FITB Skeletal Notes PDF

PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College CHAPTER...

PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College CHAPTER 6 Bones and Skeletal Tissues: Part A © Annie Leibovitz/Contact Press Images © 2013 Pearson Education, Inc.  Skull Geography Cranial sutures Cranial fossa Cranial cavity Middle and internal ear cavities Nasal cavity Orbits 85 named openings – Foramina, canals, fissures © 2013 Pearson Education, Inc.  Figure 7.3 Major cavities of the skull, frontal section. Frontal Cranial cavity bone Frontal Zygomatic sinus Orbit Orbit bone Ethmoidal Ethmoid air cells bone Maxillary Inferior sinus nasal concha Nasal cavity Maxilla Oral cavity Vomer Mandible © 2013 Pearson Education, Inc.  Figure 7.4 Anatomy of the anterior and posterior aspects of the skull. Frontal bone Parietal bone Supraorbital foramen (notch) Nasal bone Sphenoid bone Temporal bone Optic canal Ethmoid bone Lacrimal bone Zygomatic bone Infraorbital foramen Middle nasal concha Ethmoid bone Maxilla Inferior nasal concha Vomer Mandible Mental Sagittal suture foramen Sutural Parietal bone Mandibular bone symphysis Anterior view Lambdoid suture Occipital bone Mastoid process Occipitomastoid suture Occipital condyle © 2013 Pearson Education, Inc. Posterior view  Figure 7.5a Bones of the lateral aspect of the skull, external and internal views. Coronal suture Frontal bone Sphenoid bone Parietal bone Ethmoid bone Temporal bone Lacrimal bone Lambdoid Lacrimal fossa suture Squamous suture Occipital Nasal bone bone Zygomatic Zygomatic bone process Occipitomastoid Maxilla suture External acoustic meatus Mastoid process Styloid process Condylar process Mandible Mental foramen Mandibular ramus External anatomy of the right side of the skull © 2013 Pearson Education, Inc.  Figure 7.6a Inferior aspect of the skull, mandible removed. Maxilla Intermaxillary suture Hard Median palatine suture palate Palatine bone Maxilla Zygomatic bone Sphenoid bone Temporal bone (zygomatic process) Foramen ovale Vomer Foramen spinosum Foramen lacerum Mandibular Carotid canal fossa External acoustic meatus Styloid process Stylomastoid Mastoid process foramen Jugular foramen Temporal bone Occipital condyle Parietal bone Occipital bone Foramen magnum Inferior view of the skull (mandible removed) © 2013 Pearson Education, Inc.  Figure 7.14a Paranasal sinuses. Frontal sinus Ethmoidal air cells (sinus) Sphenoidal sinus Maxillary sinus Anterior aspect © 2013 Pearson Education, Inc.  Figure 7.14b Paranasal sinuses. Frontal sinus Ethmoidal air cells Sphenoidal sinus Maxillary sinus Medial aspect © 2013 Pearson Education, Inc.  Developmental Aspects: Fetal Skull Infant skull has more bones than adult skull – Skull bones such as mandible and frontal bones are unfused – Skull bones connected by fontanelles Unossified remnants of fibrous membranes Ease birth and allow brain growth Four fontanelles – Anterior, posterior, mastoid, and sphenoidal © 2013 Pearson Education, Inc.  Figure 7.36a–b Skull of a newborn. Frontal suture Frontal bone Anterior fontanelle Ossification center Parietal bone Posterior fontanelle Occipital bone Superior view Frontal bone Sphenoidal Parietal bone fontanelle Ossification center Posterior fontanelle Mastoid fontanelle Occipital bone Temporal bone (squamous portion) Lateral view © 2013 Pearson Education, Inc.  Developmental Aspects: Growth Rates At birth, cranium huge relative to face At 9 months, cranium is ½ adult size Mandible and maxilla are foreshortened but lengthen with age Arms and legs grow at faster rate than head and trunk, leading to adult proportions © 2013 Pearson Education, Inc.  Figure 7.39a Different growth rates of body parts determine body proportions. Human newborn Human adult © 2013 Pearson Education, Inc.  Vertebral Column Transmits weight of trunk to lower limbs Surrounds and protects spinal cord Flexible curved structure containing 26 irregular bones (vertebrae) in five major regions – Cervical vertebrae (7)—vertebrae of neck – Thoracic vertebrae (12)—vertebrae of thoracic cage – Lumbar vertebrae (5)—vertebrae of lower back – Sacrum—bone inferior to lumbar vertebrae – Coccyx—terminus of vertebral column © 2013 Pearson Education, Inc.  