Major Muscles of the Body and Their Actions

Infraspinatus

Shoulder muscle involved in external rotation.

Trapezius

Upper back muscle controlling shoulder movement.

Deltoid

Shoulder muscle responsible for arm abduction.

Latissimus Dorsi

Back muscle aiding in arm extension and rotation.

Rhomboid Major

Muscle retracting the scapula towards the spine.

Levator Scapulae

Elevates the scapula and assists neck movement.

Supraspinatus

Shoulder muscle initiating arm abduction.

Platysma

Superficial neck muscle aiding in facial expressions.

Orbicularis Oris

Muscle encircling the mouth, controlling lip movement.

Orbicularis Oculi

Muscle encircling the eye, controlling eyelid movement.

Temporalis

Muscle involved in closing the jaw.

Epicranius

Muscle raising the eyebrows and wrinkling forehead.

Buccinator

Muscle compressing the cheek, aiding in chewing.

Sternocleidomastoid

Neck muscle rotating and flexing the head.

Zygomaticus

Muscle elevating the corners of the mouth.

Masseter

Jaw muscle primarily responsible for chewing.

Semispinalis Capitis

Muscle extending and rotating the head.

Splenius Capitis

Muscle extending and rotating the neck.

Rectus Abdominis

Abdominal muscle flexing the spine.

Transversus Abdominis

Deep abdominal muscle stabilizing the core.

External Obliques

Muscles aiding in trunk rotation and flexion.

Internal Obliques

Muscles assisting in trunk rotation and flexion.

Linea Alba

Fibrous structure separating abdominal muscles.

Levator Ani

Pelvic muscle supporting pelvic organs.

Ischiocavernosus

Muscle aiding in erection by compressing blood vessels.

Bulbospongiosus

Muscle assisting in sexual function and urination.

Superficial Transversus Perinei

Muscle stabilizing the perineal body.

Rectus Femoris

Quadriceps muscle extending the knee.

Sartorius

Longest muscle aiding in hip flexion and rotation.

Psoas Major

Hip flexor muscle connecting spine to femur.

Iliacus

Muscle assisting in hip flexion with psoas major.

Vastus Lateralis

Quadriceps muscle extending the knee.

Vastus Medialis

Quadriceps muscle stabilizing the patella.

Tensor Fasciae Latae

Muscle assisting in hip abduction and flexion.

Gracilis

Inner thigh muscle aiding in hip adduction.

Biceps Femoris

Hamstring muscle flexing the knee.

Semitendinosus

Hamstring muscle assisting in knee flexion.

Gluteus Maximus

Largest muscle aiding in hip extension.

Gluteus Medius

Muscle stabilizing the pelvis during walking.

Semimembranosus

Hamstring muscle aiding in knee flexion.

Gastrocnemius

Calf muscle responsible for plantarflexion.