The Skeletal System

Structure, Function, and Diseases

Functions1. Support

Framework that supports body and cradles its soft organs

Without the skeleton your body would collapse like jelly.

Functions2. Protection

Protects internal organs and fragile body parts: heart, lungs, brain, lungs, spinal cord, etc.

Functions

3. Movement

bones act as levers for muscles

Functions

4. Mineral storage

calcium & phosphate

Functions5. Blood cell formation-

“hematopoiesis”

· Diaphysis· Shaft

· Composed of compact bone

· Epiphysis

· Ends of the bone

· Composed mostly of spongy bone

Gross Anatomy of a Long Bone

CHAguilar 2011

Types of Bone Cells· Osteocytes

· Mature bone cells· Osteoblasts

· Bone-forming cells· Osteoclasts

· Bone-destroying cells· Break down bone matrix for remodeling and

release of calcium· Bone remodeling is a process by both

osteoblasts and osteoclasts

Osteoblast

Osteocyte

OsteoclastEats bone

Builds new bone

Mature bone cell

Changes in the Human Skeleton

· In embryos, the skeleton is primarily hyaline cartilage

· During development, much of this cartilage is replaced by bone

· Cartilage remains in isolated areas

· Bridge of the nose

· Parts of ribs

· Joints

I. ENDOCHONDRAL OSSIFICATION- cartilage to bone

a. Circumference - deposition of osteoblasts beneath

periosteum forming new bone on the surface and increasing girth

- osteoclasts dissolve bony tissue in interior to give way to marrow cavity

b. Length- 4 regions in epiphyseal plate ( between epiphysis and diaphysis)

1. “resting” cartilage cells 2. zone of proliferation

3. zone of hypertrophy 4. zone of calcification

II. INTRAMEMBRANOUS OSSIFICATION

• Membranous tissue to bone• In flat bones of the skull• Done through appositional growth ( addition on

sides of osseous tissue)• Cannot grow by interior expansion

BONE GROWTH AND RESORPTION

• Childhood- faster ossification, slower resorption= inc in size of the bone

• Adulthood- ossification=resorption-constant size

• Late adulthood(35-40 onwards)- faster resorption, slower ossification- osteoporosis in older women

cartilagecalcified cartilage

bone

epiphyseal plate

epiphyseal line

Endochondral Ossification

2o

ossification

center

Fetus: 1st 2 months

Adult

Childhood

Just before birth

Intramembranous ossification

Bone Fractures

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· A break in a bone

· Types of bone fractures· Closed (simple) fracture – break that does not

penetrate the skin

· Open (compound) fracture – broken bone penetrates through the skin

· Bone fractures are treated by reduction and immobilization· Realignment of the bone

Common Types of Fractures

Stages in the Healing of a Bone Fracture

Bone Repair:1. Electrical stimulation of the fracture site:• Increases speed and completeness of healing• The e- stimulation inhibits PTH and slow

osteoclasts down from reabsorbing bone2. Ultrasound treatment:• Daily treatments reduce healing time of broken

bones by 25-35%3. Free vascular fibular graft technique:• Transplant fibula in arm• Gives good blood supply not available in other

treatments4. Bone substitutes:• Crushed bone from cadaver- but risk of HIV and

hepatitis• Sea bone- coral• Artificial bone- ceramic

Paranasal Sinuses

Slide 5.25a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· Hollow portions of bones surrounding the nasal cavity

Figure 5.10

• Warm and moisten air• Lighten the skull• Enhance voice resonance

Frontal Sinus

Ethmoid Sinus

Sphenoid Sinus

Maxillary Sinus

EFFECTS OF HORMONES ON BONES1. Growth hormone• hyposecretion/removal of pituitary gland

- results in premature cessation of transformation of chondrocytes to bones in epiphysis

• Hypersecretion- giantism/acromegaly

2. Parathormone- overactivity- bones become unduly fragile and fracture spontaneously and cysts form ( osteitis fibrosa cystica)

3.Thyroxine- deficiency in young- delayed/inc ossification= softer bones

4. estrogen- stimulate osteoblastic activity-def during post-menopausal stage- osteoporosis

Head shape and delivery method• Method of delivery determined thru diameter

of female pelvis and size of fetal skull

• Small pelvic measurements- cesarean operation

no molding( different shape of head) • Average pelvic measurements-natural delivery

head is molded during its passage through birth canal

• Instrumental delivery- placing forceps on head and pulling

very delicate job and could cause damage to motor cortex of brain – spastic child

Diseases and Conditions

of the Skeletal System

Arthritis

Bursitis• Inflammation of the Bursa (fluid

filled sac surrounding the joint).• bursa can become inflamed from

injury, infection or due to an underlying rheumatic condition.

• typically identified by localized pain or swelling, tenderness, and pain with motion of the tissues in the affected area.

Bunion• Swelling of bursa of great toe due to

pressure or friction from badly fitting shoes

Tendonitis• literally means inflammation of

the tendon• If normal smooth gliding

motion of tendon is impaired, the tendon will become inflamed and movement will become painful.

