Anatomy Ch.6 bones and bone tissue

Cartilage tissue consists of:

water

Water content of cartilage allows it to:

spring back to its original shape after being compressed

The perichondrium is

a layer of dense irregular cartilage tissue which surrounds the cartilage, which contains no nerves or blood vessels

The Perichondruim

1. acts like a girdle to resist outward expansion when cartilage is compressed

2. It also is the source of blood vessels, which diffuse nutrients to the matrix and chondrocytes.

Chondrocytes are

cartilage cells found in cartilage tissue

Lacunae are

small cavities that surround chondrocytes

Extracellular matrix

contains a jelly-like substance and fibers around lacunae

Hyaline Cartilage

Appearance:

i. Looks like frosted glass

ii. Most abundant skeletal cartilage

iii. Chondrocytes appear round and contain only fine collagen fibers

Where Found:

i. Articular cartilage covers ends of bones at moveable joints

ii. Costal cartilage connects ribs to sternum/brestbone

iii. Respiratory cartilage forms larynx & reinforces respiratory passages

iv. nasal cartilage which supports external nose

Elastic Cartilage

Appearance:

i. Looks similar to hyaline, but it contains more stretchy elastic fibers to withstand repeated bending

Where found

i. supports external ear

ii. Forms epiglottis

Fibrocartilage

Appearance:

i. Appears as parallel rows of chondrocytes alternating with thick collagen fibers

ii. This gives it great strength and ability to compress and withstand great pressure

Where found:

i. Knee meniscus

ii. Discs between vertebrae of spine

Function of Bones

A. Supports

B. Protects

C. Movement

D. Storage

E. Blood Cell Formation

Function of Bones: Supports

body and cradles soft organs, like legs support body trunk and rib cage supports thoracic wall

Function of Bones: Protection

of organs like fused bones of the skull protect brain, vertebrae protects spinal cord and ribs protect heart and lungs

Function of Bones: Movement

the skeletal muscles attached to bones with tendons, use the bones and levers to move body parts

Function of Bones: Storage

for minerals the most important calcium and phosphate are deposited into the blood as needed by the body; stores fat

Function of Bones: Blood cell formation

most blood cells form within the marrow cavities, This is called hematopoiesis.

Classification of bones: Compact of lamellar bones

a. Concentric rings are called lamellae

b. Dense outer covering

c. Homogenous; looks smooth and alike

d. found in most diaphysis; the shafts of long bones

e. Function protection and support, helps long bones resist stress of weight RBC .

Classification of bones: Spongy bone or cancellous bone

a. Trabecular are composed of small needle like pieces with lots of open spaces

b. Filled with red marrow to make RBC’s

c. Found at short, flat, irregular shaped bones

d. Function in adults, makes RBC in hips, ribs, sternum, vertebrae and skull

Classify by Shape: Long

These are longer than wide and have a shaft with heads at both ends. Mostly compact bone, includes bone of limbs, clavicle, hands, and feet.

Classify by Shape: Short

cube shaped and contain spongy bone; bones of ankle and wrist

Classify by Shape: Flat

thin, flattened and usually curved; 2 thin layers of compact bone sandwiching a layer of spongy bone. Mostly found in skull, ribs, sternum and scapula

Classify by Shape: Irregular

do not fit into any category, like vertebrae, hip bones, face, and sacrum

Classify by Shape: Sesamoid

tend to be short and develop with in a tendon, patella, knee cap

Structure of Long Bone: Bone structure

CT cells and extracellular matrix

Structure of Long Bone: Bone structure: Inorganic (no carbon)

a. mineral salts - calcium salts , phosphate, sodium and magnesium

b. makes bones hard and rigid to resist compression 25,000 lb/sq in. and tension 15,000lb/sq in

Structure of Long Bone: Bone structure: Organic

make up and heal bone

Structure of Long Bone: Bone structure: Organic: Types of cells

i. osteoblasts: builds new bone; synthesizing collagen and matrix materials

ii. osteocytes: mature bone cells; no longer synthesizing

iii. Osteoclasts: bone remodeling/destroying cells; remodel due to stresses

Structure of Long Bone: Bone structure: Organic function

give structure flexibility and tensile strength resist stretch8ing and twisting

Structure of Long Bone: Bone structure: Bone

is mineralized living tissue

Structure of Long Bone: Diaphysis definition

shaft that makes up most of long bones length

Structure of Long Bone: Diaphysis:

