THE SKELETONTHE SKELETON

WHAT ARE THE WHAT ARE THE FUNCTIONS OF THE FUNCTIONS OF THE

SKELETON?SKELETON?1. Framework or support for the body1. Framework or support for the body

2. Bones serve as levers that change 2. Bones serve as levers that change magnitude and direction of the forces magnitude and direction of the forces created by skeletal musclescreated by skeletal muscles

3. Bones serve as protection for the 3. Bones serve as protection for the heart, lungs, spinal cord, and brainheart, lungs, spinal cord, and brain

4. Bone marrow is the site for the 4. Bone marrow is the site for the formation of blood cellsformation of blood cells

5. Bone tissue stores calcium salts 5. Bone tissue stores calcium salts essential for maintaining normal essential for maintaining normal concentrations of calcium and concentrations of calcium and phosphate ions in body fluidsphosphate ions in body fluids

Bone TypesBone TypesThere are 206 bones that make up There are 206 bones that make up

the human skeletonthe human skeleton4 types of bones:4 types of bones:

1. LONG- 1. LONG- found in arms and legs; found in arms and legs; longer than they are widelonger than they are wide

2. SHORT- wrist and ankle; equal 2. SHORT- wrist and ankle; equal dimensionsdimensions

3. FLAT- 3. FLAT- shoulder blades and shoulder blades and cranium; thin and broadcranium; thin and broad

4. IRREGULAR- vertebrae; complex 4. IRREGULAR- vertebrae; complex shapesshapes

BONE STRUCTUREBONE STRUCTUREA long bone has:A long bone has:

DIAPHYSIS- DIAPHYSIS- central shaftcentral shaft

EPIPHYSIS (epiphyses)- make up ends of EPIPHYSIS (epiphyses)- make up ends of diaphysisdiaphysis

- - the epiphyses of adjacent bones the epiphyses of adjacent bones articulate with each other and are articulate with each other and are covered by ARTICULAR CARTILAGEcovered by ARTICULAR CARTILAGE

PERIOSTEUM- thick, double-layered PERIOSTEUM- thick, double-layered membrane that covers the bonemembrane that covers the bone

- fibrous outer layer and cellular inner - fibrous outer layer and cellular inner layerlayer

ENDOSTEUM- ENDOSTEUM- lines marrow cavity lines marrow cavity and other inner surfacesand other inner surfaces

- active during bone growth and repair- active during bone growth and repair

BONE TISSUEBONE TISSUEBone tissue is called OSSEOUS TISSUEBone tissue is called OSSEOUS TISSUE

- contains the minerals calcium and - contains the minerals calcium and phosphorusphosphorus

2 types of bone tissue:2 types of bone tissue:

1. Cancellous (spongy) bone- 1. Cancellous (spongy) bone- network of network of bony rods separated by spaces bony rods separated by spaces filled with bone marrow; fills filled with bone marrow; fills epiphysesepiphyses

2. Compact bone- more solid than 2. Compact bone- more solid than spongy; forms the diaphysisspongy; forms the diaphysis

MICROSCOPIC LOOK AT MICROSCOPIC LOOK AT BONEBONE

RECALL: WHAT ARE BONE CELLS RECALL: WHAT ARE BONE CELLS CALLED?CALLED?

OsteocytesOsteocytes

- found in small pockets called lacunae- found in small pockets called lacunae

- - the lacunae are found between the lacunae are found between narrow sheets of calcified matrix narrow sheets of calcified matrix known as LAMELLAEknown as LAMELLAE

- there are small channels called CANALICULI - there are small channels called CANALICULI that radiate through the matrix, that radiate through the matrix, interconnecting lacunae and linking them to interconnecting lacunae and linking them to nearby blood vesselsnearby blood vessels

COMPACT AND SPONGY BONECOMPACT AND SPONGY BONE

The basic functional unit of compact bone is The basic functional unit of compact bone is the OSTEON (also called Haversian system)the OSTEON (also called Haversian system)

- - in an osteon, osteocytes are arranged in an osteon, osteocytes are arranged around a central canal that contains one around a central canal that contains one or more blood vesselsor more blood vessels

- - perforating canals perforating canals provide provide passageways for linking the blood passageways for linking the blood vessels of the central canals with those vessels of the central canals with those of the periosteum or marrow cavity of the periosteum or marrow cavity

Spongy bone is arranged differently:Spongy bone is arranged differently:

- no osteons- no osteons

- - lamella form rods or plates called lamella form rods or plates called TRABECULAETRABECULAE

- these branch creating an “open” network- these branch creating an “open” network

- canaliculi radiating from the lacunae - canaliculi radiating from the lacunae of spongy bone end at the exposed of spongy bone end at the exposed surface of the trabeculae, and this is surface of the trabeculae, and this is where nutrients and wastes diffuse where nutrients and wastes diffuse between the marrow and the between the marrow and the osteocytesosteocytes

http://www.webbooks.com/eLibrary/Medicine/Physiology/http://www.webbooks.com/eLibrary/Medicine/Physiology/Skeletal/Skeletal.htmSkeletal/Skeletal.htm

Location of Compact vs. Location of Compact vs. Spongy boneSpongy bone

COMPACT:COMPACT:

