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Chapter 6 The Skeletal System 7-1 6-1: Skeletal System Functions Skeletal system supports body weight & helps body to move Includes bones, cartilages, joints, ligaments, & connective tissues 7-2 Functions of skeletal system: – Support—provides framework of body – Storage—stores calcium – Blood cell production—produces red blood cells – Protection—surrounds soft tissues & organs – Movement—works with skeletal muscle 7-3 6-1 Checkpoint 1. Name the five primary functions of the skeletal system. 7-4 6-2: Bone Classification Bone consists of cells, fibers, & calcium phosphate Macroscopic Features of Bone Types of bone: – Long – Short – Flat – Irregular 7-6 Long bone features: – Diaphysis (shaft) surrounds a marrow cavity containing bone marrow – Epiphysis at each end of the bone Bone tissue – Compact bone (in diaphysis) – Spongy bone (in epiphysis) Periosteum covers bone; endosteum is within bone 7-7 7-8 Microscopic Features of Bone Osteocytes (bone cells) are found in lacunae – Lacunae arrange in layers (lamellae) – Channels (canaliculi) connect lacunae Osteon composes compact bone – Lamellae arrange around a central canal of blood vessels – Perforating canals connect blood vessels 7-9 7 - 10 Cells in Bone Osteocytes (bone cells) maintain bone structure Osteoclasts dissolve bone – Release calcium into the bloodstream Osteoblasts build bone through ossification – Remove calcium from bloodstream 7 - 11 6-2 Checkpoint 1. Identify the four shapes of bones. 2. Mature bone cells are known as bone-building cells are known as and are bone-dissolving cells. 3. If the activity of osteoclasts exceeds that of osteoblasts in a bone, how will the mass of the bone be affected? 7 - 12 , , 6-3: Bone Formation During development, cartilage & tissues are replaced by bone (ossification) Intramembranous Ossification Sheets of membranes ossify and form the flat bones – Skull, clavicles, jaw 7 - 13 Endochondral Ossification Forms most of the skeleton’s bones Cartilage replaced by bone – A cartilage model develops – Cartilage cells get replaced by osteoblasts at primary ossification center – Epiphyseal plates (growth plates) form at ends of bone – Secondary ossification center continues lengthening bone 7 - 14 7 - 15 Requirements for Bone Growth Normal bone growth depends on: – Calcium intake – Vitamin D—helps with calcium absorption – Vitamin A & C—needed for bone growth & maintenance – Hormones 7 - 16 6-3 Checkpoint 1. How could x-rays of the femur be used to determine whether a person has reached full height? 2. Why are pregnant women given calcium supplements and encouraged to drink milk even though their skeletons are fully formed? 7 - 17 6-4: Bone Homeostasis Bones are recycled & replaced each year through remodeling by osteoclasts & osteoblasts Remodeling & Support Stressed bones become thicker & stronger – Exercise helps strengthen bones 7 - 18 Repair of Fractures Fracture—crack or break in bone Steps in healing bone: – Bleeding occurs & a clot is formed – An external callus forms over an internal callus – Osteoblasts reform damaged bone 7 - 19 Classification of Fractures Nondisplaced (bone ends keep position) vs. displaced (bone ends out of alignment) 7 - 20 Complete break (broken through) vs. incomplete break (not broken through) 7 - 21 Linear (break parallel to bone axis) vs. transverse (break perpendicular to bone axis) 7 - 22 Open fracture (bone ends penetrate skin) vs. closed fracture (bone ends don’t penetrate skin) 7 - 23 6-4 Checkpoint 1. Describe bone remodeling. 2. Why would you expect the arm bones of a weight lifter to be thicker & heavier than those of a jogger? 3. What is the difference between an closed fracture & an open fracture? 7 - 24 6-5: Osteoporosis Bones become thinner & weaker with age Osteoporosis—loss of bone density & mass; bones become more porous – More common in women – Prevention: calcium, vitamin D, exercise 7 - 25 6-5 Checkpoint 1. Define osteoporosis. 