Triceps Muscle; Origin, Insertion, Nerve Supply, Function

Origins and insertions of Triceps Muscle

The triceps brachii muscle is so named, as it is a muscle with three heads. The triceps brachii forms the bulk of the posterior or extensor compartment of the arm. The triceps is an extensor of the elbow, as well the long head acting as an extensor of the shoulder. Histological studies of the triceps muscle heads have shown that the three heads of triceps brachii consist of different types of muscle fibers.

The long head arises from the infraglenoid tubercle of the scapula, a small bony projection from the lower part of the rim of the glenoid fossa. It consists of type IIa fibers and is therefore at maximal function when the sustained contraction is required.

The lateral head arises from the posterior lateral surface of the humeral shaft, above the radial groove. It consists of largely type IIb fibers and is therefore at maximal function when short intensity high power contraction is required.

The medial head arises from the posterior medial surface of the humeral shaft, below the radial groove. It consists of type I fibers and is therefore required for continuous long-term contraction. It lies close to the radial sulcus and if it is overused, it may compress the radial nerve as it descends. The radial sulcus is where the radial nerve and profound brachial artery run in the arm. The three heads of triceps brachii converge into a single tendon that inserts onto the olecranon process.

The quadrangular space is bordered superiorly by teres minor, inferiorly by teres major, medially by the long head of triceps and laterally by humerus. The axillary nerve and posterior circumflex humeral artery pass through this space. The triangular space is inferior to the quadrangular space and has the same medial and lateral borders. It is however bordered superiorly by the teres minor muscle, inferiorly by teres major and laterally by the long head of triceps. It allows the radial nerve to enter the arm, as well as the profunda brachii artery.

Innervation

The radial nerve (ventral rami of C5 – T1) is a branch of the posterior cord of the brachial plexus. Triceps is innervated by C6,7 and 8 component of radial nerve, a separate branch for each head. It passes through the triangular space accompanied by the profunda brachii branch of the brachial artery, and the circumflex scapular artery. Here it supplies the long head of triceps.

The nerve then passes into the radial/spiral groove of the humerus, and runs between the medial and lateral head of the triceps brachii and supplies them. It emerges by passing between brachialis and brachioradialis and emerges anterior to the lateral epicondyle. The nerve continues to descend into the extensor compartment of the forearm, which it innervates via its branch, the posterior interosseus nerve. The radial sulcus is also known as the spiral groove or radial groove.

)

Blood supply

The blood supply to the triceps comes from the:

• Profunda brachial artery
• Superior ulnar collateral artery
• Posterior circumflex humeral artery

Anatomically the upper limb is divided into the arm and the forearm. The profound brachial artery supplies all of the muscles of the flexor and extensor compartment of the arm.

The venous drainage is via the brachial vein that runs with the profunda brachii artery.

The Function of Triceps Muscle

The triceps is an extensor muscle of the elbow joint and an antagonist of the biceps and brachialis muscles. It can also fixate the elbow joint when the forearm and hand are used for fine movements e.g when writing. It has been suggested that the long head fascicle is employed when sustained force generation is demanded, or when there is a need for synergistic control of the shoulder and elbow or both. The lateral head is used for movements requiring occasional high-intensity force, while the medial fascicle enables more precise, low-force movements.^[rx]

With its origin on the scapula, the long head also acts on the shoulder joint and is also involved in retroversion and adduction of the arm. It helps stabilize the shoulder joint at the top of the humerus.^[rx][rx]

Beginner Triceps Triceps Muscle

• Attach a straight or angled bar to a high pulley, says Adepitan, and hold it with your palms facing down (overhand grip) and your hands shoulder-width apart. Standing upright with your torso straight, bring your upper arms close to your body and perpendicular to the floor. Your forearms should be pointing up towards the pulley.
• Using your triceps to move your forearms, bring the bar down until it touches the front of your thighs with your arms fully extended and perpendicular to the floor. Your upper arms should remain stationary next to your torso. After holding for one second at the contracted position, bring the bar slowly back up to the starting point. Exhale as you bring the bar down and breathe in as you return to the start position

Triceps reverse press-down

• Start by setting a bar attachment (straight or EZ-bar) on a high pulley of the cable machine,” says Adepitan. “Facing the bar attachment with feet shoulder-width apart, grab it with palms facing up (supinated grip) and hands shoulder-width apart. Lower the bar by using your lats until your arms are fully extended by your sides with elbows tucked in.
• Moving your forearms but keeping your elbows and upper arms stationary by your sides, slowly bring the bar attachment up, inhaling as you go, until it is at chest height. Lower the cable bar back to the starting position while exhaling and contracting the triceps.”

