Final Common Pathway

• FCP last leg of a motor signal’s journey
• Part of the lower motor neurons (LMNs)
• Involves:
• Cranial nerves in the case of speech
• Alpha motor neurons: innervate extrafusal muscle fibers involved in muscle contraction
• Gamma motor neurons: innervate intrafusal muscle fibers involved in proprioception

FCP and Speech

• The components of speech include:
• Respiration: power for speech
• Phonation: raw sound for speech
• Resonance: tonal qualities of speech
• Articulation: speech sounds
• Prosody: musical quality of speech
• The following cranial nerves can be affected when there is LMN damage:
• –CN V Trigeminal nerve
• –CN VII Facial nerve
• –CN IX Glossopharyngeal nerve
• –CN X Vagus nerve
• –CN XI Accessory nerve
• –CN XII Hypoglossal nerve
• –Select spinal nerves (C3-C5, T2-T11)