Figure 7.16 The vertebral column. C1 2 3 Cervical curvature (concave) 4 7 vertebrae, C1 – C7 5 6 7 T1 Spinous 2 process 3 Transverse 4 processes 5 Thoracic curvature 6 (convex) 7 12 vertebrae, T1 – T12 8 9 Intervertebral discs 10 11 Intervertebral foramen 12 L1 2 Lumbar curvature 3 (concave) 5 vertebrae, L1 – L5 4 5 Sacral curvature (convex) 5 fused vertebrae sacrum Coccyx 4 fused vertebrae Anterior view Right lateral view © 2013 Pearson Education, Inc.  Vertebral Column: Curvatures Increase resilience and flexibility of spine – Cervical and lumbar curvatures Concave posteriorly – Thoracic and sacral curvatures Convex posteriorly Abnormal spine curvatures – Scoliosis - abnormal lateral curve – Kyphosis (hunchback) – exaggerated thoracic curvature – Lordosis (swayback) – accentuated lumbar curvature © 2013 Pearson Education, Inc.  Figure 7.17 Abnormal spinal curvatures. Scoliosis Kyphosis Lordosis © 2013 Pearson Education, Inc.  Figure 7.39b Different growth rates of body parts determine body proportions. Newborn 2 yrs 5 yrs 15 yrs Adult © 2013 Pearson Education, Inc.  Developmental Aspects: Spinal Curvature Primary thoracic and sacral curvatures obvious at birth – Give spine a C shape – Convex posteriorly © 2013 Pearson Education, Inc. The C-shaped spine of a newborn infant. Developmental Aspects: Spinal Curvature Secondary curvatures – Cervical and lumbar—convex anteriorly – Appear as child develops (e.g., lifts head, learns to walk)  Figure 7.19 Typical vertebral structures. Posterior Spinous process Transverse process Superior Vertebral arch articular facet and Lamina process Pedicle Vertebral foramen Body (centrum) Anterior © 2013 Pearson Education, Inc.  Figure 7.20a–b The first and second cervical vertebrae. C1 Posterior Posterior Posterior Posterior tubercle Posterior tubercle arch Inferior Posterior articular Transverse arch facet process Transverse Lateral Lateral foramen masses masses Superior articular Transverse Anterior arch facet foramen Anterior arch Anterior tubercle Facet for dens Anterior tubercle Superior view of atlas (C1) Inferior view of atlas (C1) © 2013 Pearson Education, Inc.  Figure 7.20c The first and second cervical vertebrae. Posterior C2 Spinous process Inferior Lamina articular process Pedicle Superior Transverse articular process facet Dens Body Superior view of axis (C2) © 2013 Pearson Education, Inc.  Table 7.2 Regional Characteristics of Cervical © 2013 Pearson Education, Inc.  Table 7.2 Regional Characteristics of Thoracic © 2013 Pearson Education, Inc.  Table 7.2 Regional Characteristics of Vertebrae © 2013 Pearson Education, Inc.  Figure 7.22a The sacrum and coccyx. Sacral promontory Ala Body of first sacral vertebra Transverse ridges (sites of vertebral fusion) Anterior sacral Apex foramina Coccyx Anterior view © 2013 Pearson Education, Inc.  Figure 7.22b The sacrum and coccyx. Facet of Body superior Sacral Ala canal articular process Auricular surface Median Lateral sacral sacral crest crest Posterior sacral foramina Sacral hiatus Coccyx Posterior view © 2013 Pearson Education, Inc.  Figure 7.23a The thoracic cage. Jugular notch Clavicular notch Manubrium Sternal angle Body Xiphisternal Sternum True ribs joint (1–7) Xiphoid process False ribs (8–12) Intercostal spaces L1 Costal cartilage Floating ribs Vertebra (11, 12) Costal margin Skeleton of the thoracic cage, anterior view © 2013 Pearson Education, Inc.  Figure 7.25a The pectoral girdle and clavicle. Acromio- clavicular joint Clavicle Scapula © 2013 Pearson Education, Inc. Articulated pectoral girdle  The Upper Limb 30 bones form skeletal framework of each upper limb – Arm Humerus – Forearm Radius and ulna – Hand 8 carpal bones in the wrist 5 metacarpal bones in the palm 14 phalanges in the fingers © 2013 Pearson Education, Inc.  Hand: Metacarpus and Phalanges Metacarpus (Palm) – Five metacarpal bones (I to V from thumb to little finger) form the palm Phalanges (Fingers) – Fingers numbered I to V starting at thumb (pollex) – Digit I (Pollex) has 2 bones - no middle phalanx – Digits II to V have 3 bones—distal, middle, and proximal phalanx © 2013 Pearson Education, Inc.  