pons n : a band of nerve fibers linking the medulla oblongata and the cerebellum with the midbrain [syn: pons Varolii] [also: pontes (pl)]

English

Pronunciation

• Rhymes: -ɒnz

Noun

1. A bridge-like tissue connecting two parts of an organ
2. A band of nerve fibres, the pons Varolii, within the brain stem

Translations

Latin

Etymology

Kindred with the Sanskrit pathi ("a path"); the Greek πάτος; the old German phat, pfat; modified German Pfad; Anglo-Saxon padh.

Noun

pons, pontis

1. a bridge

Derived terms

• sexagenarios de ponte

Descendants

• pont (French)
• ponte (Italian)
• pontoon (English)
• puente (Spanish)
• Ponce (old-Catalan, now Place Name and Surname)

The pons (sometimes pons Varolii after Costanzo Varolio) is a structure located on the brain stem. It is rostral to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it is above the medulla, below the midbrain, and anterior to the cerebellum.

Function

The pons relays sensory information between the cerebellum and cerebrum; aids in relaying other messages in the brain; controls arousal, and regulates respiration (see respiratory centres). In some theories, the pons has a role in dreaming.

Anatomy of the pons

The "knob-like" process (Basal pons) is 2 centimeters long and located on the anterior (front) of the brainstem. It is formed of nerves that travel from one side (left or right) to the other. Most other fibres in the brainstem travel up and down.

The posterior (back) surface of the pons forms part of the wall of the fourth ventricle of the brain.

Most blood to the pons is supplied by pontine arteries. These are small arteries that branch off the basilar artery (of the Circle of Willis). Blood also comes from the anterior inferior, and superior cerebellar arteries.

There are two main domains in the pons for control of respiration:

• the apneustic center - lower pons
• the pneumotaxic center - upper pons

Cranial nerve nuclei

A number of cranial nerve nuclei are present in the pons:

• mid-pons: The chief or pontine nucleus of the trigeminal nerve sensory nucleus (V)
• mid-pons: the motor nucleus for the trigeminal nerve (V)
• lower down in the pons: abducens nucleus (VI)
• lower down in the pons: facial nerve nucleus (VII)
• lower down in the pons: vestibulocochlear nuclei (vestibular nuclei and cochlear nuclei) (VIII)

Related diseases

• Central pontine myelinosis, a demyelination disease that causes difficulty with swallowing and speaking

Additional images

hypophysis cerebri in position. Shown in sagittal section. Image:Illu pituitary pineal glands.jpg|Pituitary and pineal glands Image:Brainstem Abducens.png|Axial section of the Brainstem (Pons) at the level of the Facial Colliculus Image:Human cerebrum lateral view, a part of temporal lobe resected description.JPG|Human cerebrum lateral view Image:Human brain frontal (coronal) section description.JPG|Human brain frontal (coronal) section Image:Human brainstem anterior view 2 description.JPG|Human brainstem anterior view

References

External links

• Diagram at UCC