Chapter 07 – Skeletal System Vocabulary

100 vocabulary flashcards summarizing essential terms and definitions from the Chapter 7 lecture on the skeletal system.

Skeletal System

Body system of bones and associated tissues that supports, protects, moves, stores minerals, and forms blood cells.

Axial Skeleton

80-bone division consisting of skull, hyoid, vertebral column, and thoracic cage.

Appendicular Skeleton

126-bone division made up of pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

Long Bone

Bone that is longer than it is wide and has expanded ends (e.g., femur).

Short Bone

Cube-like bone whose length equals width; includes sesamoid bones (e.g., carpals).

Flat Bone

Plate-like bone with broad surfaces (e.g., sternum).

Irregular Bone

Bone with varied shape that doesn’t fit other classes (e.g., vertebra).

Sesamoid Bone

Small, round bone embedded in a tendon (e.g., patella).

Epiphysis

Expanded end of a long bone that articulates with another bone.

Diaphysis

Shaft of a long bone between the epiphyses.

Metaphysis

Widening region between diaphysis and epiphysis.

Articular Cartilage

Hyaline cartilage covering epiphysis where bones meet.

Periosteum

Dense connective tissue membrane that encloses a bone except at cartilage-covered areas.

Compact (Cortical) Bone

Dense outer bone tissue forming the wall of the diaphysis.

Spongy (Cancellous) Bone

Porous bone in epiphyses composed of trabeculae.

Trabeculae

Branching plates that make up spongy bone.

Medullary Cavity

Hollow chamber in diaphysis containing marrow.

Endosteum

Membrane lining spaces and medullary cavity of bone.

Red Marrow

Bone marrow that forms red, white blood cells and platelets.

Yellow Marrow

Fat-storing marrow that replaces red marrow with age.

Osteocyte

Mature bone cell residing in a lacuna.

Lacuna

Small cavity in bone matrix housing an osteocyte.

Canaliculus

Tiny channel connecting osteocytes for nutrient/waste exchange.

Osteon

Cylindrical structural unit of compact bone; Haversian system.

Lamellae

Concentric layers of bone matrix in an osteon.

Collagen

Protein fiber giving bone tensile strength and resilience.

Hydroxyapatite

Calcium phosphate crystal that hardens bone matrix.

Hematopoiesis

Process of blood cell formation in red marrow.

Calcium Homeostasis

Regulation of blood calcium by PTH and calcitonin.

Parathyroid Hormone (PTH)

Hormone that raises blood calcium by stimulating osteoclasts.

Calcitonin

Thyroid hormone that lowers blood calcium by inhibiting osteoclasts.

Intramembranous Ossification

Bone formation within sheet-like connective tissue; produces flat bones.

Endochondral Ossification

Bone formation replacing a hyaline cartilage model; produces most bones.

Mesenchyme

Embryonic connective tissue that differentiates into osteoblasts.

Osteoblast

Bone-forming cell that deposits bone matrix.

Osteoclast

Bone-resorbing cell that breaks down matrix.

Osteoid

Unmineralized bone matrix secreted by osteoblasts.

Primary Ossification Center

First area in diaphysis where bone replaces cartilage.

Secondary Ossification Center

Ossification area in an epiphysis forming spongy bone.

Epiphyseal Plate

Cartilaginous growth plate between ossification centers; enables length growth.

Zone of Resting Cartilage

Layer of quiescent cells anchoring epiphyseal plate to epiphysis.

Zone of Proliferating Cartilage

Layer of actively dividing chondrocytes lengthening bone.

Zone of Hypertrophic Cartilage

Older chondrocytes enlarge; matrix thickens and calcifies.

Zone of Calcified Cartilage

Thin layer of dead cells and calcified matrix ready for bone deposition.

Bone Remodeling

Ongoing replacement of old bone by deposition and resorption.

Pituitary Dwarfism

Short stature from childhood growth hormone deficiency.

Gigantism

Excessive height due to childhood growth hormone excess.

