Anatomy of the Core Muscles 

Rectus Abdominus: Responsible for flexing and rotating the trunk. The "Six Pack Abs."

External Obliques: Contributes spinal stability and allows the trunk to flex and bend to the side. 

Internal Obliques:  Contributes to flexion and roation of the trunk toward same side of the body. 

Transversus Abdominus: Responsible for trunk stabaliation and compresses the abdominal wall

Multifidus: rotation and flexion of the spine by suppporting the vertebral joints. 

Quadratus Lumborum: Connects the spine to the pelvis 

Some Beginner Core Exercises

Plank: To do this correctly, you must support your body on your forearms and toes while holding your body in a straight line, from your shoulders to your ankles. 

Dead bug: Lie on your back with your arms extended towards the ceiling, with your legs raised and bent at 90 degrees. Lower your right arm and left leg at the same time until they are hovering just above the floor, and then return to the starting position. Then do the same with the opposite limbs. 

Boat: Sit on the floor with your knees bent. Lean back slightly while keeping your back straight. Hold your arms in front of you as you raise your feet off the ground with your legs together. Extend your legs so they are straight and your body forms a V shape. to make the exercise harder, raise your arms and spread your legs. 

Beginner Core Workout- From Coach Magazine 

1 Plank Time 30sec Rest 0sec

2 Dead bug Reps 10 Rest 0sec

3 Boat Time 30sec Rest 1min

Do five rounds in total of these three exercises.