Holes Human Anatomy & Physiology 2024 - Chapter 7 - Skeletal System PDF

Because learning changes everything. ® Chapter 07 Skeletal System Hole’s Human Anatomy & Physiology 2024 Release Charles J. Welsh, Cynthia Prentice Craver © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw...

Because learning changes everything. ® Chapter 07 Skeletal System Hole’s Human Anatomy & Physiology 2024 Release Charles J. Welsh, Cynthia Prentice Craver © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  7.1 Overview of the Skeletal System The bones of the skeletal system: Organs of the skeletal system Composed of many tissues: bone tissue, cartilage, dense connective tissue (tendons, ligaments), supplied with blood vessels and nerves Alive and multifunctional: Support and protect softer tissues Movement Blood cell formation Mineral storage Human skeleton is unique in adaptation for walking on 2 legs and grasping objects with the hands Skeletal system has 2 divisions: Axial Appendicular © McGraw Hill, LLC 2  7.2 Bone Shape and Structure Bones of the skeletal system vary greatly in these ways: Size Shape Bones are similar in these features: Structure Development Function © McGraw Hill, LLC 3  Bone Shapes Bone Classification by Shape: Long Bones: Long and narrow Have expanded ends Short Bones: Cube-like, length = width Include sesamoid (round) bones, which are embedded in tendons Flat Bones: Plate-like, with broad surfaces Irregular Bones: Variety of shapes Most are connected to several other bones © McGraw Hill, LLC 4  Figure 7.1 Bone Shapes Access the text alternative for slide images. © McGraw Hill, LLC 5  Structure of a Long Bone Epiphysis: expanded end Diaphysis: bone shaft Metaphysis: between diaphysis and epiphysis, widening part Articular cartilage: covers epiphysis Periosteum: encloses bone; dense connective tissue Compact (cortical) bone: wall of diaphysis Spongy (cancellous) bone: makes up epiphyses Trabeculae: branching bony plates, make up spongy bone Medullary cavity: hollow chamber in diaphysis; contains marrow Endosteum: Lines spaces, cavity Bone marrow: Red or yellow marrow, lines medullary cavity, spongy bone spaces © McGraw Hill, LLC 6  Figure 7.2 Major Parts of a Long Bone Access the text alternative for slide images. © McGraw Hill, LLC 7  Microscopic Structure of Bone Osteocytes: Mature bone cells Lacunae: Chambers occupied by osteocytes Canaliculi: Tiny passageways through which the cell processes of osteocytes exchange nutrients and wastes The extracellular matrix of bone is largely collagen fibers and inorganic salts: Collagen provides resilience to a bone Inorganic salts make bone hard © McGraw Hill, LLC 8  Compact and Spongy Bone Compact Bone: Consists of cylindrical units called osteons Osteons and layers of matrix, lamellae, cluster around central canal in each osteon Strong and solid Weight-bearing Resists compression Spongy Bone: Consists of branching plates called trabeculae Somewhat flexible Has spaces between trabeculae that reduce the bone’s weight © McGraw Hill, LLC 9  Figure 7.3 Compact and Spongy Bone (a): Ed Reschke/Getty Images (b): Courtesy of John W. Hole, Jr. (c): Courtesy of John W. Hole, Jr. Access the text alternative for slide images. © McGraw Hill, LLC 10  Figure 7.4 Compact Bone Structure Access the text alternative for slide images. © McGraw Hill, LLC 11  7.3 Bone Function Major functions of bones: Provide shape to body Support body structures Protect body structures Aid body movements Contain tissue that produces blood cells Store inorganic salts © McGraw Hill, LLC 12  Support, Protection, and Movement Bones provide shape for head, face, thorax, limbs Bones support body weight (bones of lower limbs, pelvis, vertebral column) Skull bones protect brain, ears, eyes Bones of rib cage, shoulder girdle protect heart, lungs Bones of pelvic girdle protect internal reproductive organs, lower abdominal organs Bones and muscles provide movement © McGraw Hill, LLC 13  Blood Cell Formation Hematopoiesis: Blood cell formation Blood cell production occurs in red bone marrow Red blood cells, white blood cells, and platelets are produced in red bone marrow With age, some red bone marrow is replaced by yellow bone marrow, which stores fat, but does not produce blood cells Red marrow remains in adult in skull, ribs, sternum, clavicles, vertebrae, hip bones Bone marrow transplants are used to treat a variety of conditions © McGraw Hill, LLC 14  Inorganic Salt Storage About 70% of bone matrix consists of inorganic mineral salts Most abundant salt is crystals of hydroxyapatite (calcium phosphate) Other salts include: Magnesium ions Sodium ions Potassium ions Carbonate ions Osteoporosis: a condition that results from loss of bone mineralization Since calcium is vital in