Skeletal System, Movement, and Muscular System

Comprehensive vocabulary flashcards covering the skeletal system, body movements, joint articulations, and the muscular system based on lecture slides.

Hematopoiesis

Stability of the internal environment and the mechanisms that maintain that stability.

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.

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 located.

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.

Axial skeleton

All of the bones off the main axis/trunk of the body (skull, vertebral column, chest, and rib cage) with an overall function of protecting critical organs and support.

Appendicular skeleton

All of the bones of the limbs and girdles (arms, legs, pelvic and pectoral girdles) with an overall function of providing movement and support.

Pectoral girdle

Girdle consisting of the clavicles and scapulae that attaches the upper limbs to the body's trunk and provides lots of mobility and flexibility.

Pelvic girdle

Girdle consisting of the sacrum and hip bones with extremely strong ligaments, attaching lower limbs to the trunk with high sturdiness and less mobility.

True ribs

The 7 pairs of ribs directly attached to the sternum.

False ribs

The 5 pairs of ribs that are not attached directly to the sternum.

Floating ribs

The last 2 pairs of false ribs that do not attach to the rib cage on the anterior side.

Intramembranous ossification

Process of bone formation where bone develops from a fibrous membrane to a membranous bone.

Endochondral ossification

Process of bone formation where bone develops from replacing cartilage with endochondral bone.

Synarthrosis

Type of joint that is non-moving, providing maximum stability.

Amphiarthrosis

Type of joint that is slightly moving, providing good stability.

Diarthrosis

Type of joint that is freely moving, providing the least stability.

Gliding (movement)

Joint movement where 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

Movement that increases the angle of a joint so that articulating bones get farther apart.

Hyperextension

Bending that goes beyond the anatomical position.

Rotation

Turning of a bone around its own long axis.

Supination

Turning or twisting forward.

Pronation

Turning or twisting backward.

Abduction

Moving the limb away from the median plane.

Adduction

Moving the limb toward the median plane.

Opposition

Action of touching the thumb to each fingertip.

Circumduction

Moving a limb in a circle.

Elevation

Lifting a body part superiorly.

Depression

Lowering a body part from an elevated position.

Protraction

Non-angular anterior movement (toward the front of the body).

Retraction

Non-angular posterior movement (toward the back of the body).

Dorsiflexion

Bending the foot at the ankle towards the body.

Plantar flexion

Bending the foot at the ankle away from the body.

Inversion

Moving the foot medially.

Eversion

Moving the foot laterally.

Isotonic contraction

Muscle contraction that causes a change in the length of the muscles, like when doing a push-up.

Isometric contraction

Muscle contraction that does not cause a change in the length of the muscles, like when holding a plank.

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.

Myofibrils

Organelles that make up most of our muscle cells.

Myofilaments

Thin and thick filaments (actin and myosin) that run the length of each myofibril.

Sarcomeres

The contractile unit of the muscle that makes up myofibrils.

Muscle fibers

Muscle cells; composed of myofibrils bunched together; specialized to contract.

Fascicles

Bundle of muscle fibers.

Epimysium

Connective tissue surrounding the outside of a muscle.

Perimysium

Connective tissue surrounding each fascicle.

Endomysium

Connective tissue surrounding each muscle fiber.

Resting membrane potential

The voltage across the cell membrane (usually between $-50\text{ to } -90\,\text{mV}$).

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 meet 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 moved in a lever system; represented by the insertion bone.

Myosin

Contractile protein that makes up the thick filaments; grabs and pulls the actin.

Actin

Contractile protein that makes up the thin filaments; slides past myosin and overlaps.

Acetylcholine

The neurotransmitter that motor neurons use in muscle contractions for signaling.

Biceps brachii:

Flexing the forearm

Brachialis:

Flexing the forearm; bridge between humerus and ulna

Brachioradialis:

Synergist muscle in forearm flexion

Triceps brachii:

Main arm muscle in extension

Sartorius:

Helps flex, abduct, and laterally rotate the thigh

Adductors:

Make up inner thighs and adduct the femur at the hip joint

Quadriceps femoris:

Major extensors of the knee, critical for jumping, climbing, running, and standing up from being seated

Hamstrings:

Make up the posterior thigh and antagonize the quadriceps; prime movers in thigh extension and leg flexio

Calf muscles: (Gastrocnemius, soleus, plantaris)

Movement in the ankle, foot, and toes

Tibialis anterior:

Prime mover in dorsiflexion

Trapezius:

Moving, rotating, and stabilizing the scapulae, as well as extending the head at the neck

Latissimus dorsi:

Mainly responsible for arm movements

Erector spinae:

Run the length of the vertebral column and keep our backs straight, allow for side-to-side rotation, and are prime movers in back extensionand lateral flexion of the spine.

Gluteal muscles:

Hip and thigh movement, ability to maintain good posture, and our overall strength

Epicranius:

Scalp movement

Masseter and Temporalis:

Prime mover in allowing the jaw to close (so we can chew)

Buccinators:

Main muscle of the cheek