The foramen lacerum is an opening in the human skull. It is used as a passageway for nerve fibers. This pathway can provide nerve supply to the outer and inner regions of the skull.
What is the lacerated foramen?
The foramen lacerum is a small opening in the skull. The human skull is made up of several hard bones. The substance of the bone is very strong and does not offer any possibility of passage. In this way, the skull serves to protect the brain. In it all received sensory stimuli and information are processed and behavior is controlled. Emotions arise in the brain, memory is contained there and all cognitive processes as well as consciousness is anchored there. To ensure that the brain is adequately protected, it is encased by the skull. This is composed of various bones and is divided into the cerebral and the facial skull. In order to nevertheless ensure the supply of blood or nerves between the inner and outer areas of the skull, there are various small holes. The blood and nerve pathways pass through them undamaged, thus ensuring innervation of the different areas. The foramen lacerum belongs to the region formed by the bones of the skull. It is located at the junction where the occipital bone, temporal bone and sphenoid bone meet.
Anatomy and structure
The human skull is formed from various bones. The foramen lacerum is an opening, this is located in the caudal, the posterior region of the base of the skull. It is paired on both halves of the skull. In the structure of the skull, the bones of the cerebral skull and the facial skull are to be distinguished from each other. All of them consist of hard bones and merge smoothly into each other. The cranium is formed from 6 different bones. These are the occipital bone, parietal bone, temporal bone, sphenoid bone, frontal bone and ethmoid bone. The foramen lacerum is formed by the occipital bone, the temporal bone and the sphenoid bone. Physicians refer to them as Os occipitale, Os temporale and Os spheniodale. The temporal bone contains the petrous bone. It is a pyramid-shaped bone structure called the pars petrosa ossis temporalis. A bony canal, the canalis caroticus, is located there. The foramen lacerum is located at this point. In addition, it is demarcated by the posterior margin and the proccessus petrosus of the sphenoid bone. The processus petrosus is a small process of the bone of the sphenoid bone.
Function and tasks
As a small opening in the skull, the function of the lacerated foramen is to allow passage of vessels and various fibers. This allows various blood and nerve pathways to make their way from inside the skull to the outer base of the skull. This ensures the supply of various areas inside and outside the skull. The blood pathways that pass through the foramen lacerum include various emissary veins and arteries. The emissary veins are the parietal vein, the mastoid vein, the occipital vein, the condylar vein and the occipital vein. These are smaller veins, provide a connection between the superficial veins and the sinus inside the head. In addition, the canalis pterygoidei artery and the ramus meningealis of the ascending pharyngeal artery enter through the lacerated foramen. The canalis pterygoidei artery supplies with its branches the nasal and oral cavities as well as the eustachian tube, the tuba auditiva. The ramus meningealis of the ascending pharyngeal artery, with its branches, supplies the pharyngeal muscles, the tympanic cavity, and the dura mater. In addition to the blood vessels, various nerve fibers pass through the foramen lacerum. These include the petrosal minor nerve and the canal pterygoid nerve. The latter unites the petrosal major nerve and the petrosal profundal nerve. The petrosal minor nerve is assigned to the IX cranial nerve. This is the glossopharyngeal nerve, which with its branches the parotid gland. This is the largest gland in the human body responsible for saliva production.
Diseases
The foramen lacerum provides passage for important blood and nerve pathways. The opening can be closed by tissue swelling of adjacent brain areas. This leads to blood stasis. The congestion of the blood can cause the walls of the blood vessels to tear.This causes hemorrhages that can cause dizziness, impaired consciousness or loss of consciousness. In addition, the risk of a stroke or cerebral apoplexy increases. Under certain circumstances, this can be fatal or cause lifelong paralysis of various systems of the body. In addition, an occlusion of the opening means that the nerve fibers can no longer continue their journey unhindered and the corresponding organs are no longer adequately supplied. As a result, the parotid gland as well as the eustachian tube and pharyngeal muscles are no longer sufficiently innervated and their functional activity is restricted. As soon as the parotid gland produces less saliva, this affects the swallowing process as well as speech formation. The food can no longer be sufficiently decomposed, the swallowing process becomes more difficult and the formation of speech is restricted. The pharyngeal muscles are important for the activity of the human dentition and the chewing process. The strength of the four masticatory muscles required for this is reduced. As a result, the grinding of food is more cumbersome and laborious. Failure of the systems is not to be expected, since the nerve fibers for innervation of the described organs converge via different pathways.