Muscles of the human body

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This page explains the function of the main muscles and muscle groups, as well as some exercises that can be used to train each muscle group. The aim of this explanation is not to be comprehensive, but to provide a slightly deeper understanding of what a athlete is training.

The muscles are usually referred to by their Latin name. The exercises for the muscles are indicated by their English names. This makes it easier to know which muscles and exercises we are talking about anywhere in the world.

The muscles of the upper body

Trapezius

The trapezius (trapezius muscle) is a diamond-shaped muscle at the top of the back. The trapezius runs from the base of the skull to the middle of the back, and is also connected to the shoulder blade on the sides.

The trapezius has the following functions:

• Retraction: pulling the shoulder blade back
• Elevation: lifting the shoulder blade up
• Depression: lowering the shoulder blade down

Because of the different functions of the trapezius, it should also be trained in different ways. Many back and shoulder exercises have their effect on the trapezius (exercises such as military presses, T-bar rows, and deadlifts).

Suitable exercises to train the trapezius directly are:

• Dumbbell shrugs
• Barbell shrugs

Exercises where the trapezius works hard are:

• Upright rows
• Various shoulder and back exercises

Deltoideus

The deltoid muscle (often referred to in Dutch as ‘the shoulders’) is often divided into three parts, namely an anterior, middle, and posterior part. This is due to the different attachments of the muscle to the bones, giving the parts different functions.

Deltoideus Anterior

The anterior part of the deltoid – the deltoideus anterior or pars clavicularis – has the following functions:

• Anteversion: forward tilting of the arm
• Endorotation: inward rotation of the shoulder (towards the chest)
• Adduction, increasing to abduction from sixty degrees: moving the arm away from the body

It is not really possible to train each part of the deltoid completely separately, but it is possible to focus the emphasis of an exercise on a specific part of the muscle.

Suitable exercises to train the deltoideus anterior are:

• Front raises (dumbbells, barbell, disk weight, cables)
• Military presses
• Dumbbell presses
• Upright row

Deltoideus Lateralis

The middle part (the side of the muscle, which gives the shoulders width) of the deltoid – the deltoideus lateralis or pars acromialis – has only one function:

Abduction up to 90°: moving the arm away from the body to the side up to 90° (after that, the movement is taken over by the trapezius)

Suitable exercises to train the deltoideus lateralis are:

• Lateral/side raises (dumbbells, cables)
• Arnold presses
• Upright rows

Deltoideus Medialis

The posterior part of the deltoid – the deltoideus medialis or pars spinalis – has the following functions:

• Retrolisthesis: backward tilting of the arm
• Exorotation: outward rotation of the shoulder (towards the back)
• Adduction, increasing to abduction from sixty degrees: moving the arm away from the body

Suitable exercises to train the deltoideus medialis are:

• Bent-over lateral raises (dumbbells, cables)
• Rear-delt machine
• Reverse pec-deck flyes

The deltoideus medialis also works hard with various back exercises, such as lat pulldowns and various rowing exercises.

Biceps

The biceps are located at the front of the arm, and for training purposes are divided into three separate muscles:

• Biceps brachii (long head)
• Biceps brachii (short head)
• Brachialis

The biceps have the following functions:

• Flexion of the lower arm in the elbow joint
• Supination of the lower arm in the elbow joint

Suitable exercises to train the biceps are:

• Barbell curls
• Dumbbell curls
• Preacher curls
• Concentration curls
• Hammer curls
• Cross body hammer curls
• Scott curls

When doing back exercises where the arm is pulled towards the body, such as lat pulldowns, rowing exercises, and chin-ups, the biceps are also trained.

Triceps

The triceps are located at the back of the upper arm, and for training purposes are divided into three separate muscles:

• Triceps brachii (long head)
• Triceps brachii (lateral head)
• Triceps brachii (medial head)

The triceps have the following functions:

• Extension of the lower arm in the elbow joint

Suitable exercises to train the triceps are:

• Pressdowns (various handles)
• French presses
• Overhead triceps extension (dumbbell, EZ-curl bar)
• Dips (forward leaning or upright)
• Triceps kickbacks
• Skull crushers

The triceps are also trained during chest exercises, such as bench presses and flyes.