- a layer of compact bone covers bone - a layer of compact bone covers bone surfaces almost everywheresurfaces almost everywhere

- - usually found where stresses come usually found where stresses come from a limited range of directionsfrom a limited range of directions

Ex: limb bones withstand forces applied at Ex: limb bones withstand forces applied at either end- will not bendeither end- will not bend

- - exception is in disorders that reduce exception is in disorders that reduce calcium salts in skeleton calcium salts in skeleton RICKETS RICKETS

SPONGY:SPONGY:

- found where bones are not heavily stressed - found where bones are not heavily stressed or where stresses arrive from many or where stresses arrive from many directionsdirections

Ex: Ex: at epiphyses of long bonesat epiphyses of long bones

- much lighter than compact bone - much lighter than compact bone reduces reduces weight of skeletonweight of skeleton

- - trabecular network supports and trabecular network supports and protects cells of red bone marrow, protects cells of red bone marrow, sites of blood cell formationsites of blood cell formation

BONE CELLSBONE CELLS

- Although osteocytes are most common, - Although osteocytes are most common, there are other types:there are other types:

1. OSTEOCYTES- mature bone cells1. OSTEOCYTES- mature bone cells

- maintain normal bone structure by recycling - maintain normal bone structure by recycling calcium salts in the bony matrix around calcium salts in the bony matrix around themselves and assisting in repairsthemselves and assisting in repairs

2. OSTEOCLASTS- giant cells2. OSTEOCLASTS- giant cells

- - secrete acids and enzymes that dissolve secrete acids and enzymes that dissolve the bony matrix and release stored the bony matrix and release stored mineralsminerals

3. OSTEOBLASTS- 3. OSTEOBLASTS- cells responsible cells responsible for producing new bonefor producing new bone

- produce new bone matrix (called - produce new bone matrix (called OSTEOGENESIS) and promote the OSTEOGENESIS) and promote the depositing of calcium salts in the depositing of calcium salts in the organic matrixorganic matrix

** ** At any given moment, At any given moment, osteoclasts are removing matrix osteoclasts are removing matrix and osteoblasts are adding to itand osteoblasts are adding to it

BONE BONE DEVELOPMENT DEVELOPMENT AND GROWTHAND GROWTH

Skeletal growth begins about 6 weeks Skeletal growth begins about 6 weeks after fertilization after fertilization

- - continues through adolescencecontinues through adolescence

- some portions do not stop growing until - some portions do not stop growing until about age 25about age 25

RECALL: OSTEOGENESIS- bone formation RECALL: OSTEOGENESIS- bone formation and growthand growth

- - during development, cartilage or during development, cartilage or connective tissue is replaced by boneconnective tissue is replaced by bone

OSSIFICATION- the process of replacing OSSIFICATION- the process of replacing other tissues with boneother tissues with bone

CALCIFICATION- CALCIFICATION- the depositing of the depositing of calcium saltscalcium salts

2 types of ossification:2 types of ossification:

1. INTRAMEMBRANOUS- bone develops 1. INTRAMEMBRANOUS- bone develops within sheets or membranes of connective within sheets or membranes of connective tissuetissue

2. ENDOCHONDRIAL- 2. ENDOCHONDRIAL- bone replaces bone replaces existing cartilageexisting cartilage

INTRAMEMBRANOUS INTRAMEMBRANOUS OSSIFICATIONOSSIFICATION

- begins when osteoblasts (bone forming cells) - begins when osteoblasts (bone forming cells) differentiate within embryonic or fetal differentiate within embryonic or fetal connective tissueconnective tissue

- - occurs in the deeper layers of the occurs in the deeper layers of the epidermisepidermis

- osteoblasts differentiate from connective tissue - osteoblasts differentiate from connective tissue stem cells after organic components of the stem cells after organic components of the matrix secreted by the stem cells become matrix secreted by the stem cells become calcifiedcalcified

- - where ossification first begins is called an where ossification first begins is called an OSSIFICATION CENTEROSSIFICATION CENTER

- blood vessels grow into the area of - blood vessels grow into the area of ossification, because osteoblasts require ossification, because osteoblasts require oxygen and nutrientsoxygen and nutrients

- these blood vessels become trapped in the - these blood vessels become trapped in the developing bonedeveloping bone

- at first, intramembranous bone resembles - at first, intramembranous bone resembles spongy bone, but eventually osteons (of spongy bone, but eventually osteons (of compact bone) can also be producedcompact bone) can also be produced

- - BONES OF SKULL, LOWER JAW, AND BONES OF SKULL, LOWER JAW, AND COLLARBONES are formed this wayCOLLARBONES are formed this way

ENDOCHONDRIAL ENDOCHONDRIAL OSSIFICATIONOSSIFICATION

Most bones of the skeleton are formed through Most bones of the skeleton are formed through this type of ossificationthis type of ossification

- - bone replaces existing hyaline cartilagebone replaces existing hyaline cartilage

STEPS OF ENDOCHONDRIAL OSSIFICATION:STEPS OF ENDOCHONDRIAL OSSIFICATION:

1. Chondrocytes (cartilage cells) in the 1. Chondrocytes (cartilage cells) in the cartilage enlarge, and the surrounding cartilage enlarge, and the surrounding matrix begins to calcify matrix begins to calcify

