Skeletal_System.txt

◦Bones

◦Joints

◦Cartilage

◦Ligaments

Axial Skeleton 

◦Form longitudinal axis

Appendicular skeleton

• ◦Bones of limbs and girdles
• 

Support the body

Protection - soft body organs, skull (brain), vertebrae (spinal cord), rib cage (thorax)

• Movement-
• Attach to tendons, use bones as levers(due to attached skeletal muscles)

Storage - Fat is stored in marrow, minerals (Ca, P)

• Blood cell formation - In marrow
• BuMPSS

• ◦Compact bone
• –Dense and smooth: homogeneous

• ◦Spongy bone
• –Small needle-like pieces of bone and many
• open spaces
• 

• Long bones
• Short bones
• Flat bones
• Irregular bones

• ◦Typically longer than wide
• ◦Have a shaft with heads at both ends ◦Contain mostly compact bone
• ◦Ex. Femur, Humerus (all bones of limbs, except patella, wrist and ankle bones)
• 

• ◦General cube-shaped
• ◦Mostly spongy bone
• ◦Ex. Carpals, tarsals (wrist, ankle, patella)
• 

• ◦Thin and flattened
• ◦Usually curved
• ◦Two thin layers of compact bone sandwiching a layer of spongy bone between them
• ◦Ex. Skull, ribs and sternum
• 

• ◦Irregular shape
• ◦Do not fit any other bone category
• ◦Ex. Hip, Vertebrae
• 

Diaphysis: Shaft,  compact bone

Epiphysis: Ends of bone, spongy

Periosteum: Outside covering of diaphysis, fibrous connective tissue membrane

Sharpey’s Fibers (perforating): Secures periosteum to underlying bone

Arteries: Supply bone cells with nutrients

• Articular Cartilage: Covers external surface of the epiphyses
• -- Made of hyaline cartilage
• -- Decreases friction at joint surfaces

• Medullary Cavity: Cavity of the shaft
• -- Contains yellow marrow (fat in adults)
• -- Contains red marrow (for blood cell formation in infants)

Surface features of bones

Sites of attachments for muscles, tendons and ligaments

Passages for nerves and blood vessels

◦Projections and processes- grown out from the bone surface

◦Depressions or cavities-indentations

◦Holes and Tunnels - Where blood and nerves enter bone

Tuberosity - rounded projection

Crest - narrow, prominent ridge of bone

Trochanter - large, blunt, irregular surface

Line - narrow ridge of bone

Tubercle - small rounded projection

Epicondyle - raised area above a condyle

Spine - sharp, slender projection

Process - any bone prominence

Head - bony expansion carried on a narrow neck

Facet - smooth, nearly flat articular surface

Condyle - rounded articular projection

Ramus - armlike bar of bone

Meatus - canal-like passageway

Sinus - cavity within a bone

Fossa - shallow, basin-like depression

Groove - furrow (slight indentation)

Fissure - narrow, slit-like opening

Foramen - round or oval opening through a bone

• Mature bone cells found within the matrix in tiny cavities called lacunae
• 

• A unit of bone consisting of a central (Haversian) canal and matrix rings also known as Haversian system
• 

• Tiny cavities found in the bone matrix with osteocytes
• 

• Communication pathways from the outside of the bone to its interior and the central canals that run into the compact canals at right angles
• 

◦Opening in the center of an osteon

• ◦Carries blood vessels and nerves
• 

• ◦Ring saround the central canal
• ◦Sites of Lacunae
• 

◦Tiny canals

◦Radiate from the central canal to lacunae

• ◦Form a transport system
• 

◦Bridge of the nose

◦Parts of the ribs

◦Joints

Allow for growth of long bone during childhood

Osteocystes: Mature Bone Cells

Osteoblasts: Bone-forming Cells

Osteoclasts: Bone-destroying Cells

1.Hematoma is formed (blood-filled swelling)

2.Break is splinted by fibrocartilage to form a callus

3.Fibrocartilage callus is replaced by a bony callus

4.Bony callus is remodeled to form a permanent patch

◦Skull

◦Vertebral Column

• ◦Bony thorax
• 

Fibrous membranes connecting the cranial bones of infants

◦Allows brain to grow

◦Converts to bone within 24months of birth

The only bone that does not articulate with another bone

Serves as a moveable base for the tongue

Hollow portions of bones surround the nasal cavity

Lightens the skull

Give resonance and amplification to voice

• Cervical (neck region)
• ◦C1-C7: Allows for nodding and pivoting of head

• Thoracic (Only vertebrae to articulate with the ribs)
• ◦T1-T12: Heart-shaped

• Lumbar 
• ◦L1-L5: Massive block-like bodies
• ◦Sturdiest of the vertebrae

• Sacrum 
• ◦Formed via fusion of 5 vertebrae

• Coccyx
• ◦Formed via fusion of 3-5 tiny irregular shaped vertebrae

Forms a cage to protect major organs

Made-up of three parts

◦Sternum

◦Ribs (24)

• ◦Thoracic vertebrae
• -- 7 pairs true

-- 3 pairs false

• -- 2 pairs floating
• 

Limbs

Pectoral girdle(shoulder)

• Pelvic girdle
• 

◦Clavicle (collarbone)

• ◦Scapula (shoulder blade)
• 

• The arm:
• -- Humerus

• Forearm: 
• -- Ulna(inner) 
• -- Radius(outer)

• Hand: 
• -- Carpals(wrist);
• -- Metacarpals (palm) 
• -- Phalanges (fingers)
• 

• Composed of three pairs of fused bones:
• -- Ilium,
• -- Ischium
• -- Pubic bone
• 

• Thigh:
• -- Femur

• Leg 2 bones:
• -- Tibia (inner)
• -- Fibula (outer)

• Foot:
• -- Tarsus (ankle);
• -- Metatarsals (sole);
• -- Phalanges (toes)
• 

• Synarthroses
• -- immovable joints

• Amphiarthroses
• -- slightly moveable joints, spine

• Diarthroses
• -- freely moveable joints, limbs

• Fibrous joints:
• -- Generally immovable

• Synovial joints:
• -- Freely moveable

• Cartilaginous joints:
• -- Immovable or slightly moveable

Bones united by fibrous tissue

-- Sutures

-- Syndesmoses (Allows for more movement then sutures (distal end of tibia and fibula)

Bones connected by cartilage

-- Pubic symphysis

-- Intervertebral joints

Articulating bones are separated by a joint cavity

Synovial fluid is found in the joint cavity

Articulare cartilage (hylaline cartilage) covers the ends of bones

Joint surfaces are enclosed by a fibrous articular capsule

Have a joint cavity filled with synovial fluid

Ligaments reinforce the joint

• Bursa:
• -- Flattened fibrous sacs

-- Lines with synovial membranes

-- Filled with synovial fluid

-- Not actually part of the joint

• Tendon sheath:
• -- elongated bursa that wraps around a tendon