Skeletal System Ch 3Structures

Skeletal system is the bony framework of the body

206 bones in an adult Functions

◦ Support of the body and shape & structure◦ Protection of the vital organs◦ Movement & anchorage of the muscles (levers for

muscular action)⚫Tendons – attach muscle to bone⚫Ligaments – attach bone to bone

◦ Mineral storage – calcium and phosphorus◦ Blood cell formation - hematopoiesis

Introduction

Collagen – a chief organic constituent (protein)

Inorganic calcium salts (Vit D is essential for the absorption of minerals, i.e. calcium)

Bone Composition

Cells◦ Osteoblasts-bone building, bone-repairing cells in

the periosteum◦ Osteocytes-mature bone cells within the bone

matrix◦ Osteoclast-causes the reabsorption of bone

Periosteum◦ A dense, fibrous membrane covering bone◦ Contains blood vessels◦ Essential for bone cell survival and bone

formation

Bone Composition

Grow in length at the epiphyseal line Grow in width by the addition of bone to the

surface Controlled by the anterior pituitary (growth

hormone)◦ Dwarfism-hypofunction◦ Gigantism-hyperfunction◦ Acromegaly-hyperfunction after puberty; enlarges

bones of the hands, feet, and face

Bone Growth

Bone Structures

Epiphyseal plate◦ Growth plate, found towards ends of bones

Diaphysis◦ The long shaft, major part of the bone

Condyle◦ A rounded, knuckle-like prominence usually at a point

of articulation Foramen

◦ Opening in bone through which blood vessels, nerves, and ligaments pass

Tubercles◦ A small, rounded process

Landmarks

Bone marrow◦ Red marrow

⚫hematopoietic tissue⚫Forms red blood cells, platelets, some white blood

cells, destroys old RBCs and some foreign materials◦ Yellow marrow

⚫Fat storage

Bone tissues

Pg 39

Axial◦ Central bones along your center axis◦ Protects the major organs of the nervous,

respiratory, and circulatory systems Appendicular

◦ Appendages◦ Extremities◦ Protects the organs of digestion, excretion, and

reproduction

Skeletal descriptive divisions

Skull◦ Cranium-major bones

⚫Frontal⚫Parietal-Right & Left⚫Temporal-Right & Left⚫Occipital

◦ Fontanelles-fusion of the cranial bones is not complete at birth so babies have a “soft spot”

◦ Facial

Axial skeleton-80 bones

Thoracic ◦ Ribs◦ Sternum

Spinal column-26 bones separated by intervertebral disks to cushion◦ Cervical-7, smallest vertebrae◦ Thoracic-12, progressively increase in size◦ Lumbar-5, largest and strongest◦ Sacral-five fused bones with the pelvis◦ Coccyx-3-4 fused bones, tailbone, slightly

movable to assist in childbirth

Axial skeleton

Sternum◦ Manubrium-top part◦ Body ◦ Xiphoid process-end tip

Ribs Shoulder girdle

◦ Clavicles (2)-the collarbones◦ Scapulas (2)-the shoulder blades

Appendicular skeleton-126 bones

Upper extremities◦ Humerus-upper arm◦ Radius-thumb side of forearm◦ Ulna-little finger side of forearm◦ Carpals (8)-wrist bones◦ Metacarpals (5)-hand bones◦ Phalanges (14)-finger bones

Appendicular skeleton

Pelvic Girdle◦ Os coxae (2)-contains the acetabulum (hip socket)

⚫Ilium⚫Ischium⚫Pubis

◦ Sacrum

Appendicular skeleton

Lower Extremities◦ Femur-thigh bone◦ Patella-kneecap◦ Tibia-shin bone◦ Fibula-lateral bone of the lower leg◦ Tarsals (7)-ankle bones

⚫Talus⚫calcaneus

◦ Metatarsals (5)-foot bones◦ Phalanges (14)-toe bones

Appendicular skeleton

Joints Synarthrotic-immovable

joints◦ Sutures in skull◦ Pg 39

amphiarthrotic-flexible, but not movable◦ Symphysis pubis◦ Pg 46

Diarthrotic-freely movable◦ Synovial-movable joints of

the body

Ligaments-band of fibrous connective tissue that connects one bone to another

Bursa-a fibrous sac that contains synovial fluid

Synovial fluid-a lubricant to make smooth movement of the joint possible

Joints