2Functions of Bone Supports and gives shape to the body Protects internal organsThe skull protects the brain; the breastbone and ribs protect the heart and lungs.Helps make movements possibleStores calciumHemopoiesisthe process of blood cell formation is carried on in the red bone marrow.What are the primary functions of bone? Bones form the body’s supporting framework. The hard structure of bones protect delicate structures enclosed within them. The skull protects the brain; the breastbone and ribs protect the heart and lungs.Muscles are anchored to bones. As muscles contract, they pull on bones and move them.What is the role of bone in maintaining homeostasis of blood calcium? Calcium storage: bones help maintain homeostasis of blood calcium, necessary for nerve and muscle function. Hemopoiesis: the process of blood cell formation is carried on in the red bone marrow.
3Types of Bones Long Short Flat Irregular example: humerus (upper arm) example: carpals (wrist)Flatexample: frontal (skull)Irregularexample: vertebrae (spinal cord)Ask students to name other examples of the four different types of bones.
4Structure of Long Bones Structural componentsDiaphysis or shaftMedullary cavity—hollow area inside diaphysis containing yellow marrowEpiphyses or ends of the bone—spongy bone contains red bone marrowDiaphysis – hollow tube made of hard, compact bone. Rigid, strong, yet light enough to permit easy movement.Yellow bone marrow – inactive, fatty form of marrow found in adult skeletons.Articular cartilage covers the ends of bones where they form a joint.
5Structure of Long Bones (cont’d.) Longitudinal section of a long boneDiscuss the significance of the epiphyseal line that divides the diaphysis from the epiphysis.
6Microscopic Structure of Bone and Cartilage Bone typesSpongyTexture results from needlelike threads of bone called trabeculae surrounded by a network of open spacesCompact (Dense)Structural units are called osteons or Haversian systemsWhat are the two major types of connective tissue? (bone and cartilage)What are the two types of bone?Describe osteocytes, canaliculi, lacunae.Why is the end of the bone spongy rather than dense?
7Microscopic Structure of Bone and Cartilage (cont’d.) Cell type called chondrocyteHas the flexibility of firm plasticMatrix is gel-like and lacks blood vesselsHas no blood vessels, so nutrients must diffuse through the matrix to reach cellsCartilage resembles bone in that it consists more of intercellular substance than of cells. In cartilage, the collagenous fibers that reinforce the matrix are embedded in a firm gel rather than the calcified cement substance in bone.Why does cartilage rebuild slowly after an injury? (because it lacks blood vessels)
8Microscopic Structure of Bone and Cartilage (cont’d.) Discuss the construction of the shell of the bone.
9Bone Formation and Growth The process of “remodeling”A newborn’s skeleton has many bones that have not completely ossifiedCartilage models replaced by calcified bone matrixOsteoblasts form new boneOsteoclasts resorb boneAs long as the epiphyseal plate remains between epiphyses and diaphysis, growth continuesEpiphyseal line marks where two centers of ossification have fused togetherWhat is the process of “remodeling” a bone? (“Remodeling” a growing bone as it changes from a small cartilage model to an adult bone requires continuous activity by osteoblasts.)What is responsible for “sculpting” bones? (The process of “sculpting” by osteoblasts and osteoclasts allows bones to respond to stress and injury by changing size, shape, and density.)
10Bone Formation and Growth (cont’d.) Endochondral ossificationEndochondral ossification is the process of forming bones from cartilage models.
12Divisions of Skeleton Skeleton: two divisions and their subdivisions Axial skeletonSkullSpineThoraxHyoid boneAppendicular skeletonUpper extremities, including shoulder girdleLower extremities, including hip girdleAsk the students to identify the various parts of the axial skeleton and the appendicular skeleton.
13Divisions of Skeleton (cont’d.) Axial SkeletonSkullSpine (Vertebral Column)Consists of a series of separate bones called vertebraeSections called: cervical, thoracic, lumbar, sacrum, coccyxCurves of the spine give strength to support bodyHow many bones form the face? The skull consists of eight bones that form the cranium, 14 bones that form the face, and six bones in the middle ear. The two parietal bones that give shape to the topside of the skull form immovable joints, called sutures, with several bones: the lambdoidal suture with the occipital bone; the squamous suture with the temporal bone; and the coronal suture with the frontal bone.
14Divisions of Skeleton (cont’d.) The skullAsk the students to identify the bones and sutures of the skull.
15Divisions of Skeleton (cont’d.) The spinal columnThe vertebral column consists of separate bones connected in a way that forms a flexible curved rod.Point out the cervical region, thoracic region, lumbar region, sacrum, and coccyx.Discuss the physiologic reasons for the four curves of the spine.
