Musculoskeletal System – Skeletal Anatomy & Physiology (Module 1 Topic 2)

Vocabulary flashcards that cover major bones, structures, cell types, hormones, joint classifications, and anatomical features discussed in the Module 1 Topic 2 lecture on the musculoskeletal system.

Skeletal System

Body system composed of bones, cartilages, ligaments, and associated tissues that support, protect, store minerals/fat, produce blood cells, and enable movement.

Osseous Tissue

Hard, dense connective tissue that forms most of the adult skeleton.

Axial Skeleton

Division of the skeleton (80 bones) forming the body’s central axis—skull, vertebral column, and thoracic cage.

Appendicular Skeleton

Division of the skeleton (126 bones) consisting of upper & lower limbs plus pectoral and pelvic girdles.

Long Bone

Cylinder-shaped bone longer than wide; functions in movement & support (e.g., femur, humerus).

Short Bone

Cube-like bone roughly equal in length, width, thickness; provides stability with limited motion (e.g., carpals).

Flat Bone

Thin, curved bone serving as muscle attachment & organ protection (e.g., sternum, ribs, cranial bones).

Irregular Bone

Complex-shaped bone for protection, movement, support (e.g., vertebrae, facial bones).

Sesamoid Bone

Small, round bone embedded in tendon that reduces friction (e.g., patella).

Endochondral Ossification

Bone development from cartilage models; produces most long and short bones.

Membranous (Intramembranous) Ossification

Bone formation within connective tissue membrane; forms skull flat bones and mandible.

Compact Bone

Dense, strong outer bone layer composed of tightly packed osteons.

Spongy (Cancellous) Bone

Light, porous bone with trabeculae housing marrow and resisting stress lines.

Osteon (Haversian System)

Structural unit of compact bone; concentric lamellae surrounding a central canal.

Lamella

Each ring of an osteon made of collagen fibers & calcified matrix.

Central (Haversian) Canal

Channel at an osteon’s center containing blood vessels, nerves, lymphatics.

Perforating (Volkmann) Canal

Transverse canal linking central canals to periosteum and endosteum.

Canaliculi

Microscopic channels connecting lacunae, enabling nutrient/waste exchange between osteocytes.

Trabeculae

Lattice-like matrix spikes in spongy bone aligning along stress lines.

Diaphysis

Shaft of a long bone housing the medullary cavity.

Medullary Cavity

Hollow space within diaphysis containing yellow marrow in adults.

Epiphysis

Expanded end of a long bone filled with spongy bone.

Metaphysis

Region where diaphysis meets epiphysis; contains epiphyseal plate/line.

Articular Cartilage

Thin hyaline cartilage covering epiphyses to reduce friction & absorb shock.

Periosteum

Fibrous membrane covering outer bone surface (except at joints) containing bone-forming cells, vessels, nerves.

Endosteum

Cellular membrane lining medullary cavity and trabeculae; active in growth & remodeling.

Bone Matrix

Composite of ⅓ collagen fibers (flexibility) and ⅔ hydroxyapatite salts (hardness).

Hydroxyapatite

Crystalline calcium phosphate salt giving bone its compressive strength.

Osteogenic Cell

Bone stem cell that differentiates into osteoblasts.

Osteoblast

Bone-forming cell that secretes osteoid matrix; becomes osteocyte when trapped.

Osteocyte

Mature bone cell residing in lacuna; maintains mineralized matrix.

Osteoclast

Large, multinucleated cell that resorbs bone during remodeling.

Growth Hormone

Pituitary hormone that lengthens long bones and increases density.

Thyroxine

Thyroid hormone that stimulates bone growth and matrix synthesis.

Sex Hormones

Estrogens & androgens promoting osteoblastic activity and adolescent growth spurt; close epiphyseal plates.

Calcitriol

Active vitamin D that increases intestinal absorption of calcium and phosphate.

Parathyroid Hormone (PTH)

Hormone stimulating osteoclasts and kidney calcium reabsorption to raise blood Ca²⁺.

Calcitonin

Thyroid hormone that inhibits osteoclasts and promotes bone Ca²⁺ uptake.

Articulation

Point where two bones meet; may allow movement or be immobile.

Projection (Bone Marking)

Raised bone area serving as tendon/ligament attachment site.

Hole (Bone Marking)

Opening in bone allowing passage of vessels or nerves (e.g., foramen).

Cranium

Eight-bone portion of skull encasing the brain.

Facial Bones

Fourteen skull bones forming jaws, nose, orbit, nasal cavity.

Mandible

Lower jawbone containing body, ramus, coronoid process, condylar process, mandibular notch.

