Reflex is an involuntary, nearly instantaneous response to a stimulus. Occurs via neural pathways called reflex arcs. Neural signals travel from stimulus to synapse to motor neuron. Many reflexes don't travel to brain, requiring no conscious thought
Frisson is a psychophysiological response to rewarding stimuli like music. It induces pleasurable feelings and transient skin tingling or chills. Typically lasts only a few seconds. Can be triggered by music, poetry, videos, nature, and science
Motor neurons originate in motor cortex, brainstem or spinal cord. Upper motor neurons originate in cerebral cortex and travel to brain stem/spinal cord. Lower motor neurons originate in spinal cord and control muscles and glands
Medulla is a cone-shaped structure in lower brainstem, anterior to cerebellum. Divided into upper open and lower closed parts with fourth ventricle. Contains pyramidal tracts in medullary pyramids, which cross at decussation. Features olivary bodies in upper part and gracile/cuneate tubercles in posterior
Arm refers to the upper limb between shoulder and elbow joints. Distal part between elbow and wrist is forearm, beyond wrist is hand. Shoulder girdle and axilla are components of arm
Feet are universally highly sensitive to tickling. Thousands of nerve endings called Meissner's corpuscles are present. Skin on feet is tougher than most other body parts