Skeletal muscle is a specialised contractile tissue connected to the skeleton which enables you to move your body. The skeletal muscle consists of muscle tissue, connective tissue, nerve tissue and vascular tissue. These muscle fibres are surrounded by protective membranes.
The combination of muscle fibres and membranes allows the skeletal muscle to contract and release quickly.
The layers of connective tissue covering muscle fibres support, protect and allow the cells to withstand contraction. They also create pathways for blood vessels and nerves.
Epimysium is a connective tissue sheath that surrounds the hundreds, sometimes thousands, of muscle fibres that are bundled together to make the skeletal muscle. It protects the skeletal muscle from friction against other muscles and bones.
Fascia is connective tissue outside the epimysium that surrounds and separates the muscles. Fascia contains closely packed bundles of collagen fibres in a wavy pattern parallel to the direction the muscle pulls. It is flexible and able to resist great tension forces from different directions until the wavy pattern of the collagen has straightened out.
Portions of epimysium project inward to divide the muscle into compartments. Each of these compartments contains a bundle of fibres. This is called a fascicle (fasciculus).
Perimysium is the layer of connective tissue that surrounds the fasciculus with resistance to traction.
It consists of three different layers of collagen fibres:
- Superficial: straight fibres that have a smaller diameter and spread out without a definite direction.
- Intermediate: larger-diameter fibres, flattened and curved that intersect.
- Deep: soft lamina that is in direct contact with endomysium.
In the fasciculus, each muscle fibre is surrounded by connective tissue called the endomysium. The endomysium contains minute blood vessels (capillaries) and nerves.
It is the deepest and smallest component of muscle connectivity tissue. It provides an appropriate chemical environment for calcium, sodium and potassium to be exchanged. This makes the muscles contract.
Aponeurosis and tendons
When epimysium, perimysium and endomysium extend beyond the muscle fibres it creates a tough band of connective tissue that connects muscle to bone to withstand tension (tendons) or a sheet of tissue that takes the place of a tendon in flat muscles that have a wide area of attachment (aponeurosis.
The tendon and aponeurosis form indirect attachments from muscles to a dense layer of vascular connective tissue that envelopes the bones (periosteum). Alternatively, this indirect attachment is formed to the connective tissue of other muscles.
Blood vessels and nerves
Skeletal muscles have lots of blood vessels and nerves. This is because, before the muscle can contract, the nerve has to send out an impulse.
An artery and at least one vein accompany each nerve that penetrates the epimysium of the skeletal muscle. These nerves and blood vessels follow the connective tissue of the muscle, along with a few capillaries.
The skeletal muscle is a special type of contractile tissue that allows you to move the skeleton. It is made up of various muscle components, including epimysium, fascia, fascicles, perimysium, endomysium, aponeurosis, tendons, blood vessels and nerves.
Want to discover more about anatomy and physiology? Check out our Exercise Science Course for more information.