Acromegaly

Adult growth hormone excess causing enlarged hands, feet, face.

Vitamin D

Vitamin needed for calcium absorption; deficiency causes rickets/osteomalacia.

Vitamin A

Vitamin required for osteoblast/osteoclast activity; deficiency slows bone growth.

Vitamin C

Vitamin essential for collagen synthesis; deficiency weakens bones.

Physical Stress

Mechanical loading that stimulates bone growth and remodeling.

Osteoporosis

Severe bone loss leading to porous, fragile bones.

Osteopenia

Mild to moderate loss of bone density preceding osteoporosis.

Fracture

Break in a bone classified by cause or nature of break.

Hematoma (Fracture)

Blood clot formed immediately after bone fracture.

Fibrocartilaginous (Soft) Callus

Cartilage and fibrous tissue bridging a fracture early in healing.

Bony (Hard) Callus

Spongy bone replacing cartilage callus during fracture repair.

Axial Skeleton Components

Skull, hyoid, vertebral column, thoracic cage.

Appendicular Skeleton Components

Pectoral girdle, upper limbs, pelvic girdle, lower limbs.

Sutural (Wormian) Bone

Small extra bone within a cranial suture.

Condyle

Rounded process that articulates with another bone.

Foramen

Hole in a bone allowing passage of vessels or nerves.

Fossa

Deep pit or depression in a bone.

Meatus

Tube-like passageway within a bone (e.g., external acoustic meatus).

Sinus

Air-filled cavity within a bone, reducing weight and resonating voice.

Trochanter

Large, rough projection for muscle attachment (femur).

Tuberosity

Large, rounded knob for muscle attachment.

Spine (Process)

Sharp, slender projection from a bone.

Skull

Bony structure housing brain; 22 bones in adults.

Cranium

Eight-bone portion of skull protecting the brain.

Facial Skeleton

Fourteen bones forming the face.

Paranasal Sinus

Air cavity in cranial/facial bone connected to nasal cavity.

Fontanel

Soft membranous region between cranial bones of infants.

Vertebral Column

33 infant / 26 adult vertebrae forming spinal axis and protecting cord.

Intervertebral Disc

Cartilaginous pad between vertebrae absorbing shock.

Atlas (C1)

First cervical vertebra supporting the skull.

Axis (C2)

Second cervical vertebra with dens around which atlas pivots.

Cervical Vertebrae

Seven vertebrae of the neck region with transverse foramina.

Thoracic Vertebrae

Twelve vertebrae articulating with ribs; pointed spinous processes.

Lumbar Vertebrae

Five large vertebrae in lower back; strong weight-bearers.

Sacrum

Five fused vertebrae forming posterior pelvic wall.

Coccyx

Tailbone of usually four fused vertebrae.

Kyphosis

Exaggerated thoracic curvature; hunchback.

Lordosis

Exaggerated lumbar curvature; swayback.

Scoliosis

Abnormal lateral curvature of the spine.

Thoracic Cage

Ribs, thoracic vertebrae, sternum, and costal cartilages protecting organs.

True Ribs

First seven rib pairs attaching directly to sternum via cartilage.

False Ribs

Rib pairs 8–12 not directly attached to sternum.

Floating Ribs

Rib pairs 11–12 with no anterior attachment.

Sternum

Breastbone consisting of manubrium, body, and xiphoid process.

Pectoral Girdle

Clavicles and scapulae supporting upper limbs.

Clavicle

S-shaped collarbone articulating with sternum and scapula.

Scapula

Triangular shoulder blade with spine, acromion, coracoid, glenoid cavity.

Glenoid Cavity

Shallow socket of scapula articulating with humeral head.

Humerus

Single bone of upper arm with head, tubercles, condyles.

Radius

Lateral forearm bone with head, radial tuberosity, styloid process.

Ulna

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

Carpals

Eight wrist bones forming two rows.

Metacarpals

Five hand bones between carpals and phalanges.