2. Why is osteoporosis more common in older women than in older men? 7 - 26 6-6: Skeletal Divisions Bones have external features for muscle attachment, passage of nerves & blood vessels Skeletal Divisions Axial skeleton includes the skull, rib cage, & vertebral column Appendicular skeleton includes the arms, legs, pectoral & pelvic girdles 7 - 28 7 - 29 6-6 Checkpoint 1. List the parts of the axial skeleton and the appendicular skeleton. 7 - 30 6-7: Axial Skeleton Supports & protects brain, spinal cord, organs in thoracic cavity The Skull Composed of the cranium & facial bones – Also includes auditory ossicles (ear bones) & hyoid bone (tongue attachment) Bones of the Cranium Frontal bone – Forms forehead; contains sinuses to lighten skull Parietal bones – Forms top of skull Occipital bone – Forms back of skull; contains foramen magnum for spinal cord 7 - 32 Temporal bone – Forms sides of skull; contains external acoustic meatus, mastoid & styloid processes Sphenoid & ethmoid bones – Form floor of skull Sutures connect cranial bones – Coronal, sagittal, lambdoid, squamous 7 - 33 7 - 34 7 - 35 Bones of the Face Maxillae form the upper jaw Palatine bones form roof of mouth Vomer forms nasal septum Zygomatic bones form cheeks Nasal bones form bridge of nose Mandible is the lower jaw 7 - 37 Vertebral Column Vertebral column protects the spinal cord, supports weight of skull – Consists of vertebrae, sacrum & coccyx Divisions of vertebral column: – Cervical (7 vertebrae) – Thoracic (12 vertebrae) – Lumbar (5 vertebrae) – Sacral & coccygeal (fused vertebrae) 7 - 38 7 - 39 Parts of a vertebra: – Vertebral body—bears weight of spine – Intervertebral disc—pad between vertebrae – Vertebral arch—bone around vertebral foramen (hole for spinal cord) – Pedicles—attach vertebral arch to body – Spinous process & transverse processes— attach muscles 7 - 40 7 - 41 Cervical vertebrae – Have transverse foramina for blood vessels to brain – Include atlas (C1) & axis (C2) Thoracic vertebrae – Heart-shaped body; spinous process points down Lumbar vertebrae – Largest vertebrae; support body weight 7 - 42 7 - 43 Sacrum & coccyx – Fused vertebrae; provide muscle attachment 7 - 44 The Thoracic Cage Divisions of ribs: – Ribs 1 – 7: true ribs (attach to sternum) – Ribs 8 – 10: false ribs (attach to cartilage) – Ribs 11 & 12: floating ribs (don’t attach) Ribs attach muscles & help in breathing Sternum has three parts: – Manubrium, body, & xiphoid process 7 - 45 7 - 46 6-7 Checkpoint 1. Which bone of the cranium joins directly with the vertebral column? 2. What are the sutures of the skull, and where are they found? 3. Why are the bodies of lumbar vertebrae so large? 4. What are the differences between true ribs & false ribs? 6-8: Appendicular Skeleton Includes bones of upper & lower limbs, pectoral & pelvic girdles The Pectoral Girdle Joins upper limb to chest Clavicle – Brace shoulders & connect to sternum Scapula – Flat triangular bone; provides muscle attachment points Scapula joins humerus at glenoid cavity to form shoulder joint Processes: – Acromion joins with clavicle – Coracoid process anchors biceps 7 - 49 7 - 50 The Upper Limb Humerus contains many structures on distal end: – Medial & lateral epicondyles – Trochlea & capitulum—connect to radius & ulna – Coronoid & olecranon fossa— depressions for ulnar processes 7 - 51 7 - 52 Forearm contains radius & ulna Ulna is on medial side of forearm – Contains olecranon & coronoid processes for connection with humerus Radius is on lateral side of forearm – Rotates over ulna 7 - 53 7 - 54 Wrist, hand & fingers – Carpals compose wrist bones – Metacarpals compose palm of hand – Phalanges compose fingers »Each finger has 3 phalanges; thumb has 2 phalanges 7 - 55 7 - 56 The Pelvic Girdle Joins with