Soft tissues: ligaments, tendons, bursae, periosteum, cartilage

Soft tissues are the massage therapist’s bread and butter and the domain where most the benefits of massage are derived. This is an umbrella term for a variety of bodily structures that surround, support and connect organs and parts of the body.

Typically, muscles, fibrous tissue (ligaments, tendons), synovial tissue, blood and lymph vessels, peripheral nerves, fat and even skin sometimes are referred to as ‘soft tissues’. As the name suggests, unlike bones, they are not hard. As such, it is obvious that mechanical treatment such as massage is likely to have some effect on them.
 
Let’s explore some of the soft tissues with particular significance for massage therapists in more depth.

The structure of ligaments
 
Ligaments are short thick bands composed of fibrous connective tissue. Ligaments can gradually strain when under tension but once released they return to their original shape. This property is called viscoelasticity.
 
Ligaments are made of dense fibrous bundles of collagenous fibres and a type of spindle-shaped cells called fibrocytes. They also contain a ground substance, which is a gel-like component of connective tissues.
 
Massage can be especially beneficial in reducing scar tissue formation during the healing phase of a ligament injury. This would help the joint maintain normal range of motion and reduce the likelihood of future injuries.
 
According to their structure, ligaments can be classified into two main types depending on the proportion of collagenous and elastic fibres:
 

• White ligaments are strong and have little elasticity and are made of rich collagenous fibres. Examples can be found in the lower leg. The anterior cruciate and posterior cruciate ligaments prevent the tibia from moving too far backward or forward in relation to the femur.
• Yellow ligaments are still quite strong but allow some elasticity and are rich in elastic fibres. Examples can be found in our finger joints, which for example allow us to stretch our fingers backwards beyond the normal range of motion.

 
The body has evolved in such a way as to have the best proportion of collagenous and elastic fibres. This ensures that each joint can most effectively realise its intended purpose.
 
The function of ligaments
 
Put simply, ligaments are tie everything together in the human body. They hold body parts together and prevent injuries by keeping everything in place.
 
Usually, we think of ligaments as something only found around bones. In reality, they can also support physical organs. For example, in the female reproductive system, we can find uterine ligaments and ovarian ligaments.
 
In relation to bones, ligaments’ main function is to hold bones together in articulation at the joints and to stabilise the moving surfaces. Around bones, they usually form a capsule that encloses the bone ends and the lubricating synovial membrane.
 
The basic function of ligaments can be further classified as:

• Protection – ligaments play an important role in preventing contact between bones and absorbing stress during movements.
• Proprioception – by holding the body together during movements, ligaments also help us know our position in space.
• Range of motion – as previously described, depending on their structure, ligaments determine the degree of flexibility observed at a joint.

 
There are three types of ligaments according to their function:
 

• Accessory ligaments are essentially thickenings of the joint capsule. They reduce rotation at the joint and strengthen the capsule and are often found on the lateral surface of a joint. This type of ligament is independent and lies outside of the capsule.
• Another type – extracapsular ligaments – are thick bands outside the joint capsule. They provide additional support to the capsule.
• The ones lying inside the synovial joint are called intracapsular ligaments. They prevent movements that may damage the joint. 

The structure of Tendons
 
Tendons are tissues that attach muscles to other parts of the body, usually to bones but sometimes to other muscles.
 
They are made of dense fibrous connective tissue, mainly collagenous fibres with some elastin as well. It has been approximated that collagen accounts for 65-80% and elastin for 1-2% of the dry mass of the tendon. These elements are made of spindle-shaped cells called tenoblasts (fibroblasts) and tenocytes (fibrocytes).

As the picture above illustrates, primary fibres are made of bunched fibrils, which are made of collagen.
 
Within collagen fibres, the fibrils are oriented longitudinally, transversely and horizontally. The longitudinal ones do not run only parallel but also form spirals as they cross each other. Fibres are grouped into fascicles, which form the tendon. Some sources divide tendons into even more constituents but this is beyond the scope of this work.
 
An epitenon, a fine connective tissue sheath, surrounds the entire tendon. Outside the epitenon and touching it there is a loose elastic connective tissue called paratenon. It allows the tendon to move against neighbouring tissues. The tendon, then, attaches to the bone by collagenous fibres (Sharpey fibres) that continue into the bone’s matrix.
 
Inflammation of the tendons is called tendinitis. Experience shows that healing of this condition can be accelerated with friction or deep friction (self)massage. Friction massage involves gentle rubbing back and forth over the inflamed tendon perpendicular to its fibres. The gentle stimulation provided by such mechanical treatment stimulates the natural healing response of the tissue.
 
The function of Tendons
 
The primary function of the tendons is to conduct the force of the muscle to the bone. This is what creates joint movement. The complex structure of tendons, already described, makes this possible.
 
When they move, tendons need to withstand not only to longitudinal but also to transversal and rotational forces. Additionally, they must be able to cope with direct contusions and pressures. What makes this possible and creates a buffer against forces and prevents damage is the three-dimensional internal structure of fibres described above.
 
The characteristics of collagen, the main building block, dictate the qualities of the tendon. Elastin gives some flexibility to the tendon allowing it to bend at joints, absorb shocks and reduce the likelihood of damage to the muscle.
 