Figure 7.29 Bones of the right hand. Phalanges Distal Middle Proximal Metacarpals Head Sesamoid Shaft bones Base Carpals III II Hamate V IV I Carpals II III IV V I Carpals Capitate Trapezium Trapezoid Hamate Pisiform Triquetrum Scaphoid Capitate Lunate Triquetrum Lunate Ulna Radius Ulna Anterior view of right hand Posterior view of right hand © 2013 Pearson Education, Inc.  Figure 7.30 Pelvis. © 2013 Pearson Education, Inc.  Table 7.4 Comparison of the Male and Female Pelves (1 of 3) © 2013 Pearson Education, Inc.  Figure 7.32a–b Bones of the right knee and thigh. Neck Fovea capitis Greater trochanter Head Inter- Lesser trochanter trochanteric crest Intertrochanteric line Gluteal tuberosity Apex Linea aspera Anterior Facet for lateral condyle of femur Facet for Medial and lateral supra- Lateral medial condylar lines condyle condyle of femur Popliteal surface Lateral Surface for Intercondylar fossa epicondyle patellar ligament Posterior Medial condyle Patella (kneecap) Lateral Adductor epicondyle tubercle Medial Patellar epicondyle surface Anterior view Posterior view Femur (thigh bone) © 2013 Pearson Education, Inc.  Figure 7.33a The tibia and fibula of the right leg. Intercondylar eminence Lateral condyle Medial condyle Head Tibial Superior tuberosity tibiofibular joint Interosseous membrane Anterior border Fibula Tibia Inferior tibiofibular Medial joint malleolus Lateral malleolus Inferior articular surface Anterior view © 2013 Pearson Education, Inc.  Figure 7.34a Bones of the right foot. Phalanges Distal Middle Proximal I II III Metatarsals Medial IV cuneiform V Intermediate Lateral cuneiform cuneiform Navicular Cuboid Tarsals Talus Trochlea of talus Calcaneus Superior view © 2013 Pearson Education, Inc.  Figure 7.34b Bones of the right foot. Talus Medial malleolar Intermediate Navicular facet cuneiform Sustentac- ulum tali First metatarsal (talar shelf) Medial Calcaneus cuneiform Calcaneal Medial view tuberosity © 2013 Pearson Education, Inc.  Figure 7.34c Bones of the right foot. Lateral Navicular Intermediate cuneiform malleolar facet Lateral cuneiform Talus Calcaneus Cuboid Fifth metatarsal Lateral view © 2013 Pearson Education, Inc.  Cartilage: Basic Structure, Types and Locations Skeletal cartilage – Water lends resiliency – Contains no blood vessels or nerves – Perichondrium surrounds Dense connective tissue girdle – Contains blood vessels for nutrient delivery – Resists outward expansion © 2013 Pearson Education, Inc.  Skeletal Cartilages All contain chondrocytes in lacunae and extracellular matrix Three types – Hyaline cartilage Provides support, flexibility, and resilience Collagen fibers only; most abundant type Articular, costal, respiratory, nasal cartilage – Elastic cartilage Similar to hyaline cartilage, but contains elastic fibers External ear and epiglottis – Fibrocartilage Thick collagen fibers—has great tensile strength Menisci of knee; vertebral discs © 2013 Pearson Education, Inc.  Figure 6.1 The bones and cartilages of the human skeleton. Epiglottis Thyroid Larynx cartilage Cartilage in Cartilages in Cricoid external ear nose cartilage Trachea Articular Lung cartilage of a joint Costal Cartilage in cartilage intervertebral disc Respiratory tube cartilages in neck and thorax Pubic Bones of skeleton symphysis Axial skeleton Meniscus Appendicular skeleton (padlike cartilage in knee joint) Cartilages Articular Hyaline cartilages cartilage of a joint Elastic cartilages Fibrocartilages © 2013 Pearson Education, Inc.  Classification of Bones 206 named bones in skeleton Divided into two groups – Axial skeleton Long axis of body Skull, vertebral column, rib cage – Appendicular skeleton Bones of upper and lower limbs Girdles attaching limbs to axial skeleton © 2013 Pearson Education, Inc.  Figure 7.1b The human skeleton. Cranium Bones of Clavicle pectoral girdle Scapula Sternum Upper Rib limb Humerus Vertebra Radius Ulna Bones of Carpals pelvic girdle Phalanges Metacarpals Femur Lower limb Tibia Fibula Posterior view © 2013 Pearson Education, Inc.  Figure 7.1a The human skeleton. Cranium Skull Facial bones Clavicle Thoracic Scapula cage (ribs and Sternum sternum) Rib Humerus Vertebra Vertebral Radius column Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges Anterior view © 2013 Pearson Education, Inc.  