The Atlas

All structures

• Adductor longus The most superficial adductor, and the one most often strained in sport.
• Adductor magnus The largest adductor, and a serious hip extensor that most people have never heard of.
• Anconeus A small triangular muscle at the back of the elbow, often described as a fourth head of the triceps.
• Ankle A hinge between the leg bones and the talus, which is more stable in some positions than others.
• Biceps brachii The famous arm muscle — which is a better supinator than it is a flexor, and does not touch the humerus at all.
• Biceps femoris The outer hamstring, and the muscle most often injured in sport — with two heads that do different jobs.
• Brachialis The real workhorse of elbow flexion, hidden underneath the muscle that gets the credit.
• Brachioradialis The muscle that makes the ridge on the thumb side of your forearm — an elbow flexor filed with the extensors.
• Coracobrachialis A small muscle in the armpit, sharing a tendon with the biceps and pierced by a nerve.
• Deltoid The triangular muscle capping the shoulder, whose three parts pull in three different directions.
• Diaphragm The dome of muscle that does most of your breathing, and quietly does a second job stiffening your trunk.
• Elbow Three joints in one capsule — a very good hinge with a rotation mechanism attached.
• Erector spinae muscles Three columns of muscle running the length of the back — the group that holds you upright.
• Extensor carpi radialis brevis The shorter radial wrist extensor, and the structure most often implicated in tennis elbow.
• Extensor carpi radialis longus One of the muscles that cocks the wrist back — and a large part of why you can grip hard at all.
• Extensor carpi ulnaris The wrist extensor on the little-finger side, running in its own groove in the ulna.
• Extensor digitorum The muscle that straightens your fingers — its tendons visible on the back of your hand.
• External oblique The outermost of the flat abdominal muscles, with fibres running the way your fingers point in your pockets.
• Fibularis brevis The shorter of the two everting muscles, attaching to the bony bump on the outer edge of your foot.
• Fibularis longus The muscle on the outside of the leg whose tendon crosses under the whole foot to attach on the other side.
• Flexor carpi radialis One of the two main wrist flexors, and the tendon your pulse is taken next to.
• Flexor carpi ulnaris The wrist flexor on the little-finger side, and the strongest of them.
• Flexor digitorum profundus The only muscle that can bend your fingertips — and the reason your fingers do not move fully independently.
• Flexor digitorum superficialis One of the two big finger flexors — the one that bends the middle knuckle, with tendons that split to let the other through.
• Gastrocnemius The visible calf muscle — two heads crossing both the knee and the ankle, which is why a bent knee switches it off.
• Gluteus maximus The largest single muscle in the body, built for forceful hip extension — and largely off duty when you are just walking.
• Gluteus medius The muscle that stops your pelvis dropping every time you stand on one leg — which is most of walking.
• Gluteus minimus The smallest and deepest of the three glutes, doing much the same job as gluteus medius from underneath it.
• Gracilis The thin, superficial adductor and the only one that reaches past the knee.
• Hip The other ball-and-socket joint — and the one that made the opposite trade from the shoulder.
• Iliacus The pelvic half of the iliopsoas — a fan of muscle lining the inside of your hip bone.
• Iliopsoas The strongest hip flexor, and the only muscle that connects your spine directly to your leg.
• Infraspinatus The main external rotator of the shoulder, and the largest of the four cuff muscles.
• Internal oblique The middle layer of the abdominal wall, with fibres running at right angles to the muscle above it.
• Intervertebral The joint between two vertebral bodies, made of a disc — and the disc is not a cushion that slips.
• Knee The largest joint in the body — a hinge that also rotates, held together almost entirely by ligament.
• Latissimus dorsi The broadest muscle in the body, running from your lower back to the front of your upper arm.
• Levator scapulae A twisted strap from the neck to the top corner of the shoulder blade, doing exactly what its name says.
• Multifidus A deep chain of short muscles bridging a few vertebrae at a time — thickest in the lower back.
• Palmaris longus The forearm muscle a large minority of people simply do not have — and nobody misses.
• Pectineus A short flat muscle at the very top of the inner thigh, doing hip flexion and adduction in equal measure.
• Pectoralis major The large fan across the front of the chest, with two heads that pull the arm in opposite vertical directions.
• Pectoralis minor A small muscle under the pec that pulls on the shoulder blade, not the arm — and carries a large amount of posture folklore.
