Anatomy & Physiology I: Exam 3 Review

Comprehensive vocabulary flashcards reviewing joints, skeletal muscles, muscle physiology, and nervous system fundamentals for Anatomy & Physiology I Exam 3.

Joint (Articulation)

A point where two bones meet, linking the bones of the skeletal system to either permit movement or provide an immovable connection.

Arthrology

The science of joint structure, function, and dysfunction.

Bony Joint

An immovable joint formed when the gap between two bones ossifies and fuses, becoming effectively a single bone.

Syndesmosis

A fibrous joint in which two parallel bones are bound together by relatively long collagenous fibers, such as the connection between the diaphyses of the tibia and fibula.

Synovial Joint

A freely moveable joint characterized by a joint cavity containing lubricating synovial fluid, enclosed by a joint capsule and lined with articular cartilage.

Bursa

A fibrous sac filled with synovial fluid that cushions muscles, helps tendons slide easily over joints, or modifies the direction of tendon pull.

Adduction

A movement in the frontal plane that brings a body part or limb back toward the midline of the body.

Abduction

A movement of a body part or limb in the frontal plane away from the midline of the body.

Flexion

A joint movement that decreases the angle between articulating bones, such as bending forward at the waist or bending the elbow.

Eversion

A foot movement that tilts the sole of the foot outward or laterally.

Inversion

A foot movement that tips the sole of the foot medially inward toward the other foot.

Dorsiflexion

A movement in which the toes and foot are elevated toward the shin.

Plantar Flexion

A movement of the foot so that toes point downward toward the floor.

Temporomandibular Joint (TMJ)

The articulation formed by the junction of the mandibular condyle with the mandibular fossa of the temporal bone.

Glenohumeral Joint

The shoulder joint formed by the articulation between the head of the humerus and the glenoid cavity of the scapula.

Range of Motion (ROM)

The degrees through which a joint can move, determined by the structure of articular surfaces, the tautness of ligaments and joint capsules, and the action of muscles and tendons.

Endomysium

A thin sleeve of loose connective tissue surrounding each individual muscle cell (fiber).

Perimysium

A thicker connective tissue sheath that groups muscle fibers into bundles called fascicles.

Epimysium

A fibrous connective tissue sheath that surrounds the entire skeletal muscle exterior.

Fascia

A broad sheet of connective tissue that separates neighboring muscles from each other and from the subcutaneous tissue.

Indirect Muscle Attachment

An anatomical arrangement where muscle collagen fibers continue into a distinct tendon that anchors into the periosteum and bone matrix.

Direct (Fleshy) Muscle Attachment

A muscle attachment where microscopic collagen fibers leave little separation, making the muscle appear to emerge directly from the bone surface.

Prime Mover (Agonist)

The muscle that produces most of the force during a particular joint action.

Synergist

A muscle that aids the prime mover in performing an action, coordinating movements or adding power.

Antagonist

A muscle that opposes the action of the prime mover, often moderating the speed or range of movement.

Fixator

A muscle that prevents a bone from moving, keeping it steady so that another muscle can pull firmly.

Muscles of Mastication

The four pairs of muscles responsible for producing biting and chewing movements of the mandible: temporalis, masseter, medial pterygoid, and lateral pterygoid.

Rectus Abdominis

The anterior abdominal muscle that flexes the lumbar region of the vertebral column and produces forward waist bending; divided by tendinous intersections into segmented blocks.

Rotator Cuff (SITS) Muscles

A group of four scapular muscles—supraspinatus, infraspinatus, teres minor, and subscapularis—whose tendons surround and stabilize the head of the humerus in the glenoid cavity.

Quadriceps Femoris

The anterior thigh muscle group composed of rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius that extends the knee.

Hamstring Group

The posterior thigh muscles consisting of biceps femoris, semitendinosus, and semimembranosus, which act to flex the knee.

Tibialis Anterior

An anterior lower leg muscle responsible for dorsiflexion and inversion of the foot.

Sarcomere

The basic functional, contractile repeating unit of a muscle fiber, spanning from one Z disc to the next Z disc.

