Skeletal system

Skeletal system

Functions: Provides structure and support, protects

internal organs, and facilitates movement.

-producing blood (specifically in bone marrow)

CONTAINS: BONES, LIGAMENT, TENDONS, JOINTS

Long bones

Elongated shape, greater in LENGTH than

width.

Composed of COMPACT bone surrounding a

central marrow cavity.

○COMPACT BONE:

■ solid inside

■ regulate structure

Function as levers for movement and support

body weight.

○Examples: Femur, humerus, tibia legs

appendages

Diaphysis

CYLINDRICAL shaft for

leverage and weight support, made up of

containing a medullary cavity with yellow

marrow.

Epiphyses

ENLARGED ends for joint

articulation and muscle attachment,

containing SPONGY bone with red marrow, for

blood cell production, covered by compact

bone and articular cartilage for shock

absorption.

Metaphyses

Transitional areas for GROWTH

and force transfer, containing the epiphyseal

plate (growth plate).

Articular Cartilage

HYALINE cartilage

reducing friction and absorbing shock.

Medullary Cavity

HOLLOW SPACE in the

diaphysis storing yellow marrow in adults and

red marrow in children.

Periosteum

Fibrous membrane for protection,

growth, and attachment of tendons and

ligaments.

●glossy part

●Outside

Endosteum

Lines the medullary cavity and

bone canals, aiding in bone remodeling.

●inner lining bone

Compact bone

DENSE OUTER layer for

strength and protection, organized into

OSTEONS.

Spongy Bone

• Found in epiphyses and

metaphyses

• reducing

weight and housing red marrow.

Short bones

CUBE-shaped with similar length, width, and

thickness (uniform) =

o Mostly spongy bone surrounded by compact bone.

●allows you to faci small movements flexibility

●stiff if compact -meron but way less

o Provide stability and support with limited range

motion.

o Examples: Carpals (wrists), tarsals (ankles).

Their structure helps distribute mechanical forces

across joints, reducing stress during movement.

Flat bones

Thin, flattened, and typically curved.

o Two parallel layers of compact bone surrounding

spongy bone.

●BOTH THIN spongy and compact bone

o Protect organs (protective barrier-soft organs) and provide broad muscle attachment surfaces.

●no locomotion inv

o Examples: Sternum, ribs, scapulae, cranial

bones.

Irregular bones

COMPLEX shapes that don’t fit other categories.

●not conforming; no set shape, UNIQUE

o Thin layers of compact bone surrounding

spongy bone.

o Provide structural support, protect nervous

tissue, and facilitate muscle attachment.

●mechanical digestion: chew

●specialized function- other bones cant perf

o Examples: Vertebrae, pelvic bones, facial

bones.

Osteoblasts

BONE FORMATION cells secrete the matrix

that mineralizes to become bone.

○still trying to specialize specific func; young

○composed of collagen

■ mineralizes Ca K PO ions

Responsible for bone growth and repair.

becomes LINING

Mineral deposition

■ process ensures bones are tough

and resilient, withstand damage

■ Ca

Osteocytes

• most common

● MATURE bone cells derived from osteoblasts,

MAINTENANCE bone tissue.

o Reside in small cavities (lacunae) and communicate through canaliculi, regulating bone health.

Osteoclats

Bone-RESORBTION cells - HEALING

●Rehab of bones - breaking down bone tissue

during remodeling.

●regulate minerals within bone tissue

o Release minerals into the bloodstream, regulating

calcium balance.

●teenager

Axial skeleton

Forms the central framework of the body, supporting and protecting vital organs.

Skull

22 bones protecting the brain and

supporting facial structures.

Cranial bones

Frontal, parietal,

occipital.

Facial bones

Maxilla, mandible.

Vertebral column

33 vertebrae supporting the

head, protecting the spinal cord, and enabling

movement.

• Regions: Cervical, thoracic, lumbar, sacral,

  coccygeal.

Thoracic cage

Sternum and 12 pairs of ribs

protecting the heart and lungs.

Appendicular skeleton

Includes limbs and girdles, facilitating movement and interaction with the environment.

Pectoral girdle

Clavicles and scapulae

connecting upper limbs to the axial skeleton.

Upper limbs

Humerus, radius, ulna, carpals,

metacarpals, phalanges.

• Enable intricate movements and dexterity.

Pelvic girdle

Hip bones (ilium, ischium, pubis)

attaching lower limbs and supporting body

weight.

Lower limbs

Femur, patella, tibia, fibula,

tarsals, metatarsals, phalanges.

▪ Provide stability, locomotion, and support.

Fibrous joints

Bones connected by dense connective tissue.

o NO joint cavity; MINIMAL movement.

Sutures

Immovable (skull).

glue (lines in skull)

Syndesmoses

Slightly movable (e.g.,

between radius and ulna).

Gomphoses

Peg-in-socket joints (teeth).

Cartilaginous joints

Bones connected by cartilage, allowing LIMITED

movement.

Synchondroses

Immovable

(epiphyseal plate). bones

are united by hyaline

cartilage

Symphyses

Partially movable

(e.g., intervertebral

discs ).

Synovial joints

-most common

o Freely movable joints with a fluid-filled cavity.

(synovial fluid)

●fluid ￬friction ￬resistance

o Key Features: Articular cartilage, synovial fluid, joint capsule, ligaments, bursae.

Ball-and-socket joints

Multidirectional movement

(shoulder/hips)

highest range of movements

Condyloid joints

Movement without rotation

(wrist)

Plane joints

Gliding movements

(intercarpal joints/ankles)

Saddle joints

Back and forth, side

to side (e.g., thumb).

in bw trapezium carpal

Hinge joints

Flexion and extension (e.g.,

elbow).

limited

Pivot joints

Rotation (e.g., neck).

C1&C2 vertebrae 180 degrees