Dem Bones

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Factoids• The human hand has 27 bones; your face has 14!• The longest bone in your body? Your thigh bone,

the femur -- it' s about 1/4 of your height. The smallest is the stirrup bone in the ear which can measure 1/10 of an inch.

• Did you know that humans and giraffes have the same number of bones in their necks? Giraffe neck vertebrae are just much, much longer!

• You have over 230 moveable and semi-moveable joints in your body.

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Tornado Boy

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• Bones are made of several tissues

• Primarily made of collagen and hydroxyapatite - Ca10(PO4)6(OH)2

• 206 bones in the human body (over 300 at birth).

Skeletal System

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Functions of Skeletal System• SUPPORT: Hard framework that supports and anchors the soft organs of the body.

• PROTECTION: Surrounds organs such as the brain and spinal cord.

• MOVEMENT: Allows for muscle attachment therefore the bones are used as levers.

• STORAGE: Minerals and lipids are stored within bone material.

• BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.

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Your BONES and homeostasis

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Skeletal System Organization• Axial skeleton

– Skull and bones that support it– Includes vertebra and ribs– 80 bones

• head • neck • trunk

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Skeletal System Organization• Appendicular skeleton

– Limbs– 126 bones

• upper limbs• lower limbs• pectoral girdle• pelvic girdle

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Vertebral columnFirst 7 - cervicalNext 12 - thoracicLast 5 – lumbar

Ribs (12 pairs)First 7 - trueNext 5 - false(Last 2 - floating)

MaxillaMandible

CalcaneusTalus

Illium

Ischium

Pubis

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Flat Bones (c)– cranium,

ilium, sternum, rib cage, sacrum and scapula

Short Bones (b)- bones of the wrist and ankle

Long Bones (a)– femur, tibia,

fibula, humerus, radius, and ulna , metacarpals, metatarsals, and phalanges

Bone ClassificationSesamoid (Round) Bones (e) - patella

Irregular Bones (d)– vertebrae,

sacrum, hyoid

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Features of a Long Bone:Epiphysis: Ends of the bone.

Diaphysis: The shaft of the bone which surrounds the medullary cavity.

Articular Cartilage: Cushions the ends of the bones and allows for smooth movement.

Epiphyseal Plate:Areas made of cartilage allowing for the growth of the bone.

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What are the following

depressions & openings?

Foramen Meatus Fossa

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What are the following

processes?Condyle

Facet

TuberosityHead

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Bone Structure• Periosteum – hard outer covering

– Cells for growth and repair

• Compact bone – hard strong layer– Bone cells, blood vessels, protein with Ca and P

• Spongy bone – at ends of long bones– Has small open spaces to lighten weight

• Marrow cavity – hollow in middle of long bones

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Bone Marrow• Red marrow – produces blood cells and

clotting factors– Found in humerus, femur, sternum, ribs,

vertebrae, pelvis– Produces RBC 2 million per second

• Yellow marrow – stores fat– Found in many bones

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Hematopoiesis• Occurs in cavities with red marrow

• Medullary Cavity– In children contains read marrow and is

hematopoietic– In adults the red marrow is replaced by fat –

yellow marrow (not hematopoietic)• Hematopoiesis in Adults

– Red marrow in spaces of spongy bone– Head of femur and humerus– Some flat bones: sternum, pelvic bone

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Bone Structure

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Compact & Spongy Bone

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• Bones are composed of connective tissue, chemicals, and fats

• Solid outer layer - compact bone– Composed of osteons

• An inner layer of spongy bone – a honeycomb of flat,

needle-like projections called trabeculae.

Above: Note the relationship btwn the compact and spongy bone.Below: Close up of spongy bone.

Bone Structure

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• Volkmann’s canals– Perpendicular to the

haversian canals. – Connect the blood and

nerve supply in the periosteum to those in the haversian canals and the medullary cavity.

Compact Bone

Haversian canals › allow the passage of

blood vessels, lymphatic vessels, and nerve fibers.

› Surrounded by layers of bone called a lamella.

osteon

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Bone Cells

Osteoblasts› Bone building cells› Synthesize and secrete

collogen fibers and other organic components of the bone matrix

› Initiate calcification› Found in the periosteum

and the endosteum Ossification

› Formation of bone by osteoblasts.

› Cells surround themselves by matrix.

osteoblasts

Bone matrix

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6-22

• Osteocytes. › Mature bone cells.› Osteoblasts that have

become trapped by the secretion of matrix.

› Responsible for maintaining the bone tissue

• Lacunae› spaces occupied by

osteocyte cell body• Canaliculi

› canals that allow for nutrient filled liquid to fill the lacunae

Bone Cells

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Bone Cells

OsteoclastsCells that ecretes digestive enzymes to digest bone matrix

bone resorptionConcentrated in the endosteum.On the side of the cell that faces the bone surface,

ruffled border. Pumps out hydrogen ions

Create an acid environment that eats away at the matrix. 23

www.academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_Lec/Skeletal/BoneTissue.ppt

Why is there a depression underneath the osteoclast?What advantage might a ruffled border confer? What is the name of the third cell type shown here? What do you think the tan material represents?

