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Clinical Mnemonics · Anatomy & Musculoskeletal

Some Say Marry Money but My Brother Says Big Brains Matter More

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  2. The college version
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In 30 seconds

Classifies each of the twelve cranial nerves as Sensory, Motor, or Both so the modality predicts the deficit pattern and guides the exam.

The college version

Classifies each of the twelve cranial nerves as Sensory, Motor, or Both so the modality predicts the deficit pattern and guides the exam.

Some — Sensory — Olfactory (CN I)

Sensory

CN I is purely sensory (olfaction) with no motor component.

Physiology. Olfaction only reports to the brain; it moves nothing, so the nerve is purely afferent.

Say — Sensory — Optic (CN II)

Sensory

CN II is purely sensory (vision), a direct CNS tract with no motor fibers.

Physiology. Vision is a pure input channel, making the optic nerve exclusively afferent.

Marry — Motor — Oculomotor (CN III)

Motor

CN III is predominantly motor (extraocular muscles + levator palpebrae); its parasympathetic pupil-constricting fibers are an autonomic bonus, not a sensory function.

Physiology. Its main job is moving muscles, so it is grouped as Motor.

Money — Motor — Trochlear (CN IV)

Motor

CN IV is purely motor, supplying only the superior oblique muscle.

Physiology. One muscle, no sensation — a single-purpose motor nerve.

But — Both — Trigeminal (CN V)

Both

CN V is the classic mixed nerve: sensory to the face (V1/V2/V3) and motor to the muscles of mastication.

Physiology. It senses the face and mouth while driving the jaw, so it carries both afferent and efferent fibers.

My — Motor — Abducens (CN VI)

Motor

CN VI is purely motor, supplying only the lateral rectus muscle.

Physiology. One muscle, one direction, motor only.

Brother — Both — Facial (CN VII)

Both

CN VII is mixed: motor to facial expression, sensory (taste, anterior two-thirds of tongue), plus parasympathetic output to lacrimal and salivary glands.

Physiology. It moves the face while sensing taste and protecting the eye, so it carries both directions.

Says — Sensory — Vestibulocochlear (CN VIII)

Sensory

CN VIII is purely sensory: hearing (cochlear) and balance (vestibular), with no motor component.

Physiology. Hearing and equilibrium are pure inputs, so the nerve is exclusively afferent.

Big — Both — Glossopharyngeal (CN IX)

Both

CN IX is mixed: sensory/taste to the posterior tongue and pharynx, motor to the stylopharyngeus, and the afferent limb of the gag reflex.

Physiology. It senses the throat to trigger swallowing while helping move it, so it needs both directions.

Brains — Both — Vagus (CN X)

Both

CN X is mixed: sensory to pharynx/larynx/viscera, motor to pharynx/larynx, plus extensive parasympathetic output to heart, lungs, and gut.

Physiology. The vagus senses organ state and commands them, making it the body's largest mixed nerve.

Matter — Motor — Accessory (CN XI)

Motor

CN XI is purely motor, supplying the sternocleidomastoid and trapezius.

Physiology. Movement-only, so it is classified Motor.

More — Motor — Hypoglossal (CN XII)

Motor

CN XII is purely motor, supplying the muscles of the tongue.

Physiology. The tongue is all muscle movement, so the nerve is Motor.

Memory aids

  • = Sensory — Olfactory (CN I)
  • = Sensory — Optic (CN II)
  • = Motor — Oculomotor (CN III)
  • = Motor — Trochlear (CN IV)
  • = Both — Trigeminal (CN V)
  • My = Motor — Abducens (CN VI)
  • = Both — Facial (CN VII)
  • = Sensory — Vestibulocochlear (CN VIII)
  • = Both — Glossopharyngeal (CN IX)
  • = Both — Vagus (CN X)
  • = Motor — Accessory (CN XI)
  • = Motor — Hypoglossal (CN XII)

Quick review

  • Some = Sensory — Olfactory (CN I) — Sensory
  • Say = Sensory — Optic (CN II) — Sensory
  • Marry = Motor — Oculomotor (CN III) — Motor
  • Money = Motor — Trochlear (CN IV) — Motor
  • But = Both — Trigeminal (CN V) — Both
  • My = Motor — Abducens (CN VI) — Motor
  • Brother = Both — Facial (CN VII) — Both
  • Says = Sensory — Vestibulocochlear (CN VIII) — Sensory
  • Big = Both — Glossopharyngeal (CN IX) — Both
  • Brains = Both — Vagus (CN X) — Both
  • Matter = Motor — Accessory (CN XI) — Motor
  • More = Motor — Hypoglossal (CN XII) — Motor
Eli, the EliExplains learning guide

Eli explains

The same idea, in plain words

Explain it like I’m 10

A sentence that tells you, for each of the twelve brain wires, whether it's a 'feeling-in' wire (Sensory), an 'orders-out' wire (Motor), or a 'both-ways' wire (Both).

Some — Sensory — Olfactory (CN I). Smell is a one-way trip into the brain: chemicals in the air travel up the nose and report back, so this wire only carries 'news in.'

Say — Sensory — Optic (CN II). Seeing is information going in — light enters the eye and the picture is delivered to the brain, a one-way input road.

Marry — Motor — Oculomotor (CN III). The Oculomotor nerve is the eye's mover — it pulls the eye up, down, and inward and lifts the eyelid, sending orders out to muscles.

Money — Motor — Trochlear (CN IV). The Trochlear nerve moves one muscle — the one that tips the eye down and in — a clean, single-purpose orders-out wire.

But — Both — Trigeminal (CN V). The Trigeminal nerve does two jobs at once: it feels the whole face (sensory) AND powers the chewing muscles (motor) — a two-way street.

My — Motor — Abducens (CN VI). The Abducens nerve moves one muscle — the one that slides the eye sideways toward the ear — a one-way orders-out wire.

Brother — Both — Facial (CN VII). The Facial nerve does two jobs: it moves the face to smile and frown (motor) AND tastes the front of the tongue and runs tears (sensory) — a two-way street.

Says — Sensory — Vestibulocochlear (CN VIII). 'Says' reminds you of sound: hearing is information going in, along with the balance bubble — both are inputs, so this wire is one-way in.

Big — Both — Glossopharyngeal (CN IX). The Glossopharyngeal nerve feels the back of the throat and tastes bitter things (sensory) AND helps start the swallow (motor) — a two-way street.

Brains — Both — Vagus (CN X). The Vagus is the busiest two-way street: it feels the throat and organs AND runs the voice, swallow, and calm-down controls — feeling in and orders out.

Matter — Motor — Accessory (CN XI). The Accessory nerve moves two big muscles — shrug the shoulder and turn the head — a clean orders-out wire.

More — Motor — Hypoglossal (CN XII). The Hypoglossal nerve moves the tongue so you can talk, chew, and swallow — a clean orders-out wire.

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Study tools & related lessonsKey vocabulary · Related

Key vocabulary

Some
Sensory — Olfactory (CN I)
Say
Sensory — Optic (CN II)
Marry
Motor — Oculomotor (CN III)
Money
Motor — Trochlear (CN IV)
But
Both — Trigeminal (CN V)
My
Motor — Abducens (CN VI)
Brother
Both — Facial (CN VII)
Says
Sensory — Vestibulocochlear (CN VIII)
Big
Both — Glossopharyngeal (CN IX)
Brains
Both — Vagus (CN X)
Matter
Motor — Accessory (CN XI)
More
Motor — Hypoglossal (CN XII)

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