chapter 5 the skeletal system. introduction the adult skeleton is composed of 206 bones the adult...

Chapter 5Chapter 5

The Skeletal SystemThe Skeletal System

IntroductionIntroduction

The adult skeleton is composed of The adult skeleton is composed of 206 bones206 bones

The skeletal system is subdivided The skeletal system is subdivided into 2 divisions:into 2 divisions: Axial skeletonAxial skeleton Appendicular skeletonAppendicular skeleton

The skeletal system includes joints, The skeletal system includes joints, cartilages, & ligamentscartilages, & ligaments

Bones: An OverviewBones: An Overview

Functions of the bonesFunctions of the bones Support—bones form the internal Support—bones form the internal

framework that supports & anchors all framework that supports & anchors all soft organssoft organs

Protection—bones protect body organsProtection—bones protect body organs Movement—skeletal muscles, attached Movement—skeletal muscles, attached

to bones by tendons, use the bones as to bones by tendons, use the bones as levers to move the body & its partslevers to move the body & its parts

Bones: An OverviewBones: An Overview

Functions of the bonesFunctions of the bones Storage—fat is stored in the internal Storage—fat is stored in the internal

cavities of bones, and bone serves as a cavities of bones, and bone serves as a storehouse for minerals such as calciumstorehouse for minerals such as calcium

Blood cell formation—this process is also Blood cell formation—this process is also called hematopoiesis & occurs within called hematopoiesis & occurs within the marrow of certain bonesthe marrow of certain bones

Classification of BonesClassification of Bones

There are 2 basic types of bonesThere are 2 basic types of bones Compact bone—dense & looks smoothCompact bone—dense & looks smooth Spongy bone—composed of small Spongy bone—composed of small

needlelike pieces of bone & lots of open needlelike pieces of bone & lots of open spacespace

Bones are classified into 4 groups Bones are classified into 4 groups according to shapeaccording to shape Long bones—longer than they are wide; Long bones—longer than they are wide;

mostly compact bone; includes all the mostly compact bone; includes all the bones of the limbsbones of the limbs


Bones are classified into 4 groups Bones are classified into 4 groups according to shapeaccording to shape Short bones—cube-shaped; mostly Short bones—cube-shaped; mostly

spongy bone; includes all the bones of spongy bone; includes all the bones of the wrist & ankle & also the patellathe wrist & ankle & also the patella

Flat bones—thin, flat, & curved; 2 thin Flat bones—thin, flat, & curved; 2 thin layers of compact bone with a layer of layers of compact bone with a layer of spongy bone in between; includes the spongy bone in between; includes the bones of the skull, ribs, & sternumbones of the skull, ribs, & sternum

Irregular bones—bones that do not fit Irregular bones—bones that do not fit any of the above categories; includes any of the above categories; includes the bones of the hip & vertebraethe bones of the hip & vertebrae

Structure of a Long BoneStructure of a Long Bone

DiaphysisDiaphysis Shaft of the boneShaft of the bone Makes up most of the bone’s length & is Makes up most of the bone’s length & is

composed of compact bonecomposed of compact bone PeriosteumPeriosteum

Fibrous connective tissue membraneFibrous connective tissue membrane Covers & protects the diaphysisCovers & protects the diaphysis


EpiphysesEpiphyses Ends of the long bone—proximal & distalEnds of the long bone—proximal & distal Consists of a thin layer of compact bone that Consists of a thin layer of compact bone that

encloses an area filled with spongy boneencloses an area filled with spongy bone Articular cartilageArticular cartilage

Covers the external surface of the epiphysesCovers the external surface of the epiphyses It provides a smooth, slippery surface that It provides a smooth, slippery surface that

decreases friction at joint surfacesdecreases friction at joint surfaces


Medullary cavityMedullary cavity The cavity of the shaft that is primarily a The cavity of the shaft that is primarily a

storage area for adipose tissuestorage area for adipose tissue Also known as the yellow marrow cavityAlso known as the yellow marrow cavity

Bone Formation, Growth, & Bone Formation, Growth, & RemodelingRemodeling

The skeleton is formed from two of The skeleton is formed from two of the strongest & most supportive the strongest & most supportive tissues in the body—cartilage & bonetissues in the body—cartilage & bone

In embryos, the skeleton is primarily In embryos, the skeleton is primarily made of hyaline cartilage, but in the made of hyaline cartilage, but in the young child most of the cartilage has young child most of the cartilage has been replaced by bone.been replaced by bone.


