The correct answer is the C5 root. The ulnar nerve is the most inferior nerve in the brachial plexus, meaning it would not arise from a root like C5 which is the most superior in the brachial plexus.

The correct answer is the trochlear nerve. This nerve has solely motor functions involving movement of the eye via the superior oblique muscle. The trigeminal nerve has both sensory and motor functions including general sensation of the face/scalp and opening/closing the mouth and modifying the tension of the tympanic membrane. Although both the oculomotor and abducens nerves play a role in eye movement, neither of them control the movement of the superior oblique muscle.

In this case, we are looking for a nerve with both sensory and motor function, laving only the facial and vagus nerves, as the hypoglossal and trochlear nerves are solely motor. Only the facial nerve controls the muscles in the face making it the correct answer. It also controls the tension of the ossicles.

The olfactory nerve is responsible for the sensation of smell (olfaction). The optic nerve senses visual stimuli, The vestibulocochlear nerve is a sensory nerve that is responsible for proprioception and audition, the accessory nerve (cranial nerve XI) is responsible for movement of the head and shoulders.

The accessory nerve innervates two large muscles: the sternocleidomastoid and the trapezius. Both of them are located in the neck/upper back which is the location of the accessory nerve. The trochlear nerve innervates the superior oblique.

The vestibulocochlear nerve is a sensory nerve that runs through the internal auditory canal of the ear. The ear is responsible for both our hearing and our sense of balance/equilibrium. This means that the vestibulocochlear nerve is responsible for both hearing and balance. The sense of vision of carried out by the optic nerve.

In this case, we are looking specifically for a nerve that has motor function. The correct answer is the hypoglossal nerve. The glossopharyngeal nerve is responsible for swallowing and gustation, but not for movement of the tongue. The facial nerve is responsible for moving the muscles of the face involved in facial expression and for controling the tension of the ossicles. The abducens is solely responsible for movement of the eye through its innervation of the lateral rectus.

The correct answer is the oculomotor nerve. In this case we are looking for a motor nerve that has something to do with the eye, letting us rule out both the olfactory (sensory) and facial (sensory and motor, but not of the eye) nerves. That leaves the oculomotor and optic nerves, however the optic nerve is solely sensory while the oculomotor nerve is a motor nerve.

The posterior cord of the brachial plexus gives rise to the nerves in the deep compartment of the upper arm. Those are the radial and axillary nerves. The musculocutaneous nerve comes from the lateral cord. The median nerve comes from the lateral and medial cords. The ulnar nerve comes from the medial cord.

C8 and T1 merge to give rise to the inferior trunk of the brachial plexus. They are the most inferior roots of the brachial plexus, so it would make sense that they feed into the inferior trunk.