3. Biceps brachii - biceps covers front part of upper arm and consists of a long head and a short head. The long head crosses shoulder joint and works with front deltoid to raise arm to front.

4. Triceps brachii - triceps covers the back of upper arm and consists of three sections - long, lateral and medial heads. The role of triceps is to straighten arm at elbow.

5. Brachialis - this muscle lies between upper arm bone and biceps. It helps biceps to bend elbow when palm is facing sideways.

6. Forearm muscles - forearms consist of many little muscles called flexors and extensors. The largest forearm muscle is brachioradialis that lies close to elbow.

2. Obliquus abdominis - this muscle runs diagonally along side of mid-section from lower ribcage to pubic area. There are two muscles on each side, with internal obliques lying underneath external obliques. The obliques help your torso to flex to side, twist at waist and help in bending torso forwards.

3. Transversus abdominis - this is deepest of abdominal muscles and consists of a thin strip that runs horizontally across abdomen. This muscle helps keep internal organs in place, forces out breath and stabilizes spine.

4. Erector spinae - this large muscle group runs along side of lower spine. Consisting of a pair, erector spinae keeps spine erect and helps twisting at waist.