Skeletal System

Unit 6.4 (6th Edition) Chapter 7.4 (7th Edition)

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Learning Objectives • Understand the five functions of bones (physiology) • Classify the four major types of bones • Identify the major parts (anatomy) of a bone • Identify the components of the axial and appendicular divisions of the skeleton • Identify the main bones of the human skeleton • Identify major joints and describe their motion • Describe the main diseases of the skeletal system (pathophysiology) • Distinguish between the major bone fractures

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Fun Facts About the Human Skeleton • Adult humans have 206 bones • You are born with 300 bones • Bones fuse together as you age • As human develops in mother’s womb, majority of skeleton is cartilage, not yet ossified bone • The strongest and longest bone in the femur (thigh) • The smallest bone is the stapes bone in the ear • Ounce for ounce, bone is stronger than steel and reinforced concrete • However, in a given year, doctors around the world treat tens of millions of broken bones! • One out of 20 people have an extra rib

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26 bones in head eventually fuse together with the exception of the mandible.

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Cervical Rib – attaches posteriorly at C7 and can be floating Or attach anteriorly to the first rib.

Bone Functions (Physiology) • Framework

– support the body’s muscles, fat, and skin • Protection

– surround vital organs to protect them • Levers

– muscles attach to bones to help provide movement

• Blood Cell Production – produce red and white blood cells and platelets

• Storage – store most of calcium supply of body

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Types of Bones

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Bone Anatomy

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• Diaphysis – long shaft of bone – medullary cavity contains yellow marrow (fat cells)

• Epiphysis – ends of long bone – contains red marrow

• Red Marrow – produces red blood cells – produces platelets – some white blood cells – used to diagnose blood diseases

• Periosteum – tough membrane on outside of bone – aids in bone growth, repair, nutrition

Two Divisions of the Skeleton

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• Axial Skeleton – main trunk of body – skull – spinal column – ribs – breastbone

• Appendicular Skeleton – extremities of body – shoulder girdle – arm bones – pelvic girdle – leg bones

Bones of the Skull

10 Know the Yellow Highlighted Bones

Division of Spinal (Vertebral) Column

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• Spinal Column – made of 26 bones called vertebrae – bones protect spinal cord – provide support for head and trunk

• Intervertebral Disks – pads of cartilage tissue – separate the vertebra – act as shock observers – permit bending & twisting motion

Increase Mobility – Decreased Stability

• Cervical – smaller, more mobile • Thoracic – larger, less mobile • Lumbar – largest, minimal mobility

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Ribs & Breastbone

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• Ribs – 12 pairs called costae – attached to thoracic vertebrae on dorsal surface

• True Ribs – first 7 pairs of ribs – attached directly to sternum on front of body

• False Ribs – next 5 pairs of ribs – first three pairs of false ribs attach to cartilage of the rib above – last two pairs of false ribs are called floating ribs because they do not attach to front of body

Bones of the Skeleton

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Joints

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• Joints – areas where 2+ bones join

• Ligaments – connective tissue bands – help hold long bones at joints

• Tendons – tough connective tissue cords – one way skeletal muscles attach to bone

• Four Main Types of Joints – classified according to degree of movement – arthr/o = joint – diarthroses- moveable (hip, elbow, knee) – amphiarthroses- partially moveable (ribs to vertebrae) – synarthroses- immoveable (cranium)

Diathroses (Moving) Joints

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• Three Major Joint Parts – articular cartilage – bursa (joint capsule) – synovial (joint cavity)

•Ball and Socket –shoulders, hips

•Hinge –knees, elbows

•Pivot –radius, ulna

•Gliding –vertebrae

Diseases & Abnormal Conditions • Arthritis

– inflammation of the joints • Osteoarthritis

– most common form of arthritis – chronic disease due to aging – commonly affects knees and hips – symptoms are stiffness, pain, aching, limited range of motion – no cure, but treatments include: anti-inflammatory medications, heat/ cold application, steroid injections, and rest

• Rheumatoid arthritis – affects joints and connective tissues – 3 times more common in women than men – occurs between 35 and 45 years of age – can case scar tissue formation and atrophy of bone and muscle tissue – results in deformity and immobility – rest, anti-inflammatory medications, and surgery

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Diseases & Abnormalities Continued • Bursitis

– inflammation of bursae (small, fluid-filled sacs surrounding joints) – common in shoulders, elbows, hips, or knees

• Dislocation – when bone is forcibly displaced from a joint – common in shoulders, fingers, knees, and hips

• Sprain – twisting action tears ligaments at joint – common in wrists and ankles

• Osteomyelitis – bone inflammation usually caused by pathogenic organism – abscess is formed within the bone and accumulation of pus

• Osteoporosis – increased porosity or softening of bones caused by hormone deficiency lack of calcium, and sedentary lifestyle

• Ruptured (Herniated) Disk – occurs when an intervetrebral disk ruptures/protrudes out of place

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Abnormal Curvatures of the Spine • Causes

– poor posture – congenital (at birth) defects – structural defects of vertebrae – malnutrition

• Kyphosis – hunchback or rounding of spine at the back of thoracic area

• Scoliosis – side-to-side, or lateral, curvature

• Lordosis – swayback – inward curvature of lumbar region

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Bone Fractures • Definition

– crack or break in a bone • Greenstick

– bone bends & is split causing a crack/incomplete break common in kids • Simple or Closed

– complete break of the bone with no damage to skin • Compound or Open

– bone breaks and ruptures through the skin with increased infection risk • Impacted

– broken bone ends jam into each other • Comminuted

– bone fragments/splinters into 2+ pieces • Spiral

– bone twists and results in one or more breaks • Depressed

– broken piece of skull bone moves inward • Colles

– breaking and dislocation of distal radius that causes bulge at wrist

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Bone Fractures Continued

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