Ossification—process of bone Ossification—process of bone formation & involves 2 phases:formation & involves 2 phases: The hyaline cartilage is completely The hyaline cartilage is completely

covered with bone matrix by bone-covered with bone matrix by bone-forming cells called osteoblasts.forming cells called osteoblasts.

The hyaline cartilage is digested away, The hyaline cartilage is digested away, opening a medullary cavity within the opening a medullary cavity within the newly formed bone.newly formed bone.


Bones are always changing & are Bones are always changing & are remodeled in response to changes in 2 remodeled in response to changes in 2 factors:factors: Calcium levels in the bloodCalcium levels in the blood

If blood calcium levels are too low, osteoclasts If blood calcium levels are too low, osteoclasts (bone-destroying cells) break down bone matrix (bone-destroying cells) break down bone matrix & release calcium into the blood.& release calcium into the blood.

If blood calcium levels are too high, calcium is If blood calcium levels are too high, calcium is deposited in bone matrix as hard calcium salts.deposited in bone matrix as hard calcium salts.

The pull of gravity & muscles on the The pull of gravity & muscles on the skeletonskeleton


Bone remodeling is essential if bones Bone remodeling is essential if bones are to retain normal proportions & are to retain normal proportions & strength during long-bone growth as strength during long-bone growth as the body increases in size & weightthe body increases in size & weight

Bone FracturesBone Fractures

Bones are susceptible to fractures, or Bones are susceptible to fractures, or breaks, all through life.breaks, all through life.

During youth, most fractures result During youth, most fractures result from exceptional trauma that twists from exceptional trauma that twists or smashes the bones. In old age, or smashes the bones. In old age, bones thin & weaken, & fractures bones thin & weaken, & fractures occur more often.occur more often.


2 common types of fractures: (p 123)2 common types of fractures: (p 123) Simple (closed) fractures = a fracture in Simple (closed) fractures = a fracture in

which the bones breaks cleanly but does which the bones breaks cleanly but does not penetrate the skinnot penetrate the skin

Compound (open) fractures = when the Compound (open) fractures = when the broken bone ends penetrate through the broken bone ends penetrate through the skinskin

Fractures are treated by reduction—Fractures are treated by reduction—realignment of the broken bone endsrealignment of the broken bone ends

Axial SkeletonAxial Skeleton Forms the longitudinal axis of the bodyForms the longitudinal axis of the body Divided into 3 partsDivided into 3 parts

Skull—formed by 2 sets of bonesSkull—formed by 2 sets of bones Cranium—encloses & protects the brain tissue; Cranium—encloses & protects the brain tissue;

made up of several smaller bones (pp 126-made up of several smaller bones (pp 126-127)127)

Frontal bone—forms the foreheadFrontal bone—forms the forehead Parietal bones—forms the superior & lateral wallsParietal bones—forms the superior & lateral walls Temporal bones—inferior to the parietal bonesTemporal bones—inferior to the parietal bones Occipital bone—forms the back of the craniumOccipital bone—forms the back of the cranium Sphenoid bone—butterfly-shaped & forms part of the Sphenoid bone—butterfly-shaped & forms part of the

floor of the cranial cavityfloor of the cranial cavity Ethmoid bone—lies anterior to the sphenoid & forms Ethmoid bone—lies anterior to the sphenoid & forms

the roof of the nasal cavitythe roof of the nasal cavity

Axial SkeletonAxial Skeleton Facial bones—hold the eyes in position & Facial bones—hold the eyes in position &

allow the facial muscles to show our feelings allow the facial muscles to show our feelings (p 129)(p 129)

Maxillae—upper jawMaxillae—upper jaw Palatine bones—form the posterior part of the Palatine bones—form the posterior part of the

hard palatehard palate Zygomatic bones—cheekbonesZygomatic bones—cheekbones Lacrimal bones—medial walls of the eyes & has a Lacrimal bones—medial walls of the eyes & has a

groove that serves as a passageway for tearsgroove that serves as a passageway for tears Nasal bones—forms the bridge of the noseNasal bones—forms the bridge of the nose Vomer bone—single bone in the median line of Vomer bone—single bone in the median line of

the nasal cavity (nasal septum)the nasal cavity (nasal septum) Inferior conchae—curved bones projecting from Inferior conchae—curved bones projecting from

the lateral walls of the nasal cavitythe lateral walls of the nasal cavity Mandible—lower jaw; the largest & strongest bone Mandible—lower jaw; the largest & strongest bone

of the face!!!of the face!!!

