This post is a simplified description of the various types of connective tissue that make up our bodies and where some of the connective tissue types are found. Connective tissue is also found in other parts of the body which are not mentioned here. This list has been condensed to focus on muscle anatomy and give you a general understanding of the anatomy involved.
Connective tissue is a term used to describe the cellular matrix (types of cells) that make up the different structures in our bodies which are listed below;
Skeletal muscle is the (voluntary contractile tissue) type of muscle that moves your skeleton. It is composed of muscle cells (fibers), layers of connective tissue (fascia) and nerves and blood cells.
The infrastructure of a muscle is very similar to a tropical fruit like a lime. A broad sheet of fascia encases the whole fruit, deeper layers of fascia separate the fruit into ‘wedges’ and then a thin coating of tissue surrounds each individual, tiny bud of fruit. If we use this analogy then a layer of fascia (epimysium) encases the muscle belly, a deeper layer (perimysium) wraps the long muscle fibers into bundles called ‘fascicles’ and each microscopic muscle fiber is bound in fascia (endomysium). Unlike a fruit, a muscle’s layers of connective tissue merge at either end of the muscle to form a strong tendon. The tendon attaches the muscle to a bone. A fruit only attaches at one end to a branch via its stem.
Muscle tissue has three specific characteristics that help distinguish it from other body tissues.
Simply put, tendons attach muscles to bone. …But what they actually do is connect muscles to the periosteum which is the connective tissue that surrounds the bone. Tendons are made of dense connective tissue shaped into bundles of parallel collagen fibers. Each end of a muscle has one or more tendons.
Tendons also come in a variety of shapes and sizes. Some are short and wide. Others are long and thin. There is also something called an aponeurosis which is a broad flat tendon. All tendons have a tough, smooth feel to them.
Ligaments connect bones together at a joint. They strengthen and stabilize joints. Ligaments are also made of very dense connective tissue. Ligament fibers have an uneven configuration whereas a tendon has a parallel fiber arrangement. Ie Deltoid ligament in the ankle and foot.
Some ligaments cross a joint and blend in with the joint capsule while others can span across several bones. (Ie Supraspinous ligament which extends inferiorly from the ligamentum nuchae down the spine as it attaches to each spinous process of the thoracic and lumbar vertebrae.
The ligamentum nuchae is a sheet of connective tissue that looks like a fin which runs along the sagittal plane from the external occipital protuberance to the spinous process of C7 in the neck. Its job is to help stabilize the head and neck as well as being an attachment site for muscles.
Ligaments sometimes have a taut, dense feel to them and sometimes you can feel their fiber directions. In order to distinguish a ligament from a tendon feel the tension and attachments. A tendon connects muscle belly to a bone, while a ligament attaches a bone to a bone. A tendon can become taut or slack whereas a ligament will remain taut throughout the entire action of a muscle contraction.
Fascia is a type of dense connective tissue, like ligaments and tendons. It is a continuous sheet of membrane located under the skin and around muscles and organs. It is a system of tissue that forms a three-dimensional matrix extending from head to toe throughout the entire body.
There are 2 types of fascia:
A retinaculum is a structure that holds an organ or tissue in place. It is a transverse thickening of deep fascia which straps tendons down in a particular location or position. Ie the superficial layer of the carpal tunnel which holds the flexor tendons and nerves in place.
An aponeurosis is a flat sheet of tendon-like tissue on the surface of some muscles that function as insertion sites for muscle fascicles that anchors the muscle or connects it with the part that the muscle moves.
Interosseous membrane is a fibrous tissue that binds the radius to the ulna, ensuring they remain a fixed distance apart. Tension changes occur in the interosseous membrane during movements of the forearm.
The interosseous membrane of the leg is also referred to as the middle tibiofibular ligament. This ligament extends through the fibula and tibia’s interosseous crests and separates the muscles in the back of the leg from the muscles located in the front of the leg.