- Also called:
- medulla
- On the Web:
- National Center for Biotechnology Information - Neuroanatomy, Medulla Oblongata (Oct. 28, 2026)
medulla oblongata
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What is the medulla oblongata?
The medulla oblongata is the lowest part of the brain and brainstem, connecting the pons to the midbrain and merging with the spinal cord at the skull's base. It transmits signals between the spinal cord and higher brain regions and regulates autonomic activities like heartbeat and respiration.
The medulla has two main parts: the ventral medulla and the dorsal medulla. The ventral medulla contains the pyramids and olivary bodies. Most corticospinal tracts cross in the lower medulla, forming the decussation of the pyramids. The dorsal medulla contains the lower region of the fourth ventricle and is the origin site for the last seven cranial nerves. Both myelinated and unmyelinated nerve fibers make up the medulla, and its neurons control movement, relay sensory information, and regulate arousal and sleep.
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Where is the medulla oblongata located in the body?
The medulla oblongata is the lowest part of the brain and the lowest portion of the brainstem. It is positioned at the base of the skull, where it merges with the spinal cord through an opening called the foramen magnum. The medulla oblongata connects to the midbrain via the pons and is critical for transmitting signals between the spinal cord and the higher brain regions. It also plays a vital role in controlling autonomic activities such as respiration and heartbeat.
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What basic functions does the medulla oblongata control?
The medulla oblongata, the lowest part of the brainstem, has a critical role in transmitting signals between the spinal cord and higher brain parts, as well as in controlling autonomic activities.
Key functions of the medulla oblongata:
- Autonomic Activities The medulla oblongata controls autonomic activities like heartbeat and respiration. The respiratory rhythm is generated within the pons and medulla oblongata.
- Reflex actions Other reflexes of the midbrain and medulla oblongata are the cough and sneeze reflexes.
- Transmission of impulses Neurons of the reticular formation in the medulla oblongata carry out complex integrative functions, such as control of movement, relay of somatic sensory information, and control of arousal and sleep.
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What are some main parts or structures within the medulla oblongata?
The medulla oblongata, the lowest part of the brainstem, transmits signals between the spinal cord and higher brain regions, and it regulates autonomic activities like heartbeat and respiration.
Key structures include:
* Ventral Medulla: The front portion, featuring triangular pyramids that contain the pyramidal tracts (corticospinal and corticobulbar tracts). The majority of corticospinal tracts intersect at the decussation of the pyramids. The ventral medulla also contains the olivary bodies, located laterally to the pyramids.
* Dorsal Medulla: Also known as the tegmentum, the dorsal medulla forms the lower region of the fourth ventricle. It contains white matter on the outside and gray matter on the inside, similar to the spinal cord. The last seven cranial nerves originate here, exiting ventrally.
* Reticular Formation: A network of interconnected neuron clusters that transmit motor and sensory impulses. Within the medulla, these neurons control autonomic nervous activity, movement, sensory information from internal organs, arousal, and sleep.2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does the medulla oblongata connect the brain and spinal cord?
The medulla oblongata is the lowest part of the brainstem, connecting the brain to the spinal cord. It merges with the spinal cord at the foramen magnum, the opening at the skull's base. The medulla transmits signals between the spinal cord and higher brain regions and controls autonomic functions like heartbeat and respiration.
The ventral medulla contains pyramids that house the corticospinal and corticobulbar tracts. Most corticospinal tracts cross in the lower medulla, forming the decussation of the pyramids. The dorsal medulla forms the lower region of the fourth ventricle and is the origin site for the last seven cranial nerves. The medulla consists of myelinated and unmyelinated nerve fibers that form part of the reticular formation, which is essential for transmitting motor and sensory impulses.
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What might happen if the medulla oblongata is injured or damaged?
Injury to the medulla oblongata can disrupt signal transmission between the spinal cord and brain and affect autonomic functions like heartbeat and respiration.
Damage to the middle portion of the medulla may result in medial medullary syndrome, characterized by partial paralysis on the opposite side of the body, loss of touch and position senses, and potential tongue paralysis. Lateral medulla damage can lead to lateral medullary syndrome, causing loss of pain and temperature sensations, impaired gag reflex, swallowing difficulties, vertigo, vomiting, and coordination loss. Brainstem damage, including to the medulla oblongata, is life-threatening because it houses control centers for consciousness, respiration, and blood pressure.
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medulla oblongata, the lowest part of the brain and the lowest portion of the brainstem. The medulla oblongata is connected by the pons to the midbrain and is continuous posteriorly with the spinal cord, with which it merges at the opening (foramen magnum) at the base of the skull. The medulla oblongata plays a critical role in transmitting signals between the spinal cord and the higher parts of the brain and in controlling autonomic activities, such as heartbeat and respiration.
The medulla is divided into two main parts: the ventral medulla (the frontal portion) and the dorsal medulla (the rear portion; also known as the tegmentum). The ventral medulla contains a pair of triangular structures called pyramids, within which lie the pyramidal tracts. The pyramidal tracts are made up of the corticospinal tract (running from the cerebral cortex to the spinal cord) and the corticobulbar tract (running from the motor cortex of the frontal lobe to the cranial nerves in the brainstem). In their descent through the lower portion of the medulla (immediately above the junction with the spinal cord), the vast majority (80 to 90 percent) of corticospinal tracts cross, forming the point known as the decussation of the pyramids. The ventral medulla also houses another set of paired structures, the olivary bodies, which are located laterally on the pyramids.
The upper portion of the dorsal medulla forms the lower region of the fourth ventricle (a fluid-filled cavity formed by the expansion of the central canal of the spinal cord upon entering the brain). Similar to the spinal cord, the fourth ventricle is surrounded by white matter on the outside, with the gray matter on the inside. The dorsal medulla also is the site of origin for the last seven cranial nerves, most of which exit the medulla ventrally.
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The medulla consists of both myelinated (white matter) and unmyelinated (gray matter) nerve fibres, and, similar to other structures in the brainstem, the white matter of the medulla, rather than lying beneath the gray matter, is intermingled with the latter, giving rise to part of the reticular formation (a network of interconnected neuron clusters within the brainstem). Neurons of the reticular formation play a central role in the transmission of motor and sensory impulses. Those in the medulla carry out complex integrative functions; for example, different functional centres specialize in the control of autonomic nervous activity, regulating respiration, heart rate, and digestive processes. Other activities of neurons in the medulla include control of movement, relay of somatic sensory information from internal organs, and control of arousal and sleep.
Injuries or diseases affecting the middle portion of the medulla may result in medial medullary syndrome, which is characterized by partial paralysis of the opposite side of the body, loss of the senses of touch and position, or partial paralysis of the tongue. Injuries or disease of the lateral medulla may cause lateral medullary syndrome, which is associated with a loss of pain and temperature sensations, loss of the gag reflex, difficulty in swallowing, vertigo, vomiting, or loss of coordination.