Trans Anat LE2: Introduction to the Musculoskeletal System

Comprehensive vocabulary flashcards covering the components, histology, joint classifications, and muscular mechanics presented in MED101: Introduction to the Musculoskeletal System.

Axial Skeleton

The central core of the skeletal system comprising the cranium, neck, and trunk extending down to the sacrum.

Appendicular Skeleton

The division of the skeletal system comprising the upper and lower limbs and the pectoral (shoulder) and pelvic girdles.

Calcium Hydroxyapatite

The metabolic salt complex in bone tissue that constitutes $99\%$ of the stored calcium in the human body.

Hematopoiesis

The physiological process of synthesizing red blood cells (RBC) or white blood cells (WBC) within the bone marrow.

Hyaline Cartilage

The most common form of cartilage in the body, characterized histologically by chondrocytes located within lacunae surrounded by an extracellular matrix.

Elastic Cartilage

A flexible type of cartilage containing elastic fibers within its extracellular matrix, found in structures such as the external ear.

Fibrocartilage

A cartilage type composed of dense fibrous tissue that forms secondary cartilaginous joints (symphyses).

Compact (Cortical) Bone

The thick, dense outer structural layer termed the heart of the bone that provides major mechanical strength.

Spongy (Cancellous) Bone

Bone tissue characterized by an internal lattice of struts that is fairly thick and strong, but not as strong as compact bone.

Periosteum

A vascularized and richly innervated connective tissue sheath covering the outer surface of bone (except articular areas) where osteogenesis, nerve supply, and blood supply occur.

Long Bones

Tubular, elongated bones consisting of an epiphysis, metaphysis, and diaphysis, such as the humerus, femur, tibia, and fibula.

Short Bones

Cuboidal-shaped bones found in the wrists and ankles, specifically the carpals and tarsals.

Flat Bones

Protective bones formed via intramembranous ossification consisting of flat sheets, such as the cranial bones (frontal, parietal), ribs, sternum, and hip bone.

Sesamoid Bones

Small, seed-shaped rounded bones embedded within tendons or muscles, such as the patella, hallux sesamoids, and pisiform.

Bone Markings

Specific structural landmarks on bone surfaces where tendons, ligaments, nerves, and blood vessels pass through or attach.

Endochondral Ossification

The developmental process of bone formation where a preexisting fetal hyaline cartilage model is gradually calcified and replaced by bone tissue.

Intramembranous Ossification

The direct formation of bone from mesenchymal connective tissue sheets without utilizing a preexisting cartilage model.

Howship's Lacunae

Shallow depressions or resorption pits formed on the bone surface as osteoclasts break down bone tissue during remodeling.

Osteoid

The newly deposited organic bone matrix laid down by osteoblasts that subsequently mineralizes into mature bone.

Osteon (Haversian System)

The basic structural unit of compact bone, composed of concentric lamellae of calcified matrix enclosing a central Haversian canal.

Haversian Canal

A central longitudinal canal in an osteon containing the neurovascular structures supplying compact bone tissue.

Volkmann's Canal

A transverse or oblique microscopic canal that connects adjacent Haversian canals to one another and to periosteal blood vessels.

Synovial Joint

A freely movable joint enclosed by an articular capsule whose internal synovial membrane secretes lubricating synovial fluid into the joint cavity.

Primary Cartilaginous Joint (Synchondrosis)

A cartilaginous joint united entirely by hyaline cartilage, such as the epiphyseal growth plate.

Secondary Cartilaginous Joint (Symphysis)

A cartilaginous joint united by a pad of fibrocartilage, such as an intervertebral disc.

Abduction

A joint movement that increases the angle of a joint to move a limb or body part away from the coronal midline.

Adduction

A joint movement that decreases the angle of a joint to draw a limb or body part closer to the midline.

Circumduction

A circular movement combining flexion, extension, abduction, and adduction such that the distal end of a bone describes a circle.

Plane Joint

A uniaxial synovial joint with flat articulating surfaces that permits gliding or sliding movements, such as the acromioclavicular joint.

Hinge Joint

A uniaxial synovial joint that strictly permits flexion and extension movements, such as the elbow joint.

Pivot Joint

A uniaxial synovial joint in which a rounded bony process rotates within a ring-like osteoligamentous socket, such as the atlanto-axial joint.

Saddle Joint

A biaxial synovial joint with opposing saddle-shaped heads permitting movements in two distinct planes, such as the carpometacarpal joint of the thumb.

Condyloid Joint

A biaxial synovial joint permitting flexion, extension, abduction, adduction, and circumduction, such as the metacarpophalangeal joint.

Ball and Socket Joint

A multiaxial synovial joint where a spherical head articulates within a cup-like concavity, permitting motion in three planes, such as the hip joint.

Articular Nerves

Nerves distributed to the joint capsule and synovial membrane that primarily convey sensory proprioception.

Skeletal Striated Muscle

Voluntary muscle tissue composed of large, unbranched, cylindrical, multinucleated fibers with peripheral nuclei and prominent transverse striations.

Cardiac Striated Muscle

Involuntary, intrinsically stimulated muscle tissue featuring branching and anastomosing fibers with central nuclei, striations, and intercalated discs.

Smooth Muscle

Involuntary muscle tissue composed of non-striated, spindle-shaped cells with a single central nucleus found in the walls of hollow viscera and blood vessels.

Motor Unit

The functional unit of skeletal muscle consisting of a single motor neuron from the spinal cord and all of the individual muscle fibers it innervates.

Muscle Origin

The relatively fixed and stable skeletal attachment of a muscle during contraction, which is usually the proximal end.

Muscle Insertion

The movable skeletal attachment of a muscle that is drawn toward the origin during contraction, usually located at the distal end.

Myotatic Reflex

A reflexive, involuntary stretch contraction elicited by tapping a tendon with a reflex hammer, exemplified by the patellar knee-jerk reflex.

Tonic Contraction (Muscle Tone)

A constant state of low-level muscle firmness maintained without conscious effort that stabilizes joints and sustains posture.

Concentric Contraction

A subtype of phasic isotonic contraction in which tension is generated while the muscle actively shortens to produce movement.

Eccentric Contraction

A subtype of phasic isotonic contraction characterized by controlled, gradual lengthening of an active muscle under tension.

Isometric Contraction

A muscle contraction wherein the muscle length remains constant while muscle tension changes, producing no joint movement.

Agonist (Prime Mover)

The primary muscle directly responsible for producing a specific anatomical movement, such as the biceps brachii during elbow flexion.

Antagonist

A muscle that directly opposes or controls the action of an agonist, such as the triceps brachii during elbow flexion.

Synergist

A muscle that assists and complements the action of a prime mover during joint movement.

Fixator

A muscle that contracts isometrically to anchor and stabilize proximal segments, providing a steady base for distal limb motion.

Muscle Hypertrophy

An increase in skeletal muscle fiber size resulting from anaerobic resistance strength training against heavy resistance.

Disuse Atrophy

The wasting and shrinkage of muscle mass caused by prolonged periods of physical inactivity or limb immobilization.