Cable overhead triceps extension

• Attach a rope to the bottom pulley of the cable machine,” says Adepitan. “Face away from the pulley and, holding the rope with both hands with palms facing each other (neutral grip), extend your arms until your hands are directly above your head. Your elbows should be in close to your head and the arms should be perpendicular to the floor with the knuckles pointing to the ceiling.
• Slowly lower the rope behind your head as you hold the upper arms stationary. Inhale as you perform this movement and pause when your triceps are fully stretched. Breathe out as you return to the starting position by flexing your triceps.

Press-up

• The diamond press-up variation may put more focus on the triceps, but when you’re starting out it’s a good idea to split the work between your chest and triceps so you can complete the optimal number of reps with good form. Start on all fours, supporting yourself on your toes and palms with your arms extended and hands under your shoulders.
• Your body should form a straight line between your shoulders, hips and heels. Take approximately three seconds to lower your chest to the ground, keeping your elbows tight to your sides. Once your chest is roughly 5cm off the ground, press back up with force, taking one second to return to the top position.

Dumbbell jab

• Grab two light dumbbells, no heavier than 2kg or 3kg each. Stand with your feet squared and knees slightly bent. Hold the dumbbells in front of your chin with your palms facing you and throw a straight punch at head height – standing in front of a mirror can help you keep to the right height throughout.
• The punch should end with your arm fully extended, your torso rotated to extend your reach and your palm facing the ground. Alternate arms with each punch, working at speed. Work to time rather than sets and reps.

Intermediate Triceps Muscle Exercises

• Position yourself on the left side of the bench with your right knee and right hand resting on it, says Adepitan. Using a neutral grip, pick up the dumbbell with your left hand. Keep your back straight and look forward. Tuck your left upper arm close to your torso and bend at the elbow, forming a 90° angle with your upper arm and forearm.
• Moving only below the elbow, raise the dumbbell behind you until your arm is fully extended. Pause, and then lower the dumbbell back to the starting position. Repeat this movement for the desired number of reps and then switch to your right arm.
• Using dumbbells rather than the cable machine works each arm individually, helping to even out any strength imbalances in your triceps. The move is done in the same way as with a cable machine. Start holding both dumbbells above your head with your arms extended.

Cableunilateral triceps extension

• Stand directly in front of the weight stack in a staggered stance, says Adepitan. With your right hand, grasp a single handle attached to the high pulley using an underhand grip so your palm faces up. Pull the handle down so that your upper arm and elbow are locked in to the side of your body. Your upper arm and forearm should form an acute angle (less than 90°).
• Contract your triceps and breathe out as you move your forearm to bring the attachment down to your side until your arm is straight. Squeeze your triceps and hold for a second in this contracted position. Slowly return the handle to the starting position. Complete all reps, then switch arms.

Bench dip

• Place two flat benches parallel to one another, around 1-1.5m apart (adjust the width to suit your height),” says Adepitan. Place your hands on the edge of the bench, around shoulder-width apart, and put your heels on the edge of the other bench.
• Keeping your body close to the bench, slowly lower in a dip until your elbows are at the same height as your shoulders. Slowly push back up, squeezing through the triceps. Do not lock out your elbows at the top of the exercise.”

Floor press

• If you’ve spotted someone doing this in the gym you probably assumed the queue for the bench press got out of hand, but there are more benefits to the floor press than simply avoiding a wait. By pressing from the floor you place less strain on your shoulders, and because your arms hit the floor after each rep you momentarily relieve your muscles of the load, which makes initiating every rep more of a challenge.
• Lie on the floor holding a barbell above your chest with your arms extended. Slowly lower it to your chest until your upper arms touch the ground, then press it above you.

Landmine press

• This is another pressing exercise that’s less stressful for your shoulders than the bench or overhead press. The landmine press hits your triceps hard, along with your chest and shoulders, and can be performed using a dedicated landmine holder for the bar or simply by wedging one end of the bar into a corner (if your gym won’t mind scuff marks on the wall).
• You can do the lift one- or two-handed. With the former, adopt a split stance with one foot in front of the other and begin holding the weight by your shoulder. When using two hands, stand with your feet shoulder-width apart and press the bar from the middle of your chest.

