MUSCLE OF THE DAY: “Pectoralis Major”

Show Up Fitness – Where Great Trainers Are Made

Learn more about becoming a personal trainer HERE.

The pectoralis major is one muscle with three parts located on the anterior surface of the thoracic cage. If you're a gym lover, you'll hear these muscles also being referred to as the pecs, #chesticles, and every bro in the world hits the pecs on, “International Chest Day”! The pectoralis major has a broad origin and is divided into three parts: clavicular (upper), sternal (middle) and costal region (lower) aka block region.

Origin (proximal attachment): Clavicular part: anterior surface of medial half of clavicle. Sternocostal part: anterior surface of sternum and costal cartilages of ribs 1-6. Abdominal part: anterior layer of rectus sheath.

Insertion (distal attachment): Crest of greater tubercle of humerus.

Actions: As a whole, humeral horizontal adduction, adduction, and internal rotation. Acting independently, the clavicular part helps to flex shoulder up to 90 degrees and the sternocostal part helps with shoulder extension. Draws scapula anteriorinferiorly (forward and down).

Common Injuries to the Pec Major

The pectoralis major tendon is most commonly injured during an eccentric contraction, when the external force on the muscle is greater than the force that the muscle can generate and when the arm is extended and externally rotated, like when performing a bench press. Bench pressing is the most common cause of injury (specifically incline due to the greater stress on the AC-joint). Pectoralis major injuries typically occur in men aged 20 to 40. The injury can result in pain in the chest and upper arm and weakness/deformity of the chest and upper arm. Read more on how to help fix your chest injuries from our partners at The Prehab Guys HERE.

BECOME A TRAINER AT SHOW UP FITNESS, ENROLL ONLINE TODAY!!!

If you want to become a personal trainer, Show Up Fitness has the nation's best personal training internship program that you can complete within 2-months. Whether if your NASM, NSCA, ACSM or whatever lucky certification acronym you have, our internship program is for you! Our classes are for certified personal trainers, fitness enthusiasts, and aspiring trainers who need to gain experience, learn in-depth anatomy, nutrition, sales, how to grow your social media following, and designing programming. Over 80% of trainers who get certified (usually by NASM, ACE, or ISSA), invest too much money and then quit within 12-months because they have no idea how to train and'or maintain/grow their book of business. Now that SHOW UP FITNESS is online, you can take classes at showupfitness.com , learn for 1-2 months and then SHOW UP for the in-person internship in San Diego, Los Angeles and NOW Santa Monica. We have 12-month payment plans for as little as $200/month.