Lateral view of the brain
The lateral view of the brain shows the three major parts of the brain: cerebrum, cerebellum and brainstem.
A lateral view of the cerebrum is the best perspective to appreciate the lobes of the hemispheres. Each hemisphere is conventionally divided into six lobes, but only four of them are visible from this lateral perspective. The lobes are named after the bones of the skull that overlie them:
- The frontal lobe
- The parietal lobe
- The temporal lobe
- The occipital lobe
The most caudally located portion of the brain is the brainstem, which consists of three main parts: midbrain, pons, and medulla. Attached to the dorsal surface of the brainstem is the cerebellum, divided into anterior, posterior, and flocculonodular lobes.
In this article we will introduce the main structures seen on lateral images of the human brain and take a closer look at their anatomy and functions.
Frontal lobe - frontal pole; superior, middle and inferior frontal gyri; precentral, superior frontal, inferior frontal sulci
Parietal lobe - postcentral gyrus, postcentral sulcus, superior parietal lobule, intraparietal sulcus, inferior parietal lobule, supramarginal gyrus, angular gyrus
Temporal lobe - temporal pole, superior temporal gyrus, superior temporal sulcus, middle temporal gyrus, middle temporal sulcus, inferior temporal sulcus, preoccipital notch
Occipital lobe - superior occipital gyrus, inferior occipital gyrus, occipital pole
Insular opercula - frontal, parietal, temporal portions; beneath located: short gyri, long gyrus, circular sulcus of insula
|Cerebellum||Primary fissure, anterior lobe, posterior lobe|
Midbrain - 3rd and 4th cranial nerves
Pons - 5th cranial nerve, middle cerebellar peduncle
Medulla - 9th-12th cranial nerves; anterior median fissure, anterolateral sulcus, pyramid, posterolateral sulcus, olive, fasciculus gracilis, fasciculus cuneatus
The area seen from the superolateral view of the cerebrum is known as the cerebral cortex. This is a thick area that makes up the largest portion of the brain’s total mass. It is composed of a series of tortuous folds known as the gyri (singular: gyrus). Between these gyri are grooves or indentations called sulci (singular: sulcus).
The deep sulci are known as fissures, and they separate the cerebral cortex into four main subdivisions or lobes: frontal, parietal, temporal and occipital lobes. These lobes are named according to their relation to bones of the skull.
The additional external features of the cerebral cortex are its 'pointed ends' also known as the poles. These poles, which are also named in relation to the cranial bones, include:
- The frontal pole – located anteriorly;
- The occipital pole – located posteriorly;
- The temporal pole – lying between the frontal and occipital poles, and pointed anteroinferiorly.
The frontal lobe takes up the majority of the superolateral surface, forming the most anterior portion of the cerebrum. It lies just deep to the frontal bone. The frontal lobe is separated from the parietal lobe by the central sulcus (fissure of Rolando), while the frontal and parietal lobes are separated from the temporal lobe by the lateral (Sylvian) sulcus.
The precentral sulcus runs parallel to the central sulcus and demarkates the area called the precentral gyrus.
Anterior to the precentral gyrus, there are two sulci that run in an anteroposterior direction. These are the superior and inferior frontal sulci. These sulci divide this region into superior, middle, and inferior frontal gyri.
The inferior frontal gyrus is further divided into three parts by the stem of the lateral sulcus. These three parts include:
- The orbital part
- The triangular part
- The opercular part
The frontal lobe controls a diverse range of functions such as muscle movements or muscle control as well as cognitive functions such as planning, concentration, language as well as rationale and executive control.
The temporal lobe is located inferior to the lateral sulcus (Sylvian fissure) which separates the temporal lobe from the rest of the cerebral hemisphere. It has two sulci that run parallel to the lateral sulcus known as the superior and inferior temporal sulci.
These sulci they divide the superolateral surface of the temporal lobe into three lobes:
- The superior temporal gyus
- The middle temporal gyus
- The inferior temporal gyrus
The temporal lobe is important for processing auditory stimuli, as well as in processes such as learning and memory.
Want to learn more about the parts of the brain? Try our free brain diagrams and quizzes!
The parietal lobe is defined on the by the central fissure anteriorly, and the parieto-occipital sulcus, posteriorly. Inferiorly, the lobe is defined by the posterior branch of the lateral sulcus.
Within the parietal lobe, the postcentral sulcus runs parallel to the central sulcus. These two sulci define the gyrus known as the postcentral gyrus. The cortex of this area is known as the primary somatosensory cortex involved in the processing of the sensory stimuli. The remaining part of the parietal lobe is divided into a superior parietal lobule and an inferior parietal lobule by the intraparietal sulcus which runs anteroposteriorly.