nerve impulse conduction and muscle contraction, blood calcium level is regulated by Parathyroid hormone and Calcitonin © McGraw Hill, LLC 15  Figure 7.6 Hormonal Control of Blood Calcium Access the text alternative for slide images. © McGraw Hill, LLC 16  7.4 Bone Development, Growth, and Repair Parts of the skeletal system begin to develop in first few weeks of prenatal development Bony structures continue to grow and develop into adulthood Bones form when bone tissue replaces existing connective tissue in one of two ways: Intramembranous bones Endochondral bones © McGraw Hill, LLC 17  Bone Growth and Development Fetus at 14 weeks of development shows growth of both intramembranous and endochondral bones: Intramembranous Ossification: Flat skull bones, clavicles, sternum and some facial bones Bones form between sheets of primitive connective tissue Endochondral Ossification: Long bones and most of skeleton Bones form from hyaline cartilage models Osteogenesis imperfecta: Hereditary collagen defect, in which forming bones are brittle, and fetus may have many bone fractures © McGraw Hill, LLC 18  Figure 7.7 Bone Development in Fetus (a): Biophoto Associates/Science Source; (b): Photo courtesy of T.D. Gelehrter and F.S. Collins Access the text alternative for slide images. © McGraw Hill, LLC 19  Intramembranous Bones and Ossification Intramembranous Bones: Originate within sheet-like layers of connective tissue. Broad, flat bones, such as flat bones of the skull, clavicles, sternum, and some facial bones (mandible, maxilla, zygomatic) Intramembranous Ossification: Process of replacing embryonic connective tissue to form intramembranous bone: Mesenchymal cells in primitive tissue differentiate into osteoblasts Osteoblasts: bone-forming cells that deposit bone matrix around themselves When osteoblasts are completely surrounded by matrix, they are now osteocytes in lacunae Mesenchyme on outside forms periosteum © McGraw Hill, LLC 20  Figure 7.8 Osteocyte in a Lacuna CNRI/Science Source © McGraw Hill, LLC 21  Figure 7.9 Development of Intramembranous Bone Access the text alternative for slide images. © McGraw Hill, LLC 22  Endochondral Bones Endochondral Bones: Begin as masses of hyaline cartilage Most bones of the skeleton, such as femur, humerus, radius, tibia, phalanges, vertebrae. Endochondral Ossification: Process of replacing hyaline cartilage to form an endochondral bone: Begin as hyaline cartilage models Chondrocytes (cartilage cells) enlarge, lacunae grow Matrix breaks down, chondrocytes die Osteoblasts invade area, deposit bone matrix Osteoblasts form spongy and then compact bone Once encased by matrix, osteoblasts are now osteocytes © McGraw Hill, LLC 23  Development of Endochondral Long Bones Bone begins as hyaline cartilage model Primary ossification center: Area in center of diaphysis, where bone tissue first replaces cartilage Replacement with bone tissue proceeds toward ends of bone Osteoblasts from periosteum deposit compact bone around primary center Secondary ossification centers: Area of the epiphyses, where spongy bone forms later in development Epiphyseal plate: Band of cartilage that persists between the ossification centers © McGraw Hill, LLC 24  Figure 7.10 Stages in Development of Endochondral Bones Access the text alternative for slide images. © McGraw Hill, LLC 25  Figure 7.11 Radiograph of the Bones and Epiphyseal Plates in a Child’s Hand Reschke, Ed/ Getty Images Access the text alternative for slide images. © McGraw Hill, LLC 26  Table 7.1 Major Steps in Bone Development Intramembranous Ossification Endochondral Ossification 1. Sheets of embryonic connective tissue 1. Masses of hyaline cartilage form models (mesenchyme) appear at the sites of of future bones. future bones. 2. Mesenchymal cells differentiate into 2. Cartilage tissue breaks down. osteoblasts, which deposit bone matrix. Periosteum develops. 3. Dense networks of blood vessels supply 3. Blood vessels and differentiating the developing spongy bone. osteoblasts from the periosteum invade the disintegrating tissue. 4. Osteoblasts become osteocytes when 4. Osteoblasts form spongy bone in the bony matrix completely surrounds them. space occupied by cartilage. 5. Mesenchyme on the surface of each 5. Osteoblasts beneath the periosteum developing structure condenses to form deposit compact bone. periosteum. 