Physiological properties of muscle spindles in dorsal neck muscles of the cat

Abstract

1. Single-fiber recording was used to examine the properties of 107 spindle endings in cat biventer cervicis (BC) and complexus (CM) muscles. Responses of receptors were examined following muscle contraction and ramp and hold stretch. Twenty-two endings in splenius (SP) were also examined, but their responses could not be quantitated because the anatomy of SP prevented the application of appropriate stretches. 2. Conduction velocitites of spindle afferents ranged from 13 to 90 m/s. Endings with primary response patterns usually had faster conduction velocities than secondary endings, but there was overlap in the conduction velocity ranges of the two subgroups. 3. Most neck spindle afferents could be classified as either primary or secondary by a constellation of physiological criteria including dynamic response pattern, dynamic index, and variability of resting discharge frequency. However, 22 of 107 endings from BC and CM had responses with characteristics intermediate between primary and secondary responses. The possible sources of these characteristics are discussed. 4. Despite the similarity in properties between spindles of different neck muscles, the length sensitivities of CM spindles were high compared to those of BC spindles. CM spindles showed length-related modulation of firing frequency over a more restricted range of initial muscle lengths than did BC spindles. 5. Eight Golgi tendon organs (GTO) were identified by their characteristics responses. Conduction velocities obtained for five GTO afferent nerves ranged from 50 to 67 m/s. Recordings were also made from receptros in deep muscles surrounding the vertebrae. These receptors had properties characteristic of muscle spindles.

The mammalian muscle spindle and its central control

“…In neck muscles the fraction of such bags spindles is much higher Richmond 1981, 1982;A brahams 1981). Interestingly, in these muscles a higher-than-normal proportion of afferents with intermediate dynamic response characteristics has also been found (Richmond and Abrahams 1979a). These muscles might therefore provide useful preparations for combined anatomofunctional studies on the contribution of bag~ and chain fibres to different components of the Ia response.…”

“…There is considerable scatter in the relationship between axonal conduction velocity and dynamic response (Matthews 1963;Koeze 1968Koeze , 1973a Cheney and Preston 1976a), which is partly due to the existence of spindle afferents with intermediate response properties (Rack and Westbury 1966;Browne 1975;Dutia 1980;Inoue et al 1981 (Richmond and Abrahams 1979a;Abrahams 1981). Differences in size of locally effective stretch may further account for some of the scatter at issue (Meyer-Lohmann et al 1974;Windhorst et al 1975Windhorst et al , 1976Banks et al 1981b).…”

Dissociating Self-Generated from Passively Applied Head Motion: Neural Mechanisms in the Vestibular Nuclei

“…2) to inhibit VO neurons during active head-on-body movements. During passive rotation of the body under a stationary head, the vestibular system is not activated, but, instead, neck proprioceptors are activated by the stretching of the neck musculature (e.g., Richmond and Abrahams, 1979;Kasper et al, 1989). Accordingly, VO neurons were recorded while the monkey's body was passively rotated beneath its earthstationary head and the monkey simultaneously generated neck torque to orient to targets (see Materials and Methods).…”

The Effects of Cervical Traction on the Soleus H Reflex in Stroke Patients.

“…An inhibitory effect was observed on the soleus H reflex with head rotation to the contralateral side, as well as a contrary effect with head rotation to the ipsilateral side 3) . This fact is compatible with a phenomenon called tonic neck reflex in which the receptors are neck muscle spindles, the joint receptors are at the upper cervical region [4][5][6][7] , and the pathway is propriospinal interneuron 8)9) . Accordingly, longitudinal cervical traction, which induces mechanical stimulation of the cervical region, is also expected to have an effect on the soleus H reflex.…”