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The Skeletal System Parts of the skeletal system Bones (skeleton)

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2 The Skeletal System Parts of the skeletal system Bones (skeleton)
Joints Cartilages Ligaments Two subdivisions of the skeleton Axial skeleton  bones that form the longitudinal axis of the body Appendicular skeleton  bones of the limbs and girdles

3 Functions of Bones Support the body Protect soft organs
Skull and vertebrae for brain and spinal cord Rib cage for thoracic cavity organs Allow movement due to attached skeletal muscles Store minerals and fats Calcium and phosphorus Fat in the internal marrow cavity Hematopoiesis  blood cell formation

4 Bones of the Human Body The adult skeleton has 206 bones
Two basic types of bone tissue Compact bone Dense; looks smooth and homogeneous Spongy bone Small needle-like pieces of bone Many open spaces

5 Spongy bone Compact bone Figure 5.1

6 Classification of Bones on the Basis of Shape
Bones are classified as: Long Short Flat Irregular

7 Classification of Bones
Long bones Typically longer than they are wide Shaft with heads situated at both ends Contain mostly compact bone All of the bones of the limbs (except wrist, ankle, and kneecap bones) Example: Femur Humerus

8 Figure 5.2a

9 Classification of Bones
Short bones Generally cube-shaped Contain mostly spongy bone Includes bones of the wrist and ankle Sesamoid bones are a type of short bone which form within tendons (patella) Example: Carpals Tarsals

10 Figure 5.2d

11 Classification of Bones
Flat bones Thin, flattened, and usually curved Two thin layers of compact bone surround a layer of spongy bone Example: Skull Ribs Sternum

12 Spongy bone Compact bone Figure 5.1

13 Figure 5.2c

14 Classification of Bones
Irregular bones Irregular shape Do not fit into other bone classification categories Example: Vertebrae Hip bones

15 Figure 5.2b

16 Anatomy of a Long Bone Diaphysis Shaft Composed of compact bone
Epiphysis Ends of the bone Composed mostly of spongy bone

17 Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line
Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Figure 5.3a

18 Anatomy of a Long Bone Epiphyseal plate (Growth plate)
Flat plate of hyaline cartilage seen in young, growing bone Cause the lengthwise growth of long bone Completely replaced by bone at the end of puberty (no more vertical growth)

19 Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line
Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Figure 5.3a

20 Anatomy of a Long Bone Marrow (medullary) cavity
Cavity inside of the shaft Contains yellow marrow (mostly fat) in adults Contains red marrow for blood cell formation in infants In adults, red marrow is situated in cavities of spongy bone and epiphyses of some long bones

21 Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line
Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Figure 5.3a

22 Osteon Lacuna (c) Central canal Interstitial lamellae Figure 5.4c

23 Formation of the Human Skeleton
In embryos, the skeleton is primarily hyaline cartilage During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas Bridge of the nose Parts of ribs Joints

24 Articular cartilage Hyaline cartilage Spongy bone New center of
bone growth New bone forming Epiphyseal plate cartilage Growth in bone width Medullary cavity Bone starting to replace cartilage Invading blood vessels Growth in bone length New bone forming Bone collar Hyaline cartilage model Epiphyseal plate cartilage In an embryo In a fetus In a child Figure 5.5

25 Types of Bone Cells Osteocytes  mature bone cells
Osteoblasts  bone-forming cells Osteoclasts  giant bone-destroying cells Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone Bone remodeling is performed by both osteoblasts and osteoclasts

26 Rickets A disease of children in which the bones fail to calcify. As a result, the bones soften, and the weight-bearing bones of the legs show a definite bowing. Usually due to a lack of calcium in the diet or a lack of Vitamin D

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28 Bone Fractures Fracture  break in a bone Types of bone fractures
Closed (simple) fracture—break that does not penetrate the skin Open (compound) fracture—broken bone penetrates through the skin Bone fractures are treated by: Reduction  the realignment of the broken bone ends Immobilization  cast or traction

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30 Common Types of Fractures
Comminuted  bone breaks into many fragments Compression  bone is crushed Depressed  broken bone portion is pressed inward Impacted  broken bone ends are forced into each other Spiral  ragged break occurs when excessive twisting forces are applied to a bone Greenstick  bone breaks incompletely

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32 The Axial Skeleton Forms the longitudinal axis of the body
Divided into three parts Skull Vertebral column Bony thorax