Classification of Bones by Shape Long bones – Longer than they are wide – Limb, hand, and foot bones Short bones – Cube-shaped bones (in wrist and ankle) – Sesamoid bones (within tendons, e.g., Patella) – Vary in size and number in different individuals Flat bones – Thin, flat, slightly curved – Sternum, scapulae, ribs, most skull bones Irregular bones – Complicated shapes – Vertebrae, coxal bones © 2013 Pearson Education, Inc.  Figure 6.2 Classification of bones on the basis of shape. Flat bone (sternum) Long bone (humerus) Irregular bone (vertebra), right lateral view Short bone (talus) © 2013 Pearson Education, Inc.  Physiology of Bones Seven important functions – Support – Protection – Movement – Mineral and growth factor storage – Blood cell formation (hematopoiesis) – Triglyceride (fat) storage – Hormone production (Osteocalcin) © 2013 Pearson Education, Inc.  Bones Are organs – Contain different types of tissues Bone (osseous) tissue, nervous tissue, cartilage, fibrous connective tissue, muscle and epithelial cells in its blood vessels Three levels of structure – Gross anatomy – Microscopic – Chemical © 2013 Pearson Education, Inc.  Gross Anatomy Bone textures – Compact and spongy bone Compact – Dense outer layer; smooth and solid Spongy (cancellous or trabecular) – Honeycomb of flat pieces of bone deep to compact called trabeculae © 2013 Pearson Education, Inc.  Figure 6.3 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Spongy bone (diploë) Compact bone Trabeculae of spongy bone © 2013 Pearson Education, Inc.  Structure of Typical Long Bone Diaphysis – Tubular shaft forms long axis – Compact bone surrounding medullary cavity Epiphyses – Bone ends – External compact bone; internal spongy bone – Articular cartilage covers articular surfaces – Between is epiphyseal line Remnant of childhood bone growth at epiphyseal plate © 2013 Pearson Education, Inc.  Figure 6.4a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis © 2013 Pearson Education, Inc.  Figure 6.4b The structure of a long bone (humerus of arm). Articular cartilage Compact bone Spongy bone Endosteum © 2013 Pearson Education, Inc.  Membranes: Periosteum White, double-layered membrane Covers external surfaces except joint surfaces Outer fibrous layer of dense irregular connective tissue – Sharpey's fibers secure to bone matrix Osteogenic layer abuts bone – Contains primitive stem cells – osteogenic cells Many nerve fibers and blood vessels Anchoring points for tendons and ligaments © 2013 Pearson Education, Inc.  Membranes: Endosteum Delicate connective tissue membrane covering internal bone surface Covers trabeculae of spongy bone Lines canals that pass through compact bone Contains osteogenic cells that can differentiate into other bone cells © 2013 Pearson Education, Inc.  Figure 6.4c The structure of a long bone (humerus of arm). Endosteum Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries © 2013 Pearson Education, Inc.  Hematopoietic Tissue in Bones Red marrow – Found within trabecular cavities of spongy bone and diploë of flat bones (e.g., sternum) – In medullary cavities and spongy bone of newborns – Adult long bones have little red marrow Heads of femur and humerus only – Red marrow in diploë and some irregular bones is most active – Yellow marrow can convert to red, if necessary © 2013 Pearson Education, Inc.  Microscopic Anatomy of Bone: Cells of Bone Tissue Five major cell types Each specialized form of same basic cell type – Osteogenic cells – Osteoblasts – Osteocytes – Bone lining cells – Osteoclasts © 2013 Pearson Education, Inc.  Osteoblasts Bone-forming cells Secrete unmineralized bone matrix or osteoid – Includes collagen and calcium-binding proteins Collagen = 90% of bone protein Actively mitotic © 2013 Pearson Education, Inc.  Osteocytes Mature bone cells in lacunae Monitor and maintain bone matrix Act as stress or strain sensors – Respond to and communicate mechanical stimuli to osteoblasts and osteoclasts (cells that destroy bone) so bone remodeling can occur © 2013 Pearson Education, Inc.  