Springer Nature is making Coronavirus research free. View research | View latest news | Sign up for updates

Functionally complex muscles of the cat hindlimb

III. Differential activation within biceps femoris during postural perturbations

  • 90 Accesses

  • 69 Citations


The biceps femoris (BF) muscle is divided into three neuromuscular compartments defined by the innervation patterns of the main nerve branches (English and Weeks 1987). The goals of this study were i) to determine how different regions of the biceps femoris muscle are activated in the intact cat during a broad range of limb movements evoked by perturbations of stance posture, and ii) to determine the relationship between the anatomical compartments of biceps femoris and the functional units as defined in this task. Cats were trained to stand on a moveable platform with each paw on a triaxial force plate. The animal's stance was perturbed by linear translation of the platform in each of sixteen different directions in the horizontal plane. EMG activity was recorded from eight sites across the width of the left biceps femoris muscle. During quiet stance only the anterior compartment was tonically active, presumably contributing to hip extensor torque in the maintenance of stance. During platform translation, evoked EMG activity was recorded from each electrode pair for a wide range of directions of perturbation; as direction changed progressively, the amplitude of evoked activity from any electrode pair increased to a maximum and then decreased. When the EMG amplitude was plotted in polar coordinates as a function of translation direction, the region of response formed a petal shaped area in the horizontal plane, termed the EMG tuning curve. The compartments of the BF muscle were not activated homogeneously. The tuning curve of the anterior BF compartment was similar to that of other hip extensors, and coincided with the region of postero-lateral force production by the hindlimb against the support. The tuning curve of the middle BF compartment was shifted in a counterclockwise direction from that of the anterior compartment, but overlapped extensively with it; the middle BF tuning curve was similar to that of anterior gracilis. The tuning curve of the posterior biceps compartment was rotated further counterclockwise and overlapped very little with that of the middle BF compartment. The posterior BF was activated in a pattern similar to that of other knee flexors. The functional units of BF activation were not identical with the neuromuscular compartments defined by the main nerve branches. As direction of the perturbation changed, the region of BF that was activated moved progressively across the muscle. This progression of the active region was continuous across BFa and BFm, whereas there was a jump, or discontinuity at the border between BFm and BFp. Thus, differences in activation were observed not only across compartments, but also within compartments, and different regions of the BF muscle were activated independently during responses to postural perturbations.

This is a preview of subscription content, log in to check access.


  1. Bailee-Gordon RJ, Thompson WJ (1988) The organization and development of compartmentalized innervation in rat extensor digitorum longus muscle. J Physiol 398:211–231

  2. Botterman BR, Hamm TM, Reinking RM, Stuart DG (1983) Localization of monosynaptic Ia excitatory post-synaptic potentials in the motor nucleus of the cat biceps femoris muscle. J Physiol 338:355–377

  3. Chanaud CM, Macpherson JM (1987) Independent activation of compartments of feline biceps femoris during postural responses to translations of the support surface. Neuroscience Abstr 13:370

  4. Chanaud CM, Pratt CA, Loeb GE (1991a) Functionally complex muscles of the cat hindlimb. II. Mechanical and architectural heterogeneity within a parallel-fibered muscle. Exp Brain Res 85:257–270

  5. Chanaud CM, Pratt CA, Loeb GE (1991b) Functionally complex muscles of the cat hindlimb. V. The roles of histochemical fiber-type regionalization and mechanical heterogeneity in differential muscle activation. Exp Brain Res 85:300–313

  6. Eccles RM, Lundberg A (1958) Integrative pattern of Ia synaptic actions on motoneurons of hip and knee muscles. J Physiol 144:271–298

  7. Ellaway PH (1978) Cumulative sum technique and its application to the analysis of peristimulus time histograms. Electroenceph Clin Neurophysiol 45:302–304

  8. Engberg I, Lundberg A (1969) An electromyographic analysis of muscular activity in the hindlimb of the cat during unrestrained locomotion. Acta Physiol Scand 75:614–630

  9. English AW, Letbetter WD (1981) Intramuscular “compartmentalization” of the cat biceps femoris and semitendinosus muscles: anatomy and EMG patterns. Neuroscience Abstr 7:557

  10. English AW, Weeks OI (1987) An anatomical and functional analysis of cat biceps femoris and semitendinosus muscles. J Morphol 91:161–175

  11. Hammond CGM (1987) Motor-unit territories supplied by primary branches of the phrenic nerve: an electromyographic study of the cat diaphragm. Master's thesis. Queen's University, Kingston, Ontario

  12. Henneman E, Mendell JM (1981) Functional organization of motoneuron pool and its inputs. In: Handbook of physiology: the nervous system, Vol 2, Chapt 11, Am Physiol Soc, Bethesda, MD, pp 423–507

  13. Hoffer JA, Loeb GE (1980) Implantable electrical and mechanical interfaces with nerve and muscle. Ann Biomed Eng 8:351–360

  14. Letbetter WD (1974) Influence of intramuscular nerve branching on motor unit organization in medial gastrocnemius muscle. Anat Rec 178:402

  15. Loeb GE, Gans C (1986) Electromyography for experimentalists. University of Chicago Press, Chicago

  16. Lywood DW, Adams DJ, van Eyken A, Macpherson JM (1987) Small, triaxial force plate. Med Biol Eng Comput 25:698–701

  17. Macpherson JM (1988a) Strategies that simplify the control of quadrupedal stance. 1. Forces at the ground. J Neurophysiol 60:204–217

  18. Macpherson JM (1988b) Strategies that simplify the control of quadrupedal stance. 2. Electromyographic activity. J Neurophysiol 60:218–231

  19. Macpherson JM, Craig LS (1986) Postural responses in cats to movements of the support surface in the horizontal plane: comparison of lateral and longitudinal displacements. Neuroscience Abstr 12:1300

  20. Macpherson JM, Lywood DW, van Eyken A (1987) A system for the analysis of posture and stance in quadrupeds. J Neurosci Meth 20:73–82

  21. Pratt CA, Chanaud CM, Loeb GE (1991) Functionally complex muscles of the cat hindlimb. IV. Intramuscular distribution of central inputs and cutaneous reflexes in broad, bifunctional thigh muscles. Exp Brain Res 85:281–299

  22. Pratt CA, Loeb GE (1991) Functionally complex muscles of the cat hindlimb. I. Patterns of activation across sartorius. Exp Brain Res 85:243–256

  23. Richmond FJR, MacGillis DRR, Scott DA (1985) Muscle-fiber compartmentalization in cat splenius muscles. J Neurophysiol 53:868–885

  24. Rushmer DS, Russell CJ, Macpherson J, Phillips JO, Dunbar DC (1983) Automatic postural responses in the cat: responses to headward and tailward translation. Exp Brain Res 50:45–61

  25. van Eyken A, Perlin S, Lywood DW, Macpherson JM (1987) Robotic force platform for the study of posture and stance in the quadruped. Med Biol Eng Comput 25:693–697

  26. van Ingen Schenau GJ (1989) From rotation to translation: constraints on multi-joint movements and the unique action of bi-articular muscles. Hum Mov Sci 8:301–337

Download references

Author information

Additional information

Offprint requests to: G.E. Loeb, Biomedical Engineering, Abramsky Hall, Queen's University, Kingston, Ontario K7L 3N6, Canada

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Chanaud, C.M., Macpherson, J.M. Functionally complex muscles of the cat hindlimb. Exp Brain Res 85, 271–280 (1991).

Download citation

Key words

  • Biceps femoris
  • Muscles Posture
  • Stance
  • Kinesiology
  • Electromyography
  • Differential
  • Cat