Thick Filament

A myofilament composed of several hundred intertwined myosin molecules, each possessing a double globular head and a shaft-like tail.

Thin Filament

A myofilament composed of two intertwined chains of globular G actin, tropomyosin strands covering active binding sites, and regulatory troponin complexes.

Tropomyosin

A regulatory protein on the thin filament that blocks the active sites of actin subunits when the muscle fiber is at rest, preventing myosin binding.

Troponin

A small, calcium-binding protein attached to tropomyosin on the thin filament that shifts tropomyosin to expose actin active sites upon binding $Ca^{2+}$.

Sarcoplasmic Reticulum

The specialized smooth endoplasmic reticulum of a muscle fiber that forms networks around myofibrils and acts as a reservoir to store and release calcium ions ($Ca^{2+}$).

Resting Membrane Potential (RMP)

The electrical charge difference across the plasma membrane of an unstimulated cell, maintained with an excess of anions and $K^+$ inside and an excess of $Na^+$ outside, resulting in a negative interior charge.

Phosphagen System

An anaerobic energy pathway that provides rapid ATP synthesis during the initial $10\,\text{seconds}$ of intense activity using enzymes like myokinase and creatine kinase after myoglobin oxygen is depleted.

Isometric Contraction

A muscle contraction where internal tension increases, but the muscle does not change in length or produce joint movement.

Isotonic Concentric Contraction

A muscle contraction in which the muscle shortens as it produces tension to move a load.

Isotonic Eccentric Contraction

A muscle contraction in which the muscle lengthens while continuing to maintain tension, often controlling the lowering of a load.

Neuromuscular Junction (NMJ)

The specialized synapse where the axon terminal of a somatic motor neuron meets the motor end plate of a skeletal muscle fiber.

Central Nervous System (CNS)

The major anatomical division of the nervous system consisting exclusively of the brain and spinal cord.

Peripheral Nervous System (PNS)

The division of the nervous system external to the brain and spinal cord, consisting of cranial and spinal nerves and ganglia.

Somatic Motor Division

The subdivision of the peripheral nervous system that carries motor output signals from the CNS to control skeletal muscles.

Sympathetic Division

The branch of the autonomic nervous system that readies the body for 'fight or flight', increasing heart rate and respiration while inhibiting digestion and urination.

Parasympathetic Division

The branch of the autonomic nervous system responsible for 'rest and digest' activities, slowing heart rate and breathing while stimulating digestion and urinary output.

Neurosoma

The cell body (soma) of a neuron containing the nucleus, organelles, and genetic control center.

Dendrites

Branching extensions of the neuronal cell body that receive signals from other neurons and convey them toward the soma.

Internodal Segment (Internode)

The myelin-covered segment of an axon situated between two successive nodes of Ranvier.

Node of Ranvier

An unmyelinated gap along the length of an axon between adjacent Schwann cells or oligodendrocytes where action potentials are renewed.

Saltatory Conduction

The rapid mode of nerve signal propagation along a myelinated axon, in which the action potential appears to jump from one node of Ranvier to the next.

Oligodendrocytes

Glial cells of the central nervous system that wrap around axon segments to form the insulating myelin sheath.

Ependymal Cells

Glial cells lining the internal ventricles of the brain and spinal canal that produce and circulate cerebrospinal fluid (CSF).

Microglia

Small glial cells in the central nervous system that function as specialized macrophages, clearing debris and foreign invaders in damaged areas.

Astrocytes

The most abundant neuroglia in the central nervous system; their perivascular feet wrap around capillaries to form the blood-brain barrier (BBB).

Depolarization

The phase of an action potential where voltage-gated $Na^+$ channels open rapidly, allowing $Na^+$ influx and shifting membrane voltage from threshold ($-55\,\text{mV}$) up to $+35\,\text{mV}$.

Repolarization

The phase of an action potential where $Na^+$ channels inactivate and voltage-gated $K^+$ channels open, allowing $K^+$ efflux to return the membrane potential toward resting levels.

Hyperpolarization

A brief period at the end of an action potential when the membrane potential drops below the normal resting potential (more negative than $-70\,\text{mV}$) due to slow closure of voltage-gated $K^+$ channels.