6. Osteoblasts on the inside of the 6. Osteoblasts become osteocytes when periosteum deposit compact bone over bony matrix completely surrounds them. the spongy bone. © McGraw Hill, LLC 27  Growth at the Epiphyseal Plate 1 In a growing long bone, diaphysis is separated from epiphysis by Epiphyseal Plate, the region at which bone grows in length. Cartilaginous cells of epiphyseal plate form 4 layers: Zone of resting cartilage: Layer closest to end of epiphysis Resting cells; anchor epiphyseal plate to epiphysis Zone of proliferating cartilage: Rows of young cells, undergoing mitosis Zone of hypertrophic cartilage: Rows of older cells left behind when new cells appear; thicken epiphyseal plate, lengthening the bone Matrix calcifies, cartilage cells (chondrocytes) die Zone of calcified cartilage: Thin layer of dead cartilage cells and calcified matrix © McGraw Hill, LLC 28  Figure 7.12 Epiphyseal Plate (b): Al Telser/McGraw Hill Access the text alternative for slide images. © McGraw Hill, LLC 29  Growth at the Epiphyseal Plate 2 As the chondrocytes in the zone of hypertrophic cartilage of the epiphyseal plate begin to die: Osteoclasts break down calcified matrix Osteoblasts then invade, replacing cartilage with bone tissue Bone can continue to grow in length, as long as cartilage cells of epiphyseal plate remain active. When ossification centers of the diaphysis and epiphyses meet, and the epiphyseal plate ossifies, the bone can no longer grow in length. Bone can thicken by depositing compact bone on the outside, under periosteum. © McGraw Hill, LLC 30  Figure 7.13 Bone-resorbing Osteoclasts Biophoto Associates/Science Source © McGraw Hill, LLC 31  Table 7.2 Ossification Timetable Age Occurrence Age Occurrence Third month of Ossification in long 15 to 18 years Bones of the upper prenatal bones begins. (females) limbs and scapulae development 17 to 20 years completely ossified. (males) Fourth month of Most primary ossification 16 to 21 years Bones of the lower prenatal centers have appeared (females) limbs and hip bones development in the diaphyses of long 18 to 23 years completely ossified. bones (males) Birth to 5 years Secondary ossification 21 to 23 years Bones of the centers appear in the (females) sternum, clavicles, epiphyses of long bones. 23 to 25 years and vertebrae (males) completely ossified. 5 to 12 years Ossification rapidly By 23 years Nearly all bones (females) spreads from the (females) completely ossified. 5 to 14 years ossification centers. By 25 years (males) (males) © McGraw Hill, LLC 32  Homeostasis of Bone Tissue During development of intramembranous and endochondral bones, osteoblasts and osteoclasts re-shape, or remodel, them Bone remodeling occurs throughout life Opposing processes of deposition and resorption occur on surfaces of endosteum and periosteum Bone Resorption: Removal of bone by osteoclasts Bone Deposition: Formation of bone by osteoblasts 10% to 20% of skeleton is replaced each year © McGraw Hill, LLC 33  Factors Affecting Bone Development, Growth, and Repair 1 Nutrition, sunlight exposure, hormone levels, and physical exercise all affect bone development, growth, and repair: Vitamin D: calcium absorption; deficiency causes rickets, osteomalacia Vitamin A: osteoblast and osteoclast activity; deficiency retards bone development Vitamin C: collagen synthesis; deficiency results in slender, fragile bones Growth Hormone: stimulates cartilage cell division Insufficiency in a child can result in pituitary dwarfism Excess causes gigantism in child, acromegaly in adult © McGraw Hill, LLC 34  Factors Affecting Bone Development, Growth, and Repair 2 Thyroid Hormone: Causes replacement of cartilage with bone in epiphyseal plate, osteoblast activity Parathyroid Hormone (PTH): Stimulates osteoclasts, bone breakdown Sex Hormones (estrogen, testosterone): Promote bone formation; stimulate ossification of epiphyseal plates Physical Stress: Stimulates bone growth © McGraw Hill, LLC 35  Figure 7.14 Increased Bone Deposition at Sites of Muscle Attachment due to Exercise Courtesy of John W. Hole, Jr. © McGraw Hill, LLC 36  Clinical Application 7.1 Fractures Fractures are classified by cause and nature of break: Classification by cause: Traumatic: Fracture caused by injury Spontaneous or pathologic: Fracture caused by disease Classification by nature of break: Simple (closed): Fracture protected by uninjured skin (or mucous membrane) Compound (open): Fracture in which the bone is exposed to the outside through opening in skin (or mucous membrane). © McGraw Hill, LLC 37  Clinical Application 7.1 Figure 7A Types of Fractures Access the text alternative for slide images. © McGraw Hill, LLC 38  Clinical Application 7.1 Steps in Fracture Repair Steps in Fracture Repair: Hematoma: Large blood clot; forms right after the fracture occurs Cartilaginous (soft) callus: Fibrocartilage is produced, osteoblasts invade and produce spongy bone, phagocytes remove debris Bony (hard) callus: Fibrocartilage is replaced by bone, forming the bony callus Remodeling: Bone is restored close to original shape, as osteoclasts remove excess bone © McGraw Hill, LLC 39  Clinical Application 7.1: Figure 