Axial SkeletonAxial Skeleton

Fetal skeleton—the skull of a fetus or Fetal skeleton—the skull of a fetus or newborn infant is different from an adult newborn infant is different from an adult skull. When a baby is born, its skeleton is skull. When a baby is born, its skeleton is unfinished. The skull also has regions that unfinished. The skull also has regions that yet to be converted to bone which are called yet to be converted to bone which are called fontanels. These are also known as the “soft fontanels. These are also known as the “soft spots.”spots.”

Axial SkeletonAxial Skeleton Vertebral Column (p 131)Vertebral Column (p 131)

Extends from the skull to the pelvisExtends from the skull to the pelvis Formed from 26 irregular bonesFormed from 26 irregular bones Running through the central cavity of the Running through the central cavity of the

vertebral column is the spinal cordvertebral column is the spinal cord The vertebrae are separated by pads of The vertebrae are separated by pads of

cartilage-intervertebral discs-cushion the cartilage-intervertebral discs-cushion the vertebraevertebrae

The spinal cord curves & forms an S-shaped The spinal cord curves & forms an S-shaped structurestructure

Abnormal spinal curvatures (p 132)Abnormal spinal curvatures (p 132) ScoliosisScoliosis KyphosisKyphosis lordosislordosis

Axial SkeletonAxial Skeleton 3 main types of vertebrae3 main types of vertebrae

Cervical vertebraeCervical vertebrae Identified as C1 to C7Identified as C1 to C7 Form the neck region to the spineForm the neck region to the spine

Thoracic vertebraeThoracic vertebrae Identified as T1 to T12Identified as T1 to T12 Larger than cervical vertebraeLarger than cervical vertebrae

Lumbar vertebraeLumbar vertebrae Identified as L1 to L5Identified as L1 to L5 Where most of the stress on the vertebral Where most of the stress on the vertebral

column occurscolumn occurs Sacrum—formed by the fusion of 5 vertebraeSacrum—formed by the fusion of 5 vertebrae Coccyx—formed by the fusion of 3-5 tiny Coccyx—formed by the fusion of 3-5 tiny

vertebrae; also known as the human vertebrae; also known as the human “tailbone”“tailbone”

Axial SkeletonAxial Skeleton Bony thorax—aka the thoracic cage (p 135)Bony thorax—aka the thoracic cage (p 135)

SternumSternum Aka the breastboneAka the breastbone A flat bone & the result of the fusion of 3 bones:A flat bone & the result of the fusion of 3 bones:

ManubriumManubrium BodyBody Xiphoid processXiphoid process

RibsRibs 12 pairs12 pairs Males DO NOT have 1 rib less than females!!!Males DO NOT have 1 rib less than females!!! 3 types of ribs:3 types of ribs:

True ribs—the 1True ribs—the 1stst 7 pairs that are attached directly to 7 pairs that are attached directly to the sternumthe sternum

False ribs—the next 5 pairs that are attached to the False ribs—the next 5 pairs that are attached to the sternumsternum

Floating ribs—the last 2 pairs of false ribs that lack Floating ribs—the last 2 pairs of false ribs that lack sternal attachmentsternal attachment

Appendicular SkeletonAppendicular Skeleton Composed of 126 bones of the limbs Composed of 126 bones of the limbs

& pectoral & pelvic girdles& pectoral & pelvic girdles Bones of the shoulder girdle (p 139)Bones of the shoulder girdle (p 139)

Clavicle—aka the collarboneClavicle—aka the collarbone Scapula—aka the shoulder bladesScapula—aka the shoulder blades

Bones of the upper limbs (pp 140-141)Bones of the upper limbs (pp 140-141) Arm—formed by a single bone=humerusArm—formed by a single bone=humerus Forearm—2 bones:Forearm—2 bones:

Radius—on the thumb sideRadius—on the thumb side Ulna—on the pinky sideUlna—on the pinky side

Appendicular SkeletonAppendicular Skeleton

Appendicular SkeletonAppendicular Skeleton Hand—3 sets of bonesHand—3 sets of bones

Carpals—8 bones that make up the wristCarpals—8 bones that make up the wrist Metacarpals—the palm of the handMetacarpals—the palm of the hand Phalanges—bones of the fingersPhalanges—bones of the fingers

