Muscle glossary
A–Z of the muscles we work with
Every muscle below links straight to our interactive 3D model with that muscle highlighted — click a name to see exactly where it sits and what surrounds it. A short plain-English note explains what each one does and why it matters.
Lower limb — hip, thigh, leg & foot
The largest, most superficial buttock muscle. Extends the hip to power standing up, climbing and sprinting; a very common site of tension.
On the side of the hip. Stabilises the pelvis every time you stand on one leg; weakness here often shows up as hip, knee or lower-back pain.
The deepest of the three glutes, beneath gluteus medius. Helps abduct and stabilise the hip.
A deep buttock rotator that runs close to the sciatic nerve. When tight it can mimic or contribute to sciatica (piriformis syndrome).
At the front of the hip. Tightens the IT band and helps flex and abduct the hip; frequently tight in runners and cyclists.
The thick fibrous band running down the outside of the thigh. Not a muscle, but a common source of outer-knee pain (‘runner’s knee’).
A deep hip flexor running from the lower spine to the thigh bone. Tightness affects posture and can pull on the lower back.
Sits inside the pelvis and joins psoas to flex the hip; together they are often called iliopsoas.
The central quadriceps muscle. Uniquely crosses both the hip and knee, so it flexes the hip and straightens the knee.
The teardrop-shaped inner quadriceps just above the knee; important for tracking the kneecap.
The longest muscle in the body, crossing the thigh like a sash. Flexes the hip and knee and turns the leg outward.
A prominent inner-thigh (groin) muscle that draws the leg inward; a frequent site of groin strains.
The largest inner-thigh muscle, powering hip adduction and assisting extension.
The outer hamstring (long and short heads). Bends the knee and extends the hip; commonly strained in sprinting.
The two-headed calf muscle you can see under the skin. Points the foot down and powers push-off in walking, running and jumping.
The flat, deep calf muscle beneath gastrocnemius. Built for endurance and posture; key for ankle plantarflexion when the knee is bent.
A small calf muscle with a very long thin tendon; often injured as ‘tennis leg’.
On the front of the shin. Lifts the foot and toes; overuse is a classic cause of shin splints.
A deep muscle that supports the arch of the foot and turns the sole inward.
On the outside of the lower leg. Turns the sole outward (eversion) and helps stabilise the ankle.
A shorter partner to fibularis longus, also everting and stabilising the ankle.
Runs down the front of the shin to lift the four smaller toes.
The strong tendon joining the calf muscles to the heel bone. The site of Achilles tendinopathy and one of the most-loaded tendons in the body.
The thick band along the sole of the foot. Inflammation here causes plantar fasciitis. (Tick ‘Show outer fascia’ to see it.)
Upper limb — shoulder, arm & forearm
The rounded cap of the shoulder. Its front, side and rear parts raise the arm forward, out to the side and backward.
The large fan-shaped chest muscle. Draws the arm across the body and forward; often tight with rounded-shoulder posture.
A small deep chest muscle that tilts the shoulder blade; tightness pulls the shoulder forward.
The large diamond over the neck and upper back. Shrugs and steadies the shoulder blade; the classic ‘stress-knot’ muscle.
The broad muscle of the mid-back. Pulls the arm down and back, as in a pull-up or rowing stroke.
Between the shoulder blades; squeezes them together. Aches with prolonged desk posture.
The smaller rhomboid just above major, also retracting the shoulder blade.
Runs from the neck to the top of the shoulder blade; lifts it and is a common source of neck tension.
Wraps around the ribs to the shoulder blade; holds it flat and helps you reach overhead.
A rotator-cuff muscle on top of the shoulder blade that starts lifting the arm; a frequent site of impingement.
The rotator-cuff muscle on the front of the shoulder blade; rotates the arm inward.
A small muscle at the front of the upper arm that helps flex the shoulder.
The front of the upper arm. Bends the elbow and turns the palm up (supination).
The back of the upper arm. Straightens the elbow; the main pushing muscle of the arm.
A forearm flexor that bends the wrist toward the little-finger side.
A wrist extensor on the thumb side; part of the ‘tennis elbow’ group.
A wrist extensor closely tied to tennis-elbow pain at the outer elbow.
Straightens the base of the thumb; part of the de Quervain’s area at the wrist.
Moves the thumb away from the palm; also part of the de Quervain’s group.
Hand & wrist
A thenar (thumb-base) muscle that moves the thumb away from the palm.
Brings the thumb across to touch the fingers (opposition) — key for grip.
Four small muscles that straighten the fingers while bending the knuckles — fine control for writing and gripping.
Anatomy models by the Open3D project (Kooloos, RadboudUMC, LUMC et al.), licensed CC BY-SA. Guidance here is general and educational, not a substitute for individual assessment.