lower limbs for movement – Consists of 2 coxal bones Each coxal bone is 3 fused bones – Ilium forms upper crest of pelvis – Ischium supports weight while sitting – Pubis connects coxal bones at pubic symphysis 7 - 57 Gender differences in pelvis: – Female pelvis is smoother, broader & lower than male pelvis – Female pelvis has larger pelvic outlet 7 - 59 The Lower Limb Femur is the largest & strongest bone in the body – Joins the coxal bone at the acetabulum – Lateral & medial condyles join with tibia to form knee joint Patella forms the kneecap 7 - 60 Lower leg contains tibia & fibula Tibia forms the shin bone – Medial malleolus forms inner ankle Fibula found on lateral side of leg – Provides stability – Lateral malleolus forms outer ankle 7 - 62 Ankle, foot, & toes – Tarsals compose ankle; calcaneus is heel bone – Metatarsals compose arch of foot – Phalanges compose toes 7 - 64 6-8 Checkpoint 1. The rounded projections on each side of the elbow are parts of which bone? 2. Which of the 2 arm bones is lateral in anatomical position? 3. Which 3 bones make up a coxal bone? 4. When someone breaks their heel bone, what bone is most likely broken? 6-9: Joints Joints exist where 2 bones meet Structural classification of joints: – Fibrous (no movement) – Cartilaginous (limited movement) – Synovial (freely movable) Functional classification of joints – Synarthrosis (immovable) – Amphiarthrosis (slightly movable) – Diarthroisis (freely movable) Immovable Joints (Synarthroses) Can be fibrous or cartilaginous Found in sutures of skull, teeth 7 - 68 7 - 69 Slightly Movable Joints (Amphiarthroses) Can be fibrous or cartilaginous Found in joint between tibia & fibula, pubic symphysis, intervertebral discs 7 - 70 7 - 71 Freely Movable Joints (Diarthroses) Also called synovial joints Found at ends of bones – Covered with articular cartilages Joint is surrounded by joint capsule with synovial fluid – Menisci & bursae absorb shock 7 - 72 7 - 73 Arthritis Pain, stiffness, & swelling of joint Osteoarthritis – Most common type; found in older population Rheumatoid arthritis – Body’s immune system attacks its own tissues 7 - 74 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 7 - 75 6-9 Checkpoint 1. Name & describe the 3 types of joints classified by the amount of movement possible. 2. Bones of the skull are joined by fibrous connective tissue. What type of joint is this? 3. What is arthritis? 7 - 76 6-10: Joint Movements Types of Movements—Gliding Two surfaces slide past each other – Between carpals/tarsals Angular Movements Flexion/extension – Decreases/increases angle between bones Hyperextension – Extension past anatomical position Abduction/adduction – Moving away/towards midline of body Circumduction – Moving body part in a large circle 7 - 78 7 - 79 Rotational Movements Rotation – Turning around an axis (looking L & R) Pronation/supination – Turning palm down/palm up 7 - 80 7 - 81 Special Movements Inversion/eversion – Twisting sole of foot outward/inward Dorsiflexion/plantar flexion – Lifting top of foot up/pushing foot down Protraction/retraction – Push body part forward/pull back body part Elevation/depression – Lift body part up/lower body part 7 - 83 Types of Synovial Joints Gliding joints—surfaces slide – Ex: carpals, tarsals Hinge joints—move in one direction – Ex: elbow, knee Pivot joints—allow rotation – Ex: atlas/axis, radius/ulna 7 - 85 Condylar joint—oval surface rests in a depression – Ex: radius/carpals, phalanges & metacarpals/metatarsals Saddle joints—concave & convex surfaces fit together – Ex: thumb Ball-and-socket joints—head fits in a cup-shaped depression – Ex: shoulder, hip 7 - 87 6-10 Checkpoint 1. Give the proper term for each of the following types of motion: (a) moving the humerus away from the body; (b) turning the palms up; (c) bending the elbow. 2. What are the 6 types of synovial joints? 7 - 88