Osteoclasts Derived from hematopoietic stem cells that become macrophages Giant, multinucleate cells for bone resorption When active rest in resorption bay and have ruffled border – Ruffled border increases surface area for enzyme degradation of bone and seals off area from surrounding matrix © 2013 Pearson Education, Inc.  Hormonal Regulation of Bone Growth Growth hormone – Most important in stimulating epiphyseal plate activity in infancy and childhood Thyroid hormone – Modulates activity of growth hormone – Ensures proper proportions Testosterone (males) and estrogens (females) at puberty – Promote adolescent growth spurts – End growth by inducing epiphyseal plate closure Excesses or deficits of any cause abnormal skeletal growth © 2013 Pearson Education, Inc.  Importance of Calcium Functions in – Nerve impulse transmission – Muscle contraction – Blood coagulation – Secretion by glands and nerve cells – Cell division 1200 – 1400 grams of calcium in body – 99% as bone minerals – Amount in blood tightly regulated (9-11 mg/dl) – Intestinal absorption requires Vitamin D metabolites – Dietary intake required © 2013 Pearson Education, Inc.  Hormonal Control of Blood Ca2+ Parathyroid hormone (PTH) – Produced by parathyroid glands – Removes calcium from bone regardless of bone integrity Calcitonin may be involved – Produced by parafollicular cells of thyroid gland – In high doses lowers blood calcium levels temporarily © 2013 Pearson Education, Inc.  Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels. IMB ALA NC E Calcium homeostasis of blood: 9–11 mg/100 ml BALANCE BALANCE Stimulus Falling blood IM BA Ca2+ levels L AN CE Thyroid gland Osteoclasts degrade bone Parathyroid matrix and release glands Ca2+ into blood. Parathyroid glands release parathyroid hormone (PTH). PTH © 2013 Pearson Education, Inc.  Calcium Homeostasis Even minute changes in blood calcium dangerous – Severe neuromuscular problems Hyperexcitability (levels too low) Nonresponsiveness (levels too high) – Hypercalcemia Sustained high blood calcium levels Deposits of calcium salts in blood vessels, kidneys can interfere with function © 2013 Pearson Education, Inc.  Other Hormones Affecting Bone Density Leptin – Hormone released by adipose tissue – Role in bone density regulation Inhibits osteoblasts in animals Serotonin – Neurotransmitter regulating mood and sleep – Most made in gut – Secreted into blood after eating Interferes with osteoblast activity Serotonin reuptake inhibitors (e.g., Prozac) cause lower bone density © 2013 Pearson Education, Inc.  Microscopic Anatomy of Bone: Compact Bone Also called lamellar bone Osteon or Haversian system – Structural unit of compact bone – Elongated cylinder parallel to long axis of bone – Hollow tubes of bone matrix called lamellae Collagen fibers in adjacent rings run in different directions – Withstands stress – resist twisting © 2013 Pearson Education, Inc.  Figure 6.6 A single osteon. Artery with capillaries Structures in the Vein central Nerve fiber canal Lamellae Collagen fibers run in different directions Twisting force © 2013 Pearson Education, Inc.  Microscopic Anatomy of Bone: Compact Bone Canals and canaliculi – Central (Haversian) canal runs through core of osteon Contains blood vessels and nerve fibers Perforating (Volkmann's) canals – Canals lined with endosteum at right angles to central canal – Connect blood vessels and nerves of periosteum, medullary cavity, and central canal Lacunae—small cavities that contain osteocytes Canaliculi—hairlike canals that connect lacunae to each other and central canal © 2013 Pearson Education, Inc.  Figure 6.7 Microscopic anatomy of compact bone. Compact bone Spongy bone Central Perforating (Haversian) canal (Volkmann’s) canal Endosteum lining bony canals Osteon and covering trabeculae (Haversian system) Circumferential lamellae Perforating (Sharpey’s) fibers Lamellae Periosteal blood vessel Periosteum Nerve Vein Artery Lamellae Central Canaliculi canal Osteocyte Lacunae in a lacuna Interstitial Lacuna lamella (with osteocyte) © 2013 Pearson Education, Inc.  