Hole's Human Anatomy & Physiology: Skeletal System, Joints, and Muscular System

Comprehensive vocabulary review flashcards covering bone structure, bone development, joint classification, articulation mechanics, and skeletal muscle contraction physiology from Chapters 7, 8, and 9 of Hole's Human Anatomy & Physiology.

Epiphysis

The expanded end of a long bone that articulates with another bone and is largely composed of spongy bone.

Diaphysis

The shaft of a long bone, located between the epiphyses, with a wall primarily constructed of compact bone.

Periosteum

A tough, vascular covering of dense connective tissue that encloses a bone, except for the articular cartilage on its ends.

Osteocyte

A mature bone cell situated in a tiny bony chamber called a lacuna.

Canaliculi

Microscopic passageways in bone matrix through which cellular processes of osteocytes exchange nutrients and metabolic wastes.

Osteon

A cylinder-shaped unit forming the functional structure of compact bone, consisting of osteocytes and layers of intercellular matrix (lamellae) clustered around a central canal.

Hematopoiesis

The process of blood cell formation, which occurs in the red bone marrow of bones.

Hydroxyapatite

A type of calcium phosphate crystal that constitutes the most abundant inorganic mineral salt in the extracellular matrix of bone.

Intramembranous Ossification

The process of bone development in which primitive embryonic connective tissue (mesenchyme) is replaced directly to form broad, flat bones such as skull bones, clavicles, and the sternum.

Endochondral Ossification

The process of bone formation in which masses of hyaline cartilage models are gradually broken down and replaced by bone tissue.

Epiphyseal Plate Zones

The four functional layers of cartilaginous cells responsible for bone lengthening: the zone of resting cartilage, the zone of proliferating cartilage, the zone of hypertrophic cartilage, and the zone of calcified cartilage.

Osteoclast

A large, multinucleated cell that breaks down the calcified extracellular matrix of bone tissue during resorption and remodeling.

Osteoblast

A bone-forming cell that secretes and deposits the bony extracellular matrix.

Sutural (Wormian) Bones

Small, extra islands of bone that occasionally develop within the suture lines between major flat bones of the skull.

Fontanel

A membranous region or 'soft spot' in an infant skull where fibrous connective tissue covers the space between incompletely ossified cranial bones.

Foramen

An opening through a bone that typically serves as a passageway for blood vessels, nerves, or ligaments.

Dens (Odontoid Process)

A tooth-like upward projection on the axis ($C2$) vertebra around which the atlas ($C1$) pivots to turn the head side to side.

True Ribs (Vertebrosternal Ribs)

The superior $7$ pairs of ribs that attach directly to the sternum via individual costal cartilages.

Acetabulum

A cup-shaped cavity on the lateral surface of the hip bone formed by the fusion of the ilium, ischium, and pubis, articulating with the head of the femur.

Fragility Fracture

A fracture occurring from a low-energy impact, such as a fall from standing height or less, indicating low bone density or osteoporosis.

Synarthrotic Joint

A functional classification for a joint that is immovable under normal conditions.

Amphiarthrotic Joint

A functional classification for a joint that permits slight, limited movement.

Diarthrotic Joint

A functional classification for a freely movable joint; includes all synovial joints.

Syndesmosis

A type of fibrous joint in which bones are bound together by long sheets of dense connective tissue (interosseous membrane) or bundles (interosseous ligament), functioning as an amphiarthrotic articulation.

Gomphosis

A specialized fibrous joint consisting of a cone-shaped bony process anchored in a bony socket, such as the root of a tooth held in the jaw by a periodontal ligament.

Synchondrosis

A cartilaginous joint in which bands of hyaline cartilage unite bones; usually synarthrotic, such as the temporary epiphyseal plate or permanent costosternal joint between the first rib and manubrium.

Symphysis

A cartilaginous joint where the articular surfaces of bones are coated with hyaline cartilage and attached to an intervening pad or disc of fibrocartilage, such as the pubic symphysis or intervertebral discs.

