Muscle Architecture of Leg Muscles: Functional and Clinical Significance.

Area of Science:

• Biomechanics and musculoskeletal modeling.
• Human anatomy and functional morphology.

Background:

• Muscle architectural properties are key predictors of functional capacity and force generation.
• Accurate data is vital for musculoskeletal modeling and selecting muscle-tendon units for tendon transfers.
• A significant lack of cadaveric data exists for leg muscle architecture.

Purpose of the Study:

• To investigate the gross architecture and specific fiber arrangements of human lower limb muscles.
• To measure key architectural properties including muscle weight, fiber length, and pennation angle.
• To calculate derived properties like normalized fiber length and physiological cross-sectional area (PCSA).

Main Methods:

• Sixty muscles from the anterior and lateral compartments of twelve lower limbs were analyzed.
• Gross architecture, fiber arrangements, muscle weight, muscle length, fiber length, pennation angle, and sarcomere length were measured.
• Derived metrics including normalized fiber length, FL/ML ratio, and PCSA were calculated.

Main Results:

• Muscles exhibited mixed fusiform and pennate architectural strategies.
• Tibialis anterior and peroneus longus were the heaviest, with extensive fascial origins.
• Extensor compartment muscles featured long fiber lengths and low pennation angles, suggesting suitability for excursion.

Conclusions:

• Human foot arching and eversion are linked to the greater muscle weight and PCSA of tibialis anterior and peroneus longus.
• Long fiber length and low pennation in extensor muscles are adapted for excursion.
• This research provides essential normative data for biomechanical modeling and tendon transfer applications.