Microscopic Anatomy of Bone: Spongy Bone Appears poorly organized Trabeculae – Align along lines of stress to help resist it – No osteons – Contain irregularly arranged lamellae and osteocytes interconnected by canaliculi – Capillaries in endosteum supply nutrients © 2013 Pearson Education, Inc.  Chemical Composition of Bone: Inorganic Components Hydroxyapatites (mineral salts) – 65% of bone by mass – Mainly of tiny calcium phosphate crystals in and around collagen fibers – Responsible for hardness and resistance to compression © 2013 Pearson Education, Inc.  Bone Half as strong as steel in resisting compression As strong as steel in resisting tension Last long after death because of mineral composition – Reveal information about ancient people – Can display growth arrest lines Horizontal lines on bones Proof of illness - when bones stop growing so nutrients can help fight disease © 2013 Pearson Education, Inc.  Endochondral Ossification Forms most all bones inferior to base of skull – Except clavicles Begins late in 2nd month of development Uses hyaline cartilage models Requires breakdown of hyaline cartilage prior to ossification © 2013 Pearson Education, Inc.  Figure 6.8 Endochondral ossification in a long bone. Slide 1 Week 9 Month 3 Birth Childhood to adolescence Articular cartilage Secondary ossification Spongy center bone Area of Epiphyseal deteriorating blood vessel Epiphyseal cartilage matrix plate Hyaline cartilage cartilage Medullary Spongy bone cavity formation Bone collar Blood vessel of Primary periosteal ossification bud center 1 Bone collar 2 Cartilage in the 3 The periosteal 4 The diaphysis 5 The epiphyses forms around the center of the bud invades the elongates and a ossify. When diaphysis of the diaphysis calcifies internal cavities medullary cavity completed, hyaline hyaline cartilage and then develops and spongy bone forms. Secondary cartilage remains model. cavities. forms. ossification only in the centers appear in epiphyseal plates the epiphyses. and articular cartilages. © 2013 Pearson Education, Inc.  Intramembranous Ossification Forms frontal, parietal, occipital, temporal bones, and clavicles Begins within fibrous connective tissue membranes formed by mesenchymal cells Ossification centers appear Osteoid is secreted Woven bone and periosteum form Lamellar bone replaces woven bone & red marrow appears © 2013 Pearson Education, Inc.  Figure 6.9 Intramembranous ossification. Slide 1 Mesenchymal Osteoblast cell Collagen fibril Osteoid Ossification Osteocyte center Newly Osteoid calcified bone matrix Osteoblast 1 Ossification centers appear in the fibrous 2 Osteoid is secreted within the fibrous membrane and connective tissue membrane. calcifies. Selected centrally located mesenchymal cells Osteoblasts begin to secrete osteoid, which calcifies in a few days. cluster and differentiate into osteoblasts, forming an Trapped osteoblasts become osteocytes. ossification center that produces the first trabeculae of spongy bone. Fibrous Mesenchyme periosteum condensing to form the Osteoblast periosteum Plate of compact bone Trabeculae of woven bone Diploë (spongy bone) Blood vessel cavities contain red marrow 3 Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels in 4 Lamellar bone replaces woven bone, just deep to the a manner that results in a network (instead of concentric lamellae) of periosteum. Red marrow appears. trabeculae called woven bone. Trabeculae just deep to the periosteum thicken. Mature lamellar Vascularized mesenchyme condenses on the external face of the woven bone replaces them, forming compact bone plates. bone and becomes the periosteum. Spongy bone (diploë), consisting of distinct trabeculae, persists © 2013 Pearson Education, Inc. internally and its vascular tissue becomes red marrow.  Interstitial Growth: Growth in Length of Long Bones Near end of adolescence chondroblasts divide less often Epiphyseal plate thins then is replaced by bone Epiphyseal plate closure – Bone lengthening ceases Requires presence of cartilage – Bone of epiphysis and diaphysis fuses – Females – about 18 years – Males – about 21 years © 2013 Pearson Education, Inc.  Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate. Resting zone 1 Proliferation zone Cartilage cells undergo mitosis. 