Anatomy of the Nervous System

• The front region of the brain is called rostral or anterior
• The back region of the brain is called caudal or posterior
• The top region of the brain is called dorsal or superior
• The bottom region of the brain is called ventral or inferior
• A coronal cut of the brain is a vertical cut made from the left to the right
• A sagittal cut of the brain is a vertical cut made from the rostral region to the caudal region
• A horizontal cut of the brain is made horizontal to the plane of an upright brain
• The nervous system developed from the ectoderm germ cell group which then formed into the neural tube. The neural tube contains components that will later become the central nervous system.
• The rhombencephalon is the older part of the central nervous system and is also known as the hindbrain.
• The mesencephalon is also known as the midbrain and is the region of the brain that does not change much from the 3-vesicle to the 5-vesicle stage.
• The prosencephalon is the also known as the forebrain and develops into the "higher order" brain regions such as the cerebral cortex.
• The myelencephalon and the metencephalon are the two 5-vesicle stage regions that develop from the rhombencephalon.
• The myelencephalon develops in to the medulla oblongata. The medulla oblongata contains clumps of neurons that are responsible for carrying out basic life functions.
• The metencephalon develops into the pons and cerebellum. The pons is responsible for performing basic life functions as well as the ability to hear sounds and taste foods. The pons also acts like a bridge between various brain regions. The cerebellum is also known as the little brain and is responsible for motor control functions.
• The mesencephalon performs tasks such responding to stimuli, coordinating complex movements, responding to incoming visual stimuli, and processing reward and motivation.
• The two 5-vesicle stage brain regions that develop from the prosencephalon are the diencephalon and the telencephalon.
• The diencephalon develops into the thalamus and hypothalamus. The thalamus is also known as the relay station because almost every sensory stimulus information passes through the thalamus. The hypothalamus communicates with the body's endocrine system.
• The telencephalon develops into the basal ganglia and the cerebral cortex. The basal ganglia is responsible for motor and habit learning, emotional processing, and action selection. The cerebral cortex is the outer bark of the brain and is responsible for attention, memory, and language processing.
• Gyri are the raised edges, sulci or fissures are the grooved indentations on the cortex of the brain.
• Longitudinal fissure: goes from anterior to posterior, divides the brain into the 2 hemispheres.

  Central sulcus: goes along the dorsal-ventral direction, and cuts from the 2 sides of the brain at about the halfway point on the longitudinal fissure.

  Lateral fissure: goes along the anterior-posterior direction, curves slightly dorsally and located at around the third middle point in the anterior-posterior axis.
• The occipital lobe is the smallest and posterior-most lobe. It contains the primary visual cortex.
• The temporal lobe is located by the temples of the head and is the ventral-most lobe, beneath the occipital lobe. It contains the hippocampus, responsible for memory-related processes and contains the primary auditory cortex.
• The parietal lobe is in the dorsal aspect of the brain and is between the lateral fissure and the central sulcus. It is responsible for proprioception and the sensation of different tactile differences. Proprioception is the ability to determine where different parts of the body are located. It contains the primary somatosensory cortex.
• The frontal lobe is the largest lobe in mammals and contains the primary motor cortex. It is also responsible for higher-order functions such as personality, the suppression of actions, and mental math.
• The spinal cord is housed within a series of bones called the vertebral column. There are a total of 31 sections of the spinal cord, each section leading to 2 pairs of spinal nerves: 2 efferent, 2 afferent. Afferent nerves branch from the dorsal side and the efferent nerves branch from the ventral side. These nerves meet and extend away from the spinal cord and form the spinal nerves(31 of them).
• There are 4 regions of the spinal cord: cervical, thoracic, lumbar, and sacral. (+ another one with only 1 pair of spinal nerves called the coccygeal region).
• The cervical regions contains the upper 8 spinal nerves. It delivers and receives information from the shoulders, neck, arms, and hands. This region contains the C3-C5 spinal nerves which innervate the diaphragm, therefore an injury to this area leads to rapid death.
• The thoracic region contains 12 pairs of spinal cords. It controls the middle trunk area, ribs, and abdominal muscles. It is also responsible for the activity of organs during the fight-or-flight response.
• The lumbar regions contains 5 pairs of spinal cords. It provides motor command to the hips, thighs, and knees.
• The sacral region is the posterior most region and delivers information to and from the dorsal aspects of the legs, the genital organs, as well as parasympathetic nerves.
• Somatosensory afferent nerves enter the spinal cord from the dorsal side, whereas the efferent motor cortex exit the spinal cord from the ventral side.
• Most sensory neurons are located outside of the spinal cord in a large clump of nervous tissues called the dorsal root ganglion.
• There is typically more white matter at the anterior regions compared to the posterior regions of the spinal cord.
• The peripheral nervous system is divided into 3 main branches: the somatic, autonomic, and enteric nervous systems.
• The somatic nervous system consists of all part of the PNS that are involved with the outside environment. It is responsible for muscle movements related to intentional actions, aka voluntary muscle movement.
• The autonomic nervous system consists of all branches of the PNS that deal with the internal environment of the body. It detects the internal state of nerves which influence internal organ functioning and is responsible for carrying out functions and responses unconsciously without voluntary control.
• The autonomic nervous system consists of 2 branches: sympathetic and parasympathetic.
• The sympathetic nervous system is activated when faced with a threat, leading to the fight-or-flight response. This response results in increased respiration, dilation of pupils, and decreased digestion.
• The parasympathetic nervous system is activated after a satiating meal, warm surroundings, and lack of threat, resulting in the rest-and-digest response.
• The body maintains homeostasis from both sympathetic and parasympathetic nervous systems by receiving a balance between signals from both systems. However, this balance can shift quickly in either direction to produce a corresponding response.