7B Steps in Fracture Repair Access the text alternative for slide images. © McGraw Hill, LLC 40  Clinical Application 7.2 Preventing Fragility Fractures Fragility Fracture: Fracture that occurs after a fall from less than standing height; a sign of low bone density Bone remodeling occurs throughout life With age, osteoclasts remove more bone than osteoblasts deposit Can result in osteopenia (bone loss) or progress to osteoporosis (severe bone loss that leaves spaces and canals in bone, weakens them) Estimated that 50% women and 25% men over 50 have one of the bone loss conditions Most common in postmenopausal women, due to hormone changes To prevent fragility fractures: Get 30 minutes of exercise per day; include weight-bearing exercise Get enough calcium and vitamin D Do not smoke © McGraw Hill, LLC 41  Clinical Application 7.2 Figure 7C Normal Bone and Bone with Osteoporosis David Gregory & Debbie Marshall/Wellcome Images/Science Source © McGraw Hill, LLC 42  7.5 Skeletal Organization Number of bones in the adult skeleton is about 206 Some people have extra bones, while others lack certain bones Examples of extra bones that some people have: Sutural (wormian) bones in sutures between major skull bones Small sesamoid bones in tendons; reduce friction A vertebra © McGraw Hill, LLC 43  Figure 7.15 Sutural (Wormian) Bones Access the text alternative for slide images. © McGraw Hill, LLC 44  Table 7.3 Bones of the Adult Skeleton 1. Axial Skeleton 2. Appendicular Skeleton a. Skull 22 bones a. Pectoral girdle 4 bones 8 cranial bones 14 facial bones scapula 2 frontal 1 maxilla 2 clavicle 2 parietal 2 palatine 2 occipital 1 zygomatic 2 temporal 2 lacrimal 2 sphenoid 1 nasal 2 ethmoid 1 vomer 1 inferior nasal concha 2 mandible 1 b. Middle ear bones 6 bones b. Upper limbs 60 bones malleus 2 humerus 2 incus 2 radius 2 stapes 2 carpal 16 metacarpal 10 phalanx 28 c. Hyoid 1 bone c. Pelvic girdle 2 bones hyoid bone 1 hip bone 2 d. Vertebral column 26 bones d. Lower limbs 60 bones cervical vertebra 7 femur 2 thoracic vertebra 12 tibia 2 lumbar vertebra 5 fibula 2 sacrum 1 patella 2 coccyx 1 tarsal 14 metatarsal 10 phalanx 28 e. Thoracic cage 25 bones Total 206 bones rib 24 sternum 1 © McGraw Hill, LLC 45  Divisions of the Skeleton Axial Skeleton (80 bones): Skull: Cranium and facial bones Middle ear bones: Move sound to receptors in inner ear Hyoid bone: Supports tongue and is muscle attachment site Vertebral column: Forms central axis of skeleton Thoracic cage: Ribs and sternum; protects organs Appendicular Skeleton (126 bones): Pectoral girdle: Scapula and clavicle; upper limb movement Upper limbs: Humerus, radius, ulna, hand Pelvic girdle: Hip bones; lower limb movement; forms pelvis Lower limbs: Femur, tibia, fibula, patella, foot © McGraw Hill, LLC 46  Figure 7.16 Divisions of the Skeleton Access the text alternative for slide images. © McGraw Hill, LLC 47  Figure 7.17 The Hyoid Bone Access the text alternative for slide images. © McGraw Hill, LLC 48  Table 7.4 Terms Used to Describe Skeletal Structures 1 Term Definition Example Condyle (kon′dīl) Rounded process that usually articulates Occipital condyle of the occipital with another bone bone (Figure 7.22) Crest (krest) Narrow, ridge-like projection Iliac crest of the ilium (Figure 7.49) Epicondyle (ep″ĩ- Projection situated above a condyle Medial epicondyle of the humerus kon′dīl) (Figure 7.44) Facet (fas′et) Small, nearly flat surface Costal facet of a thoracic vertebra (Figure 7.37b) Fissure (fish′ūr) Cleft or groove Inferior orbital fissure in the orbit of the eye (Figure 7.20) Fontanel (fon″tah- Soft spot in the skull where membranes Anterior fontanel between the nel′) cover the space between bones frontal and parietal bones (Figure 7.32) Foramen (fo-ra Opening through a bone that usually Foramen magnum of the occipital ′men) serves as a passageway for blood bone (Figure 7.22) vessels, nerves, or ligaments Fossa (fos′ah) Relatively deep pit or depression Olecranon fossa of the humerus (Figure 7.44b) Fovea (fo′ve-ah) Tiny pit or depression Fovea capitis of the femur (Figure 7.52b) Head (hed) Enlargement on the end of a bone Head of the humerus (Figure 7.44) © McGraw Hill, LLC 49  Table 7.4 Terms Used to Describe Skeletal Structures 2 Term Definition Example Linea (lin′e-ah) Narrow ridge Linea aspera of the femur (Figure 7.52b) Meatus (me-a′tus) Tube-like passageway within a External acoustic meatus of the bone temporal bone (Figure 7.19) Process (pros′es) Prominent projection on a bone Mastoid process of the temporal bone (Figure 7.19) Ramus (ra′mus) Branch or similar extension Ramus of the mandible (Figure 7.30a) Sinus (si′nus) Cavity within a bone Frontal sinus of the frontal bone (Figure 7.21) Spine (spīn) Thorn-like projection Spine of