Pectoralis

The pectoralis major (pectoralis major muscle) are two large, fan-shaped muscles located at the front of the upper body. The pectoralis runs from the breastbone to the upper arm.

The pectoralis has the following functions:

• Adduction: pulling the arm towards the body
• Medial rotation: inward rotation of the arm
• Flexion: pulling the arm forward

Suitable exercises to train the pectoralis are:

• Bench presses (barbell, dumbbell, machine)
• Incline bench presses (barbell, dumbbell, machine)
• Decline bench presses (barbell, dumbbell, machine)
• Push-ups (feet raised, hands close together, hands wide apart, hands on platforms)
• Flyes (barbell, dumbbell, machine)
• Chest press machine (seated, lying)
• Cable crossover (high pulley, low pulley)
• Peck deck

Exercises where the pectoralis also works hard are:

• Dips (forward leaning)
• Various shoulder exercises
• Various back exercises

Latissimus dorsi

The latissimus dorsi (often referred to in Dutch as ‘the lats’) is a large, flat muscle located at the middle and lower back. The latissimus dorsi runs from the lower back to the upper arm and is responsible for the V-shape of the back.

The latissimus dorsi has the following functions:

• Extension: pulling the arm down to the body
• Adduction: pulling the arm towards the body
• Medial rotation: inward rotation of the arm
• Retraction: pulling the shoulder blade back

Suitable exercises to train the latissimus dorsi are:

• Lat pulldowns (various grips)
• Chin-ups (various grips)
• Pull-ups (various grips)
• Bent-over rows (barbell, dumbbell, machine)
• Seated rows (low pulley, machine)
• T-bar rows
• Deadlifts (Romanian, stiff-legged, conventional, sumo)
• Various shoulder exercises

Exercises where the latissimus dorsi also works hard are:

• Various shoulder exercises
• Various chest exercises
• Various arm exercises

Rectus abdominis

The rectus abdominis (often referred to as the abs) are a long muscle located at the front of the abdomen. The rectus abdominis runs from the lower ribs to the pelvis, and consists of several segments.

The rectus abdominis has the following functions:

• Flexion: bending the upper body forward
• Flexion: pulling the pelvis up towards the ribcage

Suitable exercises to train the rectus abdominis are:

• Sit-ups (various grips)
• Crunches (various grips)
• Leg raises (lying, hanging)
• Hip thrusts
• Planks (static)
• Side planks (static)

The rectus abdominis also works hard with various back exercises, such as deadlifts and squats.

Obliquus externus abdominis and obliquus internus abdominis

The obliquus externus abdominis and obliquus internus abdominis (often referred to as the obliques) are two pairs of muscles located at the side of the abdomen. The obliques run from the lower ribs to the pelvis.

The obliques have the following functions:

• Flexion: bending the upper body sideways
• Rotation: twisting the upper body
• Lateral rotation: inward rotation of the hip
• Medial rotation: outward rotation of the hip

Suitable exercises to train the obliques are:

• Twists (seated, standing, lying)
• Side bends (standing, seated)
• Leg raises (lying, hanging)
• Planks (static)
• Side planks (static)
• Various back exercises
• Various leg exercises

The obliques also work hard with various back exercises, such as deadlifts and squats.

Serratus anterior

The serratus anterior (often referred to as ‘the serratus’) is a fan-shaped muscle located at the side of the upper body. The serratus anterior runs from the upper ribs to the scapula (shoulder blade).

The serratus anterior has the following functions:

• Protraction: pushing the shoulder blade forward
• Abduction: moving the arm away from the body
• Upward rotation: lifting the arm up

Suitable exercises to train the serratus anterior are:

• Push-ups (various grips)
• Press-ups (various grips)
• Various shoulder exercises
• Various chest exercises
• Various arm exercises
• Various back exercises

Exercises where the serratus anterior also works hard are:

• Various shoulder exercises
• Various chest exercises
• Various back exercises
• Various arm exercises
• Various leg exercises

The serratus anterior is also trained during swimming and various martial arts exercises.

