© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or...

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

THE SKELETAL SYSTEM

Chapter 7

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Introduction

• Skeleton: supporting structure

• Bones and associated cartilage, tendons and ligaments

• Works with muscles for movement


Introduction (cont’d.)

• Mineral salts form the inorganic matrix of bone

• Leonardo da Vinci: constructed first correct illustrations of all bones


THE FUNCTIONS OF THE SKELETAL SYSTEM


The Functions of the Skeletal System (cont’d.)

• Supports surrounding tissues

• Protects vital organs and soft tissues

• Provides levers for muscles to pull on

• Manufactures blood cells

• Stores mineral salts



• Cartilage– Connective tissue– Environment in which bone develops in fetus– Found at ends of bones and in joints

• Ligaments– Attach bones to bones



• Tendons– Attach muscles to bones


THE GROWTH AND FORMATION OF BONE


Introduction

• A three-month fetal skeleton is completely formed (cartilage)

• Ossification and growth begin

• Longitudinal growth continues until:– 15 years of age for girls– 16 years of age for boys

• Bone maturation until 21 years of age


Deposition of Bone

• Osteoblasts: embryonic bone cells

• Osteocytes: mature osteoblasts

• Strain on bone (exercise) increases bone strength

• Osteoclasts: bone reabsorption and remodeling


Types of Ossification

• Intramembranous– Dense connective membranes replaced by

calcium salts– Cranial bones

• Endochondral– Bone develops inside cartilage environment– All other bones of the body


Maintaining Bone

• Endocrine system control– Calcium storage– Blood calcium levels– Excretion of excess calcium

• Parathormone: calcium release

• Calcitonin: calcium storage


THE HISTOLOGY OF BONE


Introduction

• Two types of bone: compact and cancellous (spongy)– Osteocytes same but arrangement of blood

supply different– Cancellous has bone marrow


The Haversian System of Compact Bone

• Clopton Havers: histology of compact bone

• Haversian canals: run parallel to surface– Surrounded by concentric rings of bone– Lacunae: cavity containing osteocyte– Lacunae connected by canaliculi


Cancellous Bone

• Trabeculae: meshwork of bone

• Spongy appearance created by trabeculae

• Bone marrow fills spaces between trabeculae


Bone Marrow

• Red marrow– Hematopoiesis– Ribs, sternum, vertebrae, pelvis

• Yellow marrow– Fat storage– Shafts of long bones


THE CLASSIFICATION OF BONES BASED ON SHAPE


Introduction


Long Bones

• Length exceeds width

• Consist of– Diaphysis: shaft– Metaphysis: flared portion– Epiphysis: extremity


Long Bones (cont’d.)

• Structure of a long bone


Short Bones

• Not merely shorter versions of long bones

• Lack a long axis

• Somewhat irregular shape


Flat Bones

• Thin bones found wherever need for extensive muscle attachment

• Usually curved


Irregular Bones

• Very irregular shape– Example: vertebrae

• Spongy bone enclosed by thin layers of compact bone


Sesamoid Bones

• Small rounded bones

• Enclosed in tendon and fascial tissue

• Located adjacent to joints


BONE MARKINGS


Introduction

• Processes: projections

• Fossae: depressions

• Functions: muscle attachment, articulation, passageways


Processes

• Processes: projections from the surface– Spine, condyle, tubercle, trochlea, trochanter,

crest, line, head, neck


Fossae

• Fossae: depressions– Suture, foramen, meatus, sinus, sulcus


DIVISIONS OF THE SKELETON


Divisions of the Skeleton (cont’d.)

• Typically has 206 named bones

• Axial part– Skull, hyoid, vertebrae, ribs, sternum

• Appendicular part– Upper extremities or arms– Lower extremities or legs



• Adult human skeleton: anterior view



• Adult human skeleton: posterior view


THE AXIAL SKELETON


The Cranial Bones

• Frontal bone (1)

• Parietal bones (2)

• Occipital bone (1)

• Temporal bone (2)

• Sphenoid bone (1)

• Ethmoid bone (1)

• Auditory ossicles (6)


The Facial Bones

• Nasal bones (2)

• Palatine bones (2)

• Maxillary bones (2)

• Zygomatic bones (2)

• Lacrimal bones (2)

• Nasal conchae (2)


The Facial Bones (cont’d.)

• Vomer bone (1)

• Mandible (1)


The Facial Bones (cont’d.)

• Bones of the face and skull, lateral view


The Orbits

• Orbits: cavities enclose and protect the eyesArea of Orbit Participating BonesRoof Frontal, sphenoid

Floor Maxilla, zygomatic

Lateral wall Zygomatic, greater wing of sphenoid

Medial wall Maxilla, lacrimal, ethmoid


The Nasal Cavities

• Nose framework surrounds the two nasal cavities

Area of Nose Participating BonesRoof Ethmoid

Floor Maxilla, palatine

Lateral wall Maxilla, palatine

Septum of medial wall Ethmoid, vomer, nasal

Bridge Nasal


The Foramina of the Skull

• Passageways for blood vessels and nerves

• Foramen magnum: spinal cord passage


The Hyoid Bone

• No articulation with other bones

• Suspended by ligaments from styloid process

• Supports the tongue


How to Study the Bones of the Skull

• Refer to color illustrations in textbook

• Use a model of a human skull

• Search for sutures as a guide


The Torso or Trunk

• Vertebrae– Seven cervical– Twelve thoracic– Five lumbar– Sacrum– Coccyx


The Thorax

• Thorax or rib cage made up of:– Sternum– Costal cartilages– Ribs– Bodies of thoracic vertebrae

• Encloses and protects heart and lungs


The Thorax (cont’d.)


The Sternum

• Breastbone

• Has three parts– Manubrium– Gladiolus– Xiphoid process

• Attachment for diaphragm and rectus abdominis


The Ribs

• Also called costae

• Attach posteriorly to thoracic vertebrae

• 12 pairs– True ribs, false ribs, floating ribs


THE APPENDICULAR SKELETON


The Bones of the Upper Extremities

• Shoulder girdle: clavicle and scapula

• Arm– Upper arm: humerus– Forearm: ulna and radius– Wrist: carpals– Hand: metacarpals (5/hand)– Fingers: phalanges (14/hand)


The Bones of the Upper Extremities (cont’d.)

• Bones of the wrist and hand


The Bones of the Lower Extremities

• Pelvic girdle: ischium, ilium, pubis

• Leg– Upper leg: femur– Lower leg: patella, tibia, fibula– Foot

• Tarsals• Metatarsals (5/foot)• Phalanges (14/foot)


The Bones of the Lower Extremities (cont’d.)

• Right ankle and foot, lateral view


The Bones of the Lower Extremities (cont’d.)

• Right ankle and foot, superior view


THE ARCHES OF THE FOOT


The Arches of the Foot (cont’d.)

• Enable foot to bear weight while standing and to provide leverage while walking

• Medial longitudinal: highest

• Lateral longitudinal

• Transverse

• Pes planus: flat foot


Animation – Twisting Force

• The following animation illustrates the damage that can occur to muscle, bone, or joint due to a twisting action

Click Here to Play Twisting Force Animation


Animation – Direct Force

• The following animation illustrates a fracture due to direct force to the bone from another object.

Click Here to Play Direct Force Animation


Summary

• Listed the functions of the skeletal system

• Described the process of growth and formation of bone

• Described the structure of compact and cancellous bone

• Defined the various processes and fossae associated with bones


Summary (cont’d.)

• Named the bones of the axial and appendicular skeleton

• Described the arches of the foot

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or...

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