2 Hypertrophic zone Older cartilage cells enlarge. 3 Calcification zone Calcified Matrix calcifies; cartilage cartilage spicule cells die; matrix begins deteriorating; blood Osteoblast vessels invade depositing bone cavity. matrix Osseous tissue 4 Ossification zone (bone) covering New bone forms. cartilage spicules © 2013 Pearson Education, Inc.  Figure 6.11 Long bone growth and remodeling during youth. Bone growth Bone remodeling Articular cartilage Cartilage grows here. Bone Epiphyseal plate replaces cartilage Bone that was here. here has been resorbed. Cartilage grows here. Appositional growth adds Bone replaces bone here. cartilage here. Bone that was here has been resorbed. © 2013 Pearson Education, Inc.  Results of Mechanical Stressors: Wolff's Law Bones grow or remodel in response to demands placed on it Explains – Handedness (right or left handed) results in thicker and stronger bone of that upper limb – Curved bones thickest where most likely to buckle – Trabeculae form trusses along lines of stress – Large, bony projections occur where heavy, active muscles attach – Bones of fetus and bedridden featureless © 2013 Pearson Education, Inc.  Fracture Classification Three "either/or" fracture classifications – Position of bone ends after fracture Nondisplaced—ends retain normal position Displaced—ends out of normal alignment – Completeness of break Complete—broken all the way through Incomplete—not broken all the way through – Whether skin is penetrated Open (compound) - skin is penetrated Closed (simple) – skin is not penetrated © 2013 Pearson Education, Inc.  Table 6.2 Common Types of Fractures (1 of 3) © 2013 Pearson Education, Inc.  Table 6.2 Common Types of Fractures (2 of 3) © 2013 Pearson Education, Inc.  Table 6.2 Common Types of Fractures (3 of 3) © 2013 Pearson Education, Inc.  Figure 6.15 Stages in the healing of a bone fracture. Hematoma External Bony callus callus of spongy New bone Internal blood Healed callus vessels fracture (fibrous tissue and Spongy cartilage) bone trabecula 1 A hematoma forms. 2 Fibrocartilaginous 3 Bony callus 4 Bone callus forms. forms. remodeling occurs. © 2013 Pearson Education, Inc.  Homeostatic Imbalances Osteomalacia – Bones poorly mineralized – Calcium salts not adequate – Soft, weak bones – Pain upon bearing weight Rickets (osteomalacia of children) – Bowed legs and other bone deformities – Bones ends enlarged and abnormally long – Cause: Vitamin D deficiency or insufficient dietary minerals (esp. Ca) © 2013 Pearson Education, Inc.  Homeostatic Imbalances Osteoporosis – Group of diseases – Bone resorption outpaces deposit – Spongy bone of spine and neck of femur most susceptible Vertebral and hip fractures common © 2013 Pearson Education, Inc.  Figure 6.16 The contrasting architecture of normal versus osteoporotic bone. Normal bone © 2013 Pearson Education, Inc. Osteoporotic bone  Risk Factors for Osteoporosis Risk factors – Most often aged, postmenopausal women 30% 60 – 70 years of age; 70% by age 80 30% Caucasian women will fracture bone because of it – Men to lesser degree – Sex hormones maintain normal bone health and density As secretion wanes with age osteoporosis can develop © 2013 Pearson Education, Inc.  Additional Risk Factors for Osteoporosis Petite body form Insufficient exercise to stress bones Diet poor in mineral salts (esp. Ca) and protein Smoking Hormone-related conditions – Hyperthyroidism – Low blood levels of thyroid-stimulating hormone – Diabetes mellitus Immobility Males with prostate cancer taking androgen- suppressing drugs © 2013 Pearson Education, Inc.  Developmental Aspects of Bones Embryonic skeleton ossifies predictably so fetal age easily determined from X rays or sonograms Most long bones begin ossifying by 8 weeks Primary ossification centers by 12 weeks At birth, most long bones well ossified (except epiphyses) At age 25 ~ all bones completely ossified and skeletal growth ceases © 2013 Pearson Education, Inc.  Figure 6.17 Fetal primary ossification centers at 12 weeks. Parietal bone Frontal bone of skull Occipital bone Mandible Clavicle Scapula Radius Ulna Humerus Femur Tibia Ribs Vertebra Ilium © 2013 Pearson Education, Inc.