Ligaments are tough, fibrous connective tissue that connect two adjacent bones and help to keep them stabilized within a joint space. The main job of ligaments is to provide stability to joints and bones throughout the body. In fact, the function of ligaments are reflected in their name, which comes from “ligare”—the Latin word for “bind” or “tie.” When you suffer a ligament injury, you lose stability at the injured site.
Below read the full article by Pritish Kumar Halder to understand the structure, Location, different functions and types of human ligaments.
Ligaments appear as crisscross bands that attach bone to bone and help stabilize joints.
The basic building blocks of a ligament are collagen fibers. There are approximately 900 ligaments throughout the body that are composed of dense bundles of collagenous fibers. These bundles are surrounded by a gel-like substance called ground substance. They vary in size, shape, orientation, and location.
Collagen is strong, flexible, and resistant to damage from pulling or compressing stresses. This allows the ligament to withstand a wide range of forces during movement. Collagen fibers are arranged within parallel bundles to multiply the strength of the individual fibers.
The bundles of collagen that make up most ligaments attach to an outer covering that surrounds all bones called the periosteum. At this attachment site, there may also be an additional lubricating membrane, the synovial membrane, and pouch. Together this forms a bursa sac, which provides a cushion for and nutrients to the surrounding bone.
Ligaments are found throughout the body. Some help connect bones at joints, while others help to stabilize two parts of the body and restrict movement between the two, like the ligaments of the womb which keep it in the right position in the pelvis or the ligaments in the bones and forearms that keep them from pulling apart.
Most ligaments are contained around moveable joints, which include:
But some are contained around immovable bones like ribs and the bones that make up the forearm.
Ligaments attach bones to other bones, especially at the joints and allow you to move freely, easily, and without pain. Most ligaments run at different angles to the bone and muscles that they support and provide stability throughout the joints full range of motion.
Types of Ligaments
Ligaments differ based on the anatomical structure they support. Some are stretchy while others are sturdy. No matter the case, ligaments provide stability to organs and bones throughout the body and are integral to maximal range of motion, smooth movements and pain-free mobility.
- Anterior cruciate ligament (ACL): Arises from the posterior lateral portion of the femur and attaches at the medial anterior portion of the tibia, and controls twisting motions and forward movement.
- Posterior cruciate ligament (PCL): Runs from the front area of the femur and around to the back of the tibia. It prevents backward movement of the tibia in regards to the femur.
- Medial cruciate ligament (MCL): Attaches to the interior part of the tibia and primarily prevents valgus stress (excessive outward movement) and stabilizes against twisting of the leg.
- Lateral collateral ligament (LCL): Attaches to the outer portion of the tibia and fibula and prevents varus stress (excessive inward movement) and also helps stabilize against twisting.
The two ligaments of the elbow are the:
Ulnar-collateral ligament: Also called the medial collateral ligament, which runs along the inside of the elbow.
Lateral collateral ligament: Also called the radial collateral ligament, which runs along the outside of the elbow.
These two ligaments work together not only to help stabilize the elbow joint but to also allow you to flex and extend your arm.
There are five major shoulder ligaments that keep the shoulder in place and prevent it from dislocating. The five ligaments are contained within the glenohumeral and acromioclavicular joint spaces of the shoulder.
- Superior glenohumeral ligament
- Middle glenohumeral ligament
- Inferior glenohumeral ligaments
- Acromioclavicular ligament
- The coracoclavicular ligaments
The glenohumeral ligaments help to stabilize the glenohumeral joint which connects the shoulder socket, or glenoid, to the arm bone, or humerus. The glenohumeral ligaments help us to extend our arm from the shoulder blade.
The acromioclavicular (AC) joint, which is plane joint that connects the upper part of the shoulder blade to the collarbone, or clavicle, and allows for three degrees of freedom, or more simply allows the upper arm to glide in multiple directions. This flexibility also makes the shoulder more prone to injury.
If you have ever twisted or sprained your ankle, you probably injured your anterior talofibular ligament. This is one of three ligaments that make up the lateral collateral ligament complex (LCL) on the outer portion of the ankle. The other two ligaments are the calcaneofibular and the posterior talofibular ligaments. These ligaments can be damaged if you have a severe sprain or ankle fracture.
The medial collateral ligaments (MCL), also known as the deltoid ligament, are located on the inside portion of the ankle. This group of ligaments is divided into a superficial and deep group of fibers. The MCL is covered by tendons that shield it from trauma and injury.
The hip contains four major ligaments and is divided into outer capsular ligaments and inner-capsular ligaments. They both assist in the flexion and extension of the hip.
The three capsular ligaments include:
- Iliofemoral ligament (Y ligament of Bigelow): The strongest ligament in the body and attaches the anterior inferior iliac spine (AIIS) to the intertrochanteric crest of the femur.
- Pubofemoral ligaments: The pubofemoral ligament prevents excess abduction and extension of the hip.
- Ischiofemoral ligaments: The iliofemoral prevents hyperextension of the hip.
The sole intracapsular ligament is the ligamentum teres (ligament of the head of the femur) that serves as a carrier for the foveal artery, a major blood supply source in babies and young children.
There are 7 ligaments that support the spine:
- Ligamentum flavum: Located in between the vertebrae
- Facet capsular ligament: Located at the capsular insertion point along the sides of the spine
- Interspinous ligament: Located in between the spinous processes
- Supraspinous ligament: Located above and to the side of each vertebra
- Intertransverse ligament: Located in between the long pointy sides of each vertebra
- Posterior longitudinal ligaments: A long, thin ligament that runs along the backside of the spine
- Anterior longitudinal ligaments: A wide, fibrous band that runs along the front of the spine
The posterior and anterior longitudinal ligaments are the major contributors to the spine’s stability. Injury to the posterior longitudinal ligament can result in disc herniation, which may render you unable to flex backward without pain. If your back goes out, especially if you suddenly hyperflex or twist your back, you may have injured one or more of these back ligaments.