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The anterior cruciate ligament (ACL) is a band of dense connective tissue which courses from the femur to the tibia. The ACL is a key structure in the knee joint, as it resists anterior tibial translation and rotational loads. Arises from the posteromedial corner of medial aspect of lateral femoral condyle in the intercondylar notch.
What is the anterior cruciate ligament?
The main function of the ACL is restraint of anteroposterior translation of the tibia relative to the femur. It also acts as a secondary restraint to tibial rotation and valgus or varus stress. The ACL courses from the anterior tibia to posterior femur at the knee,...
What is the main function of the ACL in the knee?
For more detail on the anatomy of the ACL, please see this page: Anterior Cruciate Ligament (ACL) - Structure and Biomechanical Properties The ACL receives nerve fibers from the posterior articular branches of the tibial nerve.
Where does the anterior cruciate ligament receive nerve fibers?
Anterior cruciate ligament (ACL) injury. Four main ligaments connect these two bones: Medial collateral ligament (MCL) runs along the inside of the knee. It prevents the knee from bending in. Lateral collateral ligament (LCL) runs along the outside of the knee. It prevents the knee from bending out. Anterior cruciate ligament (ACL)...
What are the four ligaments of the ACL?
What is the function of the anterior cruciate ligament it?
The anterior cruciate ligament runs diagonally in the middle of the knee. It prevents the tibia from sliding out in front of the femur, as well as provides rotational stability to the knee.
What is the function of the anterior cruciate ligament quizlet?
Terms in this set (28) The function of the anterior cruciate ligament is to prevent the tibia from sliding forward on the femur, and to control tibio-femoral rotation.
What motions does the ACL prevent?
The ligaments hold the two bones together and prevent side to side motion. The anterior cruciate ligament (ACL) prevents forward and backward motion.
What is the purpose of an ACL quizlet?
What is the purpose of an ACL? An ACL or Access control list is a common means by which access to and denial of services is controlled. On network devices such as Routers and firewalls, they act as filters for network traffic, packet storms, services and host access.
Which of the following does the anterior cruciate ligament prevent?
It prevents the knee from bending out. Anterior cruciate ligament (ACL) is in the middle of the knee. It prevents the shin bone from sliding out in front of the thigh bone.
Can you bend knee with ACL tear?
Some people find that the knee joint feels looser than it should. Less range of motion. After you damage your ACL, it's very likely that you won't be able to bend and flex your knee like you normally would.
What is the main function of the ACL?
The anterior cruciate ligament resists the combined motions of anterior tibial translation and internal tibial rotation, which defines the concept of rotational stability. This function prevents anterior tibial subluxation of the lateral and medial tibiofemoral compartments that accounts for the pivot-shift phenomena.
Can you walk on a torn ACL?
Can you walk with a torn ACL? The short answer is yes. After the pain and swelling subsides and if there is no other injury to your knee, you may be able to walk in straight lines, go up and down stairs and even potentially jog in a straight line.
Which knee ligament prevents posterior movement of the tibia?
The function of the PCL is to prevent the femur from sliding off the anterior edge of the tibia and to prevent the tibia from displacing posterior to the femur. The posterior cruciate ligament is located within the knee.
What structure in the knee prevents hyperextension quizlet?
Terms in this set (24) a cruciate ligament of each knee that attaches the front of the tibia with the back of the femur and functions especially to prevent hyperextension of the knee and is subject to injury especially by tearing —called also ACL.
Which cruciate ligament is attached at the anterior surface of the tibia?
The anterior cruciate ligament (ACL) attaches proximally at the posteromedial margin of the lateral femoral condyle in the intercondylar fossa and distally at the anterior aspect of the tibial intercondylar eminence.
What is the function of the tibial and fibular collateral ligaments quizlet?
It protects the joint from stresses to the medial side of the knee.
Which artery is vascularized by the distal part of the cruciate ligament?
The distal part of both cruciate ligaments is vascularized by branches of the lateral and medial inferior geniculate artery. The ligament is surrounded by a synovial fold where the terminal branches of the middle and inferior arteries form a periligamentous network.
What is the ACL?
The anterior cruciate ligament (ACL) is a band of dense connective tissue which courses from the femur to the tibia. The ACL is a key structure in the knee joint, as it resists anterior tibial translation and rotational loads.
What is the ACL reflex?
The ACL reflex is an essential part of normal knee function and is involved in the updating of muscle programs. This becomes even more obvious in patients with a ruptured ACL, where the loss of feedback from mechanoreceptors in the ACL leads to quadriceps femoris weakness.
Where does the ACL nerve fiber come from?
