Chapter 3 - The Skeletal System Study Notes

CHAPTER 3 - THE SKELETAL SYSTEM

Overview of Structures, Combining Forms, and Functions of the Skeletal System

Major Structures
  • Bones: Combining forms include oss/e, oss/i, oste/o, ost/o.
  • Bone Marrow: Myel/o (also means spinal cord).
  • Cartilage: Chondr/o.
  • Joints: Arthr/o.
  • Ligaments: Ligament/o.
  • Synovial Membrane: Synovi/o, synov/o.
  • Synovial Fluid: Burs/o.
  • Bursa: Burs/o.
Primary Functions
  • Structural Framework: Acts as the framework for the body and protects the internal organs.
  • Mineral Storage: Stores calcium necessary for body functions.
  • Blood Cell Formation: Red bone marrow helps form red blood cells while yellow bone marrow stores fat.
  • Smooth Joint Movement: Cartilage provides a smooth surface for motion within joints and protects the ends of bones.
  • Facilitates Motion: Joints work with muscles to facilitate a wide variety of movements.
  • Connections: Ligaments connect one bone to another and form the lining of synovial joints, secreting synovial fluid as a lubricant.
  • Friction Reduction: Bursae cushion areas subject to friction during movement.

Vocabulary Related to the Skeletal System

Word Parts
  • ankyl/o: crooked, bent, stiff.
  • arthr/o: joint.
  • burs/o: bursa.
  • chondr/i, chondr/o: cartilage.
  • cost/o: rib.
  • crani/o: skull.
  • -desis: to bind, tie together.
  • kyph/o: bent, hump.
  • lord/o: curve, swayback, bent.
  • lumb/o: lumbar, lower back.
  • myel/o: spinal cord, bone marrow.
  • oss/e, oss/i, oste/o, ost/o: bone.
  • scoli/o: curved, bent.
  • spondyl/o: vertebrae, vertebral column, backbone.
  • synovi/o, synov/o: synovial membrane, synovial fluid.
Medical Terms
  • acetabulum: (ass-eh-TAB-you-lum) - the hip socket.
  • allogenic: (al-oh-JEN-ick) - derived from another individual.
  • ankylosing spondylitis: (ang-kih-LOH-sing spon-dih-LYE-tis) - a type of arthritis affecting the spine.
  • arthrodesis: (ar-throh-DEE-sis) - surgical fusion of a joint.
  • arthroscopy: (ar-THROS-koh-pee) - examination of a joint using an arthroscope.
  • autologous: (aw-TOL-uh-guss) - derived from the same individual.
  • avascular necrosis: (ay-VAS-cue-ler neh-KROH-sis) - death of bone tissue due to lack of blood supply.
  • bone marrow transplant: (BMT).
  • callus: (KAL-us) - a thickening formed during bone healing.
  • chondromalacia: (kon-droh-mah-LAY-shee-ah) - abnormal softening of cartilage.
  • comminuted fracture: (KOM-ih-newt-ed) - a fracture where the bone is shattered.
  • compression fracture: - fracture resulting from pressure on the bone.
  • costochondritis: (kos-toh-kon-DRIGH-tis) - inflammation of the cartilage connecting a rib to the sternum.
  • crepitation: (krep-ih-TAY-shun) - the grating sound of bone ends moving together.
  • dual x-ray absorptiometry: (ab-sorp-shee-OM-eh-tree) - a test to measure bone density.
  • fat embolus: (EM-boh-lus) - fat globules that enter the bloodstream.
  • gout: (GOWT) - arthritis characterized by deposits of uric acid crystals in joints.
  • hallux valgus: (HAL-ucks VAL-guss) - a bunion, an abnormal growth at the base of the big toe.

Learning Objectives

On completion of this chapter, students should be able to:

  1. Identify and describe the major functions and structures of the skeletal system.
  2. Describe three types of joints.
  3. Differentiate between the axial and appendicular skeletons.
  4. Identify the medical specialists who treat disorders of the skeletal system.
  5. Recognize, define, spell, and pronounce the primary terms related to the pathology and the diagnostic and treatment procedures of the skeletal system.

