Inversion/Eversion

Moving the foot medially and laterally

Insertion

Where the muscle is attached to a movable bone

Origin

Where the muscle is attached to an immovable bone

Prime mover (agonist)

Muscles that are most responsible for producing a certain movement

Antagonist

Muscles that oppose or do the reverse of a certain movement

Synergist

Muscles that help the prime mover, such as stabilizing across a joint or adding some "oomph"

Fixator

Synergist muscles that specifically immobilize the muscle's origin bone to increase the prime mover's effectiveness

Perimysium

Connective tissue surrounding each fascicle

Endomysium

Connective tissue surrounding each muscle fiber

Resting membrane potential

The voltage across the cell membrane (usually between -50 to -90 mV)

Action potential (AP)

A large change in membrane potential that spreads rapidly over long distances within the cell; can be caused by movement of ions through ion channels across the cell membrane

Neuromuscular junction (motor end plate)

Where the axon terminals of the motor neuron meets the muscle fiber, including the space between them (synaptic cleft)

Motor unit

A group of muscle fibers stimulated by the same motor neuron, resulting in a contraction felt through the entire muscle since the muscle fibers are spread throughout it

Twitch

The response of a muscle to a single stimulation causing fibers to quickly contract and then relax

Graded muscle contraction

Variations in the degree of muscle contraction by changing either the frequency or strength of the stimulus

Summation

Accumulation of effects, such as in a muscle contraction when motor neurons continually fire and keep a muscle stimulated

Tetanus

When a muscle reaches a ceiling of maximum tension and the muscle contraction is sustained due to high-frequency stimulation

Recruitment (Motor unit summation)

The process of getting more and more motor units stimulated by delivering stimuli of increasing voltage

Threshold stimulus

The weakest stimulus that is capable of producing a response in an excitable tissue, causing the first observable contraction

Muscle tone

The slight contraction that even relaxed muscles always have that keeps muscles healthy and ready to respond to stimulation

Muscle tension

The force exerted by a contracting muscle on an object

Muscle fatigue

The decline in ability of a muscle to generate force

Lever

A rigid bar that moves on a fixed point when a force is applied to it; Our bones act as levers

Fulcrum

A fixed point that a lever moves on; Our joints act as fulcrums

Effort

The applied force used to move a resistance; Created by a muscle contraction

Load

A resistance; The insertion bone