Synovial Membrane

The inner layer of the joint capsule in a synovial joint that secretes clear, viscous synovial fluid to lubricate and cushion articular surfaces.

Ball-and-Socket Joint (Spheroidal Joint)

A multiaxial synovial joint featuring a bone with a globular head articulating within a cup-shaped cavity, enabling the widest range of rotational and angular movement.

Iliofemoral Ligament

A Y-shaped band of strong fibers connecting the anterior inferior iliac spine to the intertrochanteric line of the femur; considered the strongest ligament in the human body.

Abduction

Movement of a limb or body part in the coronal plane away from the midline of the body.

Pronation

Rotational movement of the forearm that turns the palm downward or posteriorly.

Inversion

Movement of the foot such that the sole (plantar surface) turns medially toward the midline.

Gout

A painful metabolic and inflammatory arthritis characterized by the accumulation and crystallization of insoluble uric acid within synovial joints, commonly affecting the big toe.

Epimysium

The outer sheath of dense connective tissue closely surrounding an entire skeletal muscle organ beneath the deep fascia.

Perimysium

Inward extensions of connective tissue that divide skeletal muscle tissue into smaller bundles called fascicles.

Endomysium

A delicate layer of connective tissue enclosing each individual skeletal muscle fiber within a fascicle.

Sarcolemma

The selectively permeable plasma membrane enclosing a skeletal muscle fiber.

Sarcomere

The basic structural and functional repeating unit of a myofibril, delineated from one Z line to the next adjacent Z line.

Sarcoplasmic Reticulum (SR)

A modified endoplasmic reticulum network of membranous channels surrounding each myofibril that stores and releases calcium ions ($Ca^{2+}$).

Triad

A three-unit membranous structure in a skeletal muscle fiber composed of one central transverse (T) tubule flanked by two terminal cisternae of the sarcoplasmic reticulum.

Neuromuscular Junction (NMJ)

The specialized synapse where the axon terminal of a motor neuron communicates with the motor end plate of a muscle fiber.

Acetylcholinesterase

An enzyme residing in the synaptic cleft and on the motor end plate that rapidly decomposes acetylcholine into choline and acetic acid to terminate muscle stimulation.

Excitation-Contraction Coupling

The sequence of electrical and cellular events by which an action potential on the sarcolemma causes the release of $Ca^{2+}$ from the sarcoplasmic reticulum, resulting in cross-bridge formation and mechanical contraction.

Sliding Filament Model

The mechanism of muscle contraction stating that sarcomeres shorten as thin actin filaments slide past thick myosin filaments toward the center of the sarcomere without changing their absolute lengths.

Creatine Phosphate

A high-energy biochemical molecule that stores phosphate bonds to rapidly regenerate ATP from ADP during the initial $10$ seconds of intense muscle activity.

Oxygen Debt

The amount of oxygen required by liver cells to convert accumulated lactic acid back into glucose and to restore resting muscle concentrations of ATP and creatine phosphate following strenuous exertion.

Motor Unit

A single motor neuron together with all the skeletal muscle fibers it innervates and stimulates simultaneously.

Muscle Twitch

The rapid, single contractile response of an isolated muscle fiber to a single threshold stimulus, consisting of a latent period, period of contraction, and period of relaxation.

Concentric Contraction

An isotonic contraction where the muscle shortens while generating a force greater than the opposing resistance.

Isometric Contraction

A contraction in which internal muscle tension increases while the gross length of the muscle and the joint angle remain unchanged.

Slow-Twitch (Type I, SO) Fibers

Red skeletal muscle fibers rich in myoglobin and mitochondria that rely on aerobic respiration, contract slowly, generate sustained force, and exhibit high fatigue resistance.

Calmodulin

A calcium-binding protein found in smooth muscle cells that substitutes for troponin to activate myosin cross-bridge interactions.

Intercalated Discs

Specialized cell-to-cell junctions in cardiac muscle tissue containing gap junctions and desmosomes that physically couple myocytes and facilitate coordinated syncytial contraction.

Antagonist (Muscle)

A muscle whose contraction opposes the specific movement produced by a prime mover (agonist).