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The Medulla: Function, Structure, and Location

Preeti Acadecraft Bhatia, Sarah Phenix
  • Author
    Preeti Acadecraft Bhatia

    Preeti Bhatia has taught science for over two years. She also has an experience of more than two years in academic content writing. She has obtained a bachelor's degree and a Master’s degree from Miranda House College, India.

  • Instructor
    Sarah Phenix
What is the medulla and what does the medulla do? Learn the medulla definition, the medulla function, and the medulla oblongata location in the brain. Updated: 07/27/2021

What is the Medulla?

The medulla is the region that makes up the lowest of the three parts of the brainstem. It is also known as the medulla oblongata. It passes information between the higher-thinking centers of the brain and the spinal cord through the tracts within the medulla oblongata.

The medulla is responsible for regulating many autonomic functions, including respiration and the beating of the heart. Many reflex actions, swallowing and vomiting, are also regulated by the medulla oblongata.

The Medulla at Work

Imagine this…you're walking through the Alaskan woods one beautiful day when you come around a corner, and Bam! You find yourself face-to-face with an enormous Kodiak bear! You might not realize it (probably because you're too concerned with the 1,500-pound bear standing in front of you), but your body jumps right into action.

Your heartbeat quickens to pump the extra oxygen (which your quickened breathing is now taking in) to your muscles so you can make a 'fight' (truly not recommended) or 'flight' decision. And, what's more, you have totally forgotten that urgent need to go to the bathroom that you had three seconds before meeting Yogi's giant cousin (thank goodness--what a terrible time to be stuck doing a bathroom dance!). All of these responses are due to your autonomic nervous system (ANS), which is, in part, controlled by your medulla oblongata. Thanks, medulla!

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  • 0:01 Medulla at Work
  • 0:54 Location & Function
  • 1:54 ANS Control
  • 2:49 Cranial Nerves
  • 4:32 Motor Functions
  • 5:38 Lesson Summary
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Medulla Oblongata Location

The medulla oblongata is located at the base of the brainstem. Below the region of the medulla oblongata, the spinal cord begins. The opening through which the medulla and the spinal cord connect is the foramen magnum.

The structure present at the posterior surface of the medulla is known as the cerebellum, which is responsible for maintaining body balance. The cerebellar peduncle connects the cerebellum to the medulla oblongata. At the top of the medulla oblongata, a structure known as the pons is present in the brainstem. The pons works with the medulla oblongata to produce breathing rhythm during the respiration process.

The brainstem is home to the medulla oblongata.

The image shows the structures of the brain. With a red box indicating the brainstem, the region in which the medulla is found.

Structure of the Medulla

The medulla oblongata has a pyramid-like structure. The maximum width of the medulla oblongata is about 2 centimeters, and its length is about 3 centimeters. The medulla oblongata is divided into the ventral and dorsal medulla. The inferior portion of the fourth ventricle of the brain is formed by the superior portion of the dorsal medulla. The dorsal medulla gives rise to four cranial nerves.

There are three fissures at the anterior surface of the medulla oblongata:

  • Anterior median fissure (present at the midline)
  • Posterolateral sulcus
  • Ventrolateral sulcus (away from the midline)

There are several pyramid-shaped tracts present in the ventral medulla between the ventrolateral and anterior median fissure. The corticobulbar tract and the corticospinal tract make this pyramid. The corticospinal tracts moved towards the spinal cord and make a decussation of pyramids at the lower medulla due to their crossed tracts. The ventrolateral and posterolateral contain the structure called olives between them.

The posterior median sulcus is present at the midline at the posterior surface of the medulla oblongata. The fasciculus gracilis and fasciculus cuneatus separated by the posterior intermediate sulcus are two prominences away from the midline. The fasciculus gracilis contains a relay nucleus on its cranial side called the gracile nucleus that forms a synapse with the nerve fibers of the fasciculus gracilis. The gracile tubercle is a cranial enlargement formed by the gracile nucleus that can be seen on the dorsal surface of the medulla. The fasciculus cuneatus also contains a relay nucleus called the cuneate nucleus that forms an enlargement called cuneate tubercle that can be seen on the dorsal surface of the medulla. The trigeminal tubercle is another prominence present laterally to the cuneate nucleus.

