is the meniscus innervated

Full Answer

Is the meniscus innervated by blood vessels?

Most but not all of the nerve fibers were associated with blood vessels. Nerve fibers and sensory receptors were found mainly in the peripheral, vascular zone, representing the outer one-third of the meniscus, and the innervated area was wider in the anterior and posterior horns.

How many nerve endings are in the meniscus?

The horns of the menisci and the peripheral vascularized portion of the meniscal bodies are well innervated with free nerve endings (nociceptors) and three different mechanoreceptors (Ruffini corpuscles, pacinian corpuscles, and Golgi tendon organs).

Where are nerve fibers found in the meniscus?

Nerve fibers and sensory receptors were found mainly in the peripheral, vascular zone, representing the outer one-third of the meniscus, and the innervated area was wider in the anterior and posterior horns. Pacinian and Ruffini corpuscles as well as free nerve endings were identified in these areas.

Where is the meniscus in the human body?

In humans they are present in the knee, wrist, acromioclavicular, sternoclavicular, and temporomandibular joints; in other animals they may be present in other joints. Generally, the term "meniscus" is used to refer to the cartilage of the knee, either to the lateral or medial meniscus.

What nerve innervates the medial meniscus?

The innervation of menisci has been investigated in several studies [5,6,7, 14,15,16]. Nerve fibres from the recurrent peroneal branch of the common peroneal nerve penetrate the peri-meniscal tissue in the outer third of the meniscus, with a higher density in both horns.

Is the meniscus avascular?

The meniscus is a relatively avascular structure with a limited peripheral blood supply.

What part of the meniscus do not receive any blood supply?

The avascular portion is called the “white zone” due to its absence of blood supply. Red zone tears have the potential to heal and white zone tears will likely never heal. The transitional region in the middle is considered the “red-white zone.”

Where is meniscus blood supply?

The blood supply to the menisci is limited to their peripheries. The medial and lateral geniculate arteries anastomose into a parameniscal capillary plexus supplying the synovial and capsular tissues of the knee joint.

Does posterior horn of meniscus have blood supply?

The anterior and posterior homs of the menisci have a rich supply of both blood vessels and nerves.

What is the mechanism of injury for a meniscus tear?

Typical Mechanism of Injury: Most meniscal tears occur as a result of twisting the knee while the foot is planted on the ground. This can happen when making a sudden turn or change of direction or landing from a jump.

What is the red zone of the meniscus?

The outside 1/3 of each meniscus has a rich blood supply and is sometimes referred to as the 'red zone. ' A tear in this red zone can often heal on its own or be repaired surgically. The remaining 2/3 of each meniscus lacks blood supply.

How does the meniscus receive nutrients?

Nutrients are delivered to meniscal cells through the surrounding synovial fluid and the blood vessels present in the outer region of the meniscus. During maturation, vascularization progressively recedes up to the outer 10% of the tissue, leaving the majority avascular.

Does ACL have blood supply?

The ACL receives its blood supply from branches of the middle genicular artery, which from a vascular synovial envelope around the ligament. These periligamentous vessels penetrate the ligament transversely and anastomose with a longitudinal network of endoligamentous vessels.

Which part of the meniscus is most vascular?

The body of the adult meniscus has a more restricted vascular supply when compared with the anterior and posterior horns. The vascular supply is limited to the outer one-third of the meniscus, but the perimeniscal tissue in this area is still very vascular (9).

What vessels supply the knee?

The arteries to the knee joint and surrounding structures are supplied by the large femoral and popliteal arteries. The femoral artery enters the lower limb by passing deep to the inguinal ligament and into the femoral triangle.

What is the meniscus function?

The meniscus is often thought of as being shock absorbers between the thighbone and the shinbone. They work to help in the reduction of wear and tear on the knee's cartilage and bones and assist in guiding movement.

What is the meniscus made of?

The menisci are made of fibrocartilage, a special type of cartilage. They function as shock absorbers and force distributors that help to stabilize the knee. Injuries to the meniscus are the most common, and the medial meniscus is torn more often than the lateral meniscus.

How do you increase blood flow to the meniscus of the knee?

Gentle massage around the injured knee area or small flexing or extending knee movements (if not painful) will also help increase blood flow, oxygen, nutrients, and will prevent stiffness.

Can a meniscus tear lead to knee replacement?

Conclusions: In patients with knee osteoarthritis arthroscopic knee surgery with meniscectomy is associated with a three fold increase in the risk for future knee replacement surgery.

What is the meniscus?

The meniscus is a C-shaped piece of tough, rubbery cartilage that acts as a shock absorber between the shinbone and the thighbone. It can be torn if you suddenly twist your knee while bearing weight on it. A torn meniscus is one of the most common knee injuries.

What is the menisci of the knee?

The menisci of the knee are two pads of fibrocartilaginous tissue which serve to disperse friction in the knee joint between the lower leg ( tibia) and the thigh ( femur ). They are concave on the top and flat on the bottom, articulating with the tibia.

