Hindbrain: Medulla Oblongata and its features

len Alfred Ajibola - Sat, 17th October, 2020 @ 10:56 AM

Topics in Biology

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Academic Questions in Biology

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In a food chain, the primary consumers are classified under trophic level  _____.

  • A. Zero

  • B. One

  • C. Two

  • D. Three

  • E. Four

  • F. Five

Cold blooded animals are referred to as _____.

  • A. Homeotherms

  • B. Endotherms

  • C. Poilokitherms

  • D. Ectotherms

  • E. Thermotherms

  • F. None of the above

All reptiles are vertebrates.

  • A. True

  • B. False

_____ cells are responsible for the formation of osteoblasts.

  • A. Osteocytes
  • B. Chondrocytes
  • C. Chondroblasts
  • D. Osteoclasts
  • E. Osteoprogenitor cells
  • F. Osteoblastic

_____ is a bone that constitute the axial skeleton.

  • A. Clavicle
  • B. Scapula
  • C. Patella
  • D. Radius
  • E. Sternum
  • F. Femur

Which of the following is false concerning cartilages and bones?

  • A. Cartilage does not have a direct blood supply while bones have direct blood supply
  • B. The process of ossification replaces a cartilage to bone
  • C. The protein that makes up cartilage is called chondrin while that that makes up bone is called ossein
  • D. Cartilage grows from both ends while bones grow from one of its epiphysis
  • E. They both have living cells within them
  • F. Haversian system is absent in cartilage but present in bones

A diagram showing the movement of energy through a food chain is called a _____.

  • A. Food Chain
  • B. Food Web
  • C. Food Energy
  • D. Food Link
  • E. Food Flow
  • F. Food Pyramid

Which of the following is NOT a part of the wrist bones (or carpal bones)?

  • A. Cuboid
  • B. Scaphoid
  • C. Hamate
  • D. Triquetral
  • E. Pisiform
  • F. Trapezium

Hindbrain - Medulla Oblongata:

The hindbrain, also referred to as rhombencephalon is one of the parts or divisions of the brain; the others being the forebrain and midbrain respectively.

Please read the introduction to the human brain here.

The immediate processes of survival (for instance, respiration, blood circulation and digestive functions) are coordinated by the hindbrain, specifically through the medulla oblongata, a part of the hindbrain.

Meanwhile, other involuntary (or autonomic processes ongoing in our body are also controlled by the medulla oblongata. Some of these include swallowing, digestion, vasodilation, vomiting, coughing and sneezing.

Please read on the uniqueness of man here.

The medulla oblongata (simply called the medulla) is seen at the lowermost portion of the brain (or brainstem) where it continues as the spinal cord inferiorly. For this reason, it becomes the primary point of connection between the Central Nervous System (CNS) and Peripheral Nervous System (PNS).

Below is an image showing the Medulla Oblongata:

Medulla Oblongata - Len Academy

The medulla merges with the spinal cord at the foramen magnum. The foramen magnum is an opening located at the base of the skull, marking the beginning of the spinal cord. It is shown below:

Foramen Magnum - Len Academy

Superiorly, the medulla oblongata is connected to the midbrain via the pons. To this end, it plays a critical role in the transmission of nervous signals through the cerebrum (superiorly) and the spinal cord (inferiorly).

Please read on the forebrain and cerebrum here.

The medulla comprises of both myelinated white matter and unmyelinated gray matter intermingled together, thus giving rise to a network of interconnected neuronal clusters within the brainstem.

You can attempt Len Academy questions on various subjects here.

The following anatomical features are keys to help us identity the medulla oblongata:

Medulla Oblongata - Len

  • Olive (Olivary body): The olivary body is a pair of oval structures present on the surface of the medulla oblongata. It contains numerous nerve fibers that connect the medulla to the pons and cerebellum respectively.

  • Median fissures (Midline Fissures): The median fissures are shallow grooves found on the anterior and posterior parts of the medulla. The posterior median fissure is referred to as the posterior median sulcus and it commences from the end of the fourth ventricle, continuing down into the sulcus of the spinal cord. The fissure (shallow grove) present on the anterior side is simply referred to as the median fissure. It is continuous with the median sulcus of the spinal cord.