The internal structure of the medulla

The medulla's internal structure is divided into three parts:

1.The basal area forms the ventral side of the medulla

    • contains the decussation of pyramids of the corticospinal tracts

2. The tectum forms the dorsal side of the medulla

    • contains the lower region of the fourth ventricle

3. The tegmentum is present between the basal area and the tectum

    • contains the nuclei of cranial nerves and the nuclei of olives

The cranial nuclei are present in the dorsal medulla, forming the grey matter through the neuronal cell bodies. The tracts are present in the ventral medulla, forming the white matter through the bundle of axons. Based on their involvement in the body, the nuclei present in the medulla are divided into the cranial nerves, reticular nuclei, and relay nuclei. These nuclei contain raphe nuclei (release serotonin neurotransmitter), perihypoglossal nucleus (help in the movement of the eye), hypoglossal nucleus (control the muscles of the tongue), dorsal nucleus of vagus nerve (motor nucleus for visceral organs), medial vestibular nucleus (part of the vestibular system), cuneate nucleus (receives sensory information from upper limb), spinal trigeminal nucleus ( receives sensory information from face), nucleus ambiguus (provide nerve fibers to the vagus nerves, accessory cranial nerves, and glossopharyngeal nerve), lateral reticular nucleus (helps cerebellum in the planning of movements and coordination), and olivary nuclei ( helps cerebellum with the coordination of movements).

There are two types of tracts in white matter, the motor tract, and the sensory tract.

Location

The medulla oblongata, also known just as the medulla, is part of your brainstem, which is literally the stem that extends from your brain. The medulla sits below the pons and above the spinal cord and is a major relay point for information going to and from your brain and spinal cord. In fact, its 'middle-man' position is actually reflected in its name, which means 'elongated' or 'oblong' (oblongata) 'middle' (medulla).

The medulla oblongata isn't just any run-of-the-mill middleman, though. In truth, the 'upper-management' of your brain couldn't function without this middleman coming to work every day to send messages back and forth between your brain and your body.

Function

So, what exactly does the medulla oblongata do? It's sort of a big answer. Your medulla directly controls many ANS responses, in addition to playing an accessory role in the control of certain areas of your body. It also has a stake in your overall major motor functions, or body movement. Let's take a moment to explore each of these functions in detail.

ANS Control

Your autonomic nervous system--in other words, your 'automated' nervous system--automatically responds to the situation you're in without you needing to think about it. It controls everything from the dilation of your pupils to your breathing pattern, heart contractions, and need to go to the bathroom. Can you imagine having to think about making all of those things happen, in the right order, at the right speed, and in a consistent pattern that considers your body's needs at the time? Yikes!

In addition to the functions already outlined, your medulla controls the following autonomic reflexes:

  • Blood vessel dilation to increase or decrease oxygen flow and respond to heart functions
  • Digestion to turn on or off digestion during 'fight or flight' scenarios
  • Sneezing and coughing to dispel foreign particles from your nose
  • Swallowing and vomiting to get rid of anything, such as bacteria, pathogens, or poisons that could harm you

Cranial Nerves

You have 12 pairs of cranial nerves, which control everything from the movements and reflexes of your eyes to your sense of smell, tongue movement, and sense of balance. These nerves leave your central nervous system at various locations.

The last seven pair of cranial nerves originate at either the junction between the pons and the medulla or directly through the medulla itself, meaning the medulla either plays an accessory role in conducting those signals or a direct role in controlling them. As a result, any damage to your medulla could result in damage to these nerves, which include the following:

6. The abducens nerve, which controls the muscles that 'abducts' your eyes, or rotates them away from the centerline of your body.

7. The facial nerve, which controls all your facial muscles.

8. The vestibulocochlear nerve, which transmits sound and a sense of equilibrium from your ear to your brain.

9. The glossopharyngeal nerve, which receives sensations and sends motor signals to the tongue and pharynx. This nerve also enables sense of taste and pharyngeal contractions for actions such as swallowing and interacts with your inner ear. This is one of the three nerves that plays a direct role in the medulla's ANS control of swallowing, coughing, sneezing, and vomiting.

