The Intermedius nucleus of the medulla (InM) is a neurochemically diverse nucleus in the brainstem containing glutamatergic and GABAergic neurones which project to the nucleus of the solitary tract (Edwards et al. 2007). Neuronal tracing studies have identified the InM as a target of sensory afferents entering the CNS via the C1-C4 dorsal root ganglia (DRG, Neuhuber & Zenker (1989)). Stimulation of the C2 DRG at intensities which would activate Ia fibres has been shown to cause changes in sympathetic nerve activity and also in the activity of the hypoglossal and abdominal nerves (Bolton et al. 1998) suggesting that information from muscle spindles in the neck region could influence autonomic outflow. Here we provide evidence that cervical afferent inputs to the InM are of a muscle spindle origin and not targeted to a particular group of neurones therein. 5 μl 1% CTb (List) was injected into the C2 DRG of 3 adult male Wistar rats. After 3-7 days recovery time animals were perfused transcardially with 4% paraformaldehyde (PFA) under sodium pentobarbitone anaesthesia (60mg/kg, i.p.). Brainstem and cervical cord were removed and sectioned at 50μm and the CTb detected using immunohistochemistry. Using markers of muscle afferents, vesicular glutamate transporter 1 (VGluT1, Alvarez et al. (2004)) and parvalbumin (Arber et al. 2000), we investigated the origin of the CTb labelled terminals in the InM. 100% of CTb immunoreactive structures displayed immunoreactivity for both VGluT1 and parvalbumin (28/28 n=3). As all VGluT1 terminals contained parvalbumin VGluT1 immunoreactivity was used as a marker of neck muscle afferent terminals in the InM. When CTb was injected lower than C4 no terminals were observed in the InM (n=5). GAD65-GFP (n=3) and GAD67-GFP (n=3) mice were perfused transcardially with 4% PFA and their brainstems removed and cut at 50μm. Confocal microscopy was used to generate Z-stacks through individual neurones which were then used to determine the surface area and contact density of appositions on each neurone. 80% of GFP expressing neurones in the InM of GAD65-GFP mice and 70% in GAD67-GFP mice were seen to be closely apposed by VGluT1 immunoreactive terminals. Screening of wild type tissue co-stained for either parvalbumin, nNOS or calretinin; showed that 90, 95 and 80% of immunoreactive neurones were contacted respectively. The contact density of appositions on the membranes of all of the investigated groups of InM neurones fell between 0.45 and 0.65 contacts per 100μm² with no significant difference between any of the groups. As the putative neck muscle afferents shown to contact neurochemically diverse InM neurones it is likely that this information is used to generate many responses to alterations in position of the head. One possible avenue is the control of heart rate and blood pressure in response to postural changes, which could be mediated through the projections from the InM to the NTS.