Bench press

• While the close-grip bench press (below) shifts the focus to your triceps, the standard move still requires your arms to put in a shift. Lie on a weight bench, holding a barbell with your hands slightly wider than shoulder-width apart and arms extended. Lower the bar towards your chest until the barbell reaches your chest, taking three seconds to complete this phase, then push up for a count of one second.

Advanced Triceps Exercises

Roman chair dip

• Position yourself on the Roman chair (find a gym staff member to help you if you’ve not used one before),” says Adepitan. “Bend your knees, slowly lower yourself, then press back up. Make sure to look up, keep your body straight and keep your elbows next to your body so they bend back behind you, rather than out to the sides.”

Close-grip bench

• Lie with your back on a flat bench,” says Adepitan. “With hands around shoulder-width apart, lift the barbell from the rack and hold it straight over you with your arms locked.
• Lower the bar slowly until the bar touches the middle of your chest, inhaling as you go. Make sure that, as opposed to a regular bench press, you keep the elbows close to your torso at all times in order to maximize the involvement of your triceps. Pause for a second, then press the bar back to the starting position using your triceps muscles, exhaling as you go. Lock your arms in the contracted position, hold for a second and then start coming down slowly again. It should take at least twice as long to go down than to come up.

Diamond press-up

• This is similar to the standard press-up, but you bring your hands together and form a diamond shape with your index fingers and thumbs, which puts more emphasis on the triceps as you perform the exercise,” says Breckenridge.
• Make sure you keep your elbows close to your sides as you drop down and push back up – this will ensure you are hitting your triceps as hard as possible.

Barbell/EZ-bar French press

• The French press is an important exercise for the long head of the triceps,” says Martin, “but if done incorrectly it can place a huge amount of stress on the elbow joint.
• Set a bench on a high incline (90° or a notch shy of). Hold the bar overhead with a narrow grip and your elbows facing forwards. Bend at the elbows, then allow the weight of the bar to pull your arms back until your forearms are next to your head. Then drag your elbows forwards while pressing the bar back up to the start position. Use a controlled motion throughout and make sure your elbows don’t flare during the movement. To help keep tension in the muscles, don’t fully lock the elbows at the top.”

Lying dumbbell triceps extension

• Many gym-goers place an undue amount of stress on their elbow joints,” says Martin, “so if you’re going to do triceps extensions of any kind where you flex the elbow, dumbbells are preferable because they allow a greater range of movement. Lying on a flat bench, press two dumbbells above your head with your elbows facing forwards.
• Lower the dumbbells towards your shoulders by flexing at the elbow. Once there, return to the start by contracting your triceps and extending your elbows until the dumbbells are back overhead. Don’t fully lock the elbows at the top so that you maintain tension in the muscles.”

L-sit

• This classic core-buster is also tough on the arms – you may well find you can’t get airborne for the L-sit if your abs are willing but your triceps are weak. Sit with your legs outstretched in front of you and your palms pressed into the floor by your sides. Maintaining that seated position, push yourself off the floor and hold for as long as you can.

Skullcrusher

• Hold a weight above your head, then bring it closer to your head. Yep, we’ll file this one under “advanced”. As simple as it sounds, it’s not for beginners.
• Lie on your back on a flat bench holding two dumbbells with your arms extended straight up and palms facing. For (hopefully) obvious reasons, choose a light weight while you familiarise yourself with the form and demands of the move.
• Keeping your upper arms stationary throughout, bend at your elbows to slowly lower the weights under control towards your forehead, then use your triceps to raise the dumbbells back to the start. You can use an EZ-bar or a barbell, but there’s a greater chance of losing control with these, so only consider them once you’ve truly mastered the dumbbell version.

Clap press-up

• This variation is a great way to build explosive power in your triceps. If you love to prove the haters wrong, the sound of the solitary slow hand-clap you’re giving yourself may spur you on to go the extra mile. Start in the standard top press-up position with your core braced. Lower your chest towards the ground, then push up explosively. As your body comes up, bring your hands off the ground and clap them together, then place them down again before your face hits the floor.

REferences