“ The purpose of education is to replace an empty mind with an open one.” -Malcolm S. Forbes

The Skeletal System

 __________________________________________  It provides a framework for the body and gives it shape.  It supports and protects organs from injury.  _______________________________________  It provides a place for muscles, tendons, ligaments and tendons of the body to attach.  It helps make movement possible.  ____________________________  It stores minerals (Calcium)  _______________________________  It provides a place for hematopoeisis

 Two main types of bone:  _________________________ Bone  Light and spongy inner layer of bone.  Consists of tiny spicules with bone marrow between.  _________________________ Bone  Heavy and dense outer layer of all bones  Composed of haversian systems (small units of bone tissue)

 3 types of bone cells.  ____________________- cells that secrete the matrix of bone  ____________________- cells that have been trapped in the matrix they have created  _____________________- cells that remodel bone by eating it away from places it is not needed.  ______________________- covering of bone  ______________________- membrane that lines the hollow interior surface of bones.

 Osteoblasts  Cells that form bone.  Osteocytes  Osteoblasts that are no longer active & trapped inside matrix of osseous material.  Can revert back to osteoblasts  Osteoclasts  Eat bone away.  Are the remodelers of bone  Withdraw calcium when needed from bone

Haversian Systems  Concentric layers of ossified bone matrix arranged around a central Haversian canal

 Tiny vessels penetrate the periosteum.  _________________________- tiny channels in the bone matrix that vessels pass through.  Are at right angles to Haversian canals  _________________________- Where large vessels enter the bone.  Carry blood into and out of bone marrow.  Can be mistaken for fracture on radiographs.

NUTRIENT FORAMINA

DIAPHYSIS – the shaft of long bones EPIPHYSIS – the ends of long bones

 Bone is formed in 2 ways:  ____________________________  Bone formation and growth is stimulated by ____________________(GH) from the anterior pituitary (adenohypophysis) gland in the brain.

 Endochondral Bone formation  Cartilage to bone formation  How most bones develop  Starts in the ______________________ - ________________ in the diaphysis (shaft) of long bones are gradually replaced by bone.  There are ________________ that develop in epiphysis (ends) of bones

 Located between ________________and ___________________  Sites of creation of new bone that allows bone to lengthen as animal grows.  Cartilage is created on epiphyseal side while bone is created on diaphyseal side.  When bone reaches full length, all cartilage is replaced by bone and plates “close”.  Remodeling may take place but bone will not get any longer.  Young animals may have epiphyseal fractures because this area is weaker than rest of bone.

 Occurs only in _____________________bones  Bone forms directly from _____________ with no cartilage intermediary.

 Long Bones  Short Bones  Flat Bones  Irregular Bones

 Longer than they are wide.  The ends of the bones are called _________________________  There is both a _________ epiphysis and a _____________ epiphysis  Main part of bone is the shaft or _______________ which is composed of compact bone.  EXAMPLES: _______________________________ ______________________________

 Shaped like cubes.  Have core of _________________bone covered by _____________________ bone.  EXAMPLES: _____________________________

 Thin and flat bones  Consists of two layers of ______________ bone separated by _________________bone.  EXAMPLES: __________________________________________ __________________

 Miscellaneous bones that do not fit into another category.  May have characteristics of more than one category.  EXAMPLES:_________ ____________________ ___________  _____________ - is largest sesamoid bone in body.

 Fills the spaces within center of bones  Has two types:  _______________ bone marrow  ________________________- the process of forming new blood cells.  Majority of bone marrow in young animals but less in older animals  __________________ bone marrow  Consists primarily of __________________ connective tissue.  Common type of marrow in adult animals  Does not produce blood cells but can revert to red marrow if needed.

 ___________________________  Joint surfaces where bones come in contact with each other to form joints.  Consists of:  Condyles  Head  Facet  Covered by articular cartilage  Composed of what type of cartilage?

 Large, round articular surface.  Major condyle is located on end of humerus and femur.  Also located in skull.

 Somewhat spherical articular surface on the proximal end of a long bone.  Found on humerus, femur and rib.  Head is usually joined with rest of bone by a neck.

 Head of femur is removed in cases of trauma or severe arthritis.  A “false joint” forms which gives more comfort to the patient.

 A flat articular surface.  Found in carpal and tarsal bones as well as in vertebrae, radius and ulna.

 All projections of a bone.  Heads and condyles are considered to be processes.  Tendons may attach to processes

 __________________: A hole in bone.  Usually allow the passage of nerve or blood vessel.  May exist simply to lighten structure  Example: pelvis has the ____________________  ______________: A depressed or sunken area on the surface of a bone.  Usually occupied by muscles or tendons.

 Bones of head and trunk are _______________________________Skeleton  Bones of limbs and appendages are ____________________________ Skeleton.  Some animals may have __________________- bones formed in the viscera or soft organs.

Axial Skeleton: bones of head & trunk  Skull  Hyoid bone  Spinal column  Ribs  Sternum

Skull  Usually consists of 37 or 38 separate bones  Most skull bones joined by _________________  Mandible is connected to skull by a ______________(TMJ)

Skull External bones :  Frontal bones (2)  Occipital bones (1)  Parietal bones (2)  Temporal bones (2)  Incisive (2 )  Nasal (2)  Maxillary (2)  Zygomatic (2)  Mandible (2)  Palatine (2)  Turbinates (2)

 Categorized by:  Bones of Cranium  Bones of the ear  Bones of the face

 Cranium-portion of skull that surrounds the brain.  External Bones of Cranium:  Frontal Bones (2)  Interparietal Bones (2)  Occipital Bone (1)  Parietal Bones (2)  Temporal Bones (2)  Internal Bones of Cranium:  Ethmoid Bone (1)  Sphenoid Bone (1)

 Forms caudoventral portion or base of skull, most caudal skull bone.  Important because:  Where spinal cord exits skull  Skull bone that articulates with first cervical (neck) vertebrae.  ______________________is in center of occipital bone.  Occipital Condyles are on either side of foramen magnum

 Small bones located on dorsal midline between occipital and parietal bones  Clearly visible in young animals, may fuse together in older animals.

 Form the lateral walls of the cranium  Well developed in dogs, cats and humans, but relatively small in horses and cattle.

 Located ventral to the Parietal bones  Form walls of the cranium  Contain middle and inner ear structures  Form ________________________(TMJ’s) with the mandible (Lower jaw)