The ACL receives nerve fibers from the posterior articular branches of the tibial nerve. These fibers penetrate the posterior joint capsule and run along with the synovial and periligamentous vessels surrounding the ligament to reach as far anterior to the infrapatellar fat pad. Most of the fibers are associated with the endoligamentous vasculature and have a vasomotor function. The receptors of the nerve fibers mentioned are as follows:
What is the ACL made of?
The ACL has a microstructure of collagen bundles of multiple types (mostly type I) and a matrix made of a network of proteins, glycoproteins, elastic systems, and glycosaminoglycans with multiple functional interactions.
What is the function of free nerve endings?
Free-nerve endings function as nociceptors, but they may also serve as local effectors by releasing neuropeptides with vasoactive function. Thus, they may have a modulatory effect in normal tissue homeostasis or in late remodeling of grafts.
Where is the tibial attachment?
The tibial attachment is in a fossa in front of and lateral to anterior spine, a rather wide area from 11 mm in width to 17 mm in AP direction.
What is the function of the ACL?
The main function of the ACL is restraint of anteroposterior translation of the tibia relative to the femur. It also acts as a secondary restraint to tibial rotation and valgus or varus stress. The ACL courses from the anterior tibia to posterior femur at the knee, as shown:
What is anterior drawer?
The anterior drawer is performed with the patient lying supine and the knee flexed at 90 degrees. The proximal tibia is gripped with both hands and pulled anteriorly, checking for anterior translation. Often the clinician sits on the foot while performing the test to provide stability. The test is positive if there is anterior translation.
What is the mechanism of injury?
The mechanisms of injury is typically a sudden deceleration or rotational maneuver with a force that sends the tibia one way and femur another (typically because the foot is planted and the body spins). Not all such forces that exceed the strength of the ligament lead to a tear: often, the secondary restraints (the hamstrings mostly) ...
Why is aspiration important for knee?
Knee aspiration can be a very important step in the initial management: Here's why: If there is too much fluid you cannot sense laxity–the pressure of the fluid "stabilizes" the knee. The pressure of the fluid hurts! It is simply kind and humane to relieve it.
Can hamstrings help with a tear?
Not all such forces that exceed the strength of the ligament lead to a tear: often, the secondary restraints (the hamstrings mostly) can help resist a tear . When the secondary restraints are overwhelmed, the ligament can be exposed to forces it cannot bear.
Can hamstrings protect ACL?
While skiing, for example, at 10am your still-powerful hamstrings protect the ACL; at 2pm, when the tibia starts to subluxate, the hamstrings just acquiesce and let the bone subluxate, ultimately tearing the ligament.) An ACL tear is suspected first by history.
What is anterior cruciate ligament surgery?
Anterior cruciate ligament surgery is a complex operation that requires expertise in the field of orthopedic and sports medicine. Many factors should be considered when discussing surgery, including the athlete's level of competition, age, previous knee injury, other injuries sustained, leg alignment, and graft choice.
Why is the ACL called the Cruciate?
The term cruciate translates to cross. This name is fitting because the ACL crosses the posterior cruciate ligament to form an “X”. It is composed of strong, fibrous material and assists in controlling excessive motion. This is done by limiting mobility of the joint.
What is the purpose of the ACL?
Purpose. The purpose of the ACL is to resist the motions of anterior tibial translation and internal tibial rotation; this is important to have rotational stability. This function prevents anterior tibial subluxation of the lateral and medial tibiofemoral joints, which is important for the pivot-shift phenomenon.
What are the factors that affect the risk of ACL injury?
Risk differences between outcomes in men and women can be attributed to a combination of multiple factors, including anatomical, hormonal, genetic, positional, neuromuscular, and environmental factors. The size of the anterior cruciate ligament is often the most reported difference.
What is the ACL in the right knee?
Diagram of the right knee. Anterior cruciate ligament labeled at center left. The anterior cruciate ligament ( ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation.
What is the ACL?
Anatomical terminology. The anterior cruciate ligament ( ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation. In the quadruped stifle joint (analogous to the knee), ...
Which ligament is the most injured in the knee?
The ACL is the most injured ligament of the four located in the knee.
What is the anterior cruciate ligament?
There is a ligament on each side of the knee (the collateral ligaments) and two ligaments deep inside the knee. The two ligaments inside the knee that “cross” each other are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). Both ligaments attach on one side to the end of the thighbone (femur) and on the other to the top of the shinbone (tibia). [Figure 1].
What is the function of the ACL?
During activity, the ACL controls how far forward the tibia can "slide" relative to the femur: it essentially acts to prevent too much forward movement. While some degree of motion or sliding is normal and is required for knee function, too much motion may damage other structures in the knee which can lead to long term problems in some patients.