Rhomboids

The rhomboids are two muscles located at the middle of the upper back. The rhomboids run from the spine to the scapula (shoulder blade).

The rhomboids have the following functions:

• Retraction: pulling the shoulder blades back
• Elevation: lifting the shoulder blades up

Suitable exercises to train the rhomboids are:

• Various back exercises
• Various shoulder exercises
• Various arm exercises
• Various chest exercises
• Various leg exercises

Exercises where the rhomboids also work hard are:

• Various shoulder exercises
• Various chest exercises
• Various arm exercises
• Various leg exercises
• Various abdominal exercises
• Various lower back exercises

The rhomboids are also trained during swimming and various martial arts exercises.

Trapezius

The trapezius (often referred to as ‘the traps’) is a large, diamond-shaped muscle located at the upper and middle back. The trapezius runs from the base of the skull to the lower back and the spine.

The trapezius has the following functions:

• Elevation: lifting the shoulder blades up
• Depression: lowering the shoulder blades down
• Retraction: pulling the shoulder blades back
• Upward rotation: lifting the shoulder blades up
• Downward rotation: lowering the shoulder blades down
• Stabilization: stabilizing the shoulder blades

Suitable exercises to train the trapezius are:

• Shrugs (various grips)
• Upright rows (barbell, dumbbell, EZ-curl bar)
• Bent-over rows (barbell, dumbbell, machine)
• Lat pulldowns (various grips)
• Chin-ups (various grips)
• Pull-ups (various grips)
• Various shoulder exercises

Exercises where the trapezius also works hard are:

• Various shoulder exercises
• Various chest exercises
• Various arm exercises
• Various back exercises
• Various leg exercises
• Various abdominal exercises
• Various lower back exercises

The trapezius is also trained during swimming and various martial arts exercises.

Deltoids

The deltoids (often referred to as ‘the delts’) are three muscles located at the upper shoulder. The deltoids consist of three separate muscles:

• Deltoid (anterior head)
• Deltoid (lateral head)
• Deltoid (posterior head)

The deltoids have the following functions:

• Flexion: lifting the arm forward
• Abduction: lifting the arm sideways
• Medial rotation: inward rotation of the arm
• Lateral rotation: outward rotation of the arm
• Extension: lifting the arm backwards

Suitable exercises to train the deltoids are:

• Shoulder press (barbell, dumbbell, machine)
• Lateral raises (dumbbell, machine)
• Front raises (dumbbell, machine)
• Rear delt flyes (dumbbell, machine)
• Upright rows (barbell, dumbbell, EZ-curl bar)
• Shrugs (barbell, dumbbell, machine)
• Various shoulder exercises

The deltoids are also trained during various chest, back, and arm exercises.

Forearms

The forearms consist of various muscles that are responsible for the movement of the lower arm and the wrist. The forearms consist of several muscles, including:

• Flexor digitorum superficialis
• Flexor digitorum profundus
• Flexor carpi radialis
• Flexor carpi ulnaris
• Palmaris longus
• Extensor digitorum
• Extensor carpi radialis brevis
• Extensor carpi radialis longus
• Extensor carpi ulnaris
• Brachioradialis

The forearms have the following functions:

• Flexion: bending the wrist forward
• Extension: bending the wrist backward
• Abduction: moving the wrist to the side
• Adduction: moving the wrist towards the body
• Supination: turning the hand upwards
• Pronation: turning the hand downwards
• Flexion: bending the lower arm in the elbow joint
• Extension: straightening the lower arm in the elbow joint
• Rotation: turning the lower arm

Suitable exercises to train the forearms are:

• Wrist curls (dumbbell, barbell)
• Reverse wrist curls (dumbbell, barbell)
• Hammer curls
• Reverse curls
• Pinwheel curls
• Finger curls
• Various grip exercises

The forearms are also trained during various biceps, triceps, chest, back, and shoulder exercises.

