Medulla Oblongata Anatomy

Summary

The medulla oblongata, a crucial part of the brainstem, connects the spinal cord and controls vital functions like heart rate and breathing. It houses nuclei for cranial nerves 9-12, and its anatomy includes the anterior and posterior surfaces with distinct sulci and nuclei. The medulla's internal structure comprises levels of pyramid decussation, medial lemniscus, and olives, with tracts for motor and sensory functions. Understanding its complex vasculature is key to recognizing medullary lesion syndromes.

Takeaways

• 🧠 The medulla oblongata is the lowest part of the brainstem, connecting to the pons above and the spinal cord below.
• 🚀 It serves as a conduit for many essential ascending and descending nerve tracts.
• ❤️ It houses centers that control vital functions such as heart rate, breathing, and blood pressure.
• 🤖 It contains the nuclei of four cranial nerves: 9, 10, 11, and 12.
• 🌱 On the anterior surface, the midline features the anterior median fissure, and lateral to it are the ventral and posterolateral sulci.
• 🍇 The pyramids, composed of motor fibers, and the olives, containing the olivary nuclei, are significant lateral structures.
• 🔁 Posteriorly, the medulla has the posterior median sulcus and the gracilis and cuneate tubercles.
• 🧬 Internally, the medulla is divided into levels: pyramid decussation, medial lemniscus decussation, and the level of the olives and inferior cerebellar peduncles.
• 🔄 The decussation of the pyramids is where motor fibers cross from one side of the body to the other.
• 🧲 The decussation of the medial lemniscus is where sensory fibers cross, carrying information like touch and vibration.
• 🩸 The medulla's blood supply comes from the vertebral arteries, posterior spinal artery, anterior spinal artery, and the posterior inferior cerebellar artery.

Q & A

What is the medulla oblongata and its position in the brainstem?

The medulla oblongata, also known as the medulla, is one of the three sections that make up the brainstem. It is the most inferior part of the brainstem, continuous with the pons above and the spinal cord below.

What are the primary functions of the medulla oblongata?

The medulla oblongata serves as a conduit for many essential ascending and descending nerve tracts. It houses centers that control vital functions of the body such as heart rate, breathing, and blood pressure. It also contains the nuclei of four cranial nerves.

What are the key features of the anterior surface of the medulla?

The anterior surface of the medulla features the anterior median fissure at the midline, which is continuous along the length of the spinal cord. Lateral to the midline are the ventral lateral sulcus and the posterolateral sulcus, where the pyramids are located. The olives, which are swellings containing the olivary nuclei, are found lateral to the pyramids.

What are the cranial nerves associated with the medulla oblongata?

The medulla oblongata is associated with the last four cranial nerves: cranial nerves 9, 10, 11, and 12.

What is the significance of the posterior surface of the medulla oblongata?

The posterior surface of the medulla has the posterior median sulcus at the midline, which conveys sensory input from most things below the neck, including the viscera. Lateral to the midline are the gracilis tubercle and the cuneate tubercle, which contain tracts that carry sensory information from the periphery to the brain.

What are the three levels of the medulla oblongata discussed in the script?

The three levels of the medulla oblongata discussed are: the level of decussation of the pyramids, the level of decussation of the medial lemniscus, and the level of the olives and inferior cerebellar peduncles.

What is the function of the pyramids in the medulla oblongata?

The pyramids are composed of bundles of motor fibers that make up the corticospinal tract, which carries motor fibers from the brain to the periphery.

What is the role of the olivary nuclei in the medulla oblongata?

The olivary nuclei, located within the olives, play an important role in movement coordination and movement-related learning.

How does the central canal change at the level of the olives and inferior cerebellar peduncles?

At the level of the olives and inferior cerebellar peduncles, the central canal expands into the fourth ventricle, making this region the open medulla.

What are the vital functions controlled by the centers located in the medulla oblongata?

The medulla oblongata contains centers that control vital functions such as heart rate, breathing, and blood pressure.

What is the blood supply to the medulla oblongata?

The blood supply to the medulla oblongata includes the vertebral arteries, posterior spinal artery, anterior spinal artery, and the posterior inferior cerebellar artery.

Outlines

00:00

🧠 Anatomy and Functions of the Medulla Oblongata

The medulla oblongata, located in the brainstem, is the most inferior section, connecting the spinal cord below and the pons above. It serves crucial functions, acting as a conduit for ascending and descending nerve tracts and regulating vital body functions like heart rate, breathing, and blood pressure. It also contains the nuclei of four cranial nerves (IX, X, XI, XII). The anterior surface features include the anterior median fissure, pyramids (containing motor fibers), and olives, which are involved in movement coordination. Cranial nerves emerge from the ventral lateral sulcus and posterolateral sulcus.

