Arm muscles
On the front of the upper arm there are the elbow flexors (biceps brachii, the brachioradialis, the brachialis). Elbow flexion moves the wrist toward the shoulder by bending the arm. These muscles contribute to movement of the forearm in varying degrees depending on how the exercise is performed.
On the back part of the upper arm there are elbow extensors. Elbow extension moves the wrist away from the shoulder by straightening the arm. The primary elbow extensors are three heads of triceps brachii – the long head, medial head and lateral head. The long head is the largest of the three individual heads. Although all three heads perform the basic function of elbow extension, the triceps long head is unique in that, unlike the lateral and medial heads, it crosses the shoulder joint and also assists in the function of shoulder extension. The triceps make up 2/3 of your overall upper arm mass.
Biceps brachii, the brachioradialis (sval vřetenní), the brachialis (hluboký sval pažní)
Biceps brachii is the primary elbow flexor. It is composed of two heads (long and short head). Other elbow flexors are the brachialis and the brachioradialis (a major muscle in the forearm).
Function
Most of the workouts mentioned below can be executed with different grips that determine the focus on a particular muscular group. The biceps brachii works more with supinated grip (palms are facing forward), the brachioradialis with a neutral grip (palms are facing each other) and the brachialis with a pronated grip (palms are facing away/down).
List of exercises
Barbell Curl
Starting position: Legs are shoulder-width apart; knees are slightly bent. The trunk is fixed.
The barbell in both hands, holding it with a supine grip, palms facing out/up. Inhale.
Execution: Exhaling, curl slowly the barbell up toward shoulders, hold it there for one second and then slowly bring it back down to the starting position.
Incorrect execution/Faults: Elbows are not fixed at the same position close to the trunk during the whole execution, cheating, and the trunk is swinging while lifting the barbell.
Modifications: changing the width of the grip, using of EZ barbell
Dumbbell Curls
Starting position: Legs are shoulder-width apart, arms at sides of the body, dumbbells in both hands, holding them with a supine grip, palms facing out. Inhale.
Execution: Exhaling, curl slowly the dumbbells up toward shoulders, hold them there for one second and then slowly bring them back down to the starting position.
Incline Dumbbell Curls
The incline dumbbell curl is a regular dumbbell biceps curl, only you are now sitting back on an incline (60°–45°) bench. This execution allows arms to hang and the range of motion is longer. In sitting position back is straight, the pelvis in neutral position.
Starting position: To begin the exercise, sit on an incline bench with feet flat on the floor. Allow each arm to hang by your side and, one at a time, curl the dumbbell up.
Execution: Exhaling, curl slowly the dumbbells up toward shoulders, hold them there for one second and then slowly bring them back down to the starting position.
Cable Curls
Starting position: Standing position in front of the machine; a handle or the bar in each hand, depending on the shape of the handle, the exercise is focused on biceps brachii (palms are facing out/up) or brachioradialis (palms are facing each other) or the brachialis (palms are facing down).
Execution: Using the same arm motion as a barbell curl, pull the bar from your thighs toward your shoulders, and then slowly return to the starting position.
The preacher´s bench/Scott weight machine
Starting position: The workout can be performed both sitting or in standing position. Arms rest on the pad, elbows are slightly bent, and underhand grip is used.
Execution: Taking deep breath, the bar is slowly lifted upward. Inhaling, slowly lower the bar in a controlled manner until the arms are almost straightened. Do not lock the elbow joint.
Target/Aim: Middle part of the biceps brachii.
Faults: Movements of the lower back (pelvis tilting forward or backward), unstable sitting, small range of motion
Modification: Preacher´s benches can be done using barbell, dumbbell, EZ bar, triceps bar or cable (using low pulley machine).
Concentration Curls
Starting position: While sitting on a bench with feet firmly put on the floor, the back of one upper arm is placed on the inside part of the thigh. The other hand is on the other knee for better stability. The dumbbell is held by underhand grip (palms are facing forward).
Execution: Exhaling, curl slowly the barbell up toward shoulders, hold it there for one second and then slowly bring it back down to the starting position.
Target/Aim: The biceps peak
Faults: Small range of motion, leaning backwards, co-movements of the body.
Note: The hand position allows to focus the workout on a specific part of the muscle. Standard EZ bar has got two spots which can be used throughout workouts: wide position and narrow position. Narrow grip of hands results in increased muscle activity in the long head (the long head is on the outside of the arm and forms the peak of the muscle) of the biceps.
Wide grip (the short head forms much of the girth and the width of the bicep).
The wide grip curl more heavily targets the short head of the biceps (the short head is inside of the biceps and focusing on this muscle part the lateral girth and thickness of the upper-arm are more developed).
Biceps Curl with pronated grip
Starting position: Legs are shoulder-width apart; knees are slightly bent. The trunk is fixed.
The barbell in both hands, holding it with a prone grip, palms facing down. Inhale.
Execution: Exhaling, curl slowly the barbell up toward shoulders, hold it there for one second and then slowly bring it back down to the starting position.
Incorrect execution/Faults: Elbows are not fixed at the same position close the trunk during the whole execution, cheating, and the trunk swinging while lifting the barbell.
Modifications: Changing the width of the grip, using of EZ barbell, using an E-Z attachment hooked to a low pulley.
Target/Aim: Musculus brachioradialis
Note: For the Reverse Curl, the hands are in a pronated grip (palms are facing down from the body). This variation will target forearms and the grip strength much more than a regular Curl.
Reverse Curls heavily target the brachioradialis. Reverse Curls are generally a more difficult exercise than Bicep Curls, so the lighter weight has to be used. Using an EZ bar, Reverse Curls can be done with hands on the outside part of the bar, which will have palms turned slightly inward.
Hammer Curls
Hammer Curls are a variation of the traditional bicep curl. This exercise is done with a set of dumbbells rather than a barbell.
Starting position: Dumbbells in each hand, and standing with your feet shoulder-width apart and knees slightly bent, arms are down at sides and palms facing toward the body.
Execution: Slowly curl the weights up to shoulders, keeping your palms facing one another, hold for one second and then lower them back down.
Note: Hammer Curls target both heads of the biceps in addition to the brachioradialis and brachialis (a small muscle in the deep upper arm). That means you are working both your forearm and upper-arm, making Hammer Curls a well-rounded exercise. Additionally, a stronger brachioaradialis and brachialis can actually push the biceps up, making it appear bigger. Hammer Curls also place less stress on the wrist than traditional Bicep Curls or Reverse Curls.
References:
http://www.stack.com/a/curl-grips