  • Pyramids: These are two round masses of nerve fibers located on either side of the median fissure. They connect the medulla to the cerebrum, pons and spinal cord respectively. The pyramid are comprised of about one million nerves which crosses themselves in a process termed decussation of the pyramids.

You can read on the midbrain and its division here.

The medulla oblongata is divided into 2 main portions. These are:

The frontal portion (called the ventral medulla). It contains a pair of structures called pyramids (as explained above).

The backward portion is termed the dorsal medulla. It is this dorsal medulla that forms the dorsal region of the fourth ventricle.

Note: In anatomical terms, ventral means (in front or anterior) and dorsal means (rear or back or posterior).

Think of the fourth ventricle as a fluid filled space surrounded by white matter on the outside and gray matter on the inside.

The image below shows the fourth ventricle:

Fourth Ventricle - Len Academy

Recall that we have 12 cranial nerves exiting the brain, connecting to different parts of the body. It is noteworthy that the dorsal medulla gives origin to the last 7 seven cranial nerves. Below is a list of all the cranial nerves:

  1. Olfactory nerve

  2. Optic nerve

  3. Oculomotor nerve

  4. Trochlear nerve

  5. Trigeminal nerve

  6. Abducens nerve

  7. Facial nerve

  8. Vestibulocochlear nerve

  9. Glossopharyngeal nerve

  10. Vagus nerve

  11. Accessory nerve

  12. Hypoglossal nerve

You can read on homeostasis here.

The medulla oblongata is vital for human survival. Injuries related to it may lead to the following:

  • Respiratory difficulties.

  • Partial paralysis of the opposite side of the body.

  • Partial paralysis to the tongue.

  • Inability to feel the stimulus of touch, temperature and pain.

  • Difficulty in vomiting and swallowing.

  • Difficulty in coughing and sneezing.

Worthy of note is the cerebellum which is another part of the hindbrain. It plays a major role in the body's voluntary movement (especially posture). It accounts for about 10% of the brain's size and comprises of two cerebellar hemispheres separated by a structure called the vermis.

Please read more on the cerebellum here.

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Amazing facts in Biology

Panda eating bamboo - Len Academy

99% of a panda's diet is bamboo. They may eat fish or other small animals occasionally

When attacked by insects, lima beans plant will often command parasitic wasps to their defence.

When the leaves of the lima bean's leaves are eaten by insects, the plant gives off a substance that signals parasitic wasps to swam in, destroying its enemies (the leaf-eating insects) in the process

Frogs drink water through their skin

Armadillos - Len Academy

Armadillos are western mammals known for their unique armor-like shell which are bulletproof

Polka-dotted zebra - Len Academy

Although zebras are known for their characteristics black and white stripes, we still have some polka-dotted zebras

Charles Darwin is a British naturalist and biologist who contributed greatly into the study of evolution. According to research, he frequently ate the animals he studied

Lungs are the only human organ that can float on water

Unlike most snakes that lay eggs, anacondas give birth to live babies

Shrimp - Len Academy

A shrimp's heart is in its head

Women have more pain receptors than men


For a thing to be considered living, it must possess all the basic characteristics of life. These include:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

Please read the explanations on all the basic characteristics of life here

During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.

This is the concept of anaerobic respiration

Food Chain - Len Academy

A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.

Note: Habitat is a place where an organism live. It is of three types:

  • Terrestrial (Land)
  • Aquatic (Water)
  • Arboreal (Treetops)

You can read on food chain here

The term Biology originated from two Greek words. They are:

  • Bios: means life.

  • Logos: means knowledge or to study.

Biology can therefore be defined as the study of life

Anything that has life is generally considered as a living organism (or organism). All living organisms must be able to carry the following activities:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

The above listed points are often regarded as the basic characteristics of life. You can memorize them using the acronym -> MR. NIGER DAC.

You can read on the introduction to biology and the basic characteristics of life here

The gas used in the manufacture of food by plants is Carbon dioxide or Carbon(IV)oxide or CO2

Plants manufacture food through a process called photosynthesis.

Please read on photosynthesis here

It is noteworthy to state that plants are the only orgnisms that take away CO2 from the atmosphere