SKELETAL SYSTEM Includes handout of the skull, vertebrae, and skeletal system to be labeled.

5 FUNCTIONS OF THE SKELETAL SYSTEM Framework Protection Storage site Hematopoiesis Movement Triglyceride storage

TWO TYPES OF BONE TISSUE Compact spongy

TWO SUBDIVISIONS OF THE SKELETAL SYSTEM Axial –Skull, vertebrae, ribs, and sternum Appendicular –Upper/lower limbs –Hands/feet –Pelvic/pectoral girdles

SKULL Composed of cranial and facial bones Cranial bones – protects brain, organs of hearing, and organs of equilibrium Facial bones – forms the framework of the face, protects eyes, and has opening for food air and organs of smell

TERMS Suture Fontanel's

FETAL SKELETON Fontanels – areas of hyaline cartilage Allow skull to be compressed as it passes through birth canal Allows for brain to grow during pregnancy and infancy Gradually convert to bone by 22 to 24 months

VERTEBRAL COLUMN Axial support of the body 26 irregular bones Flexible and curved Protects spinal cord Adult has 24 single bones ( 33 before birth)

PARTS OF THE VERTEBRAE

Cervical vertebrae Concave (called cervical curvature) 7 vertebrae – named C 1 – C 7 1 st – atlas – lets one nod “yes” –Contains depression for the occipital condyles of the skull 2 nd – axis – pivot point for atlas and skull –Lets one nod “no” C 3 – C 7 – typical shape

THORACIC VERTEBRAE Convex curvature 12 vertebrae T 1 – T 12 Spinous process is long and hooks downward 2 articulating surfaces ( costal facets) which receives the heads of the ribs

LUMBAR VERTEBRAE 5 vertebrae L 1 – L 5 Very sturdy Supports most of the stress of the vertebral column

SACRUM Composed of 5 fused vertebrae Articulates with L 5

COCCYX Humans tailbone Remnant of other animal’s tails

INTERVERTEBRAL DISCS Pads of fibrocartilage between each vertebrae absorbs shock cushions the vertebrae younger person - discs are about 90% water as we age, the water content decreases

S SHAPE OF THE COLUMN Prevents shock as we walk, run, and exercise primary curve - present when we are born. Found in the thoracic and sacral regions. Secondary curves - develop later –cervical - starts forming when a baby raises his head –lumbar - develops when baby begins to walk

JOINTS Place where 2 bones come together. If it is a joint where bones move, the joint must not allow the bones to rub against each other. Also called articulation

FUNCTIONS OF JOINTS Secure bones together. Allows rigid bones to move

TYPES OF JOINTS Immovable / synarthrosis Slightly movable / amphiarthrosis Freely movable / diarthrosis

IMMOVABLE JOINTS Ex. Sutures between the bones of the skull. Junction is completed with connective tissue. Edges overlap (interlock)

SLIGHTLY MOVABLE Ribs , allows for breathing. Vertebral column gives greater degree of movement. Held together by cartilage and/or ligaments. Which determine the degree of movement.

FULLY MOAVABLE Several types: hinge - elbow ball and socket - shoulder

BONE STRUCTURE

DIAPHYSIS Shaft composed of compact bone

PERIOSTEUM Fibrous connective tissue membrane that covers the diaphysis. Sharpey’s fibers secure it to the diaphysis. They are connective tissue.

EPIPHYSIS Ends of the long bones. Inside is spongy bone. Layer of compact bone on top of the spongy. Articular cartilage covers the ends of the epiphysis.

MEDULLARY CAVITY Yellow marrow - stores adipose red marrow - forms RBC’s –infants - found in long bones –adults - found in spongy bone, flat bones, and some long bones.

Epiphyseal plate - causes length wise growth of long bones. If damaged it can affect growth of the bone. Epiphyseal line - in adults marks where plate was.

OSTEOGENESIS Embryo’s skeleton is entirely cartilage Occurs 6 weeks after conception Ossification occurs Embryo’s cartilage serves as the template

PROCESS OF OSTEOGENESIS Cartilage template develops periosteum Inner surface of periosteum - cartilage cells change into osteoblasts Osteoblasts secrete Ca into collagen matrix Osteoclasts remove Ca from the collagen matrix to form a medullary cavity

Blood vessels grow in the cartilage model and into the cavity This causes more cartilage cells to become osteoblasts Site of primary ossification center Process works toward epiphysis

At epiphysis – site of secondary ossification center Same process occurs but spongy bone develops No medullary cavity appears By birth most hyaline cartilage has been converted to bone except for articular cartilage and epiphyseal plate

GROWTH New cartilage is formed on the external face of the articular cartilage and epiphyseal plate Old cartilage nearer the medullary cavity is broken down and replaced by bone Controlled by growth hormone and sex hormones Ends at puberty

EXERCISE AND BONE TISSUE Mechanical stress with strength bone and increase deposition of mineral salts and production of collagen fibers. Mechanical stress – main source is the pull of skeletal muscles and the pull of gravity

Hormone control Handout

TERMS TO DEFINE Bone scan Carpal tunnel syndrome Shin splints Osteoporosis Rickts Spina bifida Scoliosis Kyphosis Lordosis Rheumatoid arthritis