- - the cells die because as the matrix the cells die because as the matrix calcifies, the nutrient supply slowscalcifies, the nutrient supply slows

2. Bone formation first 2. Bone formation first begins at the shaft begins at the shaft surfacesurface

- blood vessels invade - blood vessels invade perichondrium, and the perichondrium, and the cells of its inner layer cells of its inner layer differentiate into differentiate into osteoblasts and begin to osteoblasts and begin to produce bone matrixproduce bone matrix

3. Blood vessels invade 3. Blood vessels invade inner region of inner region of cartilage, and newly cartilage, and newly differentiated differentiated osteoblasts form osteoblasts form spongy bone in the spongy bone in the center of the shaft at a center of the shaft at a PRIMARY CENTER OF PRIMARY CENTER OF OSSIFICATIONOSSIFICATION

- - bone development bone development fills the shaft with fills the shaft with spongy bonespongy bone

4. As the bone enlarges, 4. As the bone enlarges, osteoclasts break osteoclasts break down some spongy down some spongy bone, and create a bone, and create a marrow cavitymarrow cavity

- the cartilage does not - the cartilage does not completely fill with completely fill with bone because the bone because the epiphyseal cartilages epiphyseal cartilages on the ends keep on the ends keep enlarging, increasing enlarging, increasing the length of the bonethe length of the bone

5. Centers of the 5. Centers of the epiphyses begin to epiphyses begin to calcifycalcify

- - blood vessels and blood vessels and osteoblasts enter osteoblasts enter these areas, and these areas, and SECONDARY SECONDARY CENTERS OF CENTERS OF OSSIFICATION formOSSIFICATION form

- epiphyses become - epiphyses become filled with spongy filled with spongy bonebone

- a small amount of the original - a small amount of the original cartilage remains exposed at the cartilage remains exposed at the joint cavity as ARTICULAR joint cavity as ARTICULAR CARTILAGECARTILAGE

- - bone of the shaft and the bone of bone of the shaft and the bone of the epiphysis are separated by the epiphysis are separated by areas of cartilage called areas of cartilage called EPIPHYSEAL PLATESEPIPHYSEAL PLATES

- at puberty, bone growth greatly - at puberty, bone growth greatly accelerates, and osteoblasts produce accelerates, and osteoblasts produce bone faster than epiphyseal cartilage bone faster than epiphyseal cartilage expandsexpands

- - epiphyseal plates become narrower epiphyseal plates become narrower and narrower until they disappearand narrower until they disappear

- in adults the former location of the - in adults the former location of the plate is detected in X-rays as the plate is detected in X-rays as the EPIPHYSEAL LINE (see your diagram!)EPIPHYSEAL LINE (see your diagram!)

- - end of epiphyseal growth is called end of epiphyseal growth is called CLOSURECLOSURE

As bones get longer, they also increase in As bones get longer, they also increase in diameterdiameter

- APPOSITIONAL GROWTH- - APPOSITIONAL GROWTH- enlargement enlargement of the diameter of bones at their outer of the diameter of bones at their outer surfacessurfaces

- cells of the periosteum develop into - cells of the periosteum develop into osteoblasts and produce more bony matrixosteoblasts and produce more bony matrix

- new bone is deposited on the outside as the - new bone is deposited on the outside as the inside is eroded away by osteoclasts, inside is eroded away by osteoclasts, making the marrow cavity largermaking the marrow cavity larger

DIFFERENCES IN BONE DIFFERENCES IN BONE GROWTHGROWTH

- Timing of epiphyseal closure varies - Timing of epiphyseal closure varies from bone to bone and from individual from bone to bone and from individual to individualto individual

- - Epiphyseal plates in arms and legs Epiphyseal plates in arms and legs usually close by about the age of usually close by about the age of 18 in women, and 20 in men18 in women, and 20 in men

- Differences in sex hormones accounts - Differences in sex hormones accounts for variations in size and proportions for variations in size and proportions between men and women between men and women

NORMAL GROWTH NORMAL GROWTH REQUIREMENTSREQUIREMENTS

**Normal bone growth and maintenance **Normal bone growth and maintenance requires a reliable source of minerals such as requires a reliable source of minerals such as calcium saltscalcium salts

- during prenatal development, these minerals - during prenatal development, these minerals are absorbed from the mother’s bloodstream, are absorbed from the mother’s bloodstream, so much in fact that the mother’s skeleton so much in fact that the mother’s skeleton often loses bone mass during pregnancyoften loses bone mass during pregnancy

**Vitamin D**Vitamin D33 is converted into calcitrol, a is converted into calcitrol, a hormone that stimulates the absorption of hormone that stimulates the absorption of calcium and phosphate ions in the digestive calcium and phosphate ions in the digestive tracttract

- vitamin D- vitamin D33 can be obtained from can be obtained from dietary supplements, or where else?dietary supplements, or where else?