05:01

🔍 Posterior Anatomy and Internal Structures of the Medulla

The posterior surface of the medulla is revealed by removing the cerebellum. A key feature is the posterior median sulcus, which conveys sensory input. Lateral to the midline, the gracilis and cuneatus tubercles carry sensory information to the brain. The internal anatomy of the medulla is explored through cross-sections at three levels: the decussation of the pyramids, the decussation of the medial lemniscus, and the level of the olives and inferior cerebellar peduncles. Each level has unique characteristics, such as motor and sensory tracts and nuclei like the nucleus gracilis and nucleus cuneatus.

10:03

📊 Key Levels of the Medulla: Motor and Sensory Tracts

The medulla's first level, the decussation of the pyramids, marks the crossing of motor fibers from one side to the other, transmitting signals from the brain to the periphery. Sensory tracts like the spinocerebellar tract and the lateral spinothalamic tract are also present. At the second level, the medial lemniscus decussation, sensory fibers conveying touch and vibration cross sides before traveling to the brain. Key nuclei at this level include the nucleus gracilis, nucleus cuneatus, and the spinal nucleus of cranial nerve V. Lastly, the olives and inferior cerebellar peduncles connect the brainstem to the cerebellum.

🌐 Vital Centers and Blood Supply of the Medulla

The medulla oblongata contains vital centers controlling heart rate, breathing, and blood pressure. The respiratory center and vasomotor center, housed in the medulla, regulate these essential functions. The medulla receives blood from several arteries, including the vertebral arteries, the posterior and anterior spinal arteries, and the posterior inferior cerebellar artery. Understanding these features is key to diagnosing medullary lesion syndromes, which will be covered in a separate discussion.

📚 Summary: Key Levels and Functions of the Medulla Oblongata

In summary, the medulla oblongata is an essential part of the brainstem connecting the spinal cord. Its anatomy is divided into three main levels: the olives, the medial lemniscus decussation (sensory fibers), and the pyramidal decussation (motor fibers). The medulla contains the nuclei of cranial nerves IX, X, XI, and XII, and regulates crucial bodily functions such as breathing and blood pressure. Its blood supply, mainly from vertebral and spinal arteries, is complex but vital for understanding related lesions and syndromes.

Keywords

💡Medulla Oblongata

The medulla oblongata, also known as the medulla, is the lowermost part of the brainstem. It serves as a critical relay station for many essential nerve tracts and houses centers that control vital functions such as heart rate, breathing, and blood pressure. In the script, the medulla is described as continuous with the pons above and the spinal cord below, emphasizing its role in connecting different parts of the nervous system.

💡Brainstem

The brainstem is a part of the brain that connects to the spinal cord and is responsible for many automatic functions necessary for life, such as breathing and heart rate. The script mentions the brainstem as being composed of three sections, with the medulla being the most inferior of these sections.

💡Cranial Nerves

Cranial nerves are the nerves that emerge directly from the brain, as opposed to the spinal cord. The script specifies that the medulla contains the nuclei of four cranial nerves (9, 10, 11, and 12), which are essential for various functions including swallowing, speech, and controlling certain muscles in the head and neck.

💡Pyramids

The pyramids are a pair of large bundles of nerve fibers located in the medulla. They are part of the corticospinal tract, which is responsible for voluntary motor control. The script describes the pyramids as being composed of motor fibers that descend from the brain to the spinal cord.

💡Olives

The olives are a pair of swellings located lateral to the pyramids in the medulla. They contain the olivary nuclei, which are involved in movement coordination and learning. The script mentions that the olives play an important role in movement-related functions.

💡Inferior Cerebellar Peduncles

The inferior cerebellar peduncles are the connections between the medulla and the cerebellum. They are essential for transmitting information between these two parts of the brain. The script describes how these peduncles link the medulla to the cerebellum.

💡Ventral Lateral Sulcus

The ventral lateral sulcus is one of the sulci (grooves) found on the anterior surface of the medulla. It is a landmark for locating the pyramids, which are significant for motor functions. The script uses this term to describe the anatomy of the medulla's anterior surface.

💡Decussation

Decussation refers to the crossing over of nerve fibers from one side of the body to the other. The script discusses decussation in the context of the pyramids and the medial lemniscus, where motor and sensory fibers, respectively, cross the midline.