Orbit

Bony eye socket formed by seven skull bones.

Hyoid Bone

U-shaped bone in neck not articulating with others; supports tongue & larynx.

Vertebral Column

Spine of 24 movable vertebrae plus sacrum & coccyx protecting spinal cord.

Cervical Vertebrae

Seven vertebrae (C1–C7) of the neck; C1 = atlas, C2 = axis.

Thoracic Vertebrae

Twelve vertebrae (T1–T12) articulating with ribs.

Lumbar Vertebrae

Five large vertebrae (L1–L5) of lower back bearing weight.

Sacrum

Triangular bone of five fused vertebrae forming posterior pelvis.

Coccyx

Tailbone of 3–5 fused vertebrae articulating with sacrum.

Primary Curvature

Thoracic & sacrococcygeal curves retained from fetal position (convex posteriorly).

Secondary Curvature

Cervical & lumbar curves developing after birth (concave posteriorly).

Kyphosis

Excessive posterior thoracic curvature (hunchback).

Lordosis

Excessive anterior lumbar curvature (swayback).

Scoliosis

Lateral spinal curvature with rotation.

Thoracic Cage

Bony enclosure of sternum, ribs, costal cartilages protecting thoracic organs.

Sternum

Breastbone consisting of manubrium, body, xiphoid process.

Manubrium

Superior sternum part articulating with clavicles & first ribs.

Sternal Angle

Joint between manubrium & body; landmark where 2nd rib attaches.

True Ribs

Ribs 1–7 attaching directly to sternum via costal cartilage.

False Ribs

Ribs 8–10 attaching indirectly to sternum via cartilage of rib 7.

Floating Ribs

Ribs 11–12 lacking sternal attachment.

Pectoral Girdle

Clavicle and scapula that attach upper limb to axial skeleton.

Clavicle

S-shaped collarbone connecting sternum to scapula.

Scapula

Flat shoulder blade articulating with humerus & clavicle.

Humerus

Single arm bone featuring head, greater/lesser tubercles, surgical neck.

Ulna

Medial forearm bone with trochlear notch, olecranon, styloid process.

Radius

Lateral forearm bone (not detailed in notes but implied paired with ulna).

Interosseous Membrane (Forearm)

Dense sheet uniting radius and ulna along their shafts.

Carpal Bones

Eight wrist bones: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate.

Metacarpal Bones

Five hand bones forming the palm; numbered I–V from thumb.

Phalanges (Hand)

14 finger bones—thumb with two, digits 2–5 with three each.

Pelvic Girdle

Two hip (coxal) bones forming strong attachment for lower limbs.

Ilium

Superior, fan-shaped portion of hip bone articulating with sacrum.

Ischium

Posteroinferior hip bone region supporting weight when sitting.

Pubis

Anterior hip bone region meeting at pubic symphysis.

Acetabulum

Cup-shaped lateral socket where ilium, ischium, pubis unite; receives femoral head.

Obturator Foramen

Large anteroinferior opening bounded by ischium & pubis.

Greater (False) Pelvis

Broad pelvis region superior to pelvic brim containing intestines.

Lesser (True) Pelvis

Inferior, narrower pelvis housing pelvic organs.

Subpubic Angle

Angle between pubic bones—>80° in females, <70° in males.

Femur

Thigh bone; longest, strongest bone forming hip & knee joints.

Coxa Vara

Decreased femoral neck–shaft angle (<120°).

Coxa Valga

Increased femoral neck–shaft angle (>135°).

Tibia

Medial leg bone bearing weight; has medial malleolus & tibial tuberosity.

Fibula

Slender lateral leg bone with head and lateral malleolus.

Interosseous Membrane (Leg)

Dense sheet binding tibia and fibula.

Medial Malleolus

Distal tibial projection forming inner ankle.

Lateral Malleolus

Distal fibular projection forming outer ankle.

Anterior Cruciate Ligament (ACL)

Intracapsular knee ligament preventing anterior tibial translation.

Medial Collateral Ligament (MCL)

Knee ligament resisting valgus stress; part of “unhappy triad.”

Lateral Collateral Ligament (LCL)

Knee ligament resisting varus stress.

Posterior Cruciate Ligament (PCL)

Knee ligament preventing posterior tibial translation.

Meniscus

C-shaped fibrocartilage pad (medial/lateral) cushioning knee joint.

Genu Valgum

Knock-knee deformity where knees angle medially.

Genu Varum

Bow-legged deformity where knees angle laterally.

Talus

Superior tarsal bone articulating with tibia/fibula to form ankle.

Calcaneus

Heel bone transmitting body weight from talus to ground.