How many surgeries are there for meniscus tear?

Two surgeries of the meniscus are most common. Depending on the type and location of the tear, the patient's age, and physician's preference, injured menisci are usually either repaired or removed, in part or completely (meniscectomy). Each has its advantages and disadvantages.

What are the different types of meniscus tears?

There are two general types of meniscus injuries: acute tears that are often the result of trauma or a sports injury and chronic or wear-and-tear type tears. Acute te ars have many different shapes (vertical, horizontal, radial, oblique, complex) and sizes.

What is the shape of a meniscus?

Meniscus (anatomy) For other uses, see Meniscus (disambiguation). A meniscus is a crescent-shaped fibrocartilaginous anatomical structure that, in contrast to an articular disc, only partly divides a joint cavity. In humans they are present in the knee, wrist, acromioclavicular, sternoclavicular, and temporomandibular joints;

What is the function of menisci?

The menisci act to disperse the weight of the body and reduce friction during movement. Since the condyles of the femur and tibia meet at one point (which changes during flexion and extension ), the menisci spread the load of the body's weight. This differs from sesamoid bones, which are made of osseous tissue and whose function primarily is to protect the nearby tendon and to increase its mechanical effect.

What is conservative management?

Conservative management is often considered first for a smaller or chronic tear that does not appear to require surgical repair. It consists of activity modification or physical therapy to strengthen and increase the range of motion.

Is it difficult to heal a meniscus?

Many studies show the meniscus serves a purpose and therefore doctors will attempt to repair when possible. However, the meniscus has poor blood supply, and , therefore, healing can be difficult.

Which nerve is responsible for innervation of the medial meniscus?

Posterior articular branch of tibial nerve is responsible for most of the innervation of the meniscus. Medial articular branch of saphenous nerve also contributes to the innervation of the medial meniscus [ 15 ]. The larger nerves have a circumferential pattern in the perimeniscal tissue accompanying blood vessels.

What is the vascular pattern of the meniscus?

The menisci of an adult knee are relatively avascular structures, and their vascular pattern is strongly related to its healing capacity. According to their vascularization, adult meniscus is divided into three zones. The outermost one third of it is regarded as the “red–red zone” which has an abundant blood supply. The middle one third part, named as the “red–white zone,” has a scarce vascularization when compared with the red–red zone. The innermost one third is the avascular “white–white zone” (Fig. 24.3 ). When compared to its body, the insertion sites have richer vascularization [ 37 ].

What are the cells in the meniscal tissue?

There are three types of cells within the meniscal tissue. The cells located at the peripheral part are oval- or spindle-shaped cells which resemble fibroblasts morphologically. They possess thin, long, cytoplasmic processes which are used to communicate with other cells and extracellular matrix. These cells have abundant cytoplasm which is rich in granular endoplasmic reticulum and Golgi apparatus. They do not have pericellular matrix; instead, the collagen fibers of the extracellular matrix (which are mainly type I but to a lesser extent types III and V) surround these fibroblast-like cells. The cells of the inner menisci are more oval in shape and are surrounded by pericellular matrix. Owing to their resemblance to chondrocytes, they are called fibrochondrocytes or chondrocyte-like cells. The extracellular matrix around them contains mostly type II collagen, besides much less but significant amounts of type I collagen and glycosaminoglycan more than the outer menisci. Considering the fact that this part of the meniscus contains type II collagen and aggregan which is a proteoglycan, it resembles hyaline articular cartilage. The third type of cells is the ones located at the superficial part of the meniscus which is spindle shaped similar to the fibroblast-like cells but flatter than them and does not possess cytoplasmic processes. They are considered as progenitor cells with certain capabilities [ 25, 28, 37, 54 ].

What happens to the menisci during the gestational period?

During the gestational period, the developing menisci are highly cellular in the beginning and the nucleus–cytoplasm ratio is high . In time, these cells mature and the nucleus–cytoplasm ratio declines. While the number of cells decreases, their collagen production increases. Collagen fibers begin to orient in a circumferential manner.

Where is the posterior horn of the lateral meniscus attached?

The posterior horn of the lateral meniscus is attached to the lateral part of the medial femoral condyle via anterior (Humphrey) and posterior (Wrisberg) meniscofemoral ligaments. The anterior meniscofemoral ligament passes anterior to PCL, and posterior to it, there is the posterior meniscofemoral ligament.

When does the meniscus lose its vascularity?

Meniscus vascularity. During the gestational period, the whole meniscus is vascular. After birth, the inner part starts to lose its vascularity due to endostatin accumulation. Around the 11 years of age, the inner part becomes avascular (Reprinted from Springer Cellular and Molecular Bioengineering, Sanchez-Adams and Athanasiou [ 57 ], figure 3, with kind permission from Springer Science and Business Media)

Which meniscus is attached to the capsule?

The insertion sites of the anterior and posterior horns of the lateral meniscus are closer to each other when compared with that of the medial meniscus. The peripheral part of the medial meniscus is attached to the joint capsule via meniscotibial (coronary) ligaments.