Bone Cells

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Bone Development• Initial skeleton of cartilage in infants

• Replaced with bone by osteoblasts

• More than 300 bones at birth – fuse to 206

• Always growing and breaking down– Osteoblasts – form new bone cells– Osteoclasts – break bone cells down– Osteocytes – mature bone cells

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Fractures

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Types of Fractures

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Types of Fractures• green stick

• fissured• comminuted• transverse• oblique• spiral

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Fracture Repair• Hematoma- blood clot in space between edges

of break

• Fibrocartilage callus- begins tissue repair

• Bony callus- osteoblasts produce trabeculae (structural support) of spongy bone and replace fibrocartilage

• Remodeling- osteoblasts build new compact bone, osteoclasts build new medullary cavity

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Broken BonesRegrowth of bone:

–Spongy bone forms in first few days–Blood vessels regrow and spongy

bone hardens –Full healing takes 1-2 months

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Mechanics of Movement• Tissues and Structures Involved

– Muscle– Nerve– Bone– Cartilage

• What are Tendons & Ligaments?• Types of Joints• Mechanics of Joints

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Functions of the Skeletal System

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HOW DOES MOVEMENT HAPPEN?

Muscles PULL on Tendons to Move Bones at Connections called Joints or Articulations

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Frolich, Human Anatomy, Mechanics of Movement

Tendons• Tendons are structures that connect bone to muscle,

muscle to muscle, or bone to bone

Made up of tendon tissue (connective tissue)

Can have various shapes

Typical is cord-like tendon of biceps

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Frolich, Human Anatomy, Mechanics of Movement

Ligaments connect bone-to-bone or reinforce joints--they are made up of tendonous tissue as well

Typical are knee ligaments

Ligaments

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Frolich, Human Anatomy, Mechanics of Movement

• Usually, but not always allow for movement• Formed from various connective tissues

– Fibrous– Cartilaginous– Synovial (most complex--typical limb joints)

• Functions of joints– Hold bones together– Allow for mobility

• Ways joints are classified– Functionally– Structurally

Joints

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Frolich, Human Anatomy, Mechanics of Movement

Functional ClassificationThe amount of movement the joint allowsSynarthroses

immovable joints

Amphiarthroses slightly moveable joints

Diarthroses freely moveable joints

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Frolich, Human Anatomy, Mechanics of Movement

Structural ClassificationFibrous joints

Generally immovableFibrous tissue separate the boney region at the joint

Cartilaginous jointsImmovable or slightly moveableCartilage separates the boney regions at the joint

Synovial jointsFreely moveableThe boney regions of the joint are separated by a

space

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Frolich, Human Anatomy, Mechanics of Movement

Fibrous JointsBones united by fibrous tissue –

synarthroses or largely immovable.

Skull Bones tightly bound

by minimal fiber

Syndesmosis Longer connecting

fibers Joint has more give

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Frolich, Human Anatomy, Mechanics of Movement

Cartilaginous Joints Mostly amphiarthrosis

Bones connected by cartilageSlightly movable

Pubic symphysisIntervertebral jointsHyaline cartilage unites bonesEpiphyseal growth platesCostal cartilage-sternum

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Frolich, Human Anatomy, Mechanics of Movement

Synovial JointsDiarthroses – movable jointMost common joint in the body

Articulating ends of bones are covered with hyaline cartilage

Enclosed by a capsule of fibrous connective tissue lined with synovial membranes

Joint cavity is filled with synovial fluid for lubrication

Ligaments reinforce the joint44

Frolich, Human Anatomy, Mechanics of Movement

Typical Synovial Joint

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Structures Associated with the Synovial Joints

Bursae – flattened fibrous sacsLined with synovial membranesFilled with synovial fluidNot actually part of the joint

Tendon sheathElongated bursa that wraps

around a tendon

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Types of Synovial Joints

The type of joint, in part, determines the range and direction of movement 47

Types of Synovial Joints

The type of joint, in part, determines the range and direction of movement 48

HOW DOES MOVEMENT HAPPEN? The elbow joint - a hinge joint allowing movement in 1 plane Upper arm

bone - humerus

Capsule (ligaments)Synovial membrane

CartilageCartilage

Synovial fluid

tendon

Triceps muscle

The Capsule. Holds the bones of the joint in place.

The synovial membrane. Secretes synovial fluid

The synovial fluid. Lubricates the movement of the cartilage surfaces against each other – reducing friction and preventing arthritis (inflammation and joint damage).

Cartilage. Lubricates the movement of the cartilage surfaces against each other – reducing friction and preventing arthritis (inflammation and joint damage). 49

biceps (flexor muscle), contracts

Triceps (extensor) relaxes

humerus

radiusulna

THE BICEPS AND TRICEPS ARE AN ANTAGONISTIC PAIR

When the biceps contracts the elbow joint flexes (its joint angle decreases).