1. Compact bone makes up long bones

2. Periosteum tough outer covering of shaft not covered by articular cartilage; made with a fibrous CT membrane

3. Sharpey’s fibers are hundred of CT fibers that sure periosteum to the underlying bone

4. Endosteum covers internal bone surfaces in spongy and compact bone; contains both osteoclasts and osteoblasts

Structure of Long Bones: Epiphysis Definition

End of long bones

Structure of Long bones: Epiphysis

1. Each epiphyses consists of a thin layer of compact bone enclosing an area filled with spongy bone

2. Articular cartilage instead of periosteum, covers external surface and provides a smooth slippery surface that decreases friction between joint surfaces

3. Epiphyseal line or plate looks different then rest of bone

   1. In young kids its where bones grow length wise

   2. After puberty its just a line where junction of epiphyses and diaphysis meet

Structure of Long bones: yellow marrow

is found in the shaft of long bones that stores fat in adults. In infants this area forms blood cells.

Structure of Long Bone: red marrow

confined to spongy bones cavities of flat bones and epiphyses of some long bones in adults. It makes red blood cells.

Structure of Long Bone: Bone markings

1. Projections or precesses are outgrowths from bone surface

2. Depressions or cavities are indentations in bone

Structure of Long Bone: Microscopic Anatomy: Osteocytes

mature bone cells

Lacunae

tiny cavities within the matrix that house osteocytes and are arranged in concentric circles called lamellae around central Haversian canal

a. Haverian system or osteon:

structural unit of compact bone. It is an elongated cylinder running parallel to the long axis of the bone. They are weight-bearing pillars.

i. osteon is a group of hollow tubes of bone matrix growing like growth rings of a tree

ii. Lamellae make up each matrix tube

iii. Collagen fibers in lamellae run in the same direction, however, adjacent lamellae run in the opposite direction. this design is the withstand tremendous stresses resisting twisting.

iv. Haversian canals run through the core of each osteon supplying blood and nerve fibers osteon cells

v. Canaliculi or tiny canals that radiate outward from the central canals to all lacunae. These connect all bone cells with nutrients from the blood

vi. Perforating canals lie at right angles to the shaft and connect blood and nerves to the periosteum from central canal.

Bone Formation: Ossification

process of bone formation has two major steps:

1. Process of replacing cartilage tissue with minerals to produce bone

2. Calcium phosphate deposited on collagen fibers with harden matrix

Bone Formation: Bone development

1. Embryos - hyaline cartilage is completely covered with bone matrix by bone forming cells osteoblasts

2. Fetus - hyaline cartilage bones enclosed by bony bones. Then the enclosed hyaline cartilage is digested away opening a megilary cavity.

3. Birth and young - most hyaline converted to bone, except articular cartilage and epiphyseal plates. Articular cartilage lasts for life time, reducing friction at joints. Epiphyseal plates provide growth to long bones during childhood.

Bone Formation: Controlled by Growth Hormones and Sex Hormones

1. Stresses of muscle pull and gravity on skeleton determine where bone matrix broken down and formed, so skeleton can remain strong

2. Blood calcium vexes too high, calcium deposited in bone matrix

3. PTH determines when bone formation or destruction based on calcium levels in the blood

4. Blood calcium level drops, below normal, parathyroid glands releases PTH in blood, which activates osteoclasts, bone destroying cells in bones, to breakdown hone matrix and calcitonin

5. Bone change due to: two things

   1. calcium levels in the blood

   2. pull of gravity and the muscles on skeleton

Bone Formation: Bone Growth

1. Longitudinal Growth - occur at epiphyseal plates; where new cartilage added and old cartilage replaced by bone

2. Appositional growth - placed next to or deposited of new membrane bone under periosteum followed by intramembranous ossification increases bone thickness.

Bone Formation: Bone Remodeling

1. Bone becomes thicker and forms large projections to increase strength where bulky muscles attach

2. Osteoblasts form new matrix and become trapped forming osteocytes or mature bone cells

3. Bone of bedridden or inactive persons tend to lose mass.

Bone Fractures: Types of breaks: Simple

closed fracture the bone breaks cleanly but does not break through skin

Bone Fractures: Types of breaks: Compound

broken ends of bone protrude through soft tissue and skin

Bone Fractures: Types of breaks: comminuted

bones break into many fragments; frequent in older people

Bone Fractures: Types of breaks: Compression

Bone caused and common in porous bones

Bone Fractures: Types of breaks: depression

broken bone portion pressed inward; ex skull fracture

Bone Fractures: Types of breaks: Impact

broken bone ends are forced into each other, when trying to break a fall without stretched hands or hips

Bone Fractures: Types of breaks: Spiral

ragged break when excessive twisting pressure

Bone Fractures: Types of breaks: Greenstick

bones break incompletely

Bone Fractures: Treatment

1. Closed Reduction - bones ends are manipulated back together

2. Open Reduction - bones are surgically placed together by pins and wires

3. After broken bones reduced, it is immobilized by cast or traction to allow it to heal. Simple fractures take 6-8 weeks, but longer for large bones and the elderly.