What happens to the meniscus after injury?

The mechanism of pain after meniscus injury remains unknown. After injury, some individuals suffered from acute pain, while others suffer from delayed pain. A precise nociceptor distribution pattern may provide the answer to this question.

Where are SP+ nerve fibres found?

4 ). In line with the results of gold chloride staining, nerve fibres and nociceptors that were SP+ were found mainly in the vascular outer third of the menisci; the positive area was wider in the anterior and posterior horns. Unmyelinated nerve fibres, with diameters of 0.5~1.5 μm, were more than myelinated fibres. In the intermediate middle body of the menisci, SP+ nerve fibres were not associated with blood vessels but ran through the loose connective tissue. No nerve fibres or receptors were detected in the inner third of the body of the menisci. However, in the inner third or avascular part at the junction between the anterior horn and the anterior body, a small number of isolated myelinated SP+ nerve fibres were observed.

Where does the density of nociceptors decrease?

The density of nociceptors decreased along the longitudinal axis of the meniscus from both horns to the middle part of the body, which may guide future diagnostic methods and rehabilitation protocols.

Where are nociceptive nerve fibres located?

The present study revealed that nociceptive nerve fibres are distributed mostly in both horns and the outer third body of an intact meniscus, which provides a heightened awareness when dealing with a patient complaining of knee pain with suspected meniscus tears.

Is the density of nociceptors higher in both horns or in the body of the meniscus

The present study assessed the meniscus with a more precise semi-quantitative method that focused on the exact distribution of nociceptors in specific areas of the meniscus and found that the density of nociceptors is statistically higher in both horns than in the body of meniscus .

What is single factor analysis of variance?

Single-factor analysis of variance was applied to analyse the differences among multiple groups of data. The normal distribution and homogeneity of variance were tested, and p values < 0.05 or 0.001 were considered significant. All data were analysed with the SPSS program (SPSS Statistics Version 25, Chicago, IL, USA).

Can meniscus tears cause pain?

When the meniscus is torn, pain is usually the most common symptom [ 1 ]; however, the mechanism of pain remains unknown. After injury, some patients suffer acute pain immediately, while others do not. Meniscus injury in those patients without obvious symptoms cannot be detected until the injury progresses and a locked knee develops.

What causes a meniscus tear?

The most common mechanism of menisci injury is a twisting injury with the foot anchor on the ground, often by another player's body. A slow twisting force may also cause the tear.Damage to the meniscus is due to rotational forces directed to a flexed knee (as may occur with twisting sports) is the usual underlying mechanism of injury . The meniscal tear is of following types:

Why are my menisci rubbery?

The rubbery texture of the menisci is due to their fibrocartilagenous structure. Their shape is maintained by the collagens within them. One meniscus is on the inner side of your knee--the medial meniscus. The other meniscus is on the outer side of your knee--the lateral meniscus.

What is the pain in the medial joint line?

Pain in the area of the medial joint line during hyperflexion of the knee joint. Pain during external rotation of the foot and the lower leg when the knee is flexed at different angles around 70–90°. Weakened or hypotrophied quadriceps muscle.

Why is the medial meniscus attached to the medial collateral ligament?

This is partly because the medial meniscus is attached to the medial collateral ligament, and partly because tackles are often directed towards the lateral side of the knee, causing external rotation of the tibia. Injury to the medial meniscus is about 5 times more common than injury to the lateral meniscus.

What are the three mechanoreceptors in the meniscal body?

NERVE SUPPLY: The horns of the menisci and the peripheral vascularized portion of the meniscal bodies are well innervated with free nerve endings (nociceptors) and three different mechanoreceptors (Ruffini corpuscles, pacinian corpuscles, and Golgi tendon organs).

How long is the medial meniscus?

The medial meniscus is approximately 1.4 in (3.5cm) in length. The anterior horn of the medial meniscus is attached to the anterior surface of the tibia well off the tibial plateau. The anterior fibers of the anterior cruciate attachment merge with the transverse ligament, which connects the anterior horns of the medial.

What is the role of menisci in the knee?

At knee joint the menisci plays a major role in congurency of the joint. Menisci forms the concavity in which the femoral condyles sits. Menisci rests between the thigh bone femur and the tibia and there are two knee joint ligaments. They are a type of cartilage in the joint.

What is the meniscus made of?

Made of fibroelastic cartilage. interlacing network of collagen, proteoglycan, glycoproteins, and cellular elements. composed of 65-75% water. Collagen. 90 % Type I collagen. Fibers. composed of two types of fibers which allow the meniscus to expand under compressive forces and increase contact area of the joint. radial.

Which ligament connects the medial and lateral meniscus anteriorly?

connects the meniscus peripherally. medial meniscus has less mobility with more rigid peripheral fixation than the lateral meniscus. meniscofemoral ligament. connects the meniscus into the substance of the PCL.

Overview

Structure

Function

Clinical significance

Etymology

See also