SUN EXPOSURESUN EXPOSURE

- vitamin D- vitamin D33 deficiency can cause deficiency can cause RICKETS, or softening of the bones, RICKETS, or softening of the bones, especially in childrenespecially in children

**Vitamin C deficiency can lead to **Vitamin C deficiency can lead to SCURVY- SCURVY- weak and brittle bonesweak and brittle bones

REMODELING REMODELING AND AND

HOMEOSTASISHOMEOSTASIS

REMODELINGREMODELING

In adults, osteocytes in lacunae maintain In adults, osteocytes in lacunae maintain surrounding matrix by continually removing and surrounding matrix by continually removing and replacing the surrounding calcium saltsreplacing the surrounding calcium salts

- - osteoclasts and osteoblasts also remain active osteoclasts and osteoblasts also remain active even after epiphyseal plates have closedeven after epiphyseal plates have closed

- the activities of these cells are usually balanced: - the activities of these cells are usually balanced: as osteoblasts form an osteon, osteoclasts destroy as osteoblasts form an osteon, osteoclasts destroy oneone

- - protein and mineral components are removed protein and mineral components are removed and replaced through REMODELINGand replaced through REMODELING

The purpose of this remodeling is to give The purpose of this remodeling is to give bones the ability to adapt to new stressesbones the ability to adapt to new stresses

- bones that are heavily stressed become - bones that are heavily stressed become thicker and strongerthicker and stronger

*** *** Exercise is important in maintaining Exercise is important in maintaining normal bone structure***normal bone structure***

- degeneration in the skeleton can occur even - degeneration in the skeleton can occur even after short periods of inactivityafter short periods of inactivity

* think of what happens to a person’s leg when * think of what happens to a person’s leg when they have to use crutches for a few weeksthey have to use crutches for a few weeks

MINERAL STORAGEMINERAL STORAGE

DID YOU KNOW?DID YOU KNOW?

The human body typically contains about The human body typically contains about 2.2 to 4.4 lbs of calcium, with 99% of it 2.2 to 4.4 lbs of calcium, with 99% of it deposited in the skeleton!deposited in the skeleton!

- - calcium ion concentrations in the calcium ion concentrations in the body must be closely regulatedbody must be closely regulated

Ex: if calcium concentrations in body fluids Ex: if calcium concentrations in body fluids increase, neurons and muscle cells increase, neurons and muscle cells become unresponsive; if concentrations become unresponsive; if concentrations decrease, they become over-excited decrease, they become over-excited

- - by providing a calcium reserve, by providing a calcium reserve, the skeleton helps maintain the skeleton helps maintain calcium HOMEOSTASIS in body calcium HOMEOSTASIS in body fluidsfluids

INJURY AND REPAIRINJURY AND REPAIR

Even though bone is very strong, sometimes Even though bone is very strong, sometimes cracks or breaks do occurcracks or breaks do occur

- - all cracks or breaks in bone are called all cracks or breaks in bone are called FRACTURESFRACTURES

- fractures are classified according to their - fractures are classified according to their external appearance, the site of the external appearance, the site of the fracture, and the nature of the breakfracture, and the nature of the break

- though bone repair may take anywhere - though bone repair may take anywhere from 4 months to over a year, bones will from 4 months to over a year, bones will usually heal even after severe damageusually heal even after severe damage

STEPS IN REPAIR OF A STEPS IN REPAIR OF A FRACTUREFRACTURE

1. Blood vessels are broken and bleeding occurs1. Blood vessels are broken and bleeding occurs

- blood pools and clots, and a swollen area called a - blood pools and clots, and a swollen area called a FRACTURE HEMATOMA forms- this closes off the FRACTURE HEMATOMA forms- this closes off the injured blood vesselsinjured blood vessels

2. Cells of periosteum and endosteum divide and move 2. Cells of periosteum and endosteum divide and move to the fracture zoneto the fracture zone

- - the cells form thickenings called an EXTERNAL the cells form thickenings called an EXTERNAL CALLUS and an INTERNAL CALLUSCALLUS and an INTERNAL CALLUS

- at the center of the external callus, cells differentiate - at the center of the external callus, cells differentiate into chondrocytes and build cartilageinto chondrocytes and build cartilage

3. Osteoblasts replace this cartilage with spongy 3. Osteoblasts replace this cartilage with spongy bonebone

- when this process is complete, both the internal - when this process is complete, both the internal and external calluses form a continuous brace of and external calluses form a continuous brace of spongy bone at the fracture sitespongy bone at the fracture site

4. When remodeling of the spongy bone is 4. When remodeling of the spongy bone is complete (4 months to 1 year) fragments of dead complete (4 months to 1 year) fragments of dead bone and the spongy bone will be gone, and bone and the spongy bone will be gone, and living compact bone will remainliving compact bone will remain

- - bone may just be slightly thicker at fracture bone may just be slightly thicker at fracture sitesite

AGINGAGING

Bones become thinner and weaker with ageBones become thinner and weaker with age

OSTEOPENIA- OSTEOPENIA- inadequate ossificationinadequate ossification

- all people become slightly osteopenic as - all people become slightly osteopenic as they agethey age

- occurs between ages of about 30-40: - occurs between ages of about 30-40: osteoblast activity begins to decline as osteoblast activity begins to decline as osteoclast activity continuesosteoclast activity continues

- - women lose about 8% of their body mass women lose about 8% of their body mass every 10 years, as compared to the 3% every 10 years, as compared to the 3% for menfor men

- epiphyses, vertebrae, and jaws lose more - epiphyses, vertebrae, and jaws lose more than other bones than other bones fragile limbs, reduced fragile limbs, reduced height, loss of teethheight, loss of teeth

