From the Research
The human body has approximately 68 muscles in the upper limbs and 62 muscles in the lower limbs, totaling about 130 muscles across all four limbs. The upper limbs contain muscles that control the shoulder, arm, forearm, wrist, and hand movements, including major muscle groups like the deltoids, biceps, triceps, and the smaller intrinsic hand muscles. The lower limbs feature muscles controlling the hip, thigh, leg, ankle, and foot movements, including large muscle groups like the gluteals, quadriceps, hamstrings, and calf muscles. This muscle distribution reflects the different functional requirements of our limbs - upper limbs are specialized for precise manipulation and dexterity, while lower limbs are designed for weight-bearing, stability, and locomotion. Some key points to consider include:
- The exact muscle count may vary slightly among anatomical texts due to differences in classification and naming conventions, but this represents the standard anatomical understanding 1, 2, 3, 4, 5.
- Studies have shown that there is an association between the duration of daily muscle activity and the proportion of type I muscle fibers, with upper-limb muscles being active for 18% of the recording time, whereas leg muscles were active for only 10% of the recording time 3.
- Interlimb neural coupling affects muscle recruitment during maximal effort upper and lower limb rhythmic exercise, with neural coupling being primarily from active upper limb muscles to passive ipsilateral lower limb muscles 5.
- The use of muscle relaxants may vary for treatment of acute and chronic pain, with appropriate medication selection based on clinical indications being crucial 2, 4.