Structures and Functions of the Skeletal System

  • Composition: The skeletal system consists of bones, bone marrow, cartilage, joints, ligaments, synovial membranes, synovial fluid, and bursae.
  • Functions:
    • Framework and support for the body.
    • Protection for internal organs.
    • Assists with body movements via muscle interaction.
    • Storage of calcium.
    • Houses red bone marrow, important for blood cell formation.
Formation of Bones
  • Ossification: The process by which a newborn's skeleton transforms from membranes and cartilage into bone, generally begins after three months of age and continues into adolescence.
  • Bone remodeling occurs throughout life, facilitated by osteoclasts (which break down old bones) and osteoblasts (which help form new bones).
Structure of Bones
  • Types of Bone Tissue:
    • Periosteum: The fibrous outer covering of bones.
    • Compact Bone: Dense, strong bone making up most of the skeleton, accounts for more than 75% of bone matter.
    • Spongy Bone: Lighter, less dense, contains red marrow, and is typically found at the ends of long bones.
Major Bone Types
  • Long Bones: E.g., femur, humerus; have a distinct shaft (diaphysis), two ends (epiphyses), and include medullary cavity.
  • Short Bones: E.g., carpals and tarsals; provide stability and flexibility while allowing motion.
Cartilage
  • Definition: Smooth, rubbery connective tissue that acts as a shock absorber between bones and provides flexibility.
  • Types:
    • Articular Cartilage: Covers bone surfaces in joints.
    • Meniscus: Curved cartilage in certain joints like the knee.
Joints
  • Definition: Connections between two or more bones, classified by structure and movement capacity.
Types of Joints
  1. Fibrous Joints: Fixed joints with no movement (e.g., sutures in skull).
  2. Cartilaginous Joints: Allow limited movement (e.g., ribs connecting to the sternum).
  3. Synovial Joints: Freely movable joints with a lubricating synovial fluid (e.g., knee, elbow).
Components of Synovial Joints
  • Synovial Capsule: Outer layer surrounding the joint.
  • Synovial Fluid: Lubricates and nourishes the articular cartilage.
  • Bursa: Fluid-filled sacs that ease friction.
Axial vs. Appendicular Skeleton
  1. Axial Skeleton: Comprises 80 bones protecting major organs (skull, vertebral column, ribs).
  2. Appendicular Skeleton: Comprises 126 bones facilitating movement (limbs, pelvis).
Bones of the Skull
  • Comprised of 8 cranial bones (e.g., frontal, parietal), 14 facial bones (e.g., nasal, zygomatic), and 6 middle ear bones.
Ribs and Sternum
  • Ribs: 12 pairs, categorized as true, false, and floating ribs.
  • Sternum: Divided into the manubrium, body, and xiphoid process.
Major Bones of the Limbs and Girdles
  • Shoulder (Pectoral Girdle): Clavicle and scapula support the upper limbs.
  • Arms: Humerus, radius, and ulna make up the arm structure.
  • Legs: Femur, tibia, and fibula constitute the leg.
  • Feet: Comprising tarsals, metatarsals, and phalanges.
Medical Specialties Related to the Skeletal System
  • Chiropractor: Specializes in spinal manipulation.
  • Orthopedic Surgeon: Treats disorders involving bones, joints, and muscles.
  • Osteopath: Focuses on bone health and manipulation.
  • Podiatrist: Specializes in foot disorders.
  • Rheumatologist: Treats arthritis and related inflammatory conditions.

Pathology of the Skeletal System

Common Disorders
  • Ankylosis: Stiffness or immobility of a joint.
  • Arthritis: Inflammation of one or more joints.
    • Subtypes include osteoarthritis, rheumatoid arthritis, and gout.
  • Fractures: Types of fractures include comminuted, open, and closed.
  • Osteoporosis: Condition characterized by bone density loss.
Specific Conditions
  1. Hallux Valgus (Bunion): Joint enlargement of the big toe.
  2. Osteochondroma: Benign growth of cartilage and bone.
  3. Paget's Disease: Bone deformities from abnormal remodeling.

Diagnostic Procedures

  • X-rays: Imaging to visualize abnormalities and fractures.
  • Arthroscopy: Minimally invasive joint examination.
  • Bone Density Testing: Evaluates for osteoporosis and similar conditions.

Treatment Procedures

  • Medications: Bisphosphonates for osteoporosis.
  • Surgery: Includes arthroplasty (joint replacements), and procedures such as spinal fusion and laminectomy.
  • Rehabilitation: Physical therapy for mobility restoration post-injury or surgery.