OSTEOPOROSIS- reduction in bone mass great OSTEOPOROSIS- reduction in bone mass great enough to compromise normal functionenough to compromise normal function

- 29% of women ages 45 to 79 are considered - 29% of women ages 45 to 79 are considered osteoporotic (compared to 18% of men)osteoporotic (compared to 18% of men)

- - this is linked to decreases in the this is linked to decreases in the production of estrogens (sex hormones) production of estrogens (sex hormones) after menopauseafter menopause

EFFECTS:EFFECTS:

- - bones break easily and do not bones break easily and do not repair well; vertebrae may repair well; vertebrae may collapsecollapse

- estrogen therapies, diets that - estrogen therapies, diets that increase calcium, and exercise slow increase calcium, and exercise slow development of osteoporosis, but do development of osteoporosis, but do not prevent it completelynot prevent it completely

CHAPTER 6 CHAPTER 6 NOTES PART 2NOTES PART 2

SKELETAL ANATOMYSKELETAL ANATOMY

SURFACE FEATURES OF SURFACE FEATURES OF BONES (BONE BONES (BONE MARKINGS)MARKINGS)Some bones have projections, Some bones have projections,

depressions, or even holes depressions, or even holes

Projections on the surface of bones are Projections on the surface of bones are called called processesprocesses::

HeadHead- a large rounded articular surface- a large rounded articular surface

NeckNeck- the narrow part of a bone - the narrow part of a bone between the head and shaftbetween the head and shaft

SpineSpine- a sharp slender process (back of - a sharp slender process (back of the shoulder blade)the shoulder blade)

CONDYLECONDYLE- a rounded knuckle-like process - a rounded knuckle-like process located where the bone articulates with located where the bone articulates with another boneanother bone

CRESTCREST- a ridge of bone that is unusually - a ridge of bone that is unusually narrownarrow

TROCHANTERTROCHANTER- a large projection for the - a large projection for the attachment of musclesattachment of muscles

Depressions Depressions and openings on the surface of and openings on the surface of bones include:bones include:

FOSSAFOSSA- a shallow depression in the surface - a shallow depression in the surface of a boneof a bone

FORAMENFORAMEN- rounded passageway for blood - rounded passageway for blood vessels and/or nervesvessels and/or nerves

SINUSSINUS- a chamber within a bone, - a chamber within a bone, usually filled with airusually filled with air

DIVISIONS OF THE DIVISIONS OF THE SKELETONSKELETON

RECALL: Skeleton consists of 206 RECALL: Skeleton consists of 206 separate bones and associated separate bones and associated cartilagecartilage

2 DIVISIONS:2 DIVISIONS:

AXIAL SKELETON- forms longitudinal AXIAL SKELETON- forms longitudinal axis of the body- 80 bonesaxis of the body- 80 bones

- skull (+ ossicles and hyoid bone)- skull (+ ossicles and hyoid bone)

- vertebral column- vertebral column

- thoracic cage- thoracic cage

APPENDICULAR SKELETON- bones APPENDICULAR SKELETON- bones of limbs and pectoral and pelvic of limbs and pectoral and pelvic girdlesgirdles

AXIAL AXIAL SKELETONSKELETON

80 BONES80 BONES

SKULL: CRANIUM AND SKULL: CRANIUM AND FACEFACE

SEE FIRST PAGE OF YOUR SKULL SEE FIRST PAGE OF YOUR SKULL HANDOUT FOR PARTS THAT YOU HANDOUT FOR PARTS THAT YOU NEED TO KNOW!NEED TO KNOW!

- REQUIRED PARTS ARE IN BOLD- REQUIRED PARTS ARE IN BOLD

HYOID BONEHYOID BONE

- U-shaped bone that hangs below the - U-shaped bone that hangs below the skull, suspended by ligaments from skull, suspended by ligaments from the styloid processes of the temporal the styloid processes of the temporal bones bones

- serves as a base for muscles - serves as a base for muscles associated with the larynx (voice associated with the larynx (voice box), tongue, and pharynxbox), tongue, and pharynx

- supports and stabilizes position of - supports and stabilizes position of the larynxthe larynx

SKULLS OF INFANTS SKULLS OF INFANTS AND CHILDRENAND CHILDREN

At birth the cranial At birth the cranial bones are connected bones are connected by areas of fibrous by areas of fibrous connective tissue connective tissue known as known as FONTANELSFONTANELS

- “soft spots”- “soft spots”

- flexible, permit - flexible, permit distortion of the skull distortion of the skull without damage (such without damage (such as during delivery)as during delivery)

VERTEBRAL COLUMNVERTEBRAL COLUMN

The vertebral column is made up of a series The vertebral column is made up of a series of 26 bones called of 26 bones called vertebraevertebrae

- linked together by cartilage to allow - linked together by cartilage to allow flexibilityflexibility

- protects the spinal cord- protects the spinal cord

- divided into - divided into cervical (neck), thoracic cervical (neck), thoracic (chest), lumbar (small of back), sacral (chest), lumbar (small of back), sacral (between hip bones), and coccygeal (between hip bones), and coccygeal (tail bone) (tail bone) regionsregions

