Question #355
Which of the following cranial nerves transmits branchial motor signals?
Branchial motor refers to those striated muscles of the head and neck which are derived from the pharyngeal arches. Each arch has a cranial nerve which ultimately supplies these muscles.
You may have learnt these pharyngeal arch cranial nerves as V, VII, IX, and X. In addition the cranial accessory nerve, which is very variable, often sends fibres that run with the vagus and sometimes glossopharyngeal nerves as part of the pharyngeal plexus to supply a range of different muscles in the neck.
Some texts seem to classify the spinal part of the accessory nerve also as branchial motor. Since neither sternocleidomastoid nor trapezius is derived from a pharyngeal arch this is incorrect.
To makes matters more confusing branchial arches are the gill bars only found in fish. In humans the homologous structures are the pharyngeal arches. However, the efferent fibres are still called branchial motor rather than pharyngeal motor.