Bone Fractures: Bone Repair involved 4 major events: Hematoma

forms when blood vessels rupture. Blood filled swelling called hematoma. Bone deprived or nutrients 24 hrs.

Bone Fractures: Bone Repair involved 4 major events: Break

splinted by a fibrocartilage callus; mass of repair tissue that contains some cartilage matrix, bony matrix and collagen fibers when splint broken bones

a. Growth of new capillaries into clotted blood at site of damage

b. Phagocytes eat dead tissue 40 hrs

Bone Fractures: Bone Repair involved 4 major events: Bony Callys forms

as more osteoblasts and osteoclasts come int area and multiply. Fibrocartilage is replaced by callus of spongy bone; one month

Bone Fractures: Bone Repair involved 4 major events: Bone callus remodeled

to form strong patch at site of fracture; 6-12 months.

Axial Skeleton

A. Forms longitudinal axis of the body is divided into 3 parts

i. Skull

ii. Vertebral

iii. Bony thorax (Ribs and sternum)

Appendicular Skeleton

Composed of 126 bones of the limbs pectoral and pelvic girdles, which attach limbs to axial skeleton

Skeletal disorders: Rickets

Disease of children in which bones do not calcify. Bones soften and bowing of legs occur due to a lack of vitamin d or calcium mineral in diet.

Skeletal Disorders: herniated disks

drying of the discs and weakening of ligaments in vertebral column. common in older people, if protruding disc presses on spinal cord or spinal nerves result in numbness and pain.

Skeletal Disorders: Spinal Curvatures

1. Scoliosis: sideways curvature of spine

2. Kyphosis: excessive outward curvature of spine; causing hunching of the back

3. Lordosis: excessive inward curve of lower spinal area

Skeletal Disorders: Dislocation

when bone is forced out of normal position

Skeletal Disorders: Bursitis

“water on the knee” inflammation o the bursae or sinorial membrane

Skeletal Disorders: Sprains

ligament or tendon damaged by excessive stretching or torn away from bone.

Skeletal Disorders: Arthritis

join inflammation and mostly widespread, crippling disease in the US usual symptoms are pain, stiffness and joint swelling.

Skeletal Disorders: Arthritis Osteoarthritis

a. Chronic degenerative condition effects aged and called wear and tear arthritis, affects articular cartilage.

b. over years carriage softens, frays, then breaks down.

c. as progresses, exposed bone thickens and extra bone forms called spurs which grow around margin of eroded cartilage

d. These protrude into join cavity restricting movement

e. medication, pt, and sometimes surgery can help

Skeletal Disorders: Arthritis: Rheumatoid arthritis

a. chronic inflammatory disorder

b. effects more women than men 40-50

c. autoimmune diease

d. beings with inflammation of synovial membrane, which thicken and joints swell

e. the WBC enters joint vanity and forms pannus, abnormal tissue that clings to and erodes cartilage

f. As cartilage destroyed, scar tissue forms and connects bones which fuse together

g. drug treatment to p[recent deformity, medication for pain and cold packs for swelling

Skeletal Disorders: Gout

a. Disease in which uric acid accumulates in blood and deposited in need-shaped crystals in the soft tissues of joints.

b. more common in males

c. isolates a single join like big toe

d. its genetic

e. if untreated bone ends fuse and joints become immobile

f. controlled by diet and medication

Skeletal Disorders: Osteoporosis

loss of bone mass leading to thin, fragile bones particularly in women

1. Factors that contribute

   1. estrogen deficiency

   2. diets poor in calcium, protein, and vitamin d

   3. smoking or vaping

   4. non weight bearing excersice

Skeletal Disorders: Osteomalacia “soft bones”

Factors that contribute

1. inadequate mineralization

2. Osteiod produced but calcium salts not deposited and bones weaken

3. pain

Skeletal Disorders: K. Paget’s Disease

1. Excessive or abnormal bone break down and formation

2. Reduced mineralization so bones are large but weak

3. late in lease, osteoblasts work and build up bone

4. Mostly found in spine pelvis femur and skull which become deformed and it tissue painful

5. most occur after age of 40

6. cause unknown, but could be started by dormant virus in the bones.