Medulla Oblongata

Bookmark added to your notes.
View Notes
×

Introduction

The brain is regarded as one of the master organs which helps in the control and communication within the body and also the surroundings. In comparison to all other organs of the body, the brain is the most complicated and also highly developed organ. Larger and more complicated animals have a greater need for an organ to regulate activities of the body. Hence, the more an animal is developed, the more its highly evolved brains. 


Basic Features of a Brain

However, brains have great differences, they also possess some common features to look at - 

  • Nerve cells and neurons are some of the components of which brains are composed of. 

  • All brains possess a minimum of three major sections: a sensory section, an integrating section and a motor section

The overall function of the brain, which is deemed as behaviour, is decided by two factors – the precise way during which these three divisions are connected and therefore the presence of other special brain centres.


What is Medulla Oblongata? 

The brain majorly is often classified into the forebrain, midbrain and therefore the hindbrain. This lower part of the brain, hindbrain, further is often distinguished into the Cerebellum, medulla and pons.

The word medulla has its origins from Latin, where “medis” corresponds to middle and “oblongata” corresponds to long. Hence, the medulla may be a long-stem like structure, piriform, conic resembling. It is found within the lowest region of the brain chiefly regulating the autonomic functions like breathing, heartbeat and digestion. It is critically important because it connects the medulla spinalis, pons and therefore the cerebral mantle. Additionally, it assists to take care of body posture and governs our reflexes.

Medulla Oblongata is also known as the ‘Spinal Cord of the Head’ for being the main controlling element of head and facial musculature. 


Medulla Oblongata – Highlights

  • The medulla oblongata develops from the myelencephalon

  • It is the foremost caudal brainstem structure situated within the posterior-most part of the brainstem merging with the medulla spinalis

  • Dimensions – at its largest, the medulla is 3 cm long and a couple of cm wide with a thickness of 1.25 cm

  • It is home to all or any descending and ascending tracts carrying signals between the medulla spinalis and therefore the brain

  • Its broad portions unite the overlying pons hence the narrow section continues with the medulla spinalis

  • The intersection between the medulla spinalis and medulla concurs with the upper border of the primary neck bone (Atlas)

  • In addition to the opposite sections of the hindbrain, the medulla spaces call at the infratentorial space

  • The medulla regulates a number of autonomic functions

  • Commissural fibres define the base of the medulla. It crosses over from the ipsilateral side within the medulla spinalis to the contralateral side within the brainstem, underlying which is that the medulla spinalis

It Can Be Segregated Into –

  • An upper posterior section connected to the lower a part of "> a part of the 4th ventricle – it's the “open part of the medulla”

  • Lower section with the central canal – it's the “closed a part of the medulla”

Medulla Oblongata – Location

It is located anterior to the cerebellum within the brain stem, inferior to the pons. It is the lowest section of the hindbrain. It is situated within the anterior section of the posterior cranial fossa, stretching right down to the foramen

Posteriorly – vallecula of the cerebellum

Anteriorly – meninges and clivus

The topmost part of the medulla goes on to make the fourth cerebral ventricle. This ventricle may be a cavity holding the spinal fluid and continues with the Sylvian aqueduct.


Medulla Oblongata Anatomy – Structure

The medulla may be a portion of the brainstem linking the medulla spinalis and therefore the pons. It extends through the foramen to the amount of the atlas. It is embraced dorsally above the foramen by the cerebral hemispheres.

Medulla extends from the pronto-medullary junction until the plane below the foramen on the brink of 0.5 cm. The spinal cord features a central canal that extends into its lower half to open within the four ventricles at its upper half. The spinal fluid surrounds the medulla from the within (central canal) and out of doors (subarachnoid space). The medulla is situated between the 2 lobes of the cerebellum (anterior cerebellar notch).


Key Components of the Medulla Oblongata

Medulla is divided into two major parts –

  • Ventral medulla – the front portion

  • Dorsal medulla – rear portion. It is also known as the tegmentum

Components:

1. Median fissures

Shallow grooves can be found along the posterior and anterior portions of the medulla which are the median fissures.

2. Pyramids

The pyramids can be regarded as the upper part of the medulla ventrally which is deeply grooved in the midline along with a bold complexity on either side. It is a result of the contained cortico-spinal fibres. Some of the fibres overlap one another hence obliterating the anterior median fissure, which is understood because of the decussation of the pyramids. They are the 2 round masses of substantia alba situated on the facing sides of the anterior median fissure.

3. Olivary bodies

In the upper part of the medulla, the world between the posterolateral and anterolateral sulcus is distinguished by swelling, a pair of oval structures referred to as the olivary bodies or olives. It contains nerve fibres linking the cerebellum and pons with the medulla. The swelling is a result of the massive mass of grey matter, the inferior olivary nucleus

4. Fasciculus gracilis

The buttocks of the medulla between the posterolateral sulcus and posterior median comprise tracts entering from the posterior funiculus of the medulla spinalis. These structures are the Fasciculus gracilis situated intermediate to the midline and laterally to the fasciculus cuneatus. These structures typically are the continuation of the bundle of nerve fibre tracts extending from the medulla spinalis to the medulla.

The terminal end of the fasciculi possesses round elevations mentioned because of the gracile and cuneate tubercles. These are as a result of the nucleus cuneatus and nucleus gracilis. Overlying the tubercles, a triangular fossa occupies the posterior aspect of the medulla forming the ground of the 4th ventricle. Right laterally immediate to the present fasciculus cuneatus is that the tuberculum cinereum, which is yet one more longitudinal elevation caused as a result of the spinal nucleus of the trigeminal. 


Medulla Oblongata Function

The medulla is critical in performing some important body functions concerning the regulation of mental, motor and sensory processing. It is responsible to manage the autonomic functions of the body while it connects the upper levels of the brain thereto of the medulla spinalis.

  • It relays nerve impulses between the medulla spinalis and therefore the brain

  • Controls autonomic functions

  • Regulates mood

  • Coordinates movements of the body

  • For coughing, vomiting, sneezing and swallowing, it is the reflex centre

  • It is the vasomotor center: baroreceptors

  • Parasympathetic and sympathetic system are the cardiac centres

Primarily, the medulla is the control centre for respiratory and cardiovascular activities. It is responsible to manage the vital sign, pulse, rate of respiration and other such life-sustaining activities. Additionally, it also regulates involuntary reflexes like gagging, sneezing and swallowing. It coordinates the voluntary actions namely movement of the attention too.

Medulla houses many nerve nuclei crucial for the top, speech, digestion of food and movement of the shoulder. The medulla also relays sensory information to the thalamus which finally reaches the cerebral mantle.

FAQ (Frequently Asked Questions)

1. Explain How the Nervous System is Classified.

Ans. The nervous system in humans can be broadly classified into two types, namely, the peripheral nervous system and central nervous system.

2. Describe the Central Nervous System.

Ans. The central nervous system primarily consists of the brain and the spinal cord. The system coordinates and controls various aspects of life, ranging from physical attributes (heartbeat, breathing) to mental capabilities (memory, intelligence).