Summary
The cat sartorius (SA) can be divided functionally into an anterior (SAa), knee extensor portion and a medial (SAm), knee flexor portion; it can be further subdivided anatomically by multiple nerve branches into parallel longitudinal columns that terminate in a distributed insertion at the knee with a continuous range of moment arms. Thus, SA may be controlled by a discrete number of motoneuron task groups reflecting a small number of central command signals or by a continuum of activation patterns associated with a continuum of moment arms. To resolve this question, the activation patterns across the width of the SA were recorded with an electrode array during three kinematically different movements — treadmill locomotion, scratching and paw shaking, in awake, unrestrained cats. Uniformity of activation along the longitudinal axis was also examined because individual muscle fibers do not extend the length of the SA. In addition, the cutaneous reflex responses were recorded throughout all regions of the SA during locomotion. Two fascial surface-patch arrays, each carrying 4–8 pairs of bipolar EMG electrodes, were sutured to the inner surface of the SA, one placed proximally and the other more distally. Each array sampled separate sites across the anterior to medial axis of SA. During locomotion, two basic EMG patterns were observed: the two burst-per-step-cycle pattern typical of SAa and the single burst pattern typical of SAm. There was an abrupt transition in the pattern of activation recorded in the two parts of SA during locomotion, and no continuum in the activation pattern was observed. Stimulation of both sural and saphenous cutaneous nerves during locomotion produced reflex responses that were uniformly distributed throughout SA, in contrast to the regional differences noted during unperturbed walking. Similarly, during scratching and paw shaking all parts of the SA were active simultaneously but with regional differences in EMG amplitude. The abrupt functional border between SAa and SAm coincided with the division of the SA into a knee flexor vs. a knee extensor. In all cases, the quantitative and qualitative differences in SAa and SAm EMGs were uniformly recorded throughout the entire extent of SAa or SAm; i.e., there was no segregation of activity within either SAa or SAm. Furthermore, the time course of EMG from each proximal recording site was nearly identical to the corresponding distal site, indicating no segregation of function along the longitudinal axis of SA. These results indicate that SAa and SAm constitute the smallest functional modules that can be recruited in SA. The functional subdivision of the SA motor nucleus is reflected in the central pattern generators for these movements to permit a task-dependent recruitment of any combination of SAa and SAm. Our data indicate that the number of task groups even in an anatomically and functionally complex muscle like the SA is small and appears to be related to the kinematic conditions under which the muscle operates.
Similar content being viewed by others
References
Abraham LD, Loeb GE (1985) The distal musculature of the cat: patterns of normal use. Exp Brain Res 58:580–593
Abraham LD, Marks WM, Loeb GE (1985) The distal hindlimb musculature of the cat: cutaneous reflexes during locomotion. Exp Brain Res 58:594–603
Andersson O, Forssberg H, Grillner S, Lindquist M (1978) Phasic gain control of the transmission in cutaneous reflex pathways to motoneurones during “fictive” locomotion. Brain Res 149:503–507
Bak MJ, Loeb GE (1979) A pulsed integrator for EMG analysis. Electroencephalogr. Clin Neurophysiol 47:738–741
Bernstein N (1967) The coordination and regulation of movement. Pergamon, New York