Bones of the pelvic girdle (p 142)Bones of the pelvic girdle (p 142) Formed by 2 coxal bones called hip Formed by 2 coxal bones called hip

bonesbones Each hip bone is formed by the fusion of Each hip bone is formed by the fusion of

3 bones:3 bones: IliumIlium IschiumIschium pubispubis

Appendicular SkeletonAppendicular Skeleton Differences between the male & female Differences between the male & female

pelvis:pelvis: Female pelvis is shallowerFemale pelvis is shallower Female bones are lighter & thinnerFemale bones are lighter & thinner Female sacrum is shorter & less curvedFemale sacrum is shorter & less curved

Bones of the lower limbs (pp 144-Bones of the lower limbs (pp 144-145)145) Thigh—formed by a single bone=femurThigh—formed by a single bone=femur Leg—2 bonesLeg—2 bones

Tibia—shinbone=larger & more medialTibia—shinbone=larger & more medial Fibula—lies next to the tibiaFibula—lies next to the tibia


Foot—3 sets of bonesFoot—3 sets of bones Tarsals—7 bones that make up the posterior Tarsals—7 bones that make up the posterior

footfoot Metatarsals—the sole of the footMetatarsals—the sole of the foot Phalanges—the bones of the toesPhalanges—the bones of the toes

JointsJoints Also called articulationsAlso called articulations 2 main functions2 main functions

Hold bones together securelyHold bones together securely Give the skeleton mobilityGive the skeleton mobility

Classified in 2 waysClassified in 2 ways FunctionallyFunctionally StructurallyStructurally

JointsJoints Functional classification--focuses on the Functional classification--focuses on the

amount of movement allowed by the jointamount of movement allowed by the joint Immovable jointImmovable joint Slightly movable jointsSlightly movable joints Freely movable jointsFreely movable joints

Structural classification—focuses on the type Structural classification—focuses on the type of tissueof tissue Fibrous joints—bones are united by fibrous tissueFibrous joints—bones are united by fibrous tissue Cartilaginous joints—bones are united by cartilageCartilaginous joints—bones are united by cartilage Synovial joints—joint cavity contains synovial fluidSynovial joints—joint cavity contains synovial fluid

JointsJoints Types of synovial joints based on Types of synovial joints based on

shapeshape Plane joint—short slipping or gliding; ie Plane joint—short slipping or gliding; ie

joints of the wristjoints of the wrist Hinge joint—movement in one direction; Hinge joint—movement in one direction;

ie elbow, ankle, & the joints between the ie elbow, ankle, & the joints between the bones of the fingersbones of the fingers

Pivot joint—rotating movement; ie Pivot joint—rotating movement; ie between the radius & ulnabetween the radius & ulna

Condyloid joint—bones move from side Condyloid joint—bones move from side to side or back & forth; ie your knucklesto side or back & forth; ie your knuckles

JointsJoints

Saddle joint—same movement as Saddle joint—same movement as condyloid; ie twiddling your thumbscondyloid; ie twiddling your thumbs

Ball-and-socket joint—head of one bone Ball-and-socket joint—head of one bone fits into a round socket; ie shoulder & fits into a round socket; ie shoulder & hip jointhip joint

JointsJoints

JointsJoints

Inflammatory disorders of jointsInflammatory disorders of joints ArthritisArthritis

Inflammation of the jointInflammation of the joint Most widespread disease in the U.S.Most widespread disease in the U.S. Symptoms=pain, stiffness, & swelling of the Symptoms=pain, stiffness, & swelling of the

jointjoint OsteoarthritisOsteoarthritis

Most common type of arthritisMost common type of arthritis Chronic degenerative condition that affects Chronic degenerative condition that affects

the agedthe aged

JointsJoints Rheumatoid arthritisRheumatoid arthritis

Chronic inflammatory disorderChronic inflammatory disorder Affects more women than menAffects more women than men The body’s immune system attempts to The body’s immune system attempts to

destroy tissuesdestroy tissues GoutGout

Uric acid accumulates in the blood & may be Uric acid accumulates in the blood & may be deposited as needle-shaped crystals in the deposited as needle-shaped crystals in the soft tissues of jointssoft tissues of joints

Usually affects the great toeUsually affects the great toe

chapter 5 the skeletal system. introduction the adult skeleton is composed of 206 bones the adult...

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