macrostructure of skeletal muscle

• muscles are separated from other tissues in the body by the epimysium

epimysium - connective tissue that wraps around the whole muscle

• inside muscles, the cells (called muscle fibres) are separated into bundles, which allows them to operate independently from each other

• this mean that muscles can recruit some or all muscle cells when contracting

Perimysium

• divides muscle into bundles called fascicles

• this allows each fascicle to work as an individual unit, so they can slide across each other during contraction

• allows nerves and blood vessels to access muscle fibres

• each fascicle contains many muscle fibres

• the endomysium wraps around each individual muscle fibre

• the epimysium, perimysium and endomysium, join at the end of the muscle to form the tendon, the older a person gets, the more connective tissue they have

• muscle cells are called muscle fibres and each fibre has many nuclei

• these cells have a long cylindrical shape, lie parallel to each other and can be as long as the entire muscle

• the prefix sacro- refers to skeletal muscle

• muscles contain

• sarcolemma (membrane)

• sarcoplasm and sarcoplasmic reticulum which contains the calcium needed for contraction

• lots (100s - 1000s) of myofibrils, which are long cylindrical structures made of protein, that lie parallel to each other

• myofibrils are divided into sarcomeres which are made up of myofilaments of 2 types

1. thick: made of myosin

2. thin: made of actin

• actin and myosin slide over each other, shortening the length of the myofibril to bring about contraction and create a banded appearance

skeletal muscle is made up of fascicles that are bundles of muscle fibres which contain myofilaments of 2 types called actin and myosin