The Skeletal System About the Bones… - PowerPoint Presentation

Slide1

The Skeletal System

Slide2

About the Bones…

It is the FRAMEWORK for the body.

There are

206

individual bones in the adult

Slide3

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Functions of Skeletal System

Support

structure and provide shape

Protection

Allows for

movement and anchorage of muscles

Provides

mineral storage

Site of

hemopoiesis

Blood cell formation in red marrow of long bones

Slide5

STUCTURE OF BONES

Osteocytes

Microscopic cells of bones

Mature bone cell (osteocyte

)

Bone is made up of

35% organic - is a protein

called

collagen

degree of flexibility

65% inorganic

- mineral

salts

(calcium) and water

Give

bone its hardness and durability

Slide6

Bone Formation

Embryonic skeleton initially consists of collagenous protein fibers secreted by osteoblasts (primitive embryonic cells)

Later, cartilage is deposited between the fibers

At 8

wks

,

OSSIFICATION

begins

Mineral matter begins to replace cartilage, creating bone

Slide7

Formation

Infant bones are very soft and pliable because of incomplete ossification at birth

For example: soft spot on a baby’s head: fontanel

Ossification due to mineral deposits will continue through childhood making the bone hard and more capable of bearing weight

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Structure of Long Bone

A typical long bone contains a shaft:

diaphysis

Hollow

cylinder -

hard, compact bone

Makes a long bone strong and hard yet light enough for

movement

At each end is an

epiphysis

Slide11

Structure long bone

cont

In the center of the shaft is the

medullary canal

.

Filled with yellow bone marrow, mostly made of fat cells

Marrow contains many blood vessels and some cells which form WBCs, called leukocytes

Yellow marrow functions as a fat storage center

Endosteum

:

lining

of the marrow canal that keeps the cavity intact

Slide12

Structure

cont

…

Shaft

is

compact

bone

ends of the shaft

are

spongy bone

(dissolved bone where less strength is needed)

Ends of the long bone contain the red marrow where some RBCs (erythrocytes) and some WBCs are made

Periosteum

: tough fibrous tissue (

outside covering

of bone) which contains blood vessels, lymph vessels, and nerves

Necessary for bone growth, repair, and nutrition

Slide13

Last on Structure

Covering the epiphysis is a thin layer of cartilage: articular cartilage

Acts as a shock absorber between 2 bones that meet to form a joint

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Growth

A bone increases its circumference by the addition of more bone to the outer surface of the diaphysis by

osteoblasts

bone cells that deposit new bone

As girth increases, bone material is being dissolved from the center: medullary canal (gets larger as diameter increases)

Slide16

Growth

Dissolution of bone from the medullary canal results from the action of cells called

osteoclasts

Immense bone cells that secrete enzymes

Enzymes digest bony material, splitting the bone minerals (calcium and phosphorus) and enabling them to be absorbed by the surrounding fluid

Medullary canal eventually fills with yellow marrow

Slide17

Growth

Avg

growth in females: 18 years

Avg

growth in males: 20-21 years

Slide18

Bone Types

Four types:

1. Long bones: found in upper and lower arms and legs

2. Flat bones: skull/head bones and ribs

3. Irregular bones: bones of spinal column

4. Short bones: wrist and ankle bones

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PARTS OF THE SKELETON

Axial

Skull, spinal column, ribs, sternum

(breast bone),

and hyoid (U-shaped bone in the neck – tongue attached to it)

Appendicular

Shoulder girdle, arms, wrists, hands, hip girdle (pelvis), legs, ankles, and feet

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Axial Skeleton

Skull: cranium and facial bones

22 bones total

Cranium houses and protects the brain

Facial bones guard and support the eyes, ears, nose, and mouth

Some facial bones are made of bone and cartilage for example the nose (which part is bone and which is cartilage?)

Slide24

Cranium

Cranial bones are thin and slightly curved

During infancy they are held together by an irregular band of connective tissue called a

suture

As the child grows, the connective tissue ossifies and turns into hard bone

The dome shape gives better protection than a flat surface, deflecting blows directed toward the head

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8 Cranium Bones

1 frontal: forms the forehead

2 parietal: form the roof and sides of the skull

2 temporal: house the ears

1 occipital: forms the base of the skull and contains the foramen magnum (what is that?)

1

ethmoid

: (located b/t the eyes) forms part of the nasal septum

1

sphenoid

: (resembles a bat) considered the key bone of the skull

; all other bones

of the skull connect

to it

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14 Facial Bones

5 nasal

2 are bones that form the bridge of the nose

1 is the

vomer

bone which forms the lower part, or midline, of the nasal septum

2 are

inferior concha

which make up the side walls of the nasal cavity

2 maxilla: make up the upper jaw

2 lacrimal: (in the inner aspect of the eyes) contain the tear ducts

2

zygomatic

: form the prominence of the cheek

2 palatine: form the hard palate of the mouth

1

mandible

: lower jaw and the

only movable bone in the face

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Spinal Column/Vertebra

Strong and flexible, supports the head, provides for attachment of the ribs, and encloses the spinal cord