the scapula (Figure 7.42a, b) Sulcus (sul′kus) Furrow or groove Intertubucular sulcus of the humerus (Figure 7.44a) Suture (soo′cher) Interlocking line of union between Lambdoid suture between the occipital bones and parietal bones (Figure 7.19) Trochanter (tro-kan′ter) Relatively large process Greater trochanter of the femur (Figure 7.52a) Tubercle (tu′ber-kl) Knob-like process Tubercle of a rib (Figure 7.40) Tuberosity (tu″bĕ-ros′ĭ-te) Knob-like process usually larger Radial tuberosity of the radius (Figure than a tubercle 7.45a) © McGraw Hill, LLC 50  7.6 The Skull The skull is typically composed of 22 bones All skull bones are interlocked along sutures, except the lower jaw (mandible) The skull = cranium + facial skeleton Cranium contains 8 bones; encloses and protects brain Facial skeleton contains 14 bones; forms shape of face Mandible is movable, and held in place next to cranium by ligaments Orbit of eye is formed by some facial and cranial bones Paranasal sinuses: Air-filled cavities found in some cranial and facial bones Reduce weight of skull and increase intensity of voice © McGraw Hill, LLC 51  Figure 7.18 Anterior View of the Skull Access the text alternative for slide images. © McGraw Hill, LLC 52  Figure 7.19 Lateral View of the Skull Access the text alternative for slide images. © McGraw Hill, LLC 53  Figures 7.20 and 7.21 Eye Orbit and Paranasal Sinuses Access the text alternative for slide images. © McGraw Hill, LLC 54  Cranium 1 Frontal Bone (1): Forms forehead, roof of nasal cavity, roofs of eye orbits Contains frontal sinuses Contains supraorbital foramen or notch Parietal Bones (2): Form sides and roof of cranium Sagittal suture joins the 2 parietal bones Coronal suture joins them to Frontal Bone Occipital Bone (1): Forms back of skull, base of cranium Contains foramen magnum: opening for brain to meet spinal cord Occipital condyles articulate with Atlas Lambdoid suture forms junction with parietal bones © McGraw Hill, LLC 55  Figure 7.22 Inferior View of the Skull Access the text alternative for slide images. © McGraw Hill, LLC 56  Cranium 2 Temporal Bones (2): Form sides and base of cranium, floors, and sides of orbits Squamous suture connects them to Parietal Bones External acoustic meatus leads to inner portions of ear Mandibular fossa articulates with mandibular condyles Mastoid process: Muscle attachment site Styloid process: Muscle attachment site Zygomatic process: Helps form cheek prominence and zygomatic arch © McGraw Hill, LLC 57  Cranium 3 Sphenoid Bone (1): Forms base of cranium, sides of skull, floors and sides of eye orbits Sella turcica holds pituitary gland Contains sphenoid sinuses Ethmoid Bone (1): Lies in front of sphenoid Forms roof and walls of nasal cavity, floor of cranium, wall of eye orbits Cribriform plates contain openings for axons of olfactory (smell) neurons Perpendicular plate forms main portion of nasal septum Superior and middle nasal conchae support mucous membranes of nasal cavity Ethmoidal air cells together form ethmoidal sinuses Crista galli holds membranes that enclose brain © McGraw Hill, LLC 58  Figures 7.23 and 7.24 Sphenoid and Ethmoid Bones Access the text alternative for slide images. © McGraw Hill, LLC 59  Figure 7.25 Lateral Wall of Nasal Cavity Access the text alternative for slide images. © McGraw Hill, LLC 60  Figure 7.26 Floor of Cranial Cavity, Superior View Access the text alternative for slide images. © McGraw Hill, LLC 61  Facial Skeleton 1 Facial Skeleton: Composed of 13 immovable bones and 1 movable bone (mandible) Maxillae (2): Form upper jaw, anterior roof of mouth (hard palate), floors of eye orbits, sides and floors of nasal cavity Alveolar processes hold upper teeth Maxillary sinuses are the largest sinuses Palatine processes: Fuse along midline to form most of hard palate Cleft palate is result of incomplete fusion of palatine processes during fetal development © McGraw Hill, LLC 62  Facial Skeleton 2 Palatine Bones (2): L-shaped bones located behind the maxillae Posterior section of hard palate Floor and lateral walls of nasal cavity Zygomatic Bones (2): Prominences of cheeks Lateral walls and floors of orbits Temporal process joins zygomatic process to form zygomatic arch Lacrimal Bones (2): Form medial walls of orbits Contain groove leading from orbit to nasal cavity for tears © McGraw Hill, LLC 63  Figure 7.27 Palatine Bones Access the text alternative for slide images. © McGraw Hill, LLC 64  Facial Skeleton 3 Nasal Bones (2): Together form bridge of nose Long, thin, rectangular Vomer Bone (1): Along midline of nasal cavity Forms inferior portion of nasal septum Inferior Nasal Conchae (2): Scroll-shaped bones Extend inward from lateral walls of nasal cavity Largest of the conchae Support mucous