Skeletal System Lecture Notes PDF

Chapter 6-Skeletal System Functions 1. Support 2. Protect 3. Movement 4. Storage 5. Blood cell production 1  Components of Skeletal System Bone Cartilage: reduce friction and model for bone formation Tendons: attach bone to muscle...

Chapter 6-Skeletal System Functions 1. Support 2. Protect 3. Movement 4. Storage 5. Blood cell production 1  Components of Skeletal System Bone Cartilage: reduce friction and model for bone formation Tendons: attach bone to muscle Ligaments: attach bone to bone 2  Background Information Bones, cartilage, tendons, and ligaments are connective tissues. Proteoglycans: - large polysaccharides attached to proteins - part of ground substance - store water 3  Bone’s extracellular matrix is collagen and minerals (flexible and able to bear weight) Cartilage’s extracellular matrix is collagen and proteoglycans (good shock absorber) Tendons and ligaments’ extracellular matrix is collagen (very tough) 4  Classification of Bones Based on shape: long, short, flat, irregular Type of bone tissue: compact and spongy (cancellous) 5  Bone Shapes Long: - Ex. Femur, tibia, fibula Short: – Ex. Carpals, tarsals, phlanges Flat: – Ex. Ribs, sternum, skull Irregular: – Ex. Vertebrae and facial 6  Long Bone Structures Diaphysis: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. – shaft Articular cartilage Epiphysis – compact bone Epiphyseal plates in juveniles tissue (on outside) Epiphysis: Spongy bone – ends Compact bone Medullary cavity (contains – spongy bone tissue Diaphysis red marrow in juveniles and yellow marrow in adults) Articular cartilage: Periosteum Endosteum - covers epiphyses Young bone - reduces friction (a) 7  Epiphyseal plate: – site of growth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular cartilage Epiphysis – between diaphysis and epiphysis Epiphyseal lines in adults Spongy bone Compact bone Medullary cavity: Medullary cavity (contains red marrow in juveniles and yellow marrow in adults) Diaphysis – center of diaphysis Periosteum Endosteum – red or yellow marrow (b) Adult bone  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Periosteum: Articular cartilage Epiphysis membrane around Epiphyseal plates in juveniles bone’s outer surface Spongy bone Compact bone Endosteum: Medullary cavity (contains Diaphysis red marrow in juveniles membrane that lines and yellow marrow in adults) medullary cavity Periosteum Endosteum Young bone (a) 9  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular cartilage Epiphysis Epiphyseal plates in juveniles Epiphyseal lines in adults Spongy bone Compact bone Medullary cavity (contains Diaphysis red marrow in juveniles and Diaphysis yellow marrow in adults) Periosteum Endosteum Young bone Adult bone (a) (b) Osteons (haversian systems) Endosteum Inner layer Periosteum Outer layer Compact bone Central canals Spongy bone with trabeculae Connecting vessels Medullary cavity 10 Adult bone (c)  Compact Bone Tissue Location: outer part of diaphysis (long Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. bones) and thinner surfaces of Osteons other bones (haversian systems) Endosteum Inner layer Osteon: Periosteum Outer - structural unit of compact layer Compact bone bone Central canals - includes lamella, lacunae, Spongy bone with trabeculae canaliculus, central canal, Connecting vessels osteocytes Medullary cavity Adult bone Lamella: (c) rings of bone matrix 11  Lacunae: spaces between lamella Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Canaliculus: - tiny canals Osteons (haversian systems) Endosteum Inner - transport nutrients and Periosteum layer remove waste Outer layer Compact bone Central canals Spongy bone Central canal: with trabeculae - center of osteon Medullary Connecting vessels cavity - contains blood vessels (c) Adult bone 12  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Osteon Lamellae on Concentric rings surface of bone of lamellae Lamellae between osteons Central canal Periosteum Blood vessel within the periosteum Blood vessels connecting to a central canal Blood vessels within a central (Haversian) canal Canaliculi LM 400x Osteocytes in lacunae Canaliculi (b) (a) Lacunae Blood vessel connecting to a central canal between osteons a: © Trent Stephens  Spongy Bone Tissue Cancellous bone Location: epiphyses of long bones and center of other bones Trabeculae: interconnecting rods, spaces contain marrow No osteons 14  Bone Cells Osteocytes: maintain bone matrix Osteoblasts: build bone Osteoclasts: carve bone 15  Bone Formation Ossification: process of bone formation (occurs in utero) Osteoblast’s role: - build bone - after an osteoblast becomes surrounded by bone matrix it becomes an osteocyte 16  Ossification center: where bone formation begins Primary ossification center: - where bone 1st begins to appear - forms diaphyses Secondary ossification center: forms epiphyses 17 Intramembranous Ossification Bone formation within connective tissue membranes Osteoblasts build bone Ex. Skull bones 18  Endochondral Ossification Bone formation inside cartilage Cartilage models are replaced by bone Ex. All bones (except skull) 20 Steps in Endochondral Ossification 1. Chondroblasts build a cartilage model, the chrondroblasts become chondrocytes. 