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The Pons

Anatomy || Importance in Disease || Overview || Related Articles
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The pons is one of the three sections of the brainstem. It has an unmistakable out-pouching on its front side that makes it look like a big grape. This out-pouching makes it easy to localize on imaging studies.

The pons is home to discrete collections of neurons known as "nuclei". These collections of neurons work together to perform specific functions.

The nuclei of several cranial nerves reside in the pons. These nuclei help control movement of the face, tongue, and eyes. They also pass sensory information from the face and tongue to higher cortical areas.

The most complicated collections of neurons in the pons receive and send information through the fifth cranial nerve (aka: the trigeminal nerve). These nuclei include: the main trigeminal nucleus, the spinal trigeminal nucleus, the motor nucleus, and the mesencephalic nucleus.

The main trigeminal nucleus passes touch and position information about the face and tongue to the cortex. The spinal trigeminal nucleus functions similarly, but instead of sending touch and position information, it sends pain and temperature information. The mesencephalic nucleus receives information regarding the position of the jaw in space; it functions in the jaw jerk reflex.

The motor nucleus of the trigeminal nerve controls the muscles necessary to help you open and close your jaw (ie: the masseter, pterygoid, and temporalis muscles). These muscles are important in mastication.

The next cranial nerve nuclei that resides in the pons is the abducens nucleus. It contains lower motor neurons that control the lateral rectus muscles of the eyes. The axons that originate from this nucleus form the sixth cranial nerve (aka: the abducens nerve). The abducens nerve stimulates the lateral rectus muscle and allows the eyeball to look laterally.

The pons also contains the lower motor neurons that are responsible for most facial movements. These neurons are located in the aptly named facial nucleus. Their axons form the seventh cranial nerve (aka: facial nerve).

Brainstem Anatomy

The final cranial nerve nuclei that reside within the pons are the vestibular and cochlear nuclei. These nuclei receive information from the eighth cranial nerve.

The vestibular nuclei obtain information from the middle ear structures that are involved in balance and position sense (ie: the semicircular canals, saccule, and utricle).

The cochlear nucleus processes sound information from the ear, and then relays it to higher areas of the brain for interpretation.

The pons also serves as a relay station for information passing from the cortex to the cerebellum (ie: the cauliflower looking thing hanging off the back of the brainstem). Neurons in the motor cortex of the frontal lobes send information to a collection of neurons in the pons known collectively as the "pontine grey". These neurons then relay information to the cerebellum via an anatomical bridge known as the middle cerebellar peduncle (aka: the brachium pontis, or "arm of the pons" in Latin). This flow of motor information is vital to ensuring smooth and coordinated movement of the limbs.

Like the other brainstem structures, the pons also has many information tracts traveling up and down its length. For example, sensory and motor information from the body and brain travel through the pons to reach their respective destinations in the cortex and spinal cord.

Importance in Disease

The pons is a pricey piece of real estate because it contains so many nuclei responsible for facial function. For example, damage to the facial nucleus can cause an inability to close the eye, which can lead to corneal damage and potentially blindness!

Damage to the pons can also interrupt information traveling from the spinal cord to the brain or vice versa. Therefore, even small areas of damage to the pons can have devastating clinical consequences including quadriplegia.


The pons contains the nuclei of the fifth, sixth, seventh, and eighth cranial nerves. It also contains nuclei that relay motor information from the cortex to the cerebellum. The pons hosts numerous information pathways sending signals to and from the spinal cord and brain. Damage to the pons can have significant clinical consequences.

References and Resources

(1) Abe H, Rhoton AL Jr. Microsurgical anatomy of the cochlear nuclei. Neurosurgery. 2006 Apr;58(4):728-39; discussion 728-39.

(2) Bickley LS, Szilagyi PG. Bates' Guide to Physical Examination and History Taking. Ninth Edition. New York: Lippincott Williams and Wilkins, 2007.

(3) Nolte J. The Human Brain: An Introduction to its Functional Anatomy. Sixth Edition. Philadelphia: Mosby, 2008.

(4) Netter FH. Atlas of Human Anatomy: with Student Consult Access (Netter Basic Science). Fifth Edition. Philadelphia: Saunders Elsevier, 2010.

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