Skeletal System - A&P I

Skeletal System STUDY GUIDE

Epiphysis

The end part of a long bone, initially separated from the main body of the bone by a layer of cartilage, which later fuses to the diaphysis as the individual matures.

Articular cartilage –

Smooth cartilage covering bone ends in joints to reduce friction.

Diaphysis

The shaft of a long bone.

Periosteum

Tough outer membrane covering bones.

Medullary cavity

Hollow central cavity inside the diaphysis.

Endosteum

Thin membrane lining the medullary cavity

Red marrow

Tissue that produces blood cells

Yellow marrow

stores adipose tissue in adults (fat)

Compact bone

Dense, strong outer bone layer

Spongy bone

Porous bone inside, containing trabeculae

Osteocytes

Mature bone cells that maintain bone tissue

Haversian (Central) canals

Canals in compact bone holding blood vessels and nerves

Osteoblasts

Bone forming cells

Osteoclasts

Bone resorbing (breakdown) cells

Intramembranous bones

Bones formed directly from connective tissue (e.g., skull)

Endochondral bones

Bones formed from cartilage (most bones)

Epiphyseal plate (growth plate)

Cartilage zone where long bones lengthen

Long bone

Longer than wide (femur)

Short bone

cube-shaped bones (carpals)

Flat bone

thin and flattened (skull)

Sesamoid bone

small bone in tendons (patella)

Irregular bone

complex shape (coxae)

Skull/Cranium/Facial bones

Protects brain, forms face, axial skeleton

Hyoid bone

U-shaped bone in neck, not touching other bones (sesamoid) (axial)

Vertebral column

Spine; supports body and protects spinal cord (axial)

Atlas

First cervical vertebra, allows nodding “yes” (axial)

Axis

Second cervical vertebra; allows rotation “no” (axial)

Intervertebral discs

Cartilage pads between vertebrae for cushioning (axial)

Cervical vertebrae (C1-C7)

neck region(axial)

Thoracic vertebrae (T1-T12)

Upper/mid-back; rib attachments (axial)

Lumbar vertebrae (L1-L5)

Lower back;largest vertebrae (axial)

Sacrum

Five fused vertebrae at spine base (axial)

Coccyx

Tailbone; 3-5 fused vertebrae (axial)

Thoracic cage

Ribs and sternum protecting thoracic organs (axial)

Ribs/Costal cartilages

Ribs and cartilage connecting them to sternum (axial)

Pectorial girdle

Clavicles + scapulae (attaches arms) (appendicular)

Pelvic girdle

Coxal bones; attaches legs and supports organs (appendicular)

Articulation

A joint where bones meet

Lacuna

Small cavity holding an osteocyte

fibruous joint

Immovable joints (sutures)

Cartilaginous joints

Slightly movable joints

Synovial joints

Freely movable joints with synovial fluid

Meniscus/menisci

Cartilage pads in knee for cushioning

Ball-and-socket joint

Multidirectional movement synovial joint

Condylar joint

Synovial back-and-fouth/side-to-side movement

Plane (Gliding)

Sliding movements (Carpals)

Hinge

Flexion and extension (elbow)

Pivot

Rotation

Saddle

wide range, thumb joint

Flexion

Decreases angle

Extension

Increases angle

Abduction

Away from midline

adDuction

towards midline

Supination

Palm up

Pronation

Palm down

Eversion

outward sole

Inversion

sole turns inward

Dorsiflexion

Foot upward

Plantar flexion

foot downward

Protraction

Forward movement

Retraction

Backward movement

Arthritis

Joint inflammation and degeneration

Maxilla

Upper jaw

Mandible

Lower jaw

Acromion process

High point of shoulder; scapula projection

Manubrium

Upper sternum

Body

Middle portion of sternum

Xiphoid process

Small lower tip of sternum