• Piriformis A small deep rotator with an outsized reputation, because the sciatic nerve passes right by it.
• Plantaris A tiny muscle with an absurdly long tendon, absent in a good number of people, and doing almost nothing in the rest.
• Popliteus A small muscle behind the knee whose job is unlocking it — the only muscle that has to fire before you can bend your leg.
• Pronator quadratus A small square muscle just above the wrist that is the primary pronator, despite pronator teres getting the name recognition.
• Pronator teres The upper of the two muscles that turn your palm downward, with the median nerve running between its heads.
• Psoas major The spinal half of the iliopsoas, and the only muscle joining the spine to the leg.
• Quadratus lumborum A deep quadrilateral muscle between the pelvis and the last rib, and the main side-bender of the lower back.
• Quadriceps femoris The four-headed muscle group at the front of the thigh, and the largest muscle mass in the body.
• Rectus abdominis The abdominal muscle everyone means by "abs" — and the segments are tendon, not muscle.
• Rectus femoris The only one of the four quadriceps that crosses the hip, which changes everything about how it behaves.
• Rhomboid major A flat sheet between the spine and the shoulder blade that pulls the blade inward and slightly up.
• Rhomboid minor The smaller upper rhomboid, frequently indistinguishable from the larger one beneath it.
• Rotatores muscles The deepest and shortest spinal muscles — and probably position sensors more than movers.
• Sacroiliac The joint between the sacrum and the pelvis — built for transferring load, not for moving.
• Sartorius The longest muscle in the body — a thin strap spiralling across the thigh, named after tailors.
• Scalenus anterior The front scalene, a landmark muscle with the nerves of the arm passing right behind it.
• Scalenus medius The largest and longest of the three scalenes, forming the back wall of the gap the arm's nerves pass through.
• Semimembranosus The deepest and broadest hamstring, named for the flat membrane-like tendon it starts from.
• Semitendinosus The inner hamstring with the very long tendon — half muscle, half cord, as its name says.
• Serratus anterior The muscle that holds your shoulder blade against your ribcage, and rotates it so you can reach overhead.
• Shoulder The most mobile joint in the body, and mobile precisely because it gives up bony stability to get there.
• Soleus The deep calf muscle that does not cross the knee — and the one holding you upright all day.
• Splenius capitis A flat bandage-like muscle wrapping the back of the neck, rotating the head to its own side.
• Splenius cervicis The lower half of the splenius pair, attaching to the neck vertebrae rather than the skull.
• Sternocleidomastoid The prominent strap down the side of the neck, whose name is simply a list of its attachments.
• Subscapularis The only rotator cuff muscle on the front of the shoulder blade, and the only one that rotates inward.
• Subtalar The joint beneath the talus that turns the sole in and out — and does the work usually credited to the ankle.
• Supinator The muscle that wraps around the top of the radius to turn your palm up — with a nerve running through it.
• Supraspinatus The rotator cuff muscle that starts the arm moving sideways — and the one most often torn.
• Tensor fasciae latae A small muscle at the front of the hip that pulls on the IT band — and is not the same thing as the IT band.
• Teres major Not a rotator cuff muscle, despite its position and its name — it is effectively a small partner to latissimus dorsi.
• Teres minor The smallest rotator cuff muscle, working alongside infraspinatus and easily confused with its larger namesake.
• Tibialis anterior The muscle on the front of your shin that lifts your foot — and stops you tripping over it.
• Tibialis posterior The deepest muscle of the calf, and the main dynamic support of the arch of the foot.
• Transversus abdominis The deepest abdominal muscle, wrapping horizontally like a belt — and the subject of a training idea that did not survive scrutiny.
• Trapezius A huge diamond across the upper back whose three parts lift, pull back and pull down the shoulder blade — often at the same time.
• Triceps brachii The three-headed muscle at the back of the arm, and much the larger part of your upper arm's mass.
• Triceps surae The calf, properly named — two muscles and three heads sharing the thickest tendon in the body.
• Vastus intermedius The quadriceps head you will never see, lying directly on the femur beneath the other three.
• Vastus lateralis The largest of the four quadriceps, forming the outer sweep of the thigh.
• Vastus medialis The inner quadriceps, and the subject of the most durable disputed claim in lower-limb training.
• Wrist The radiocarpal joint — where the radius alone meets the hand, with the ulna deliberately kept out of it.
• Zygapophysial The facet joints — small paired joints at the back of the spine that decide which way each segment can move.