33 Figure 5.8a Cranium Skull Facial bones Clavicle Thoracic cage Scapula
(ribs and sternum) Scapula Sternum Rib Humerus Vertebra Vertebral column Radius Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges (a) Anterior view Figure 5.8a

34 The Skull Two sets of bones
Cranium  encloses and protects the fragile brain tissue Facial bones  hold the eyes in an anterior position and allow facial muscles to show feelings Bones are joined by sutures Only the mandible is attached by a freely movable joint

35 Coronal suture Frontal bone Parietal bone Sphenoid bone Temporal bone Ethmoid bone Lambdoid suture Lacrimal bone Squamous suture Nasal bone Occipital bone Zygomatic bone Zygomatic process Maxilla External acoustic meatus Mastoid process Alveolar processes Styloid process Mandible (body) Mental foramen Mandibular ramus Figure 5.9

36 Maxilla (palatine process) Hard palate Palatine bone Maxilla
Zygomatic bone Sphenoid bone (greater wing) Temporal bone (zygomatic process) Foramen ovale Vomer Mandibular fossa Carotid canal Styloid process Mastoid process Jugular foramen Occipital condyle Temporal bone Parietal bone Foramen magnum Occipital bone Figure 5.11

37 Coronal suture Frontal bone Parietal bone Nasal bone Superior orbital fissure Sphenoid bone Optic canal Ethmoid bone Temporal bone Lacrimal bone Zygomatic bone Middle nasal concha of ethmoid bone Maxilla Inferior nasal concha Vomer Mandible Alveolar processes Figure 5.12

38 Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity Functions of paranasal sinuses Lighten the skull Give resonance and amplification to voice

39 Frontal sinus Ethmoid sinus Sphenoidal sinus Maxillary sinus
(a) Anterior view Figure 5.13a

40 The Hyoid Bone The only bone that does not articulate with another bone Serves as a moveable base for the tongue Aids in swallowing and speech

41 Greater horn Lesser horn Body Figure 5.14

42 The Vertebral Column Each vertebrae is given a name according to its location There are 24 single vertebral bones separated by intervertebral discs Cervical vertebrae  7 in the neck Thoracic vertebrae  12 in the chest region Lumbar vertebrae  5 associated with the lower back

43 Anterior Posterior 1st cervical vertebra (atlas) Cervical curvature (concave) 7 vertebrae, C1 – C7 2nd cervical vertebra (axis) 1st thoracic vertebra Transverse process Spinous process Thoracic curvature (convex) 12 vertebrae, T1 – T12 Intervertebral disc Intervertebral foramen 1st lumbar vertebra Lumbar curvature (concave) 5 vertebrae, L1 – L5 Sacral curvature (convex) 5 fused vertebrae Coccyx 4 fused vertebrae Figure 5.16

44 Posterior Vertebral Lamina arch Transverse Spinous process process
Superior articular process and facet Pedicle Vertebral foramen Body Anterior Figure 5.19

45 Sacrum and Coccyx Sacrum Formed by the fusion of five vertebrae Coccyx
Formed from the fusion of three to five vertebrae “Tailbone,” or remnant of a tail that other vertebrates have

46 Superior articular process Auricular surface Sacral canal Ala Body Median sacral crest Sacrum Posterior sacral foramina Sacral hiatus Coccyx Figure 5.21

47 The Vertebral Column Problems
Herniated (“slipped”) Disc Can occur in two ways: Drying of the discs, along with a weakening of the surrounding ligaments Exceptional twisting forces on the spine If the disc presses on the spinal cord or spinal nerves it can cause numbness in the legs and excruciating pain

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49 The Vertebral Column Problems
Scoliosis  abnormal curvature of the spine where the spine is curve side to side in an “s-shape” Kyphosis  curving of the spine that causes a bowing of the spine that results in a hunchback Lordosis  an inward curvature of a portion of the lumbar spine

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51 The Bony Thorax Forms a cage to protect major organs
Consists of three parts Sternum Ribs True ribs  attach directly to the sternum by costal cartilages (pairs 1–7) False ribs  either attach indirectly to the sternum or not at all (pairs 8–12) Floating ribs  no sternal attachment at all (pairs 11–12) Thoracic vertebrae

52 T1 vertebra Jugular notch Clavicular notch Manubrium Sternal angle
Body Sternum Xiphisternal joint True ribs (1 –7) Xiphoid process False ribs (8 –12) Intercostal spaces L1 Vertebra Costal cartilage Floating ribs (11, 12) (a) Figure 5.22a

