Orthopedics: Bones, Joints, Ligaments, and Tendons
Author: Disabled World (DW)
Updated/Revised Date: 3 Aug 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
Learn how orthopedics studies the musculoskeletal system, including the bones, joints, muscles, ligaments, and tendons that give the body form and movement.
At a Glance
- 1 - A bursa is a fluid-filled sac that cushions the space between bones and nearby tendons or muscles.
- 2 - Bone marrow holds stem cells that produce the body's red blood cells and platelets.
- 3 - Bones fall into five classes - long, short, flat, irregular, and sesamoid - and consist of an outer compact layer over spongy cancellous bone.
- 4 - Joints range from immovable synarthroses like skull sutures to freely moving diarthroses such as the elbow, knee, shoulder, and wrist.
Topic Definition
- Orthopedics
Orthopedics is the branch of medicine devoted to the musculoskeletal system, the framework of bones, muscles, cartilage, tendons, ligaments, joints, and other connective tissue that gives the human body its form, stability, and ability to move. Doctors in this field, known as orthopedic specialists, diagnose and treat a broad range of conditions in patients of every age, and over the years the discipline has grown to include many sub-specialties. Using both surgical and non-surgical methods, orthopedic surgeons address musculoskeletal trauma, sports injuries, degenerative diseases, infections, tumors, and conditions present from birth. Because the system it covers is so wide-reaching, orthopedics touches nearly everything that supports and powers movement, from the calcium and collagen that make bones strong to the blood-forming marrow within them and the joints that let one bone move against another.
Overview
Orthopedics is the study of the musculoskeletal system. Orthopedic doctors specialize in diagnosis and treatment of problems of the musculoskeletal system. Over the years, the field has expanded to encompass many sub-specialties and the treatment of a wide variety of musculoskeletal disorders in patients of all ages.
Orthopedic surgeons use both surgical and non-surgical means to treat musculoskeletal trauma, sports injuries, degenerative diseases, infections, tumors, and congenital conditions. The musculoskeletal system provides form, stability, and movement to the human body. It is made up of the body's bones (the skeleton), muscles, cartilage, tendons, ligaments, joints, and other connective tissue.
Basic Terms
- Bursa: A small fluid-filled sac made of white fibrous tissue and lined with synovial membrane. It provides a cushion between bones and tendons or muscles around a joint
- Ligament: A small band of dense, white, fibrous elastic tissue. Ligaments connect the ends of bones together to form a joint.
- Tendon: A tough, flexible band of fibrous connective tissue that connects muscles to bones.
- Joints: Structures that connect individual bones and may allow bones to move against each other to cause movement. There are two divisions of joints, diarthroses which allow extensive mobility between two or more articular heads, and false joints or synarthroses, immovable joints, that allow little or no movement and are predominantly fibrous.
The Two Main Parts to Your Skeleton Are:
- The bones of your head and torso
- The bones in the arms and legs
The Two Types of Bone Are:
- Compact bone is the solid, hard, outside part of the bone.
- Cancellous bone, which looks like a sponge, is inside the compact bone.
The Five General Classifications of Bones Are:
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Sesamoid bones
The human skeleton is composed of both fused and individual bones supported by ligaments, tendons, muscles, and cartilage. Bones are made up of calcium, phosphorus, sodium, and other minerals, as well as the protein collagen. Calcium is needed to make bones hard, which allows them to support body weight. The soft bone marrow inside many of the bones is where most of the blood cells are made. The bone marrow contains stem cells, which produce the body's red blood cells and platelets.
Bones can move because of the way they are joined. The place where two or more bones come together is called a joint. The bones at a joint are held together by strong bands of tissue called ligaments, which allow the bones to move.
Joint Types
- A joint that permits no movement is known as a synarthrosis. The sutures of the skull and the gomphoses that connect the teeth to the skull are examples of synarthroses.
- An amphiarthrosis allows a slight amount of movement at the joint. Examples of amphiarthroses include the intervertebral disks of the spine and the pubic symphysis of the hips.
- The third functional class of joints is the freely movable diarthrosis joints. Diarthroses have the highest range of motion of any joint and include the elbow, knee, shoulder, and wrist.
Conditions that can affect the bones, muscles, and joints include:
Frequently Asked Questions
What is the difference between an orthopedist and a rheumatologist
An orthopedist focuses on the bones, joints, and soft tissues and often treats injuries surgically, while a rheumatologist manages inflammatory and autoimmune joint diseases mainly with medication.
What is the difference between a ligament and a tendon
A ligament is a band of fibrous tissue that connects one bone to another to form a joint, while a tendon connects muscle to bone so the muscle can move the bone.
When should you see an orthopedic doctor
You should consider seeing an orthopedic doctor for persistent joint or bone pain, reduced range of motion, swelling that does not improve, or injuries that affect your ability to move normally.
Do orthopedic surgeons only perform surgery
No, orthopedic surgeons use both surgical and non-surgical treatments, and many musculoskeletal problems are managed with physical therapy, medication, bracing, or lifestyle changes before surgery is considered.
What is cartilage and what does it do
Cartilage is a firm yet flexible connective tissue that cushions the ends of bones within joints, reducing friction and helping the bones move smoothly against one another.
What are the most common orthopedic injuries
Common orthopedic injuries include fractures, strains and sprains, tendonitis, and repetitive stress injuries, many of which arise from sports, overuse, or accidents.
How can you keep your bones and joints healthy
Regular weight-bearing exercise, adequate calcium and vitamin D, maintaining a healthy weight, and avoiding overuse injuries all help keep bones and joints strong and functioning well.
Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.
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