How is an ACL injury diagnosed?
An ACL tear can be diagnosed by a physician through a history and physical examination. On physical examination, the physician can specifically assess the amount of motion present and determine if the ACL is torn. Additionally, evaluation of other structures within the knee is done also, as ACL tears are often found in association with injury to other structures within the knee, such as the cartilage and collateral ligaments.
How is the ACL injured? What are the symptoms?
The ACL can be injured or torn in a number of different ways. The most common mechanism is that of a sudden pivoting or cutting maneuver during sporting activity , which is commonly seen in football, basketball and soccer. The ligament can also tear due to work injuries or automobile accidents.
How to tell if you have an ACL tear?
What are the symptoms of an ACL injury or tear? 1 A “pop” in the knee at the time of injury 2 Swelling of the knee 3 Inability to bear weight on leg (though some have little or no pain) 4 Instability of the knee
Why do you need a knee scan for ACL tear?
The scan is also useful for evaluating the cartilage or meniscus tissue in the knee if this information is necessary to make decisions regarding the best treatment for a specific patient.
Which ligaments attach to the thighbone?
The two ligaments inside the knee that “cross” each other are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). Both ligaments attach on one side to the end of the thighbone (femur) and on the other to the top of the shinbone (tibia). [Figure 1].
What is the term for a tear in the anterior cruciate ligament?
Anterior cruciate ligament (ACL) injury. An anterior cruciate ligament injury is the over-stretching or tearing of the anterior cruciate ligament (ACL) in the knee. A tear may be partial or complete.
Which ligaments connect the bones of the knee?
Four main ligaments connect these two bones: Medial collateral ligament (MCL) runs along the inside of the knee. It prevents the knee from bending in. Lateral collateral ligament (LCL) runs along the outside of the knee. It prevents the knee from bending out. Anterior cruciate ligament (ACL) is in the middle of the knee.
What is the ACL in the knee?
Anterior cruciate ligament (ACL) is in the middle of the knee. It prevents the shin bone from sliding out in front of the thigh bone.
What sports have ACL tears?
Basketball, football, soccer, and skiing are common sports linked to ACL tears. ACL injuries often occur with other injuries. For example, an ACL tear often occurs along with tears to the MCL and the shock-absorbing cartilage in the knee (meniscus). Most ACL tears occur in the middle of the ligament, or the ligament is pulled off the thigh bone.
What to do if you have an ACL injury?
It may also show other knee injuries. First aid for an ACL injury may include: Raising your leg above the level of the heart. Putting ice on the knee. Pain relievers, such as nonsteroidal anti-inflammatory drugs (such as ibuprofen) You also may need: Crutches to walk until the swelling and pain get better.
Where do ACL tears occur?
Most ACL tears occur in the middle of the ligament, or the ligament is pulled off the thigh bone. These injuries form a gap between the torn edges, and do not heal on their own. Those who have only a mild injury may notice that the knee feels unstable or seems to "give way" when using it.
How to keep knee straight?
Use a splint to keep the knee straight until you see a doctor. Do NOT return to play or other activities until you have been treated. Call your provider right away if you have a serious knee injury. Get immediate medical attention if the foot is cool and blue after a knee injury.
Why does my knee have a ligament?
Causes. Ligaments are strong bands of tissue that connect one bone to another. The ACL, one of two ligaments that cross in the middle of the knee, connects your thighbone to your shinbone and helps stabilize your knee joint. ACL injuries often happen during sports and fitness activities that can put stress on the knee:
What is the ACL?
Overview. The anterior cruciate ligament (ACL) is one of the key ligaments that help stabilize your knee joint. The ACL connects your thighbone (femur) to your shinbone (tibia). It's most commonly torn during sports that involve sudden stops and changes in direction — such as basketball, soccer, tennis and volleyball.
How to prevent ACL injury in female athletes?
Training to strengthen muscles of the legs, hips and core — as well as training to improve jumping and landing techniques and to prevent inward movement of the knee — may help to reduce the higher ACL injury risk in female athletes.
Why do women have higher risk of ACL injury?
There are a number of factors that increase your risk of an ACL injury, including: Being female — possibly due to differences in anatomy, muscle strength and hormonal influences. Participating in certain sports, such as soccer, football, basketball, gymnastics and downhill skiing. Poor conditioning.
How to reduce the risk of ACL injury?
Proper training and exercise can help reduce the risk of ACL injury. A sports medicine physician, physical therapist, athletic trainer or other specialist in sports medicine can provide assessment, instruction and feedback that can help you reduce risks.
What to do if you have an ACL injury?