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Video Transcript

The Medulla at Work

Imagine this…you're walking through the Alaskan woods one beautiful day when you come around a corner, and Bam! You find yourself face-to-face with an enormous Kodiak bear! You might not realize it (probably because you're too concerned with the 1,500-pound bear standing in front of you), but your body jumps right into action.

Your heartbeat quickens to pump the extra oxygen (which your quickened breathing is now taking in) to your muscles so you can make a 'fight' (truly not recommended) or 'flight' decision. And, what's more, you have totally forgotten that urgent need to go to the bathroom that you had three seconds before meeting Yogi's giant cousin (thank goodness--what a terrible time to be stuck doing a bathroom dance!). All of these responses are due to your autonomic nervous system (ANS), which is, in part, controlled by your medulla oblongata. Thanks, medulla!

Location

The medulla oblongata, also known just as the medulla, is part of your brainstem, which is literally the stem that extends from your brain. The medulla sits below the pons and above the spinal cord and is a major relay point for information going to and from your brain and spinal cord. In fact, its 'middle-man' position is actually reflected in its name, which means 'elongated' or 'oblong' (oblongata) 'middle' (medulla).

The medulla oblongata isn't just any run-of-the-mill middleman, though. In truth, the 'upper-management' of your brain couldn't function without this middleman coming to work every day to send messages back and forth between your brain and your body.

Function

So, what exactly does the medulla oblongata do? It's sort of a big answer. Your medulla directly controls many ANS responses, in addition to playing an accessory role in the control of certain areas of your body. It also has a stake in your overall major motor functions, or body movement. Let's take a moment to explore each of these functions in detail.

ANS Control

Your autonomic nervous system--in other words, your 'automated' nervous system--automatically responds to the situation you're in without you needing to think about it. It controls everything from the dilation of your pupils to your breathing pattern, heart contractions, and need to go to the bathroom. Can you imagine having to think about making all of those things happen, in the right order, at the right speed, and in a consistent pattern that considers your body's needs at the time? Yikes!

In addition to the functions already outlined, your medulla controls the following autonomic reflexes:

  • Blood vessel dilation to increase or decrease oxygen flow and respond to heart functions
  • Digestion to turn on or off digestion during 'fight or flight' scenarios
  • Sneezing and coughing to dispel foreign particles from your nose
  • Swallowing and vomiting to get rid of anything, such as bacteria, pathogens, or poisons that could harm you

Cranial Nerves

You have 12 pairs of cranial nerves, which control everything from the movements and reflexes of your eyes to your sense of smell, tongue movement, and sense of balance. These nerves leave your central nervous system at various locations.

The last seven pair of cranial nerves originate at either the junction between the pons and the medulla or directly through the medulla itself, meaning the medulla either plays an accessory role in conducting those signals or a direct role in controlling them. As a result, any damage to your medulla could result in damage to these nerves, which include the following:

6. The abducens nerve, which controls the muscles that 'abducts' your eyes, or rotates them away from the centerline of your body.

7. The facial nerve, which controls all your facial muscles.

8. The vestibulocochlear nerve, which transmits sound and a sense of equilibrium from your ear to your brain.

9. The glossopharyngeal nerve, which receives sensations and sends motor signals to the tongue and pharynx. This nerve also enables sense of taste and pharyngeal contractions for actions such as swallowing and interacts with your inner ear. This is one of the three nerves that plays a direct role in the medulla's ANS control of swallowing, coughing, sneezing, and vomiting.

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Frequently Asked Questions

Why is the medulla important for our survival?

The medulla is significant for the survival of human beings because it regulates autonomic functions such as heart rate, respiration, and blood vessel diameter.

Where is the medulla located and what is its function?

The medulla is located in the brainstem, where it helps in the regulation of respiration, heart rate, and blood vessels diameter. It also helps in actions such as swallowing, peristalsis, and speech.

What is the medulla part of?

The medulla is the lowest part of the brain present at the base of the brainstem. It is responsible for various brain activities that involve the autonomic nervous response, such as heart rate and respiration process.

What are 3 functions or responsibilities of the medulla?

The three functions of the medulla include the regulation of respiration, the regulation of heart rate and blood vessels by the vasomotor center, and the reflex actions such as swallowing by the cranial nerves.

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