Consists of small bones: vertebrae

Separated from each other by pads of cartilage tissue called

intervertebral disks

Cushions b/t the vertebrae and act as shock absorbers

During our lifetime they become thinner, accounting for loss of height as we age

Slide31

5 Sections of Vertebral Column

Cervical vertebra

Thoracic vertebra

Lumbar vertebra

Sacrum

Coccyx

Slide32

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Cervical Vertebrae

7 total; located in the neck area

Atlas

: the

first

cervical vertebra that articulates, or is jointed, with the occipital bone; permits us to

nod our heads

Axis

: the

2

nd

vertebra; is the odontoid process which forms a pivot on which the atlas rotates; permits us to

turn

our

heads

Slide34

Thoracic and Lumbar Vertebrae

Thoracic: 12 total; located in the chest area

Articulate with the ribs

Lumbar: 5 total; located in the back

Have large bodies that bear most of he body’s weight

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Sacrum and Coccyx

Sacrum: wedge-shaped bone formed by 5 fused bones

Forms the posterior pelvic girdle and serves as an articulation point for the hips

Coccyx: known as the tailbone

Formed by 4 fused bones

Slide37

Ribs and Sternum figure 6-7

Thoracic area protected and supported by the thoracic vertebrae, ribs, and sternum

Sternum

: (breastbone) is divided into 3 parts:

upper region (

manubrium

), the

body

, and a lower cartilaginous part: the

xiphoid process

Attached to each side of the upper region , by means of ligaments, are the 2

clavicles(collar bones)

Slide38

continued

Human body contains

12 pairs of ribs

7 pairs

of costal cartilages join 7 pairs of ribs directly to the sternum

True ribs

Next

3 pairs

are attached to the 7

th

rib (instead of the sternum) by their costal cartilages

False ribs

Last

2 pairs

are not connected to costal cartilages or sternum

Floating ribs

Slide39

The Appendicular Skeleton

Upper Extremities

shoulder girdles

arms

wrist

hands

Lower Extremities

hip girdle

legs

ankles

feet

Slide40

Shoulder Girdle

Also called pectoral girdle

Consists of 4 bones

2

clavicles (collar bones)

2 triangular

scapulae (shoulder bones

)

Clavicles help to brace the shoulders and prevent excessive forward motion

Scapulae permit the attachment of muscles that assist in arm movement and serve as a place of attachment for the arms

Slide41

Arm

Consists of the

humerus

, radius, and ulna

Humerus

Upper arm – 2

nd

largest in body

Upper end articulates with the scapulae

Forearm

Radius

on thumb side (RADIAL PULSE SITE)

Rotates around the ulna- good flexibility

Ulna

on pinky side

Limited movement

Olecranon

process(FUNNY BONE)

articulates with the

humerus

Slide42

Hand

Has 27 bones

Carpals

(wrist bone): consists of 8 small bones arranged in 2 rows

Metacarpals

(5)

Phalanges

(14) – each finger has 3, the thumb has 2

Slide43

Pelvic Girdle

3 bones in youth

ilium, ischium, and pubis

Eventually fuse with the sacrum to form a bowl-shaped structure (the pelvic girdle)

Eventually the 2 sets of bones form a joint with the bones in the front:

symphysis

pubis and with the sacrum in the back: sacroiliac joint

Slide44

Male vs

Female Pelvis

Female pelvis is wider

Necessary for childbirth

Male pelvis is heavier

Slide45

Upper Leg

Femur (thigh)

LONGEST

and

STRONGEST

bone in body

Upper part of the femur has a smooth, rounded head

Fits neatly into a cavity of the ilium known as the

acetebulum

, forming a ball and socket joint

Slide46

Lower Leg

Consists of 2 bones:

Tibia

: largest of the 2

Fibula

The

patella

(kneecap) is found in front of the knee joint; it is a flat, triangular,

sesamoid

bone

Formed in the tendons of the

quadricep

in front of the femur

4

bursae

surround the patella which serve to cushion the knee joint

Slide47

Sesamoid Bone

Found where a tendon passes over a joint

Holds the tendon slightly farther away from the center of the joint and thus increases its movement

Prevents the tendon from flattening into the joint as tension increases

Slide48

Ankle

7

tarsal

bones which provide a connection b/t the foot and leg bones

Largest ankle bone is the heel bone or

calcaneus

Tibia and fibula articulate with a broad tarsal bone called the talus

Movement is a sliding motion, allowing the foot to extend and flex when walking

Slide49

Foot

Has 5

metatarsal

bones

Arranged to form 2 distinct arches

One runs longitudinally from the calcaneus to the head of the metatarsals: longitudinal arch

Other lies perpendicular to the longitudinal arch: transverse arch

Arches strengthen the foot and provide flexibility and springiness to the stride

Strong ligaments and leg muscle tendons help to hold the foot bones in place

Slide50

Foot continued

Arches can “fall” d/t weak foot ligaments and tendons

Downward pressure by weight of the body slowly flattens them, causing fallen arches or

flatfeet

Cause a good deal of stress and strain on the foot muscles

Factors leading to it may be: fatigue, overweight, poor posture, and improperly fitting shoes

Slide51

Foot…

Toes are similar in composition to the fingers

There are 3 phalanges but the big toe has 2

Total of 14 phalanges in each foot

Slide52

Types of Motion

Flexion

: act of bringing 2 bones closer together which decreases the angle b/t the 2 bones

Extension

:

act of increasing the angle b/t 2 bones, which results in a straightening motion

Abduction

:

movement of an extremity away from the midline

Adduction

:

movement toward the midline

Circumduction

:

includes flexion, extension, abduction, and adduction

Rotation

:

movement that allows a bone to move around 1 central axis (for example: turning your head from side to side = pivot)

Pronation

:

the forearm turns the hand so the palm is downward or backward

Supination

:

the palm is forward or upward