Ana&Physio 5 - The Skeletal System.pdf

7/29/2019 Ana&Physio 5 - The Skeletal System.pdf

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The Skeletal

SystemProf. Yvette Marris E. Legaspi, RN, MAN


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ObjectivesAt the end of the lecture-discussion,

you will be able to :

Identify the subdivisions of theskeleton as axial or appendicular.

List at least three functions of the

skeletal system. Name and describe the various

types of fractures.


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Bones: An Overview


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Parts of the skeletal system

Bones (skeleton)

Joints

Cartilages

Ligaments

Divided into 2 divisionsAxial skeleton

Appendicular skeleton


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At birth, there are over 270 bones in

an infant human's body, but many of

these fuse together as the child

grows, leaving a total of 206separate bones in an adult.

The largest bone in the human body

is the femur and the smallest bones

are auditory ossicles.


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Functions of the Bones

1. Support

Form the internal framework of the

body

Ribcage supports the thoracic wall

Legs support the torso

2. Protection Bones

protect soft body organs Skull shields the brain

Ribcage and shoulder girdle protects

the heart and lungs


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3. Movement

Skeletal muscle attach to bones by

tendons

The skeletal muscles use the bones aslevers to produce locomotion

4. Storage

The internal cavities of bone store fat

The matrix of bone tissue is a storage

medium for minerals

They are found in the form of

inorganic salts

two primary minerals:

Calcium

Phosphorus


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5. Blood Cell Formation

Certain bones have marrow

cavities which contain red

marrow

red marrow is the site of

hematopoiesis


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Classification of Bones

Types of bone tissue

Compact

Spongy

Classification of bone based on

structure

Long Short

Flat

Irregular


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Paranasal Sinuses Hollow parts of bones surrounding nasal cavity

Functions:

Lighten the skull

Resonate and amplify voice


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The Hyoid Bone

Only bone that

doesnt articulate

with anotherbone

Moveable basefor tongue


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Structure of a Long Bone

Diaphysis (Shaft)

Compact bone

Periosteum

Cover and protection

Fibrous connective tissuemembrane


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Perforating Fibers , also called

Sharpey's fibers

Secure the periosteum to the

underlying bone

Medullary Cavity

Yellow MarrowAdult:Storage for adipose

tissue

Infant: forms RBC


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Epiphysis

End of a long bone

Articular Cartilage

Covers the external surface

Smooth, slippery surface


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Epiphyseal Plate

Cause the lengthwise

growth of a long bone

Epiphyseal Line

Remnant of the epiphysealplate


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Spongy bone

Contains Red Marrow


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Bone Markings

It is where muscles, tendons,

and ligaments were attached

and where blood vessels and

nerves passed.

Two categories:

Projections or processes

Depressions or cavities


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Projections or Processes

Grow out from the bone

surface

Depressions or Cavities

Indentations in the bone


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Projections That are Sites of Muscle

and Ligament Attachment

Name Description

Tuberosity

Large, rounded

projection; may be

roughened

CrestNarrow ridge of bone;

usually prominent

Trochanter

Very large, blunt,

irregularly shaped

process. These are found

only on the femur

Line

Narrow ridge of bone;

less prominent than a

crest


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Name Description

TubercleSmall, rounded

projection or process

EpicondyleRaised area on or

above a condyle

Spine

Sharp, slender, often

pointed projection orprocess

ProcessAny bony

prominence


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Crest Epicondyle


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Tubercle Tuberosity


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Trochanter Spine


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Projections That Help to

Form Joints

Name Description

Head

Bony expansion

carried on a

narrow neck

FacetSmooth, nearly flat

articular surface

Condyle Rounded articularprojection

RamusArmlike bar of

bone


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Head Facet


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Depressions and Openings Allowing

Blood Vessels and Nerves to Pass

Name Description

Meatus Canal-like passageway

Sinus

Cavity within a bone, filled

with air and lined with

mucous membrane

Fossa

Shallow, basinlike

depression in a bone,

often serving as an

articular surface

Groove Furrow

Fissure Narrow, slitlike opening

ForamenRound or oval opening

through a bone


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Fissure Sinus


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Foramen Groove


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Microscopic Anatomyof Compact Bone