The inferior parietal lobule is further divided into two gyri:
- The supramarginal gyrus – the part that arches over the upturned end of the lateral sulcus.
- The angular gyrus – the part that arches over the superior temporal sulcus.
The occipital lobe is the most caudal portion of the cerebrum. It is defined anteriorly by the parieto-occipital sulcus and the upturned posterior end of the inferior temporal sulcus.
The occipital lobe hosts three short sulci.
- The lateral occipital sulcus - this sulcus horizontally and divides the lobe into superior and inferior occipital gyri.
- The lunate sulcus - this sulcus runs inferiorly and slightly anteriorly just in front of the occipital pole and defines a vertical strip just in front of it. This strip is called the gyrus descendens.
- The transverse occipital sulcus is located in the uppermost part of the occipital lobe. It defines an area just superior to itself. This area is called the arcus parieto-occipitalis. As its name suggests, this portion belongs partly to the parietal lobe and partly to the occipital lobe).
The occipital lobe is mostly involved in visual processing.
Insula is a Latin word for 'island'. As its name implies, it is located more centrally in the brain and it does not belong to any of the four lobes described above. The insula is located deep to the lateral sulcus and it's considered another brain lobe.
The surface of the insula is divided into a number of gyri. The areas that cover the insula are called opercula (meaning lids) and they include:
- The frontal operculum - lying between the anterior and ascending rami of lateral sulcus;
- The frontoparietal operculum - which lies above the posterior ramus of lateral sulcus;
- The temporal operculum - which lies below the posterior ramus of lateral sulcus.
The brainstem is made up of (moving superior to inferior) the midbrain, pons and medulla. It is continuous superiorly with the diencephalon and inferiorly with the spinal cord. Posteriorly, the brainstem is related to the cerebellum. The outer surface of the brainstem is intimately related to the meninges, arteries, veins, and a number of cranial nerves that emerge from it.
The midbrain is the uppermost part of the brainstem. Ventrally, it is directly connected with the cerebrum via the cerebral peduncles. From the lateral perspective, we can also see the tectum of the midbrain with the four coliculi that contain the reflex centers of the auditory and visual pathways. The oculomotor (CN III) and trochlear (CN IV) nerves originate from the midbrain.
The pons is the middle part of the brainstem, located just inferior to the midbrain. It is connected with the cerebellum via the middle cerebellar peduncles. With its strategic relay position it is an important relay center between the cerebrum and the cerebellum. The trigeminal nerve (CN V) arises from the pons. The dorsal aspect of the pons participates in the formation of the fourth ventricle.
The medulla oblongata is located just inferior to the pons and superior to the spinal cord. The pons and medulla comprise the pontomedullary junction which is an important origin point for several cranial nerves including the abducens nerve (CN VI), the facial nerve (CN VII) and the vestibulocochlear nerve (CN VIII). On the dorsal surface of the medulla there are olivary bodies (a.k.a. olives) that contain olivary nuclei involved in motor learning and perception of sound. Medial to the olives, there is a pair of meduallry pyramids that contain the corticospinal fibers of the pyramidal tract. Similar to the other parts of the brainstem, the medulla hosts several cranial nuclei including the glossopharyngeal nerve (CN IX), the vagus nerve (CN X), the accessory nerve (CN XI) and the hypoglossal nerve (CN XII).
The cerebellum, also known as the 'small brain' is a mass of neural tissue that lies in the posterior cranial fossa. The cerebellum lies posterior to the brainstem, and it is separated from the cerebrum by a fold of dura mater called the tentorium cerebelli.
The cerebellum consists of a part lying near the midline called the vermis, and of two lateral hemispheres. Similar to the cerebrum, the whole outer surface of the cerebellum is covered by a superficial layer of gray matter, called the cerebellar cortex.
The outer surface of the cerebellum is marked by a series of fissures that run more or less parallel to one another. The fissures subdivide the surface of the cerebellum into narrow leaf-like bands or folia. Some features of the surface of the cerebellum are deeper than others, and they divide the cerebellum into lobes within which smaller lobule may be recognized. The deepest fissures in the cerebellum are the primary fissure which runs transversely across the superior surface, and the posterolateral fissure seen on the inferior aspect. These features divide the cerebellum into three lobes; the anterior, posterior and flocculonodular lobes. The anterior and posterior lobes together form the corpus cerebelli.
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