- SEE DIAGRAM- SEE DIAGRAM

SPINAL CURVATURESPINAL CURVATURE

The spinal column is made up of 4 spinal The spinal column is made up of 4 spinal curves:curves:

PRIMARY CURVES-PRIMARY CURVES- thoracic and sacral curves thoracic and sacral curves

- appear late in fetal development- appear late in fetal development

SECONDARY CURVES-SECONDARY CURVES- cervical and lumbar cervical and lumbar curvescurves

- do not appear until months after birth- do not appear until months after birth

- cervical develops as infant learns to balance - cervical develops as infant learns to balance the head upright; lumbar develops with the the head upright; lumbar develops with the ability to standability to stand

- all 4 curves are developed by - all 4 curves are developed by the age of 10the age of 10

ABNORMAL DISTORTIONS:ABNORMAL DISTORTIONS:

SCOLIOSIS- abnormal lateral SCOLIOSIS- abnormal lateral curvaturecurvature

TYPICAL VERTEBRATYPICAL VERTEBRA

- composed of a BODY with an arch on - composed of a BODY with an arch on the posterior surfacethe posterior surface

- arch roofs over an opening, the - arch roofs over an opening, the VERTEBRAL FORAMEN, through VERTEBRAL FORAMEN, through which the spinal cord passeswhich the spinal cord passes

- there are several processes:- there are several processes:

* SPINOUS PROCESS- attachment of * SPINOUS PROCESS- attachment of ligaments and muscles of the backligaments and muscles of the back

* TRANSVERSE PROCESSES- (2) * TRANSVERSE PROCESSES- (2) project on either side for attachment project on either side for attachment of musclesof muscles

* ARTICULAR PROCESSES- form the * ARTICULAR PROCESSES- form the joints connecting the individual joints connecting the individual vertebraevertebrae

SURFACES OF THESE PROCESSES SURFACES OF THESE PROCESSES ARE COVERED WITH CARTILAGEARE COVERED WITH CARTILAGE

CERVICAL VERTEBRAECERVICAL VERTEBRAE

The first 7 vertebrae are The first 7 vertebrae are CERVICALCERVICAL

The top 2 vertebrae are different:The top 2 vertebrae are different:

** the first, the ATLAS, supports the skull** the first, the ATLAS, supports the skull

- has no body and therefore appears as a - has no body and therefore appears as a ring with 2 transverse processesring with 2 transverse processes

** the second, the AXIS, has a protruding ** the second, the AXIS, has a protruding upper surface called the DENS- forms a upper surface called the DENS- forms a pivot around which the axis rotates to pivot around which the axis rotates to allow movement of the headallow movement of the head

THORACIC VERTEBRAETHORACIC VERTEBRAE

The next 12 vertebrae are THORACICThe next 12 vertebrae are THORACIC

- distinguished by the presence of RIB - distinguished by the presence of RIB FACETS- provide attachment for the FACETS- provide attachment for the ribsribs

- most thoracic vertebrae have 3 - most thoracic vertebrae have 3 facetsfacets

LUMBAR VERTEBRAELUMBAR VERTEBRAE

The next 5 vertebrae are LUMBARThe next 5 vertebrae are LUMBAR

- have largest bodies since most of the - have largest bodies since most of the weight of the body is supported by weight of the body is supported by this regionthis region

SACRUM AND COCCYXSACRUM AND COCCYX

SACRUM- triangular shaped bone SACRUM- triangular shaped bone containing foramina that are containing foramina that are passageways for nerves and blood passageways for nerves and blood vesselsvessels

- consists of 5 fused sacral vertebrae- consists of 5 fused sacral vertebrae

COCCYX- considered vestigial remains COCCYX- considered vestigial remains of 4 fused coccygeal vertebraeof 4 fused coccygeal vertebrae

* SEE DIAGRAMS* SEE DIAGRAMS

THORAX: STERNUM THORAX: STERNUM AND RIBSAND RIBS

STERNUM- thin flat bone divided into 3 STERNUM- thin flat bone divided into 3 parts:parts:

* MANUBRIUM- upper part* MANUBRIUM- upper part

* BODY- long and narrow* BODY- long and narrow

* XIPHOID PROCESS- made of * XIPHOID PROCESS- made of cartilagecartilage

- ligaments form the attachment of the - ligaments form the attachment of the clavicles (collar bones) to each side of clavicles (collar bones) to each side of the top of the sternumthe top of the sternum

- 7 pairs of COSTAL CARTILAGES form the - 7 pairs of COSTAL CARTILAGES form the attachment of the ribs to the body of the attachment of the ribs to the body of the sternumsternum

- there are 12 pairs of ribs- there are 12 pairs of ribs

- they are attached posteriorly with the - they are attached posteriorly with the thoracic vertebrae and anteriorly with the thoracic vertebrae and anteriorly with the sternumsternum

- first 7 are TRUE RIBS because each has a - first 7 are TRUE RIBS because each has a direct costal cartilage connection with direct costal cartilage connection with the sternumthe sternum

- next 3 pairs are called FALSE RIBS - next 3 pairs are called FALSE RIBS because their cartilage connections because their cartilage connections join indirectly with the sternumjoin indirectly with the sternum

- last 2 pairs are called FLOATING - last 2 pairs are called FLOATING RIBS because they have no RIBS because they have no connection with the sternumconnection with the sternum