membranes of nasal cavity © McGraw Hill, LLC 65  Figure 7.28 Sagittal Section of the Skull Access the text alternative for slide images. © McGraw Hill, LLC 66  Figure 7.29 Frontal Section of the Skull, Posterior View Access the text alternative for slide images. © McGraw Hill, LLC 67  Facial Skeleton 4 Mandible (1): Lower jawbone Horseshoe-shaped body Ramus projects upward on each side Mandibular condyle articulates with mandibular fossa Coronoid process attaches to chewing muscles Alveolar process holds lower teeth Mandibular foramen admits blood vessels and nerves for lower teeth Mental foramen allows blood vessels and nerves to emerge in chin area © McGraw Hill, LLC 68  Figure 7.30 Mandible: Left Lateral and Inferior Views Access the text alternative for slide images. © McGraw Hill, LLC 69  Infantile Skull Characteristics of the Infantile Skull: Incompletely developed at birth Small face, large orbits, prominent forehead Small nasal cavity and jaw Sinuses are not completely formed Bones are thin and flexible Fontanels (soft spots): Fibrous membranes that connect cranial bones, where intramembranous ossification is incomplete Allow skull to change shape slightly during birth Four major fontanels close between 2 months and 2 years of age © McGraw Hill, LLC 70  Figure 7.32 Infantile Skull with Fontanels Access the text alternative for slide images. © McGraw Hill, LLC 71  7.7 Vertebral Column Vertebral Column: Forms vertical axis of skeleton Consists of many vertebrae separated by cartilaginous intervertebral discs, and connected by ligaments Supports head and trunk, permits several types of movements Protects spinal cord in vertebral canal 33 separate bones in infant, 26 in adult © McGraw Hill, LLC 72  Vertebral Column Curvatures and Composition 4 Curvatures of Vertebral Column: Cervical curvature (secondary) Thoracic curvature (primary) Lumbar curvature (secondary) Sacral curvature (primary) Vertebral Column consists of: 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 fused sacral vertebrae form sacrum 4 fused coccygeal vertebrae form coccyx © McGraw Hill, LLC 73  Figure 7.33 Vertebral Column: Right Lateral and Posterior Views Access the text alternative for slide images. © McGraw Hill, LLC 74  A Typical Vertebra A typical vertebra contains the following parts: Body: Drum-shaped, anterior portion Pedicles: Stalks that project from body, form sides of vertebral foramen Laminae: Plates that arise from pedicles, fuse to become spinous process Spinous process: Posterior projection Transverse processes: Lateral projections Vertebral foramen: Opening for spinal cord Superior and inferior articular processes: Project upward and downward, to articulate with adjacent vertebrae Facets: Cartilage-covered articulating surfaces of articular processes © McGraw Hill, LLC 75  Figure 7.34 A Typical Vertebra Access the text alternative for slide images. © McGraw Hill, LLC 76  Cervical Vertebrae 7 cervical vertebrae: Found in neck region Smallest vertebrae Transverse foramina: openings for arteries leading to brain; only found on cervical vertebrae Bifid spinous processes on C2 to C6 Vertebral prominens: C7, spinous process is longer than those of other cervical vertebrae Atlas: C1, supports head, articulates with occipital condyles Axis: C2; Atlas pivots around the dens of Axis © McGraw Hill, LLC 77  Figure 7.35 Cervical Vertebrae: C1 and C2 Access the text alternative for slide images. © McGraw Hill, LLC 78  Thoracic and Lumbar Vertebrae 12 thoracic vertebrae: Found in chest region Larger than cervical vertebrae Articulate with ribs Long, pointed spinous process, slopes downward 5 lumbar vertebrae: Found in small of back Large bodies Weight-bearing Thick, short spinous processes, almost horizontal © McGraw Hill, LLC 79  Figure 7.37 Cervical, Thoracic, and Lumbar Vertebrae Access the text alternative for slide images. © McGraw Hill, LLC 80  Sacrum and Coccyx Sacrum: Triangular structure at base of vertebral column Typically consists of 5 fused vertebrae Median sacral crest: Fused spinous processes of vertebrae Posterior sacral foramina: Openings for blood vessels and nerves Forms sacroiliac joints, which transmit body weight to legs Forms posterior wall of pelvic cavity Sacral promontory: Projection at upper margin Sacral canal: Formed by vertebral foramina Sacral hiatus: Opening at inferior tip of sacrum Coccyx: Tailbone Usually consists of 4 fused vertebrae Fuse between ages of 25 and 30 © McGraw Hill, LLC 81  Figure 7.38 Sacrum and Coccyx Access the text alternative for slide images. © McGraw Hill, LLC 82  Table 7.8 Bones of the Vertebral Column Bones Number Special Features Bones Number Special Features Cervical 7 Transverse foramina; Lumbar 5 Large bodies; thinner vertebra facets of atlas that