Nervous System of Guinea Pig

In this article, we will learn about the nervous system of guinea pig or Cavia porcellus in detail. Let’s jump to the nervous system of the Cavia porcellus.

Table of Contents

The nervous system is the system of cells, tissues, and organs that regulates the body’s responses to internal and external stimuli. The entire nervous system of guinea pig is divided into three parts –

Central Nervous System: Includes the brain and spinal cord.
Peripheral Nervous System: consists of cranial nerves and spinal nerves.
Autonomic Nervous System: consists of sympathetic nerve cord and ganglia.

A. Central Nervous System

The central nervous system includes 1. The brain and 2. The spinal cord.

1. The Brain

Fig: Brain of the Guinea pig – Cavia porcellus. First – Dorsal view, Second – Ventral view

- - The brain consists of five divisions. They are telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.
  - Three-layered meninges cover the brain.
  - The outer layer of meninges is called the dura mater, the inner layer is called the pia mater and the middle layer is called the arachnoid layer.
  - The brain is large in size. Olfactory lobes are small and club-shaped.
  - Cerebral hemispheres and cerebellum are more convoluted to increase the area.
  - Cerebral hemispheres are large, elongated, and cover the diencephalon and mesencephalon. Each cerebral hemisphere is divided into four lobes and they are frontal, parietal, temporal, and occipital.
  - Corpus Callosum connects the two cerebral hemispheres.
  - The ventral side of the diencephalon is known as the hypothalamus. It is well developed.
  - The hypothalamus bears optic chiasma, a pituitary body, and a pair of mammillary bodies.
  - The pineal body and choroid plexus are located at the dorsal side of the diencephalon.
  - The mesencephalon is thick and contains 4 optic lobes called corpora quadrigemina.
  - The cerebellum is divided into a median vermis and two lateral lobes.
  - Each lateral lobe of the cerebellum is with a short flocculus.
  - Pons varolii is present on the ventral side of the cerebellum.
  - Medulla Oblongata carries a posterior choroid plexus.

2. Spinal Cord

- - The spinal cord runs through the neural canal of the vertebral column.
  - It runs up to the posteriormost end of the vertebral column.
  - At the posterior end, the spinal cord forms a narrow and triangular cone which is known as conus terminalis.
  - A bunch of nerves arises from the conus terminalis.
  - The spinal cord is slightly swollen in the brachial and lumbar regions.

B. Peripheral Nervous System

The peripheral nervous system consists of 1. cranial nerves and 2. spinal nerves.

1. Cranial Nerves

Guinea pigs or Cavia porcellus have 12 pairs of cranial nerves and they are given below.

2. Spinal Nerves

- - In guinea pigs, 32 pairs of spinal nerves are present.
  - The fourth and fifth spinal nerves unite and form the phrenic nerve to supply the muscles of the diaphragm.
  - The first four nerves of the cervical region and the first thoracic nerve unite to form the brachial plexus.
  - The brachial plexus innervates the forelimbs.
  - The last two lumbar nerves and sacral nerves form the sciatic plexus.
  - The sciatic plexus innervates the hindlimbs.

C. Autonomic Nervous System

It consists of the sympathetic nerve cord and ganglia.
The sympathetic nerve cords are one on each side of the aorta.
Each nerve cord bears one anterior and one posterior cervical ganglia.

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Nervous System of Guinea Pig | Cavia porcellus | Diagram