53 The Appendicular Skeleton
Composed of 126 bones Limbs (appendages) Pectoral girdle Pelvic girdle

54 Figure 5.8a Cranium Skull Facial bones Clavicle Thoracic cage Scapula
(ribs and sternum) Scapula Sternum Rib Humerus Vertebra Vertebral column Radius Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges (a) Anterior view Figure 5.8a

55 Figure 5.8b Cranium Bones of pectoral girdle Clavicle Scapula Upper
limb Rib Humerus Vertebra Radius Bones of pelvic girdle Ulna Carpals Phalanges Metacarpals Femur Lower limb Tibia Fibula (b) Posterior view Figure 5.8b

56 The Pectoral (Shoulder) Girdle
Composed of two bones Clavicle  collarbone Articulates with the sternum medially and with the scapula laterally Scapula  shoulder blade Articulates with the clavicle at the acromioclavicular joint These bones allow the upper limb to have exceptionally free movement

57 Acromio clavicular joint Clavicle Scapula (a) Articulated right shoulder (pectoral) girdle showing the relationship to bones of the thorax and sternum Figure 5.23a

58 Acromial (lateral) end Anterior
Posterior Sternal (medial) end Acromial (lateral) end Anterior Superior view Acromial end Sternal end Anterior Posterior Inferior view (b) Right clavicle, superior and inferior views Figure 5.23b

59 Glenoid cavity at lateral angle
Coracoid process Suprascapular notch Superior angle Acromion Glenoid cavity at lateral angle Spine Medial border Lateral border (c) Right scapula, posterior aspect Figure 5.23c

60 (d) Right scapula, anterior aspect
Acromion Suprascapular notch Superior border Coracoid process Superior angle Glenoid cavity Lateral (axillary) border Medial (vertebral) border Inferior angle (d) Right scapula, anterior aspect Figure 5.23d

61 Bones of the Upper Limbs
Humerus Forms the upper arm Single bone Proximal end articulation Head articulates with the glenoid cavity of the scapula Distal end articulation Trochlea and capitulum articulate with the bones of the forearm

62 Head of humerus Greater tubercle Lesser tubercle Anatomical neck Intertubercular sulcus Deltoid tuberosity Radial fossa Medial epicondyle Coronoid fossa Capitulum Trochlea (a) Figure 5.24a

63 Head of humerus Anatomical neck Surgical neck Radial groove Deltoid tuberosity Medial epicondyle Olecranon fossa Lateral epicondyle Trochlea (b) Figure 5.24b

64 Bones of the Upper Limbs
The forearm has two bones Ulna  medial bone of forearm in anatomical position Proximal end articulation Coronoid process and olecranon articulate with the humerus Radius  lateral bone of forearm in anatomical position Head articulates with the capitulum of the humerus

65 Trochlear notch Olecranon Head Coronoid process Neck Proximal radioulnar joint Radial tuberosity Radius Ulna Inter- osseous membrane Ulnar styloid process Radial styloid process Distal radioulnar joint (c) Figure 5.24c

66 Bones of the Upper Limbs
Hand Carpals  wrist Eight bones arranged in two rows of four bones in each hand Metacarpals  palm Five per hand Phalanges  fingers and thumb Fourteen phalanges in each hand In each finger, there are three bones In the thumb, there are only two bones

67 Distal Middle Phalanges (fingers) Proximal 3 2 4 Metacarpals (palm) 5
1 Hamate Trapezium Carpals (wrist) Pisiform Trapezoid Triquetrum Scaphoid Lunate Capitate Ulna Radius Figure 5.25

68 Bones of the Pelvic Girdle
Formed by two coxal (ossa coxae) bones Composed of three pairs of fused bones Ilium  large flaring bone that forms most of the hip bone Ischium  “sit down” bone; forms the most inferior part Pubis  most anterior part of pelvis Pelvic girdle = 2 coxal bones, sacrum Bony pelvis = 2 coxal bones, sacrum, coccyx

69 lliac crest Sacroiliac joint llium Coxal bone (or hip bone) Sacrum Pelvic brim Pubis Coccyx Ischial spine Acetabulum Ischium Pubic symphysis Pubic arch (a) Figure 5.26a

70 Pubic arch (less than 90°)
False pelvis Inlet of true pelvis Pelvic brim Pubic arch (less than 90°) False pelvis Inlet of true pelvis Pelvic brim Pubic arch (more than 90°) (c) Figure 5.26c