Seek immediate care if any injury to your knee causes signs or symptoms of an ACL injury. The knee joint is a complex structure of bones, ligaments, tendons and other tissues that work together. It's important to get a prompt and accurate diagnosis to determine the severity of the injury and get proper treatment.
How to tell if you have an ACL injury?
Signs and symptoms of an ACL injury usually include: A loud pop or a "popping" sensation in the knee. Severe pain and inability to continue activity. Rapid swelling. Loss of range of motion. A feeling of instability or "giving way" with weight bearing.
Introduction
Attachments
- Origin
Arises from the posteromedial corner of medial aspect of lateral femoral condyle in the intercondylar notch. This femoral attachment of ACL is on posterior part of medial surface of lateral condyle well posterior to longitudinal axis of the femoral shaft. The attachment is actuall… - Orientation
It runs inferiorly, medially and anteriorly.
Nerve Supply
- The ACL receives nerve fibers from the posterior articular branches of the tibial nerve. These fibers penetrate the posterior joint capsule and run along with the synovial and periligamentous vessels surrounding the ligament to reach as far anterior to the infrapatellar fat pad. Most of the fibers are associated with the endoligamentous vasculature and have a vasomotor function. Th…
Vascular Supply
- The major blood supply of the cruciate ligaments arises from the middle geniculate artery. The distal part of both cruciate ligaments is vascularized by branches of the lateral and medial inferior geniculate artery. The ligament is surrounded by a synovial fold where the terminal branches of the middle and inferior arteries form a periligamentous network. From the synovial sheath bloo…
Composition
- The ACL has a microstructure of collagen bundles of multiple types (mostly type I) and a matrix made of a network of proteins, glycoproteins, elastic systems, and glycosaminoglycans with multiple functional interactions.
Bundles
- There are two components of the ACL, the smaller anteromedial bundle (AMB) and the larger posterolateral bundle (PLB), named according to where the bundles insert into the tibial plateau. The anteromedial bundle is tight in flexion and the posterolateral bundle is tight in extension. In extension both bundles are parallel; in flexion the femoral insertion site of the posterolateral bun…
Function
- The ACL provides approximately 85% of total restraining force of anterior translation. It also prevents excessive tibial medial and lateral rotation, as well as varus and valgus stresses. To a lesser degree, the ACL checks extension and hyperextension. Together with the posterior cruciate ligament (PCL), the ACL guides the instantaneous center of r...
Overview
The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation. In the quadruped stifle joint (analogous to the knee), based on its anatomical position, it is also referred to as the cranial cruciate ligament. The term cruciate translates to cross. This name is fitting because the ACL crosses the posterio…
Clinical significance
An ACL tear is one of the most common knee injuries, with over 100,000 tears occurring annually in the US. Most ACL tears are a result of a non-contact mechanism such as a sudden change in a direction causing the knee to rotate inward. As the knee rotates inward, additional strain is placed on the ACL, since the femur and tibia, which are the two bones that articulate together forming the knee joint, move in opposite directions, causing the ACL to tear. Most athletes require reconstru…
Structure
The ACL originates from deep within the notch of the distal femur. Its proximal fibers fan out along the medial wall of the lateral femoral condyle. The two bundles of the ACL are the anteromedial and the posterolateral, named according to where the bundles insert into the tibial plateau. The tibial plateau is a critical weight-bearing region on the upper extremity of the tibia. The ACL attaches in front of the intercondyloid eminence of the tibia, where it blends with the anterior hor…
Purpose
The purpose of the ACL is to resist the motions of anterior tibial translation and internal tibial rotation; this is important to have rotational stability. This function prevents anterior tibial subluxation of the lateral and medial tibiofemoral joints, which is important for the pivot-shift phenomenon. The ACL has mechanoreceptors that detect changes in direction of movement, position of the knee joint, and changes in acceleration, speed, and tension. A key factor in instab…
Gallery
• Right knee joint, from the front, showing interior ligaments
• Left knee joint from behind, showing interior ligaments
• Head of right tibia seen from above, showing menisci and attachments of ligaments
See also
• Posterior cruciate ligament
• Anterior cruciate ligament reconstruction
• Anterior drawer test
• Anterolateral ligament
External links
• Anatomy photo:17:02-0701 at the SUNY Downstate Medical Center - "Extremity: Knee joint"
• Anatomy figure: 17:07-08 at Human Anatomy Online, SUNY Downstate Medical Center - "Superior view of the tibia."
• Anatomy figure: 17:08-03 at Human Anatomy Online, SUNY Downstate Medical Center - "Medial and lateral views of the knee joint and cruciate ligaments."