According to their function, tendons can be classified as:

• Positional – help maintain the position of a limb in space – found in the fingers.
• Energy storing – owing to their degree of extensibility, tendons can store energy. This produces a spring-like motion which makes the movement more efficient.

The structure and function of Bursae
 
Within the body of mammals, there are small sacs between tendons, muscles or skin and bony prominences. These are called bursae, singular bursa, and there are about 160 of them in an adult’s body. Essentially, they are thin, lubricated cushions, which are like tiny water balloons with only a few drops of fluid located at points of friction.
 
Four distinct types of bursa can be identified:

• Adventitious, also called accidental, appear due to repeated shearing stresses around bony prominences. A bunion, a deformity of the big toe, is an example.
• Subcutaneous bursae usually present themselves as poorly-defined clefts at the junction of subcutaneous tissue and deep fascia. They only become distinct when abnormal, which can then classify them as adventitious. The olecranon bursa between the loose skin of the elbow and the ulna is a subcutaneous bursa.
• Synovial bursae are thin-walled sacs lined with a synovial membrane with a layer of viscous synovial fluid. Most of the bursa in a human’s body is synovial. They tend to be located in major joints such as the knees and shoulders.
• Submuscular bursae are found between a muscle and a bone, or between adjacent muscles. As an example, the greater trochanteric bursa can be found between the greater trochanter of the femur and gluteus maximus.

 
It is worth mentioning that a healthy bursa is thin. The relatively large bursa between the kneecap and the skin, for example, is only about 4 centimetres in diameter and just a few millimetres thick. As can be expected, bursae vary in size depending on their location and the individual.
 
The number of bursae we have is not fixed at birth. The olecranon bursa, for example, develops after the age of 7 for most people. Additionally, depending on how much friction we experience at specific areas of the body new bursae can develop. Constricting shoes can lead to the development of a bursa outside of the big toe.
 
Improper usage of the body by subjecting it to excessive stresses around joints repeatedly can inflame the adjacent bursae. This inflammatory condition of the synovial membrane is called bursitis and is usually caused by localised mechanical irritation. The inflamed synovium thickens producing excess fluid and causing a swelling.
 
Infections can also cause bursitis. This condition, called septic bursitis, can lead to filling up of the bursa with puss. It can be difficult to identify but commons symptoms include a fever, localised warmness and redness, tenderness and joint pain. Massage would be contraindicated in such cases.
 
Other cases, such as trochanteric bursitis, tend to respond reasonably well to massage. The pain is relieved by releasing tightness in the muscles and tendons around the hip.

​The structure and function of Periosteum 
 
Periosteum is the covering of bones. It is a dense membrane consisting of an outer fibrous layer and an inner cellular layer called cambium. 

By OpenStax College [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

The outer layer is made up mostly of collagen. It has nerve fibres inside making it susceptible to pain when there is damage. It is layered with blood vessels that supply osteocytes to the bone. These vessels go through the bone along channels known as Volkmann canals.
 
The inner layer contains the bone-producing cells – osteoblasts. It is most prominent during the development of the foetus in early childhood when active bone formation takes place. After maturity, these cells are less evident and they play more of a maintenance and remodelling role.
 
The periosteum also plays a role in cases of fracture. The periosteal vessels bleed around the area of the trauma forming clots. Within approximately 48 hours there is a multiplication of osteoblasts and the cambium thickens. Then the cells start differentiating and repairing the fracture by laying down new bone.
 
All of the bone’s surfaces except the ones capped with cartilage are covered by periosteum. The periosteum on the inside of the cranium is modified as it joins the membrane protecting the brain – dura mater.
 
The inflammatory condition of the periosteum where there is pain, mild swelling and tenderness is called periostitis. 
 
Cartilage
 
Cartilage is a supportive connective tissue, which is both flexible and strong. What differentiates it from other connective tissues is that it has no blood vessels. Cartilage plays a major role in humans by forming a model for later growth of the skeleton.
 
There are three basic types of cartilage:

By Shiloh117981894 (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

Hyaline cartilage
 
Hyaline cartilage is the most common type. It can be found in the ribs, nose, larynx, and trachea. It is considered a precursor to bone. The density of its fibres is the same as the substance surrounding them, which makes it glassy almost invisible.
 
Hyaline cartilage is strengthened by widely dispersed fine collagen fibres (type II). Usually, it is considered the weakest type of cartilage and has a perichondrium.
 
Fibro-cartilage 
 
Fibro-cartilage contains fine collagen fibres, which are arranged in layered arrays. Unlike hyaline cartilage, it has a more open, spongy structure. There are gaps between lacunae and collagen fibre bundles. Fibro-cartilage is found in intervertebral disks, joint capsules and ligaments.
 
It combines layers of hyaline cartilage matrix with thick layers of dense collagen fibres oriented in the direction of functional stresses. This makes it the strongest kind of cartilage. Usually, it acts as a transitional layer between hyaline cartilage and tendon or ligament, so it does not have a perichondrium.
 
Elastic cartilage
 
Elastic cartilage can be found in the external ear, epiglottis and larynx. Here, the chondrocytes form a threadlike network of elastic fibres. It maintains the shape of structures such as the ear providing strength and elasticity and does have a perichondrium. ​