The Skeletal System Mr. Abercrombie Anatomy & Physiology Strategy to learn the bones There are 206 bones in the body You will learn many of their names See table 7.3 for a breakdown of how many are found where Brief lectures each day then spend most of class drawing, learning, and constructing a full-size skeleton. Each day will wrap up with a short quiz Functions of Skeleton 1. Support- framework that supports body & cradles organs 2. Protection- skull, vertebra, thorax 3. Movement- levers used by muscles for movement 4. Mineral storage - Ca Blood Cell Formation Skeletal Components Bone tissue Cartilage Ligaments Bones of the Human Body Composed of 206 bones Two types of osseous (bone) tissue: Compactsmooth looking and homogeneous Spongysmall needle-like pieces of bone and open space Structure determined by function Unique size and shape of each bone many different functions 4 types of bones: Long, short, flat, and irregular Sesamoid bones or round bones e.g. kneecap Long Bones Longer than they are wide Made of shafts with two heads at each end Shafts are mostly compact bone Found in the limbs (arms and legs) Anatomy of a Long Bone Epiphysisends of the long bone which form a joint with another. Proximal epiphysis near torso Distal epiphysis farthest from torso Articular cartilage hyaline cartilage that covers the epiphyses decreases friction in joint Anatomy of a Long Bone Diaphysisshaft makes up most of length Periosteum fibrous connective tissue that covers and protects the diaphysis (helps heal breaks) Notice the epiphyseal line which is found in adult bones remnant of epiphyseal plate in a growing bone (growth plate) Endosteumthin membrane of bone- forming cells Medullary cavity hollow chamber filled with marrow two types: yellow (adipose tissue) and redforms red blood cells (found here only in infants) Here you can see the difference between spongy bone and compact bone and the location of each in a long bone. Bumps and ridges may indicate where bones are attached to ligaments Holes exist where blood vessels and nerves pass 15 Parts of a Long Bone epiphysis distal proximal diaphysis compact bone spongy bone articular cartilage periosteum endosteum medullary cavity marrow red yellow Microscopic Anatomy Compact bone has passageways carrying nerves, blood vessels that bring in nutrients and take away wastes. Mature bone cells osteocytesfound in cavities in compact bone tissue Introduction to bone biology video This intricate system of vessels: Means bone cells are well nourished Allows bone to heal rapidly Calcium salts deposited in matrix give bones strength Lightweight design withstands lots of stress Bone Formation and Growth Skeleton of embryo is hyaline cartilage Through time, cartilage is replaced by bone almost entirely = ossification Ossification (bone formation) Hyaline cartilage is the model Becomes covered by bone- forming cells called osteoblasts (cartilage bones become encased by bony bones in fetuses for a short time) Ossification continued Enclosed hyaline cartilage model is digested away Opens up the medullary cavity within the newly formed bone By birth, most hyaline cartilage has been converted to bone except for epyphyseal plates and articular cartilage Bones grow wider too! Appositional growth bone expands and widens Osteoblasts in periosteum add bone tissue to the outside, osteoclasts in endosteum remove bone from inner surface Long bone growth control By hormones: Growth hormone During puberty, by sex hormones Ends during adolescence when epiphyseal plates are converted to bone. So, are bones lifeless structures? NO! Dynamic and active tissue Remodeled continuously in response to two things: Calcium levels in the blood Pull of gravity and muscles (=Wolffs Law) Response to calcium levels If calcium levels are low, osteoclasts (giant, bone-destroying cells in bones) break down bone matrix to release calcium into bloodstream (= i.e Osteoporosis) When high, calcium deposited into bone matrix as hard calcium salts Constant remodeling of bone Lifelong Process of Remodeling Usually progresses at a normal, balanced rate Can be problems Osteoporosis 30 Factors Affecting