* SEE DIAGRAMS* SEE DIAGRAMS

APPENDICULAR APPENDICULAR SKELETONSKELETON

126 BONES126 BONES

PECTORAL GIRDLEPECTORAL GIRDLE

Consists of 2 pairs of bones:Consists of 2 pairs of bones:

SCAPULAE (shoulder blades) & CLAVICLES SCAPULAE (shoulder blades) & CLAVICLES (collar bones)(collar bones)

SCAPULAESCAPULAE

- flat, triangular-shaped bones- flat, triangular-shaped bones

- shelf-like ridge extending across the - shelf-like ridge extending across the posterior surface of the bone called SPINEposterior surface of the bone called SPINE

- spine ends in a flattened projection called - spine ends in a flattened projection called the ACROMION PROCESSthe ACROMION PROCESS

- clavicle articulates with acromion of the - clavicle articulates with acromion of the scapulascapula

- other end of the clavicle rests against the - other end of the clavicle rests against the top of the sternumtop of the sternum

- beneath acromion is a rounded concave - beneath acromion is a rounded concave fossa called the GLENOID CAVITY- head fossa called the GLENOID CAVITY- head of humerus fits into this cavityof humerus fits into this cavity

- underneath the clavicle is the CORACOID - underneath the clavicle is the CORACOID PROCESS- projects forward and serves PROCESS- projects forward and serves as the attachment for several muscles as the attachment for several muscles and ligamentsand ligaments

* SEE DIAGRAMS* SEE DIAGRAMS

ARM AND FOREARMARM AND FOREARM

Each arm is made up of 3 main bones: Each arm is made up of 3 main bones: HUMERUS, ULNA, RADIUSHUMERUS, ULNA, RADIUS

HUMERUS- long bone of the upper armHUMERUS- long bone of the upper arm

- rounded head of the humerus articulates - rounded head of the humerus articulates with the scapulawith the scapula

- GREATER and LESSER TUBERCLES - GREATER and LESSER TUBERCLES provide attachment for musclesprovide attachment for muscles

- DELTOID TUBEROSITY runs along the - DELTOID TUBEROSITY runs along the shaft and provides attachment for the shaft and provides attachment for the deltoid muscledeltoid muscle

- MEDIAL and LATERAL EPICONDYLES project to - MEDIAL and LATERAL EPICONDYLES project to either side providing additional muscle either side providing additional muscle attachmentattachment

- CONDYLE makes up the inferior surface of the - CONDYLE makes up the inferior surface of the humerushumerus

* TROCHLEA is the large medial portion of the * TROCHLEA is the large medial portion of the condylecondyle

* CORONOID FOSSA is a depression on the lower * CORONOID FOSSA is a depression on the lower anterior surface, while on lower posterior surface anterior surface, while on lower posterior surface is a notch called the OLECRANON FOSSAis a notch called the OLECRANON FOSSA

ULNA- longer bone along the back of the ULNA- longer bone along the back of the forearmforearm

- at the upper end is the OLECRANON - at the upper end is the OLECRANON PROCESS- fits into the olecranon fossa of PROCESS- fits into the olecranon fossa of the humerus when the arm is extended the humerus when the arm is extended (point of elbow)(point of elbow)

- on the lateral side of the ulna is the RADIAL - on the lateral side of the ulna is the RADIAL NOTCH for the head of the radiusNOTCH for the head of the radius

- the flattened surface at the lower end of the - the flattened surface at the lower end of the radius enables it to rotate around the ulnaradius enables it to rotate around the ulna

- STYLOID PROCESSES of radius and - STYLOID PROCESSES of radius and ulna articulate with the carpal ulna articulate with the carpal (wrist) bones(wrist) bones

* SEE DIAGRAMS* SEE DIAGRAMS

WRIST AND HANDWRIST AND HAND

The wrist consists of 8 small bones The wrist consists of 8 small bones which are held tightly together by which are held tightly together by ligamentsligaments

CARPAL BONES- arranged in 2 rows to CARPAL BONES- arranged in 2 rows to allow the wrist to flexallow the wrist to flex

Palm of the hand consists of 5 Palm of the hand consists of 5 METACARPAL BONESMETACARPAL BONES

- articulate with bones of the wrist, and - articulate with bones of the wrist, and bones of the fingersbones of the fingers

The bones of the fingers contain 14 The bones of the fingers contain 14 PHALANGESPHALANGES

- each of the 4 fingers has 3 phalanges - each of the 4 fingers has 3 phalanges and the thumb has 2and the thumb has 2

- thumb has greatest movement - thumb has greatest movement because its metacarpal is more because its metacarpal is more rounded, and it is attached to many rounded, and it is attached to many muscles in the handmuscles in the hand

* SEE DIAGRAMS* SEE DIAGRAMS

PELVIC GIRDLEPELVIC GIRDLE

Consists of 2 large hip bones joined Consists of 2 large hip bones joined togethertogether

- connect with the sacrum to form the pelvis- connect with the sacrum to form the pelvis

Each hip bone is composed of 3 fused Each hip bone is composed of 3 fused bones: ILIUM, ISCHIUM, PUBISbones: ILIUM, ISCHIUM, PUBIS