2. Cartilage model calcifies (hardens). 3. Osteoblasts invade calcified cartilage and a primary ossification center forms diaphysis. 4. Secondary ossification centers form epiphysis. 5. Original cartilage model is almost completely ossified and remaining cartilage is articular cartilage. 21  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Femur Patella Epiphysis Epiphyseal plate Diaphysis (a) Length of bone increases. Epiphyseal side 1 New cartilage is Thickness of produced on 1 epiphyseal the epiphyseal side plate remains of the plate as the Chondrocytes 1 unchanged. chondrocytes divide Epiphyseal divide and enlarge. and form stacks plate of cells. 2 2 Chondrocytes mature and 2 Bone is 3 added to enlarge. Calcified cartilage diaphysis. 3 Matrix is calcified, is replaced by bone. and chondrocytes die. 3 Bone of 4 The cartilage on diaphysis 4 the diaphyseal side 4 of the plate is LM 400x (b) replaced by bone. Diaphyseal side (c) (a): © Ed Reschke/Peter Arnold, Inc./ Photolibrary.com; (c): © Bio-Photo Assocs/Photo Researchers, Inc. 23  Bone Growth Infancy and youth: - long bones lengthen at epiphyseal plate - long bones widen by adding more lamella End of bone growth (in length): epiphyseal plate is replaced by an epiphyseal line 24 Figure 6.2b Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 26  Bone Remodeling What is it? - removal of existing bone by osteoclasts and deposition of new bone by osteoblasts - occurs in all bones - responsible for changes in bone shape, bone repair, adjustment of bone to stress, and calcium ion regulation 27  Bone Repair 1. Broken bone causes bleeding and a blood clot forms. 2. Callus forms which is a fibrous network between 2 fragments. 3. Cartilage model forms first then, osteoblasts enter the callus and form cancellous bone this continues for 4-6 weeks after injury. 4. Cancellous bone is slowly remodeled to form compact and cancellous bone. 28 Bone and Calcium Homeostasis Bone is a major storage site for calcium Movement of calcium in and out of bone helps determine blood levels of calcium Calcium moves into bone as osteoblasts build new bone Calcium move out of bone as osteoclasts break down bone Calcium homeostasis is maintained by parathyroid hormone (PTH) and calcitonin 30  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Decreased Increased 1 5 blood Ca2+ blood Ca2+ Posterior aspect of thyroid gland Parathyroid 1 Decreased blood Ca2+ stimulates PTH glands secretion from parathyroid glands. Kidney Thyroid gland 2 PTH stimulates osteoclasts to break down bone and release Ca2+ into the blood. 3 In the kidneys, PTH increases Ca2+ reabsorption from the urine. PTH also 3 stimulates active Vitamin D formation. PTH Calcitonin 4 Vitamin D promotes Ca2+ absorption from the small intestine into the blood. 2 6 Stimulates 5 Increased blood Ca2+ stimulates calcitonin Vitamin D Inhibits secretion from the thyroid gland. osteoclasts osteoclasts 6 Calcitonin inhibits osteoclasts, which Bone allows for enhanced osteoblast uptake of Osteoclasts Ca2+ from the blood to deposit into bone. promote Ca2+ uptake from Ca2+ 4 bone. Osteoblasts promote Ca2+ deposition in bone. Small intestine Ca2+ Blood  Hematopoietic Tissue What is it? tissue that makes blood cells Red marrow: location of blood forming cells Yellow marrow: mostly fat 32  Location of hematopoietic tissue in newborns: most bones (red marrow) Location of hematopoietic tissue in adults: - red is replaced with yellow marrow - red marrow is mainly in epiphyses of femur and humerus 33  Bone Anatomy Foramen: - hole - Ex. Foramen magnum Fossa: - depression - Ex. Glenoid fossa Process: - projection - Ex. Mastoid process 34  Condyle: - smooth, rounded end - Ex. Occipital condyle Meatus: - canal-like passageway - Ex. External auditory meatus Tubercle: - lump of bone - Ex. Greater tubercle 35 36  Axial Skeleton Mastoid process: attached to neck muscles External auditory meatus: ear canal Nasolacrimal canal: - canal between nasal cavity and eye - conducts tears 37  Styloid process: attachment site for tongue Mandibular fossa: depression where lower jaw and skull meet Glenoid fossa: where humerus meets scapula 38  Hard palate: roof of mouth Foramen magnum: hole where spinal cord joins brainstem 39  Zygomatic: cheek bone Mandible: lower jaw Maxilla: upper jaw 40  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Incisive fossa Maxilla Palatine process of maxillary bone Hard Horizontal plate of palatine bone palate Inferior orbital fissure Zygomatic bone Sphenoid bone Vomer Foramen ovale Foramen spinosum Styloid process Mandibular fossa External