When the triceps contracts the elbow joint extends (its joint angle increases).

The biceps and triceps are called antagonistic muscles because they have the opposite effect on the same joint.

Remember that for this to work properly the biceps must relax when the triceps contracts, and vice versa.

HOW DOES MOVEMENT HAPPEN? The elbow joint -

how the bicep and triceps control movement

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Inflammatory Conditions Associated with JointsBursitis – inflammation of a bursa usually

caused by a blow or frictionTendonitis – inflammation of tendon sheathsArthritis – inflammatory or degenerative

diseases of jointsOver 100 different typesThe most widespread crippling disease in the

United States51

Frolich, Human Anatomy, Mechanics of Movement

Clinical Forms of ArthritisOsteoarthritis

Most common chronic arthritisProbably related to normal aging processes

Rheumatoid arthritisAn autoimmune disease – the immune system

attacks the jointsSymptoms begin with bilateral inflammation of

certain jointsOften leads to deformities

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Frolich, Human Anatomy, Mechanics of Movement

X-ray of hand affected by arthritis

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Osteoarthritis

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Frolich, Human Anatomy, Mechanics of Movement

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Frolich, Human Anatomy, Mechanics of Movement

Artificial Hip Joint

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Click on the picture for the web sports injury clinic

Lots of problems with joints result

from sports injuries

What can go wrong with joints

Dislocation The bones move out of position, causing pain and preventing joint movement

Cartilage damage Movement becomes painful or impossible and the joint becomes inflamed.

Antagonistic muscle damage due to too overloading Making

movement of the joint painful and difficult

Tendons strain or tear Making movement of the joint

painful and difficult

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• Caused by elevated levels of uric acid in the blood which crystallize and are deposited in joints, tendons, and surrounding tissues.

Gout• Characterized by

recurrent attacks of acute inflammatory arthritis.

• Metatarsal-phalangeal joint at the base of the big toe is the most commonly affected.

• Gout was historically known as "the disease of kings" or "rich man's disease".

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Bunions• A deformity

characterized by lateral deviation of the great toe. As the great toe turns in toward the second toe the tissues surrounding the joint may become swollen and tender.

• The bump is partly due to the swollen bursal sac.

• The larger part of the bump is a normal part of the head of first metatarsal bone that has tilted sideways to stick out at its top.

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Homeostatic Imbalances

Rickets• Disease of children due to a lack of vitamin D.• Calcium is not deposited in bones.• Bones become soft.• Bowing of the bones, and other deformities occur.

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Homeostatic Imbalances

Osteomalacia• “Rickets” of adults.• Due to a lack of vitamin D.• Calcium is not deposited in the bones.• Bones become brittle.

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Osteogenesis Imperfecta

(sometimes known as brittle bone disease)genetic bone disorder• born with

defective connective tissue, or without the ability to make it.

Type V in a child

Type V in an adult

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Homeostatic ImbalancesOsteoporosis

• Bone reabsorption is greater than bone deposition.

• Due to any of the following:

• Increased Risk for Fracturecompression fractures of vertebraehip fractures

• Lack of estrogen in women.• Lack of exercise to stress the bones.• Inadequate intake of calcium and phosphorus.• Abnormalities of vitamin D metabolism.• Loss of muscle mass.

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Osteoporosis

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Life-Span Changes• decrease in height at about age 30

• calcium levels fall• bones become brittle• osteoclasts outnumber osteoblasts• spongy bone weakens before compact bone• bone loss rapid in menopausal women• hip fractures common• vertebral compression fractures common

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Factors Affecting Bone Development, Growth and Repair• Deficiency of Vitamin A – retards bone development

• Deficiency of Vitamin C – results in fragile bones • Deficiency of Vitamin D – rickets, osteomalacia• Insufficient Growth Hormone – dwarfism• Excessive Growth Hormone – gigantism, acromegaly • Insufficient Thyroid Hormone – delays bone growth• Sex Hormones – promote bone formation; stimulate

ossification of epiphyseal plates• Physical Stress – stimulates bone growth

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How does a forensic Pathologist determine the sex of a skeleton?

• The male pelvis is more robust, narrower, and taller than the female pelvis. The angle of the male pubic arch and the sacrum are narrower as well.

• The female pelvis is more delicate, wider and not as high as the male pelvis. The angle of the female pubic arch is wide and round. The female sacrum is wider than the male's and the iliac bone is flatter. The pelvic basin of the female is more spacious and less funnel-shaped.68

Male: • Heavier • Skull size is larger than females.• Bones are thicker• The forehead is slightly sloping or

receding.• The vault of the skull is more rounded.• The overall length of the skull is

longer • The chin is bigger and projects more

forwards• The zygomatic bones are also more

massive.• Supraorbital • margins ore • rounded

Female: • Lighter• Skull size is smaller compared to

males.• Bones are Thinner• The forehead is vertical.• The vault is flattened.• The skull is Rounded• The facial bones are smoother B• Both the mandible and the

maxilla are smaller.• Supraorbital

margin is sharp

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