💡Medial Lemniscus

The medial lemniscus is a tract in the brainstem that carries sensory information related to touch and proprioception from the body to the brain. The script describes the level of decussation of the medial lemniscus as a significant point where sensory fibers cross to the opposite side before ascending to the brain.

💡Fourth Ventricle

The fourth ventricle is a cavity filled with cerebrospinal fluid located in the brainstem. The script mentions that at the level of the olives, the central canal of the spinal cord expands into the fourth ventricle, marking the transition from the closed medulla to the open medulla.

💡Respiratory Center

The respiratory center is a group of neurons located in the medulla that controls the rate and depth of breathing. The script highlights the importance of the respiratory center within the medulla for regulating vital respiratory functions.

Highlights

The medulla oblongata is part of the brainstem and is continuous with the spinal cord below.

It serves as a conduit for essential ascending and descending nerve tracts.

The medulla houses centers that control vital functions such as heart rate, breathing, and blood pressure.

It contains the nuclei of four cranial nerves: 9, 10, 11, and 12.

The anterior surface of the medulla features the anterior median fissure, ventral lateral sulcus, and posterolateral sulcus.

The pyramids, composed of motor fibers, and the olives, containing the olivary nuclei, are located on the anterior surface.

The inferior cerebellar peduncles connect the medulla to the cerebellum.

Cranial nerves 9, 10, 11, and 12 emerge from the ventro lateral sulcus and the posterolateral sulcus.

The posterior surface of the medulla has the posterior median sulcus, which conveys sensory input from below the neck.

The gracilis and cuneate tubercles are lateral to the midline on the posterior surface and contain sensory tracts.

Cross-sectional views of the medulla reveal three main levels: the level of the olives, the level of decussation of the medial lemniscus, and the level of decussation of the pyramids.

The level of decussation of the pyramids is a major point of crossing for descending motor fibers.

The level of decussation of the medial lemniscus is a major crossing point for sensory fibers carrying touch and vibration information.

At the level of the olives, the central canal expands into the fourth ventricle, marking the open medulla.

The medulla contains important centers for controlling heart rate, breathing, and blood pressure, including the respiratory and vasomotor centers.

The blood supply of the medulla is complex and includes the vertebral arteries, posterior spinal artery, anterior spinal artery, and the posterior inferior cerebellar artery.

Understanding the medulla's anatomy is crucial for recognizing medullary lesion syndromes, which will be discussed in a separate video.