vertebra transverse processes articulate with that project laterally; occipital condyles of short, thick spinous skull; dens of axis that processes that project articulates with atlas; posteriorly nearly spinous processes of horizontal second through sixth vertebrae are bifid Thoracic 12 Transverse processes Sacrum 5 Posterior sacral vertebra that project posteriorly vertebrae foramina, auricular at sharp angles; fused surfaces, sacral pointed spinous promontory, sacral processes that slope canal, sacral hiatus, downward; facets that anterior sacral articulate with ribs foramina Coccyx 4 Attached by ligaments vertebrae to the margins of the fused sacral hiatus © McGraw Hill, LLC 83  Clinical Application 7.3 Disorders of the Vertebral Column Herniated or Ruptured (protruding) disc: break in the outer portion of an intervertebral disc; compresses spinal nerves, causing numbness, pain, loss of muscle function Spondylolisthesis: results from vertebra sliding out of place over the vertebra beneath it; very painful Kyphosis: exaggerated thoracic curvature of the spine; rounded shoulders and hunchback; caused by poor posture, injury, disease Scoliosis: abnormal lateral curvature of the spine; one shoulder or hip may be lower than the other, leading to compression of visceral organs Lordosis: exaggerated lumbar curvature of the spine; swayback Compression fractures: fractures of vertebral bodies become more common with age, as intervertebral discs become rigid and shrink; back may bow due to accentuated curvature © McGraw Hill, LLC 84  Figure 7D Pathological Curvatures of the Vertebral Column Access the text alternative for slide images. © McGraw Hill, LLC 85  7.8 Thoracic Cage Thoracic cage: Includes ribs, thoracic vertebrae, sternum, and costal cartilages that attach the ribs to the sternum Supports pectoral girdle and upper limbs Protects thoracic and upper abdominal viscera Role in breathing © McGraw Hill, LLC 86  Ribs and Their Structure Humans have 12 pairs of ribs: True ribs: Vertebrosternal, 7 pairs, connect directly to sternum False ribs (5 pairs): Vertebrochondral ribs: Upper 3 pairs, costal cartilages connect to Cartilage #7 Floating ribs: Vertebral, lower 2 pairs, no connection to sternum Structure of a rib: Shaft: main portion; long and slender Head: posterior end; articulates with vertebrae Tubercle: articulates with vertebra Costal cartilage: hyaline cartilage, connects rib to sternum © McGraw Hill, LLC 87  Figure 7.39 The Thoracic Cage (b): Jupiterimages/Thinkstock/Getty Images Access the text alternative for slide images. © McGraw Hill, LLC 88  Figure 7.40 A Typical Rib Access the text alternative for slide images. © McGraw Hill, LLC 89  Sternum Sternum (breastbone): Along midline of anterior thoracic cage 3 parts: Manubrium: Upper part Body: Middle and largest part Xiphoid process: Lower part Articulates with costal cartilages of ribs, and clavicles © McGraw Hill, LLC 90  7.9 Pectoral Girdle Pectoral (shoulder) girdle: Consists of 2 clavicles and 2 scapulae: Clavicles = collarbones; anterior portions Scapulae = shoulder blades; posterior portions Forms incomplete ring; open in back Supports upper limbs Attachment site for muscles that move upper limbs © McGraw Hill, LLC 91  Figure 7.41 Pectoral Girdle: Clavicles and Scapulae (b): Courtesy, Dale Butler Access the text alternative for slide images. © McGraw Hill, LLC 92  Clavicles and Scapulae Clavicles: S-shaped Articulate with manubrium and scapulae Brace the scapulae, which are freely movable Attachments for muscles of chest, back, and upper limbs Scapulae: Broad, thin, triangular bones in upper back Spine: Divided posterior surface into 2 parts Supraspinous fossa: Depression above spine Infraspinous fossa: Depression below spine Acromion process: Tip of shoulder Coracoid process: Attaches to upper limb and chest muscles Glenoid cavity (fossa): Articulates with head of humerus © McGraw Hill, LLC 93  Figure 7.42 Scapula Access the text alternative for slide images. © McGraw Hill, LLC 94  7.10 Upper Limb Bones of the Upper Limb: Form framework of upper arm, forearm, hand Provide muscle attachments, and work with muscles for limb movement Bones of the upper limb: Humerus Radius Ulna Carpals Metacarpals Phalanges © McGraw Hill, LLC 95  Figure 7.43 Upper Limb (d): Courtesy, Dale Butler Access the text alternative for slide images. © McGraw Hill, LLC 96  Humerus Humerus: Only bone of upper arm Head Greater tubercle Lesser tubercle Anatomical neck Surgical neck Deltoid tuberosity Capitulum (lateral condyle) Trochlea (medial condyle Lateral epicondyle Medial epicondyle Coronoid fossa Olecranon fossa © McGraw Hill, LLC 97  Figure 7.44 Humerus Access the text alternative for slide images. © McGraw Hill, LLC 98  Radius and Ulna Radius: Lateral forearm bone; shorter than ulna Head Radial tuberosity Styloid process Ulnar notch Ulna: Medial forearm bone: longer than radius Trochlear notch (U-shaped) Olecranon process Coronoid process Radial notch Head (at distal end) Styloid process © McGraw Hill, LLC 99  Figure 7.45 Radius and Ulna Access the text alternative for slide images. © McGraw Hill, LLC 100  Hand Each hand consists of the wrist, palm, and fingers (digits): Carpal (wrist) bones (8): Scaphoid Lunate Triquetrum Pisiform Hamate Capitate Trapezoid Trapezium Metacarpal (hand) bones (5) Phalanges (finger bones, 14): Proximal phalanx Middle phalanx Distal phalanx © McGraw Hill, LLC 101  Figure 7.46 Hand (c): Courtesy, Dale Butler Access the text alternative for slide images. © McGraw Hill, LLC 102  7.11 Pelvic Girdle Pelvic Girdle consists of 2 hip (coxal, pelvic, or innominate) bones Pelvis = pelvic girdle + sacrum + coccyx Pelvic Girdle: Supports trunk of body Protects viscera, such as urinary bladder Transmits weight to lower limbs Provides attachment for lower limbs © McGraw Hill, LLC 103  Figure 7.48 Pelvic Girdle (c): Image Source/Getty Images Access the text alternative for slide images. © McGraw Hill, LLC 104  Hip Bones Each hip bone consists of 3 fused bones: Ilium (largest, most superior part): Iliac crest Iliac spines Greater sciatic notch Ischium (L-shaped, lowest part): Supports weight while sitting Ischial spines Ischial tuberosity Pubis (anterior portion): Pubic symphysis Pubic arch Acetabulum: Depression for head of femur Obturator foramen: Opening between pubis and ischium © McGraw Hill, LLC 105  Figure 7.49 Hip Bones: Medial and Lateral Views Access the text alternative for slide images. © McGraw Hill, LLC 106  True Pelvis and False Pelvis False (Upper, Greater) Pelvis: Superior to pelvic brim Bounded by lumbar vertebrae posteriorly Bounded by iliac bones laterally Bounded by abdominal wall anteriorly Helps support abdominal organs True (Lower, Lesser) Pelvis: Inferior to pelvic brim Bounded by sacrum and coccyx posteriorly Bounded by lower ilium, ischium, and pubic bones laterally and anteriorly © McGraw Hill, LLC 107  Differences Between a Male and Female Pelvis Female pelvis: Functions as birth canal Iliac bones more flared Broader hips than male Pelvic cavity wider than male Pubic arch angle greater More distance between ischial spines and ischial tuberosities Sacral curvature shorter and flatter Lighter in weight Male pelvis: Less flared Heavier in weight © McGraw Hill, LLC 108  Figure 7.50 Female Pelvis and Male Pelvis Access the text alternative for slide images. © McGraw Hill, LLC 109  7.12 Lower Limb Lower limb bones form framework of each thigh, leg, and foot Bones of the lower limb: Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges © McGraw Hill, LLC 110  Figure 7.51 Lower Limb (d): Courtesy, Dale Butler Access the text alternative for slide images. © McGraw Hill, LLC 111  Femur Femur (thigh bone): Longest bone of body Parts of the femur: Head Fovea capitis Neck Greater trochanter Lesser trochanter Linea aspera Medial and lateral condyles Medial and lateral epicondyles © McGraw Hill, LLC 112  Figure 7.52 Femur Access the text alternative for slide images. © McGraw Hill, LLC 113  Patella Patella (Kneecap): Flat sesamoid bone located in the quadriceps tendon Anterior surface of knee joint Helps with lever actions with movement of lower limbs © McGraw Hill, LLC 114  Tibia and Fibula Tibia (shin bone): Larger of 2 leg bones; lies medial to fibula Condyles at proximal end Tibial tuberosity is attachment site for patellar ligament Medial malleolus Fibula: Long, slender bone; lateral side of tibia Non-weight bearing Head Lateral malleolus © McGraw Hill, LLC 115  Figure 7.53 Tibia and Fibula Access the text alternative for slide images. © McGraw Hill, LLC 116  Foot Tarsal (Ankle) Bones (7): Calcaneus: Heel bone Talus: Articulates with tibia Navicular Cuboid Lateral cuneiform Intermediate cuneiform Medial cuneiform Metatarsal (Foot) Bones (5) Phalanges (Toe Bones, 14): Proximal Middle Distal © McGraw Hill, LLC 117  Figure 7.54 Foot, Medial View (a): Courtesy, Dale Butler Access the text alternative for slide images. © McGraw Hill, LLC 118  Figure 7.55 Foot, Superior View (b): Courtesy, Dale Butler © McGraw Hill, LLC 119  7.13 Life-Span Changes Decrease in height begins at about age 30 Calcium levels fall Bones become brittle and more prone to fracture Osteoclasts outnumber osteoblasts Spongy bone weakens before compact bone Bone loss rapid in menopausal women Hip fractures common Vertebral compression fractures common © McGraw Hill, LLC 120  End of Main Content Because learning changes everything. ® www.mheducation.com © McGraw Hill LLC. 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