Bodine S, Roy RR, Meadows DA, Zernicke RF, Sacks RD, Fournier M, Edgerton R (1982) Architectural, histochemical, and contractile characteristics of a unique biarticular muscle: the cat semitendinosus. J Neurophysiol 48:192–201
Burke RE (1990) Selective recruitment of motor units. In: Humphrey DR, Freund H-J (eds) What are the output units of motor behavior and how are they controlled? Dahlem Konferenzen. John Wiley & Sons, LTD, Chichester (in press)
Carlson Kuhta P, Smith JL (1990) Scratch responses in normal cats: hindlimb kinematics and muscle synergies. J Neurophysiol 64:1653–1667
Carter MC, Smith JL (1986) Simultaneous control of two rhythmical behaviors. I. Locomotion with paw-shake response in normal cat. J Neurophysiol 56:171–183
Chanaud CM, Macpherson JA (1991) Functionally complex muscles of the cat hindlimb. III. Differential activation within biceps femoris during postural perturbations. Exp Brain Res 85:271–280
Chanaud CM, Pratt CA, Loeb, GE (1991a) Functionally complex muscles of the cat hindlimb. II. Mechanical and architectural heterogeneity within the biceps femoris. Exp Brain Res 85:257–270
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
Desmedt JE, Godaux E (1981) Spinal motoneuron recruitment in man: rank deordering with direction but not with speed of voluntary movement. Science 214:933–936
Duysens J, Loeb GE (1980) Modulation of ipsi- and contralateral reflex responses in unrestrained walking cats. J Neurophysiol 44:1024–1037
Eccles RM, Lundberg A (1958) Integrative pattern of Ia synaptic action on motoneurones of hip and knee muscles. J Physiol (Lond) 144:271–298
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
English AW, Letbetter WD (1982) Anatomy and innervation patterns of cat lateral gastrocnemius and plantaris muscles. Am J Anat 164:67–77
English AW, Weeks O (1984) Compartmentalization of single muscle units in cat lateral gastrocnemius. Exp Brain Res 56:361–368
English AW, Weeks O (1987) An anatomical and functional analysis of cat biceps femoris and semitendinosus muscles. J Morph 191:161–175
Forssberg H (1979) Stumbling corrective reaction: a phase-dependent compensatory reaction during locomotion. J Neurophysiol 42:936–953
Gordon DC, Loeb GE, Richmond FJR (1991) Distribution of motoneurons supplying cat sartorius and tensor fasciae latae, demonstrated by retrograde multiple-labelling methods. J Comp Neurol 304:357–372
Henneman E, Mendell LM (1981) Functional organization of the motoneuron pool and its inputs. In: Brooks VB (ed) Handbook of physiology, Sect. I. The nervous system. Vol II, Part 1. American Physiological Society, Washington DC pp:423–507
Hoffer JA, Loeb GE, O'Donovan MJ, Pratt CA (1980) Unitary activity patterns during walking confirm the existence of two functionally distinct classes of sartorius motoneurones in cats. J Physiol (Lond) 308:20P
Hofler JA, O'Donovan MJ, Pratt CA, Loeb GE (1981) Discharge patterns of hindlimb motoneurons during normal cat locomotion. Science 216:466–468
Hoffer JA, Loeb GE, Marks WM, O'Donovan M, Pratt CA, Sugano N (1987a) Cat hindlimb motoneurons during locomotion. I. Destination, axonal conduction velocity and recruitment threshold. J Neurophysiol 57:510–529
Hoffer JA, Sugano N, Loeb GE, Marks WM, O'Donovan MJ, Pratt CA (1987b) Cat hindlimb motoneurons during locomotion, II. Normal activity patterns. J Neurophysiol 57:530–553
Hoffer JA, Sugano N, Loeb GE, Marks WM, O'Donovan MJ, Pratt CA (1987c) Cat hindlimb motoneurons during locomotion. III. Functional segregation in sartorius. J Neurophysiol 57:554–562
Hoy MG, Zernicke RF, Smith JL (1985) Contrasting roles of inertial and muscle moments at knee and ankle during pawshake response. J Neurophysiol 54:1282–1294
Levine WS (1986) Kinesiological modeling of the cat hindlimb musculature during locomotion. Final Report, NIH Contract #NO1-NS-3–2348, Univ. of Maryland, College park, MD 20734
Loeb GE (1985) Motoneurone task groups: coping with kinematic heterogeneity. J Exp Biol 115:137–146