16Divisions of Skeleton (cont’d.) Axial SkeletonThoraxFormed by:12 pairs of ribsThe sternum (breastbone)Thoracic vertebraeWhat is another name for the breastbone? (sternum)What is the difference between “true ribs” and “false ribs”?(The first seven pairs of ribs are called true ribs and are attached to the sternum.The eighth, ninth, and tenth ribs are attached to the cartilage of the seventh pair of ribs; they are called false ribs.The last two pairs of ribs are not attached to costal cartilage; they are called floating cartilage.)
17Divisions of Skeleton (cont’d.) Bones of the thorax
18Divisions of Skeleton (cont’d.) Appendicular SkeletonUpper ExtremityFormed by:Scapula (shoulder blade)Clavicle (collarbone)Attached by sternoclavicular jointHumerusRadius and ulnaWrist and hands—27 bones in allIn what part of the body is the humerus?( Humerus is attached to the scapula at its proximal end and articulates with the two bones of the forearm at the elbow joint.)In what part of the body are the radius and ulna? (Bones of the forearm are the radius and ulna.)Why is the anatomy of the elbow a good example of how structure is related to function? (Bony process of the ulna, called olecranon process, fits into the olecranon fossa and makes movement possible.)
19Divisions of Skeleton (cont’d.) Bones of the arm, elbow joint, and forearm
20Divisions of Skeleton (cont’d.) Appendicular SkeletonLower ExtremityTwo coxal (pelvic) bonesFemur; longest bone in the bodyArticulates proximally with coxal bone in socket called the acetabulumPatella (kneecap)Tibia (shinbone)Fibula (slender bone in the lower leg)Phalanges, composed of metatarsals and tarsalsCoxal bone in infant consists of three separate bones: ilium, ischium, and pubis.The bones of the foot are comparable to the bones of the hand. Each foot contains five metatarsals (each hand contains five metacarpal bones) and seven tarsals (compared to the hand’s eight carpals).What is the name of the heel bone? (calcaneus)
21Divisions of Skeleton (cont’d.) Bones of the thigh, knee joint, and leg
22Divisions of Skeleton (cont’d.) Bones of the right footCompare the names of the foot bones with the names of the hand bones.
23Differences Between a Man’s and a Woman’s Skeleton Size—male skeleton generally largerShape of pelvis—male pelvis deep and narrow, female pelvis broad and shallowSize of pelvic inlet—female pelvic inlet generally wider, normally large enough for baby’s head to pass through itPubic angle—angle between pubic bones of female generally widerWhat are the primary differences between a male and female skeleton? (In general, the female pelvis can accommodate the body of a fetus before birth and allow it to pass through it during birth. Male hipbones are generally larger and narrower than the female’s.)
24Differences Between a Man’s and a Woman’s Skeleton (cont’d.) Comparison of the male and female pelvisNotice the narrower width of the male pelvis, giving it a more funnel-like shape than the female pelvis.
25Joints (Articulations) Kinds of jointsSynarthrosis (no movement)Fibrous connective tissue grows between articulating bonesExample: sutures of skullAmphiarthrosis (slight movement)Cartilage connects articulating bonesExample: symphysis pubisEvery bone in the body, except for one, connects to at least one other bone. What is the exception? (The hyoid bone in the neck, to which the tongue anchors.)In general, what functions do bone joints serve? (Joints hold the bones together securely and at the same time make it possible for movement to occur between the bones.)What are three classifications of joints?(Synarthroses are joints in which fibrous connective tissue grows between the articulating bones, holding them close together. The joints between cranial bones are synarthroses. Amphiarthroses are joints in which cartilage connects the articulating bones. The joints between the bodies of the vertebrae are amphiarthroses. The joints make it possible to flex forward, sideways, and to rotate.)
26Joints (Articulations) (cont’d.) Diarthrosis (free movement)—most joints belong to this classStructures of freely movable joints—joint capsule and ligaments hold adjoining bones together but permit movement at jointArticular cartilage—covers joint ends of bones and absorbs joltsSynovial membrane—lines joint capsule and secretes lubricating fluidJoint cavity—space between joint ends of bonesDiarthroses allow considerable movement; sometimes in many directions and sometimes in only one direction.What are the types of freely movable joints? (ball-and-socket, hinge, pivot, saddle, gliding, and condyloid)
27Joints (Articulations) (cont’d.) Joints of the Skeleton
28Joints (Articulations) (cont’d.) Types of diarthrotic jointsBall-and-socket joints (shoulder and hip) permit the widest range of movement.Hinge joints (elbow) allow movement in only two directions: flexion and extension.Pivot joints (neck) allow rotation.Saddle joints (between thumb and wrist) allow great mobility.Gliding joints (between vertebrae) allow limited gliding movements.Condyloid joints fit into an elliptical socket (distal end of radius fits into depressions in carpal bones)