skeletal system

The skeletal system

Provides support protects vital organs and is essential for producing blood cells in the bone marrow and for storing and releasing minerals like calcium and phosphorus

Axial Skeleton

Central axis of body 80 bones

Skull vertebral column rib cage sternum

Appendicular skeletal

Bones of the limbs (arms and legs),

pelvis, and shoulder area connect the

limbs to the axial skeleton (126 bones)

Primary function:

Movement and locomotion.

Proximal epiphysis

End of long bone contains spongy bone red bone marrow for blood cell production

Articulate cartilage

Smooth cartilage covering epiphysis reproduces friction at joints

Metaphysis

Between epiphysis and diaphysis includes epiphyseal line plate growth plate

Epiphyseal line

Remnant of growth plate

Diaphysis

Shaft of long bone made mostly of compact bone for strength

Spongy bone

Porous inner bone houses red marrow for hematopoietic

Red bone marrow

Produces rbc wbc and platelets

Yellow bone marrow

Found in medullary cavity of diaphysis stores fat

Endosteum

Membrane lining the medullary cavity;

contains cells for bone growth and repair.

Periosteum

Outer fibrous covering of bone; protects,

nourishes, and serves as an attachment for

tendons/ligaments.

Long bones

Facilitate movement

Femur tibia numerous

Short bones

Support and stability with a little movement

Wrist carpal ankles tarsal

Flat bones

Protects internal organs and muscle attachment

Sternum ribs skull

Irregular bones

Vertebrae some facial bones

Sesamoid bones

Protects tendons

Patella

Ligaments

Connect bone to bone

Stabilize joints, limit excessive movement.

Example: ACL (knee).

TEAS Focus: Think L = Link bones

Tendons

Connect muscle to bone.

Transfer force from muscle contraction

→ bone movement.

Example: Achilles tendon (calf → heel).

TEAS Focus: Think T = T Bone Steak =

Muscle to Bone

Osteocytes

“Maintainers

” → mature bone cells that monitor and

maintain bone tissue; derived from osteoblasts

trapped in the matrix.

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Osteoblast

Builders form new bone by secreting bone matrix

Osteoclasts

Crashers

” → break down and resorb bone

tissue, releasing calcium into blood.

Osteocyte

“Maintainers

” → mature bone cells that monitor and

maintain bone tissue; derived from osteoblasts

trapped in the matrix.

Ball and socket joint

Description: Rounded head fits

into a cup-like cavity.

Movement: Multiaxial—flexion,

extension, abduction, adduction,

rotation, circumduction.

Examples: Shoulder, hip.

Hinge joint

Description: Works like a door

hinge.

Movement: Uniaxial—flexion and

extension only.

Examples: Elbow, knee, fingers,

toes.

Pivot joint

Description: Bone rotates around

a central axis.

Movement: Rotation only.

Examples: Atlas/axis in neck

(head rotation

“

no

”), radius/ulna

at elbow (supination/pronation).

Saddle joint

Thumb

Candyloid joint

Wrist knuckles

Gliding plane joint

Carpals tarsals vertebrae facets