Loeb GE (1990) The functional organization of muscles, motor units, and tasks. In: Binder MD, Mendell LM (eds) The segmental motor system. Oxford Univ Press, New York, pp 23–35
Loeb GE and Gans C (1986) Electromyography for experimentalists. The University of Chicago Press, Chicago, pp 66–67
Loeb GE, Hoffer JA, Pratt CA (1985a) Activity of spindle afferents from cat anterior thigh muscles. I. Identification and patterns during normal locomotion. J Neurophysiol 54:549–564
Loeb GE, Hoffer JA, Marks WM (1985b) Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli. J Neurophysiol 54:578–591
Loeb GE, Marks WB, Hoffer JA (1987a) Cat hindlimb motoneurons during locomotion. IV. Participation in cutaneous reflexes. J Neurophysiol 57:563–573
Loeb GE, Pratt CA, Chanaud CM, Richmond FJR (1987b) Distribution and innervation of short, interdigitated muscle fibers in parallel-fibered muscles of the cat hindlimb. J Morph 191:1–15
Loeb GE, Pratt CA, Marks WM (1984) Segregation of normal and reflex activity in the cat sartorius muscle. Soc Neurosci Abstr 10:629
Perret C, Cabelguen J-M (1980) Main characteristics of the hindlimb locomotor cycle in the decorticate cat with special reference to bifunctional muscles. Brain Res 187:333–352
Phillipson M (1905) L'autonomie et la centralisation dans le systeme nerveux des animaux. Trav Lab Physiol Inst Solvay, Bruxelles 7:1–208
Pratt CA, Yee WJ, Chanaud CM, Loeb GE (1984) Organization of the cat sartorius motoneuron pool. Soc Neurosci Abstr 10:629
Pratt CA, Chanaud CM, Loeb GE (1986) Single motor unit territories in the cat sartorius. Soc Neurosci Abstr 12:1083
Pratt CA, Chanaud CM, Loeb GE (1991) Functionally complex muscles of the cat hindlimb. IV. Intramuscular distribution of movement command signals and cutaneous reflexes in broad, bifunctional thigh muscles. Exp Brain Res 85:281–299
Romanes GJ (1953) The motor cell columns of the lumbo-sacral spinal cord of the cat. J Comp Neurol 94:313–363
Sherrington CS (1910) Flexion-reflex of the limb, crossed extension reflex, and reflex stepping and standing. J Physiol 40:28–121
Smith JL, Betts B, Edgerton VR, Zernicke RF (1980) Rapid ankle extension during paw shakes: selective recruitment of fast ankle extensors. J Neurophysiol 43:612–620
Smith JL, Hoy MG, Koshland GF, Phillips DM, Zernicke RF (1985) Intralimb coordination of the paw-shake response: a novel mixed synergy. J Neurophysiol 54:1271–1281
Smith JL, Zernicke RF (1987) Predictions for neural control based on limb dynamics. TINS 10:123–128
Ter Haar Romeny, Denier van der Gon BM, Gielen CC (1984) Relation between location of a motor unit in the human biceps brachii and its critical firing level for different tasks. Exp Neurol 85:631–650
Thomson DB, Scott SH, Richmond FJR, Loeb GE (1990) Complex motor unit architecture of anterior sartorius muscle in the cat. Abstr First World Congress of Biomechanics
Van Ingen Schenau GJ (1989) From rotation to translation: constraints on multi-joint movements and the unique action of bi-articular muscles. Human Movem Sci 8:301–337
Windhorst U, Hamm TM, Stuart DG (1989) On the function of muscle and reflex partitioning. Behav Brain Sci 12:629–681
Windhorst UR, Burke RE, Dieringer N, Evinger C, Feldman AG, Hasan Z, Hultborn HRA, Illert M, Lundberg AP, Macpherson JM, Massion J, Nichols TR, Schwarz HRM, Vilis T (1990) What are the output units of motor behavior and how are they controlled? In: Humphrey DR, Freund H-J (eds) Motor control: concepts and issues. Dahlem Konferenzen. John Wiley & Sons Ltd, Chichester
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pratt, C.A., Loeb, G.E. Functionally complex muscles of the cat hindlimb. Exp Brain Res 85, 243–256 (1991). https://doi.org/10.1007/BF00229404
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00229404