• The most common cause of tendonitis is overuse.

Carpal Tunnel Syndrome• Due to any condition that causes

swelling or a change in position of the tissue within the carpal tunnel

• can squeeze and irritate the median nerve.

• This causes tingling and numbness of the thumb, index, and the middle fingers, a condition known as "carpal tunnel syndrome."

Osteoporosis• means "porous bones.“

Risk Factors: • Being female:decreased estrogen after

menopause• Small frame• Caucasian or Asian ethnicity• Little weight-bearing exercise• diet poor in Ca++ and protein• abnormal vitamin D receptors• Smoking• Drinking alcohol

Scoliosis• Scoliosis is an abnormal curvature of

the spine. • Scoliosis runs in families, but doctors

often don't know the cause.• More girls than boys have severe

scoliosis. • Adult scoliosis may be a worsening of a

condition that began in childhood• scoliosis may also result from a

degenerative joint condition in the spine.

Kyphosis• With kyphosis, your spine may look normal

or you may develop a hump. • Kyphosis can occur as a result of

developmental problems; degenerative diseases, such as arthritis of the spine; osteoporosis with compression fractures of the vertebrae; or trauma to the spine.

• It can affect children, adolescents and adults.

Lordosis• A spine affected by

lordosis shows evidence of a curvature of the back bones (vertebrae) in the lower back area, giving the child a "swayback" appearance.

Tuberculosis of the Spine- (Pott’s Disease)

• A form of extrapulmonary tuberculosis that impacts the spine,

• Aka arthritis for the vertebrae• More properly known as tuberculosis

spondylitis,• Pott’s disease is often experienced as a local

phenomenon that begins in the thoracic section of the spinal column.

• Early signs of the presence of Pott’s disease generally begin with a simple back pain that in short order,will begin to multiply.

Rickets• Rickets is the softening and

weakening of bones in children, usually because of an extreme and prolonged vitamin D deficiency.

• Some skeletal deformities caused by rickets may need corrective surgery.

Knock knees

Bow legs

Beaded ribs

Scurvy

• Consumption of fruits and vegetables or diets fortified with vitamin C are essential to avoid ascorbic acid deficiency.

• Even though scurvy is uncommon, it still occurs and can affect adults and children who have chronic dietary vitamin C deficiency.

Gout• results from an overload of uric acid in

the body which leads to the formation of tiny crystals of urate that deposit in the joints.

• When crystals form in the joints it causes recurring attacks of joint inflammation (arthritis).

• Chronic gout can also lead to deposits of hard lumps of uric acid in and around the joints and may cause joint destruction, decreased kidney function and kidney stones

Acromegaly• occurs when the pituitary gland

produces too much growth • When there is too much growth

hormone in the body, these tissues grow larger than normal.

• This excessive growth can cause serious disease and even premature death.

Poliomyelitis

• a highly infectious disease caused by a virus which invades the nervous system causing total paralysis in a matter of hours.

• can strike at any age, but affects mainly children under three (over 50% of all cases).

• The virus enters the body through the mouth and multiplies in the intestine. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs.

• One in 200 infections leads to irreversible paralysis (usually in the legs). Amongst those paralysed, 5%-10% die when their breathing muscles become immobilized.

• As most people infected with poliovirus have no signs of illness, poliovirus can spread widely

• After initial infection with poliovirus, the virus is shed intermittently in faeces (excrement) for several weeks. During that time, polio can spread rapidly through the community.

Herniated Disk• Soft inner central portion of intervertebral

disk protrudes into vertebral canal and exerts pressure on spinal cord

• Laminectomy-operation to correct condition

Spina Bifida• birth defect that involves the incomplete

development of the spinal cord or its coverings.

• The term spina bifida comes from Latin and literally means "split" or "open" spine.

• Spina bifida occurs at the end of the first month of pregnancy when the two sides of the ﾊ embryo's spine fail to join together, leaving an open area.

• In some cases, the spinal cord or other membranes may push through this opening in the back. The condition usually is ﾊdetected before a baby is born and treated right away.

Talipes Equinovarus- “Clubfoot”

• A deformity of the whole foot that is present at birth.

• Aka as 'talipes', as the deformity is mostly in the talus (a bone in the ankle).

• The most common of the talipes is what is known as "talipes equino varus“

• In talipes equino varus, the child is born with the foot pointing down and twisted inwards at the ankle.

Sarcoma• Osteosarcoma-The most common

type of bone cancer. • arises in bone and is most

commonly found in children and adolescents

• A rare form occurs in adults, particularly in patients who have been cured of other cancers with radiation therapy.

Myeloma• a cancer in which

abnormal cells collect in the bone marrow and form tumors.

• Sometimes these abnormal cells (called myeloma cells) collect in only one bone and form a single tumor known as a plasmacytoma.

• However, in most cases, the myeloma cells collect in many bones, forming several tumors and causing other problems ( multiple myeloma).

Bone Marrow Biopsy