Cuneate nucleus

About: Cuneate nucleus is a research topic. Over the lifetime, 614 publications have been published within this topic receiving 24859 citations. The topic is also known as: cuneate nucleus of spinal cord.

Central projections of the rat radial nerve investigated with transganglionic degeneration and transganglionic transport of horseradish peroxidase.

Abstract: Transganglionic degeneration and transganglionic transport of HRP were used for investigation of the spinal cord and brainstem projections from the superficial, cutaneous (SR) and deep, muscular (DR) branches of the radial nerve. The HRP study included a numerical and size analysis of labelled dorsal root ganglion (DRG) cells. In degeneration experiments the SR nerve was found to project somatotopically to laminae III–IV, but degeneration was also found in lamina I and inconsistently in lamina II. Transection of the DR nerve was found to give rise to a small amount of degeneration, which in “sham” operations was established to result from the skin injury during dissection of the DR nerve. With the HRP method, the SR nerve was found to project somatotopically to laminae I–IV, whereas the DR nerve projected more diffusely to the medial part of laminae V–VII. HRP application to the SR and DR nerves resulted in labelling of a mean of 1,024 and 310 DRG cells, respectively. These labelled neurons had a median cell area of 381 and 562 μm2 for the SR and DR nerves, respectively, and both small and large cells were labelled in both types of experiments. In the lower brainstem, projections from the SR nerve were found only in the ipsilateral dorsal part of the main cuneate nucleus (MCN) with both methods. Brainstem projections from the DR nerve that were found only with the HRP method were found in the ipsilateral ventral part of the MCN together with a projection to the ipsilateral external cuneate nucleus. No projections were found to the central cervical nucleus. The present results indicate that cutaneous compared to muscular primary sensory neurons are much more prone to react with transganglionic degeneration after peripheral nerve transection. Furthermore, in the rat the SR nerve projects somatotopically, whereas the DR nerve does not. Both nerve branches are connected to small and large spinal ganglion cells, although the median cell area is larger in muscular neurons.

Patterns of primary afferent termination in the external cuneate nucleus from cervical axial muscles in the cat.

Abstract: Using the method of transganglionic transport of horseradish peroxidase (HRP), the distribution of primary afferent projections was examined in the external cuneate nucleus (ECN) from different muscle groups in the forequarter of the cat. The terminal zones of afferent fibers from three shoulder muscles--clavotrapezius, acromiotrapezius, and spinotrapezius--were compared to projections from suboccipital muscles, dorsal neck extensors, and muscles of the proximal forelimb. Each muscle group had a labelled terminal zone that occupied a different subvolume of the ECN. The zone labelled from trapezius muscles formed a continuous column in the ECN running from the caudal pole of the nucleus to a level 3.0 mm rostral to the obex. Terminal zones of suboccipital muscles and dorsal neck extensors formed longer columns that extended into the most rostral tip of the ECN, while those of proximal forelimb muscles formed shorter columns confined to the caudal two-thirds of the ECN. At comparable cross-sectional levels in the caudal and middle portions of the ECN, terminal zones from proximal limb muscles were located most dorsomedially, while those from shoulder muscles, dorsal neck muscles, and suboccipital muscles were located in progressively more ventral and lateral regions. The subvolume of the ECN occupied by projections from cervical axial muscles was estimated to be more than 40% of the volume of the nucleus, suggesting that the ECN has a major role in the transmission of sensory information from axial musculature to the cerebellum. Following exposure of all muscle nerves to tracer, a second labelled zone was also identified close to the ECN in the descending vestibular nucleus at transverse levels 2.0-3.0 mm rostral to the obex. Here, reaction product was concentrated around a circumscribed collection of medium-sized, multipolar cells.

Distribution of external cuneate nucleus afferents to the cerebellum: I. Notes on the projections from the main cuneate and other adjacent nuclei. An experimental study with radioactive tracers in the cat

Abstract: Transport of radioactive leucine was used to demonstrate cerebellar projections from the external cuneate nucleus (NCE) and from adjacent portions of the main cuneate nucleus (NC), of the spinal trigeminal nucleus (N.tr.sp.V) and of the vestibular nuclei. Projections from NCE and NC in part terminate over exclusive regions and in part overlap. After injections limited to NCE, labeling is found in all regions of the anterior lobe and lobule VI, in vermal lobules VII, VIII, and IX, and in medial regions of central folia of the paramedian lobule. Afferents from NC are observed in intermediate and lateral regions of lobules IV-VI, in lobules VIII and IX, in medial portions of crura I and II, and in lateral parts of central folia of the paramedian lobule as well as in its rostral folia. Afferents from N.tr.sp.V are distributed in lateral regions of lobules II-VI, in the rostral folium of lobule IX, in medial parts of crura I and II, and in rostral folia of the paramedian lobule. Afferents from the vestibular nuclei are present in vermal lobules VII, IX, and X and in the paramedian lobule. Projections from NCE are bilateral with ipsilateral predominance, whereas those from NC and N.tr.sp.V are ipsilateral. Projections from NCE are generally much denser than those from the other nuclei. Throughout the projection area, afferents from NCE are distributed in greater amounts in folia close to the medullary core and are much less dense near the surface. Afferents from the other nuclei do not show surface-to-depth density differences.