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Complex Structure

Passageways for

Nerves

Blood vessels

Provides the living bones with

nutrients and for removal ofwastes


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1. Lacunae

Cavities containingmature bone cells(osteocytes)

Arranged in concentricrings

2. Lamellae

Rings around thecentral canal

Sites of lacunae


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3. Central (Haversian) canal

Carries blood vessels and nerves to

the group of lamella surrounding it

Run lengthwise through the bonymatrix

4. Osteon (Haversian System)

Central canal and the lamellae

5. Perforating (Volkmans) canal

Canal perpendicular to the centralcanal, run perpendicular to the shaft

Carries blood vessels and nerves


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6. Canaliculi

Tiny canals

Radiate from thecentral canal tolacunae

Form a transport

system to connect allthe bone cells to thenutrient supplythrough the hardbone matrix


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Bone Formation, Growth,and Remodeling


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In embryos, the skeleton is

primarily hyaline cartilage

During development, much ofthis cartilage is replaced by bone

Cartilage remains in isolated

areas

1. Bridge of the nose

2. Parts of ribs

3. Joints


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Bone Growth Ossification

The process of bone formation

Two Steps

Hyaline cartilage model iscovered with bone matrix by

osteoblasts (bone forming cells)

The enclosed hyaline cartilage is

digested away, opening up themedullary cavity within the newly

formed bone


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By birth or shortly after hyaline

cartilage models have been

converted to bone

EXCEPT for two regions

The articular cartilage

Epiphyseal plates


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Epiphyseal plates allow for growth of

long bone during childhood

New cartilage is continuouslyformed:

1. On the external face of articular

cartilage

2. Epiphyseal plate (furthest away

from medullary cavity)

Older cartilage becomes ossified:

1. Internal face of articular cartilage

2. Medullary cavity


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Long Bone Formation and Growth


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Long Bone Growth

Controlled by hormones

Growth hormones

Sex hormones during puberty

Growth ends during

adolescence when the

epiphyseal plates are

completely converted into bone.


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Types of Bone Cells Osteocytes

Mature bone cells

Osteoblasts

Bone-forming cells

Osteoclasts

Bone-destroying cells

Break down bone matrix for remodelingand release of calcium

Bone remodeling is a process by bothosteoblasts and osteoclasts


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Developmental Aspects At birth, skull bones

incomplete

Bones joined by fibrous

membranesfontanelles

Fontanelles replaced by

bone within 2 years

Fetal skull is large

compared to total body

length


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Bone Remodeling

Bones are dynamic and active

tissue

Bones are remodeled due to

Calcium levels in the blood Pull of gravity and muscles on the

skeleton

Essential if bones are to retainnormal proportions and strength

during long bone growth

Bone remodeling


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Bone remodeling

calcium levels

When blood calcium levels drop

below homeostatic levels:

PTH is released into the blood

(from parathyroid gland) Activates osteoclasts to break

down bone matrix and release

calcium into the blood

When blood calcium levels are too

high calcium is deposited into the

bone matrix as calcium salts.

Bone remodeling


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Bone remodeling

muscle attachment

Bones become thicker and form

large projections to increase

their strength in areas where

bulky muscles are attached

Osteoblasts lay down new

matrix and become trapped

Bones of inactive people tend tolose mass.


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Rickets

a softening of bones in children

due to deficiency or impaired

metabolism of vitamin D,

magnesium, phosphorus orcalcium, potentially leading to

fractures and deformity.


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Bone Fractures A break in a bone

Types

1. Closed (simple) fracture does notpenetrate skin

2. Open (compound) fracturepenetrates through skin

Bone fractures are treated byreduction and immobilization

- Realignment of the bone


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Common Types of Fractures


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Comminuted Fracture


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Compression Fracture


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Depressed Fracture


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Impacted Fracture


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Spiral Fracture


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Greenstick Fracture


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Repair of Bone Fractures

1. Hematoma (blood-filled

swelling) is formed

2. Break is splinted byfibrocartilage to form a callus

3. Fibrocartilage callus is replaced

by a bony callus

4. Bony callus is remodeled to

form a permanent patch

Stages in the Healing of a Bone


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Stages in the Healing of a Bone

Fracture

Ana&Physio 5 - The Skeletal System.pdf

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