Transcripts

the medulla or medulla oblongata is one

of the three sections that make up the

brain stem

of the three sections that make up the

brainstem it is the most inferior and is

continuous with the pawns above and the

spinal cord below

the medulla has many important features

and functions it is a conduit for many

essential ascending and descending nerve

tracts it houses a sentence that control

vital functions of the body such as

heart rate breathing and blood pressure

and also contains the nuclei of four

cranial nerves

let's focus on the external anatomy of

the medulla focusing on the anterior

surface

so this is the anterior surface of the

medulla at the midline you'll find the

anterior median fissure which is

continuous along the length of the

spinal cord

As you move lateral from the midline

there are two sulci the ventral lateral

sulcus and the posterolateral sulcus

you can find the pyramids here

the pyramids are composed of bundles of

motor fibers which make up the

corticospinal tract

the olives also appear as a pair of

swellings like olives you eat however

they are located lateral of the pyramids

the olives contain the olivary nuclei

which play an important role in movement

coordination and movement related

learning

posterior to the olives are the inferior

cerebellar head uncles which connect the

medulla to the cerebellum

the ventro lateral sulcus and the

postural lateral circles also have

cranial nerves coming out of them

at the medulla the cranial nerves to

remember are cranial nerves 9 10 11 and

12 so the last four

now let's look at the external anatomy

of the medulla on the posterior surface

so the back of the medulla in order to

appreciate the posterior surface of the

medulla the cerebellum which normally

connects to the back of the Mandela part

of it must be removed

like the anterior surface of the medulla

the posterior surface also has a midline

structure this is called the posterior

median sulcus

this is continuous below as the

posterior median sulcus of the spinal

cord

the posterior median sulcus conveys

sensory input from most things below the

neck including the viscera

lateral from the midline you find the

gracilis tubercle and the cuneat

tubercle

the gracilis and cuneat tubercle

contains

essentially tracts that carry sensory

information

from the periphery to the brain mainly

touch information

that was the external anatomy of the

mandala now let us focus on the internal

anatomy

in order to understand the internal

structures of the medulla we are going

to view the medulla in Cross sections

and we're going to discuss the internal

anatomy by discussing three levels of

the medulla these are level of

decoration of the pyramids level of

decoration of the medial lemon Sky level

of the olives and inferior cerebellar

poduncles some also say there's a fourth

level just below the ponds but we won't

discuss that

firstly we will discuss the most distal

level of the medulla which is the level

of decisation of the pyramids this level

is then continuous with the spinal cord

now the level of decoration of the

pyramids as the name suggests in this

level is the major decisation point of

the descending mode of fibers because

the pyramids carry your motor fibers

from your brain to your periphery

now decisation essentially means when

the motor nerve fibers travel and move

from one side to the other so for

example from the left to the right or

from the right to the left decasating

within this level you can also find

sensory tracts as well such as the spino

cerebellar tract which carry unconscious

proprioceptive information or the

lateral spinal thalamic tract which

carries information about temperature

and pain to the brain there's also

spinal tract for cranial nerve five

next we will discuss the level of

decussation of the medial laminiscus

in this level we have the major

decisation point of the medial Lemonis

skull fibers the great sensory

decoration

the medial laminisco tract carries

sensory information of touch and

vibration along the posterior spinal

cord to the medulla before the sensory

fibers traveling from the spinal cord

synapse with fibers at the nucleus

gracilis and the nucleus cuneaters

the fibers from the nuclear gracilis and

cunitis then decasate at this level

so moving from one side to the other

side before moving up to the brain stem

and traveling through to the thalamus

and then to the sensory cortex in the

brain

again

decisation means mood the nerve fibers

moving from one side of the body to the

other so from the right side to the left

side

the other sensory tracts include the

spinal cerebellar tract and the lateral

spinal thalamic tract as well as a

spinal tract for cranial nerve number

five just as before

we also have the motor tracked at this

level because remember the motor fibers

are traveling within the pyramids but

they will deficit in the level below

there are nuclei at this level which

include the nucleus gracilis and nucleus

cuneatus which we mentioned there's a

continuation of the spinal nucleus for

cranial nerve five the accessory nucleus

and the hypoglossal nucleus

which carries cranial nerve number 12.

lastly we will discuss the level of the

olives and inferior cerebellar peduncles

now this level is very structurally

different both externally and internally

compared to the previous two levels

firstly at this level the central Canal

has expanded into the fourth ventricle

making this region

the open medulla

at this level the inferior cerebellum

paduncles will join the brain stem to

the cerebellum

the motor tracts will travel through the

pyramids just like before and they'll

keep going down

towards the level of the decisation of

the pyramids

there are sensory tracts here including

the medial longitudinal fasciculus tract

protective spinal tract the spinal

cerebellar tract and the lateral spinal

thalamic tract

spinal tract for cranial nerve five

important nuclei at this level include

the Oliveira nucleus

glossopharyngeal nucleus vagal nucleus

continuation of the spinal nucleus of

cranial nerve 5 continuation of the

hypoglossal nucleus which is your

cranial nerve 12.

so those were the important levels of

the medulla oblongata from the top that

was the levels of the olives the level

of the medial and minuscal decassation

and then the level of the pyramid

decisation for the motor tracts

now there are other important centers so

remember the medulla is the house for

the nuclei of cranial nerves 9 10 11 and

12. the medulla also contains many other

centers that are important for

controlling vital functions of the body

such as the heart rate breathing and

blood pressure the respiratory Center is

a group of nuclear that are located in

the ponds and the medulla oblongata and

then you have the Vaso motor Center

which is important in controlling blood

pressure this also lies within the

medulla oblongata and is responsible for

collecting you know information from the

body which can then influence heart rate

and everything else

now the blood supply or the vasculature

of the medulla is complex and is

dependent on the level being viewed

but essentially it includes

the vertebral arteries which you know

come up from branches of the aortic Arch

the posterior spinal artery

the anterior spinal artery and the

posterior inferior cerebellar artery

now all that information we have learned

about the medulla oblongata the external

the internal the important nuclei as

well as the blood supply is important to

understand some medullary lesion

syndromes which will be discussed in a

separate video

so in summary

the medulla oblongata is part of the

brain stem and is continuous with the

spinal cord below

there are three main levels which

include from the very top the level of

the olives below that is the level of

decoration of the medial and meniscal

tract which carries sensory information

to the brain

and then below that you have the level

of the decisation of the pyramids which

is the decoration of the motor tracts

from the brain to the peripheries

thank you for watching

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