Skeletal System No bones about it!!!

What does the skeletal system do? Support, Protection, Movement, Storage, Hemopoiesis

Types of bones in body Long (most bones of limbs (humerus, femur, fingers, toes except wrist, ankle, knee cap) - shaft is greater in length than width, mostly compact bone), short (carpals, tarsals-cube shaped, small layer of compact bone ), flat (skull, sternum or scapula-flat, thin, curved and generally 2 layers of compact bone sandwiching spongey bone) irregular (spine, pelvis) thin layers of compact bone surrounding a spongy interior Sesamoid bones are bones embedded in tendons. Since they act to hold the tendon further away from the joint, the angle of the tendon is increased and thus the leverage of the muscle is increased. Examples of sesamoid bones are the patella

Structure of long bone Diaphysis - shaft of long bone Medullary cavity - hollow tube Epiphyses - ends Articular cartilage - covering epiphysis

Microscopic structure of bone Two types of connective tissue - _________ & ________. Outer layer of bone is _______, _______ Porous bone on ends are _________ bone Needlelike threads of spongy bone surround a network of spaces called _____________. Bones, tendons dense, compact Spongy trabeculae

Matrix of Bone Osteon/Haversian System Concentric Lamella Osteocytes Lacunae Canaliculi Periosteum Osteons/haversian systems -structural unit of bone Concentric lamella - Calcified layers that surround central canal where blood vessels are found Bone cells - osteocytes Lacunae - hard layers where bone cells are found Canaliculi - tiny canals b/t lacunae and haversian system. Nutrients pass thru here. Periosteum - outer layer of bone

Internal Bone Structure Haversian System Osteon Concentric Lamellae

Bone Formation Osteoblasts - Osteoclasts - Combined efforts of ____________ & __________ sculpts bones into adult shapes Calcium salts - Osteoblasts - bone forming cells Osteoclasts - bone reabsorbing cells Combined efforts of cells sculpts bones into adult shapes Laying down of calcium salts is ongoing process for strength

Osteoblasts - bone forming cells Osteoclasts - bone reabsorbing cells

Echondral Ossification “Formed in cartilage” Cartilage in epiphyseal plate leads to growth Growth ceases when all epiphyseal cartilage is transformed to bone Growth plate determines growth in children to adult

Axial division of skeleton center axis of body Skull, ribs, vertebrae

Appendicular division of skeleton Upper and lower extremities Shoulder, arm, wrists, hands Hip girdle, legs, ankles, feet

Articulations (joints) 3 main types according to degree of movement Synarthroses (no movement) - cranial bones, commonly called “sutures”, fibrous tissue grows b/t holding close together Amphiarthroses (slight movement) - connected by cartilage, ex. Symphysis pubis where pubic bones connect Diarthroses (free movement) see next slides

Diathrotic types

Diathrotic types cont’d

Movement of joints Flexion - reduces angle of joint Extension - increases angle of joint Rotation - spins one bone relative to another Circumduction - moves distal end in a circle while keeping proximal end relatively stable Abduction - increase angle of joint to move away from midline Adduction - decrease angle of joint to move toward midline

Flexion & Extension

Rotation & Circumduction

ABduction & ADduction