Bone Development, Growth, and Repair Deficiency of Vitamin A retards bone development Deficiency of Vitamin C results in fragile bones Deficiency of Vitamin D rickets Insufficient Growth Hormone dwarfism Excessive Growth Hormone gigantism Insufficient Thyroid Hormone delays growth Sex Hormones promote bone formation; stimulate ossification of epiphyseal plates Physical Stress stimulates bone growth Assignment Read pages Compare and contrast intramembranous and endochondral ossification in your own words Describe the growth of the epiphyseal plate and what happens to this structure when the bone stops growing Draw a diagram that illustrates the major internal/external features of a long bone Bellringer Warm up Read Clinical Application 7.1 (pgs ) List and describe the 6 types of fractures. List the steps of fracture repair List three factors that affect rate of fracture repair. Bone Fractures You do not have to memorize the names of the many different types of fractures. You will be responsible for the stages of the healing process. Stages in healing a fracture Considerable bleeding at site of fractures Blood collects between bone fragments and under periosteum Stages of healing of a fracture In a few days a blood clot (hematoma) forms. Soon the clot is invaded by osteoblasts from the nearby bone and from the periosteum. Stages of healing The osteoblasts lay down new bone which fills the gap between the fragments and bulges out at the sides. This is the callus. Final stage of healing Over a period of many months the callus is absorbed, and new bone is made exactly like the original one. 38 Skeletal Organization Axial Skeleton head neck trunk Appendicular Skeleton upper limbs lower limbs pectoral girdle pelvic girdle Bones of the Skull Cranium Frontal, parietal, occipital, temporal, sphenoid, ethmoid Facial Maxillary bones, palatine, zygomatic, lacrimal, nasal, vomer, inferior nasal conchae, mandible Hyoid bone supports tongue The bones of skull are firmly interlocked along sutures Sphenoid bone Ethmoid bone Perpendicul ar plate of ethmoid bone Vomer bone Inferior nasal concha Ethmoid bone Mandible Vertebral Column Extends from skull to pelvis Protects the spinal cord Irregular bones Adult: 26 vertebrae #s of Vertebrae Cervicalneck7 Thoracicarticulate with ribs12 Lumbarsmall of back5 Sacrumtriangle of 5 fused vert. Coccyx--tailbone-4 fused vertebrae Atlas 1 st cervical vertebra unique because lacks a body Arch of atlas Axis second cervical vertebra Hyoid bone attaches to tongue Scoliosis Scoliosis treatment Thoracic Cage Ribs and sternum 7 True ribs attach to sternum via cartilage False ribs dont attach in front Sternum protects heart and lungs Pectoral Girdle Supports the upper limbs and serves as an attachment for the muscles that move them 2 clavicles and 2 scapulae Considered a part of the appendicular skeleton Pectoral girdle Upper Limb Humeruslong bone from scapula to elbow Two smooth rounded processes on shoulder end for attachment of muscles Upper Limb continued Radiusthumb side of forearm Ulnapinkie side of forearm longer than the radius overlaps the end of the humerus at the proximal end Wrist and handcarpal bones, metacarpals, and phalanges X-ray of this arm shows a break in both the ulna and the radius Pelvic girdle 2 coxae (hip bones) which articulate with each other anterially and with the sacrum posterially Forms the pelvis which supports the lower limbs and protects the urinary and reproductive organs Lower Limbs Femurlarge bone in thigh, longest bone in body Distal end has two rounded processes that articulate with the tibia Patellakneecapflat bone Below the knee Tibiashin bonelarger of the two leg bondslocated on medial side Fibulalong, slender bone located laterally to the tibia It fibs to make you think it is the larger bone (longer name) Ankle and foot Talus moves freely where it joins the tibia and fibula Tarsal bones make up the upper part of the foot near ankle Metatarsalsbetween toes and tarsals Phalangestoe bones 67 Skeletal Organization Bone Fractures Two types: Simplebone breaks cleanly but does not penetrate skin Compoundbroken bone ends penetrate the skin