karotisksinusafferenter

Karotisksinusafferenter, or carotid sinus afferents, are the sensory fibers that carry information from the carotid sinus to the brainstem. The carotid sinus is a small dilated area at the bifurcation of the common carotid artery that contains baroreceptors, which detect changes in arterial wall stretch associated with mean arterial pressure. The afferent fibers originate in the carotid sinus receptors and travel via the carotid sinus nerve (Hering’s nerve), a branch of the glossopharyngeal nerve (cranial nerve IX), to the glossopharyngeal sensory ganglia and onward to the nucleus tractus solitarius in the medulla.

Within the brainstem, second-order neurons in the nucleus tractus solitarius integrate baroreceptor input and influence autonomic output. The carotid sinus afferent pathway forms a key part of the baroreflex: when arterial pressure rises, increased firing of carotid sinus afferents leads to enhanced parasympathetic (vagal) activity and reduced sympathetic outflow. This produces a decrease in heart rate and a reduction in peripheral vascular resistance, helping to stabilize blood pressure. When arterial pressure falls, reduced afferent firing lowers parasympathetic tone and allows greater sympathetic activity, increasing heart rate and vascular resistance.

Clinical relevance includes carotid sinus hypersensitivity, which can cause syncope in some individuals, particularly the elderly. Carotid sinus massage, performed under clinical supervision, can be used in certain diagnostic and therapeutic contexts but carries risks in patients with carotid artery disease or vascular abnormalities.