Unit 4 Skeletal System Study

Basic functions of the Skeletal System

Support, protection, assist in movement, storage of calcium, production of blood cells, storage of chemical energy

Storage of calcium

When needed, bones release minerals into the blood to maintain homeostasis

Production of blood cells

Red bone marrow produces RBCs, WBCs, and platelets

Storage of chemical energy

Yellow bone marrow stores fat/reserve energy

Axial Skeleton

Skull, vertebral column, sternum, ribs

Appendicular Skeleton

Hands/feet, wrists/ankles, arms/legs, pectoral/pelvic girdle

Long bones

Greater length than width (ex. femur, tibia/fibula, humerus, ulna and radius

Short bones

Somewhat cube shaped; nearly equal in length and width (ex. carpals/tarsals)

Flat bones

Generally thin; extensive surface for muscle attachment; provide considerable protection (ex. cranial bones, sternum, ribs, scapulae)

Irregular bones

Complex shapes (ex. vertebrae of backbone; some facial bones)

Sesamoid bone

Protects tendons from wear and tear (ex. patella)

Diaphysis

Long, cylindrical, main portion f the bone; adds to length

Epiphysis

Distal and proximal ends of the bone: help to form joints; contain spongy bone

Metaphysis

Regions in mature bone were epiphysis meets the diaphysis

Epiphyseal plate

Layer of cartilage that is being replaced by bone. Bone grows in length at the epiphyseal plate; when growth stops, cartilage is replaced by bone creating feature known as the epiphyseal line

Cartilage

Reduces friction/absorbs shock at joints

Spongy Bone

Contains red marrow; found in hip bones, ribs, breast bones, vertebrae, and the ends of long bones; irregular, criss-crossing of thin columns of bone

Compact bone

Solid, dense bone, external layer of all bones of the body and the bulk of the body of long bones, provides protection/support/resistance to stress

Marrow cavity

Space within the diaphysis which contains fatty yellow marrow in adults

Periosteum

Tough sheath of dense irregular connective tissue; surrounds the bone surface, protects the bone, assists in fracture repair, helps nourish bone, servers as point of attachment for ligaments/tendons

Endosteum

Lines the surface of marrow cavity, contains bone forming cells that contribute to growth in width of the bone

Compound fracture

Ends of bones protruding through the skin (open)

Comminuted fracture

Bone splinters/fragments between the two main fragments; due to compression (simple; doesn’t penetrate the skin)

Greenstick fracture

Partial fracture; one side breaks and the other bends (occurs only in children whose bones are not fully ossified)

Spiral fracture

A bone breaks in half by a twisting force or impact

Transverse fracture

Breaks straight through the bone

Stress fracture

A very thin crack, also called a hairline fracture

First step in Fracture Repair

Fracture Hematoma: bleeding, brushing, blood clotting form around the fracture, creating pressure that temporarily stabilizes the fracture (several days to a few weeks)

Second Step in Fracture Repair

Soft Callus Formation: Osteoclast cells absorb fragments of bone while osteoblast cells form new spongy bone across fracture; blood vessels and soft tissue heal and grow throughout soft Callus to air formation (several weeks)

Third Step in Fracture Repair

Bony/Hard Callus Formation: Osteoblasts form compact bone around and through soft Callus; the bone is now functional and stabilized; the bony Callus is not in the shape of the original bone (several months)

Fourth Step in Fracture Repair

Bone Remodeling: Osteoclasts slowly absorb the bony Callus while Osteoblasts form new bone to match the original shape of the bone (years)

Fibrous (Immoveable) Joint

Bones held together by fibrous connective tissue rich in collagen; no synovial cavity; no movement (ex. sutures of skull, teeth in skull)

Cartilaginous (Semi-moveable joints)

Lack synovial cavity; little or no movement (ex. Vertebral disc to bone)

Synovial (fully moveable) Joints

Have a space called the synovial cavity between articulating bones; the bones freely move

Ligaments

Tough bands of connective tissue that attach bone to bone; stabilize joint

Tendons

Tough bands of connective tissue that connect muscle to bone

Synovial membrane

Lines joint cavity

Synovial fluid

Secreted by membrane; reduces friction, lubricates joint

Articular Capsule

Protects joint space

Joint cavity

Space between bones

Hinge (synovial)

Angular, open-closing motion on a single plan; ex. knee, elbow

Pivot (synovial)

“Peg in a hole”; allows rotation around a central axis ex. atlantoaxial join - allows head to move side to side on vertebrae

Planar (synovial)

2 opposed flat surfaces that glide over each other; side to side and back and forth gliding ex. articular facets of the vertebrae; intercarpal and intertarsal joints

Sprain

Twisting/wrenching of a joint that stretches or tears its ligaments but does not dislocate the bone - may damage blood vessels, muscles, tendons, and nerves, considerable swelling, pain, and bruising occurs

Displacement

Displacement of a bone from a joint with tearing of ligaments, tendons, and articular capsule; causes: intense pain, joint instability, reduced muscle strength, difficulty moving joint/stiffness

Subluxation

Partial dislocation; ex: vertebrae commonly undergo subluxation

Female Spread of Pelvis

More flared/ oval

Male Spread of Pelvis

More vertical/ less flared

Female Shape of Obturator Foramen

Wider/ triangular

Male Shape of Obturator Foramen

Larger/ Rounder

Female Angle across public symphysis

Greater than 90 degrees

Male Angle across pubic symphysis

Less than 90 degrees

Female inner diameter of pelvic inlet

Larger; room for baby’s head

Male inner diameter of pelvic inlet

Smaller

Male skull overall appearance

Larger, heavier appearance; pronounced muscle attachment points

Female skull overall appearance

Small, light appearance

Male eye orbit shape

Oval/smaller

Female eye orbit shape

Rounded/larger

Male brow ridge

Heavy/ pronounced; sloping forehead

Female brow ridge

Smooth/flat; vertical forehead

Male Chin

V-shaped / broad

Female Chin

V-shaped / narrow

Male Jawline Shape

Angular; 90 degrees

Female Jawline shape

Rounded, obtuse angle

Bone mass peaks

Third decade of life

Puberty

Estrogen and androgen hormones begin being secreted in larger quantities - causes growth spurt in height, widening of pelvis in females, skull exaggeration in males, cartilage in ossification centers at ends of long Bone finalizes conversion to bone

Old Age

Decreased collagen production leads to bones being more brittle, less flexible, reduction of weight bearing exercise, less activity causes bone loss, reduced production of specific hormones (estrogen) leads to bones loss

Osteoporosis

Condition of porous bones in later life - effects middle-aged and elderly people; 80% are women