Gluteus

The gluteus (often referred to as ‘the glutes’) are a group of three muscles located at the buttocks. The gluteus consists of three separate muscles:

• Gluteus maximus
• Gluteus medius
• Gluteus minimus

The gluteus have the following functions:

• Extension: moving the leg backwards
• Abduction: moving the leg sideways
• Lateral rotation: outward rotation of the leg
• Medial rotation: inward rotation of the leg
• Anteversion: forward tilting of the pelvis
• Posterior: backward tilting of the pelvis
• Abduction: moving the hip away from the body
• Adduction: moving the hip towards the body

Suitable exercises to train the gluteus are:

• Squats (barbell, dumbbell, Smith machine)
• Deadlifts (Romanian, stiff-legged, conventional, sumo)
• Lunges (barbell, dumbbell, Smith machine)
• Leg press (various foot positions)
• Leg curls (lying, seated, standing)
• Step-ups (barbell, dumbbell)
• Various abdominal exercises

The gluteus are also trained during various leg exercises.

Quadriceps

The quadriceps (often referred to as ‘the quads’) are a group of four muscles located at the front of the thigh. The quadriceps consist of four separate muscles:

• Rectus femoris
• Vastus lateralis
• Vastus intermedius
• Vastus medialis

The quadriceps have the following functions:

• Extension: straightening the leg
• Flexion: bending the leg
• Abduction: moving the leg sideways
• Adduction: moving the leg towards the body
• Rotation: turning the leg

Suitable exercises to train the quadriceps are:

• Squats (barbell, dumbbell, Smith machine)
• Leg press (various foot positions)
• Lunges (barbell, dumbbell, Smith machine)
• Leg extensions (seated, lying)
• Step-ups (barbell, dumbbell)
• Various abdominal exercises

The quadriceps are also trained during various leg exercises.

Hamstrings

The hamstrings (often referred to as ‘the hammies’) are a group of three muscles located at the back of the thigh. The hamstrings consist of three separate muscles:

• Biceps femoris
• Semitendinosus
• Semimembranosus

The hamstrings have the following functions:

• Flexion: bending the leg
• Extension: straightening the leg
• Adduction: moving the leg towards the body
• Abduction: moving the leg away from the body
• Lateral rotation: outward rotation of the leg
• Medial rotation: inward rotation of the leg
• Posterior: backward tilting of the pelvis
• Anteversion: forward tilting of the pelvis
• Abduction: moving the hip away from the body
• Adduction: moving the hip towards the body
• Rotation: turning the hip

Suitable exercises to train the hamstrings are:

• Deadlifts (Romanian, stiff-legged, conventional, sumo)
• Lunges (barbell, dumbbell, Smith machine)
• Leg curls (lying, seated, standing)
• Good mornings (barbell, dumbbell)
• Various abdominal exercises

The hamstrings are also trained during various leg exercises.

Calves

The calves (often referred to as ‘the calves’) are a group of two muscles located at the back of the lower leg. The calves consist of two separate muscles:

• Gastrocnemius
• Soleus

The calves have the following functions:

• Flexion: bending the ankle forward
• Extension: bending the ankle backward
• Adduction: moving the ankle towards the body
• Abduction: moving the ankle away from the body
• Supination: turning the foot inwards
• Pronation: turning the foot outwards

Suitable exercises to train the calves are:

• Calf raises (standing, seated)
• Leg press (various foot positions)
• Deadlifts (Romanian, stiff-legged, conventional, sumo)
• Various abdominal exercises
• Various leg exercises

The calves are also trained during various leg and back exercises.

Conclusion

The human body consists of numerous muscles, each with its own function and range of motion. By understanding the anatomy of the muscles and how they work together, athletes can develop more effective training programs to target specific muscle groups and achieve their fitness goals.

It’s important to note that while certain exercises may primarily target one muscle group, many exercises also engage secondary and supporting muscles. Therefore, incorporating a variety of exercises into a training routine is key to achieving overall muscle balance and strength.

Additionally, proper form and technique are crucial to prevent injury and maximize the effectiveness of each exercise. Athletes should always consult with a qualified fitness professional before beginning any new exercise program, especially if they have pre-existing injuries or medical conditions.