71 Bones of the Lower Limbs
Femur  thigh bone The heaviest, strongest bone in the body Proximal end articulation Head articulates with the acetabulum of the coxal (hip) bone Distal end articulation Lateral and medial condyles articulate with the tibia in the lower leg

72 Neck Head Inter- trochanteric line Lesser trochanter Lateral condyle Patellar surface (a) Figure 5.27a

73 Bones of the Lower Limbs
The lower leg has two bones Tibia  Shinbone; larger and medially oriented Proximal end articulation Medial and lateral condyles articulate with the femur to form the knee joint Fibula  Thin and sticklike; lateral to the tibia Has no role in forming the knee joint

74 Intercondylar eminence
Lateral condyle Medial condyle Head Tibial tuberosity Proximal tibiofibular joint Interosseous membrane Anterior border Fibula Tibia Distal tibiofibular joint Medial malleolus Lateral malleolus (c) Figure 5.27c

75 Bones of the Lower Limbs
The foot Tarsals  seven bones in the ankle Two largest tarsals Calcaneus (heel bone) Talus Metatarsals  five bones form the sole of the foot Phalanges  fourteen bones form the toes

76 Intermediatecuneiform Lateral cuneiform
Phalanges: Distal Middle Proximal Tarsals: Medial cuneiform Metatarsals Tarsals: Intermediatecuneiform Lateral cuneiform Navicular Cuboid Talus Calcaneus Figure 5.28

77 Joints The site where two or more bones meet Articulations of bones
Functions of joints Hold bones together Allow for mobility Two ways joints are classified Functionally Structurally

78 Nonaxial Uniaxial Biaxial Multiaxial
(a) Plane joint  the articular surfaces are essentially flat, and only short slipping or gliding movements are allowed. (a) Figure 5.32a

79 Nonaxial Uniaxial Biaxial Multiaxial
(b) Hinge joint  angular movement is allowed in just one plane like a hinge (b) Humerus Ulna Figure 5.32b

80 Nonaxial Uniaxial Biaxial Multiaxial
(c) Pivot joint  rotation bone can only turn around one axis, or pivot Ulna (c) Radius Figure 5.32c

81 Nonaxial Uniaxial Biaxial Multiaxial (d) Condylar joint  “knuckle like”; bone can move side to side and back and forth but cannot rotate around its long axis (d) Metacarpal Phalanx Figure 5.32d

82 Nonaxial Uniaxial Biaxial Multiaxial (e) Saddle joint  similar shape to a saddle, these allow for essentially the same movement as condylar joints Carpal Metacarpal #1 (e) Figure 5.32e

83 Nonaxial Uniaxial Biaxial Multiaxial (f)
(f) Ball-and-socket joint  spherical head of one bone fits into a rounded socket of another; allows for multi-axial movement Head of humerus Scapula Figure 5.32f

84 Problems Associated with Joints
Dislocation This happens when a bone is forced out of its normal position in the joint cavity

85 Problems Associated with Joints
Sprain An injury in the joint caused by the ligament being stretched beyond its capacity. Can occur in any joint, but are most common in the ankle and wrist.

86 Inflammatory Conditions Associated with Joints
Bursitis  inflammation of a bursa usually caused by a blow or friction

87 Inflammatory Conditions Associated with Joints
Tendonitis  inflammation of tendon sheaths Arthritis  inflammatory or degenerative diseases of joints Over 100 different types The most widespread crippling disease in the United States Initial symptoms: pain, stiffness, swelling of the joint

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89 Clinical Forms of Arthritis
Osteoarthritis (OA) Most common chronic arthritis Probably related to normal aging processes Rheumatoid Arthritis (RA) An autoimmune disease—the immune system attacks the joints Symptoms begin with bilateral inflammation of certain joints Often leads to deformities

90 Figure 5.33

91 Clinical Forms of Arthritis
Gouty Arthritis (Gout) Inflammation of joints is caused by a deposition of uric acid crystals from the blood Can usually be controlled with diet More common in men

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93 Skeletal Changes Throughout Life
Osteoporosis Bone-thinning disease afflicting 50 percent of women over age 65 20 percent of men over age 70 Disease makes bones fragile and bones can easily fracture Vertebral collapse results in kyphosis Estrogen aids in health and normal density of a female skeleton

94 Figure 5.36


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