auditory canal Carotid canal Jugular foramen Occipital condyle Mastoid process Foramen magnum Temporal bone Occipital bone Nuchal lines Inferior view 44  Vertebral Column 7 cervical vertebra 12 thoracic vertebra 5 lumbar vertebra 1 sacrum 1 coccyx Atlas: - 1st vertebra - holds head Axis: - 2nd vertebra - rotates head 45 Functions of Vertebral Column Support Protect spinal cord Movement 49  Thoracic Cage Protects vital organs 12 pair of ribs Sternum: breastbone True ribs: attach directly to sternum by cartilage False ribs: attach indirectly to sternum by cartilage Floating ribs: not attached to sternum 50 Pectoral Girdle Scapula: shoulder blade Clavicle: collar bone 52 Upper Limb Bones Humerus: upper limb Ulna: forearm Radius: forearm Carpals: wrist Metacarpals: hand 54  Pelvic Girdle Where lower limbs attach to body Pelvis: includes pelvic girdle and coccyx Ischium: inferior and posterior region Ilium: most superior region Acetabulum: hip socket (joint) 59  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Iliac crest Ilium Articular surface (area of Iliac fossa articulation with sacrum) Pelvic brim Greater Acetabulum sciatic notch Greater Ischium sciatic notch Pubis Ischial spine Ischial spine Ischium Pubic symphysis Obturator foramen Ischial tuberosity (a) Lateral view (b) Medial view 63 Lower Limb Bones Femur: thigh Patella: knee cap Tibia: large lower leg Fibula: small lower leg 64  Tarsals: ankle Metatarsals: foot Phalanges: toes and fingers 65  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Head Head Greater trochanter Greater trochanter Neck Neck Lesser trochanter Linea aspera Body (shaft) of femur Medial epicondyle Lateral epicondyle Lateral epicondyle Intercondylar fossa Lateral condyle Medial condyle Patellar groove (a) Anterior view Posterior view (b) Anterior surface 67 Anterior view 70  Articulations What are they? where 2 bones come together (joint) Synarthrosis: - nonmovable joint - Ex. skull Amphiarthrosis: - slightly movable joint - Ex. Between vertebrae Diarthrosis: - freely movable joint - Ex. knee, elbow, wrist 71 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Parietal bone Frontal Squamous bone suture Coronal suture Occipital bone Lambdoid suture Mastoid (posterolateral) fontanel Sphenoidal (anterolateral) fontanel Temporal bone (a) Lateral view Frontal bones (not yet fused into a single bone) Frontal (anterior) fontanel Parietal Sagittal bone suture Occipital (posterior) fontanel Occipital 72 bone (b) Superior view  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Synovial membrane Joint Blood vessel Fibrous part of joint capsule Nerve capsule Bursa Joint cavity (filled with synovial fluid) Articular cartilage Tendon sheath Tendon Outer layer Bone Periosteum Inner layer 73  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Class and Example Structures Joined Movement of Joint Plane Acromioclavicular Acromion process of Slight scapul Carpometacarpal a and clavicle Carpals and metacarpals Multiple axes as 2–5 a group Costovertebral Ribs and vertebrae Slight Intercarpal Between carpal bones Slight Intermetatarsal Between metatarsal bones Slight Intertarsal Between tarsal bones Slight Intervertebral Between articular processes Slight of Sacroiliac adjacentsacrum Between vertebrae and coxal Slight bone Plane (complex joint with several planes and synchondroses) Tarsometatarsal Tarsal bones and metatarsal Slight bones Saddle Carpometacarpal Carpal and metacarpal Two axes pollicis of thumb Intercarpal Between carpal bones Slight Sternoclavicular Manubrium of sternum Slight and clavicle Saddle Hinge Cubital (elbow) Humerus, ulna, and radius One axis Knee Femur and tibia One axis Interphalangeal Between phalanges One axis Talocrural (ankle) Talus, tibia, and fibula Multiple axes; one predominates Hinge Pivot Medial atlantoaxial Atlas and axis Rotation Proximal radioulnar Radius and ulna Rotation Distal radioulnar Radius and ulna Rotation Pivot Ball-and-Socket Coxal (hip) Coxal bone and femur Multiple axes Humeral (shoulder) Scapula and humerus Multiple axes Ball-and-socket Ellipsoid Atlantooccipital Atlas and occipital Two axes Metacarpopha- bone Metacarpal bones Two axes langeal and (knuckles) Metatarsopha- phalanges Metatarsal bones Two axes langeal (ball of foot) Radiocarpal (wrist) and phalanges Radius and carpal Multiple axes 74 Temporomandibular bones Mandible and temporal Multiple axes; Ellipsoid bone one predominates  Types of Movement Flexion: bending Extension: straightening Abduction: movement away from midline Adduction: movement toward the midline Pronation: rotation of the forearm with palms down Supination: rotation of the forearm with palms up Rotation: movement of a structure about the long axis 75 Effects of Aging on the Skeletal System and Joints 1. Decrease Collagen Production 2. Loss of Bone Density 3. Degenerative Changes 78 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 79