ILIUM- largest, forms the upper portion of ILIUM- largest, forms the upper portion of the hip bonethe hip bone

ISCHIUM- forms the posterior portionISCHIUM- forms the posterior portion

PUBIS- forms the anterior portionPUBIS- forms the anterior portion

As the hip bone develops, the 3 bones As the hip bone develops, the 3 bones fuse into a single bonefuse into a single bone

- eventually the 2 sets of bones meet - eventually the 2 sets of bones meet in front and form the PUBIC in front and form the PUBIC SYMPHYSISSYMPHYSIS

- SACROILIAC JOINT- forms in the - SACROILIAC JOINT- forms in the back by the articulation of the hip back by the articulation of the hip bones and the sacrumbones and the sacrum

DIFFERENCE IN MALE DIFFERENCE IN MALE AND FEMALE PELVISAND FEMALE PELVIS

MALE- angle of the 2 pubic bones is MALE- angle of the 2 pubic bones is more pointed and narrowmore pointed and narrow

- pelvis is deeper and the cavity is - pelvis is deeper and the cavity is smallersmaller

FEMALE- pubic arch is much wider and FEMALE- pubic arch is much wider and roundedrounded

- pelvis is shallow and has a larger - pelvis is shallow and has a larger cavitycavity

- adapted to childbearing- adapted to childbearing

THIGH AND LOWER LEGTHIGH AND LOWER LEG

FEMUR- upper leg or thigh boneFEMUR- upper leg or thigh bone

- longest and strongest bone in the human skeleton- longest and strongest bone in the human skeleton

- HEAD is rounded and smooth and articulates with - HEAD is rounded and smooth and articulates with the ilium at the ACETABULUMthe ilium at the ACETABULUM

- GREATER and LESSER TROCHANTERS are large - GREATER and LESSER TROCHANTERS are large projections that extend laterally from the junction projections that extend laterally from the junction of the neck and shaft; where tendons attach to of the neck and shaft; where tendons attach to the femurthe femur

- below head is the NECK- becomes more porous in - below head is the NECK- becomes more porous in older people so common site of fractureolder people so common site of fracture

- on posterior surface of femur is an elevation - on posterior surface of femur is an elevation called LINEA ASPERA which marks attachment called LINEA ASPERA which marks attachment of powerful thigh musclesof powerful thigh muscles

- lower end of femur expands into large flattened - lower end of femur expands into large flattened area with 2 bony processes on each side: area with 2 bony processes on each side: MEDIAL EPICONDYLE, LATERAL EPICONDYLEMEDIAL EPICONDYLE, LATERAL EPICONDYLE

- inferior surfaces of epicondyles form LATERAL - inferior surfaces of epicondyles form LATERAL and MEDIAL CONDYLESand MEDIAL CONDYLES

- these come together to form the PATELLAR - these come together to form the PATELLAR SURFACE over which the PATELLA (kneecap) SURFACE over which the PATELLA (kneecap) glidesglides

TIBIA- larger bone of lower leg joins with TIBIA- larger bone of lower leg joins with processes to form the knee jointprocesses to form the knee joint

- patella is joined to tibia with a ligament- patella is joined to tibia with a ligament

FIBULA- on outside of tibia, blunt end FIBULA- on outside of tibia, blunt end articulates with the tibia below the knee articulates with the tibia below the knee jointjoint

** ** A fib is a small lie; the fibula is the A fib is a small lie; the fibula is the smaller bonesmaller bone

- lower end of tibia forms projecting - lower end of tibia forms projecting ankle bone on the inside of the leg ankle bone on the inside of the leg MEDIAL MALLEOLUSMEDIAL MALLEOLUS

- at the end of the fibula is a lateral - at the end of the fibula is a lateral projection, the LATERAL projection, the LATERAL MALLEOLUS, which completes the MALLEOLUS, which completes the ankle joint at the sideankle joint at the side

ANKLE AND FOOTANKLE AND FOOT

Composed of 7 TARSAL BONESComposed of 7 TARSAL BONES

- similar to bones of wrist- similar to bones of wrist

- tibia and fibula articulate with a tarsal - tibia and fibula articulate with a tarsal bone called the TALUS- allows foot to bone called the TALUS- allows foot to move up and down in single planemove up and down in single plane

- largest bone of tarsals is the heel bone - largest bone of tarsals is the heel bone or CALCANEUSor CALCANEUS

- 5 METATARSAL BONES- similar to - 5 METATARSAL BONES- similar to metacarpal bonesmetacarpal bones

Foot is shaped to form 2 main arches- formed Foot is shaped to form 2 main arches- formed by the joining of the metatarsals with the by the joining of the metatarsals with the tarsalstarsals

LONGITUDINAL ARCHLONGITUDINAL ARCH

TRANSVERSE ARCH- lies perpendicular to TRANSVERSE ARCH- lies perpendicular to longitudinal longitudinal

- strengthen the foot and act as a spring to - strengthen the foot and act as a spring to cushion movementscushion movements

- lowered arches or flat feet can occur- lowered arches or flat feet can occur

PHALANGES- 4 toes have 3 phalanges and PHALANGES- 4 toes have 3 phalanges and the hallux has only 2 (is like thumb)the hallux has only 2 (is like thumb)