An opening or Orifice in the skeleton through which some structures emerges such as, nerves, arteries, veins, muscles and ligaments pass. There is multiple such foramen locates on the lower behalf of the skull that acts as pathways for the different structures which pass via them.
So here we listed out the different foramen seen in the skull and also the structures running through them. There is a lot more foramen probably be small and big which have structures enter into them, and we have listed most of the prominent foramen in the base of the skull and the structures passing through these holes.
Contents of the Foramina of skull:
Here I am going to be looking at the different structures that approach through the foramina in the skull, so the vessels and nerves can pass through these tiny holes. It’s very much important to know because a well, medical schools love asking about which complex structures pass through the foramina. Let’s start the countdown.
The spinal cord basically runs through the large foramen magnum doping up the occipital bone. The foramen magnum is situated in the back and beneath the skull. The occipital bone of the spinal cord composes of four equivalent parts: the basilar part, a couple of condylar parts and the squamous part as well. The basilar part sits opposite to the foramen magnum and joins the sphenoid bone. The squamous part is the curved piece located behind it, and that helps in cradles the brain, with the two condylar parts forming the sides. The foramen magnum also allows passing the accessory nerves, the vertebral arteries, the anterior and posterior spinal arteries, and the membrane tectoria and alar ligaments respectively to exit via the occipital bone.
The vertebral artery (VA) emerges from the subclavian artery, ascends in the neck to deliver the posterior fossa and occipital lobes as well as gives segmental vertebral and spinal column an oxygenated blood supply.
Spinal accessory nerve:
The spinal accessory nerve, also known as accessory nerve, is the 11th cranial nerve (CN XI) and is consisted of two prominent parts, the cranial part, and the spinal part respectively.
The cranial part ( the accessory portion) is quite smaller of the two. Its fibers emerge from the cells of the nucleus ambiguous and produce as 4 or 5 delicate rootlets from the side of the medulla oblongata, situates beneath the roots of the vagus nerve. It goes through laterally to the jugular foramen, where it interchanges fibers with the spinal part or can become united to it for a short distance; here it can also be connected by almost 1 or 2 filaments with the jugular ganglion of the vagus. It then crosses via the jugular foramen, totally separates from the spinal portion and is continued over the large surface of the ganglion nodosum of the vagus, to the surface of which it is cohesive, and is equivalently distributed to the pharyngeal and superior laryngeal little sub-branches of the vagus. Through the pharyngeal branch it probably deliverers the blood flow to the musculus uvulae and levator veli palatini. Some few filaments from it are continued into the trunk seem structure of the vagus located below the ganglion, to be distributed with the recurrent nerve and probably also with the cardiac nerves (an important branch supporting in balancing).
The spinal part is actually firm in texture, and its fibers emerge from the ventral horn-shaped cells in the spinal cord present between the C1 and C5 of the cervical plexus. The fibers emerge from the spinal cord laterally between the anterior and posterior spinal nerve roots to make a single trunk, which goes through into the skull via the aid of foramen magnum. It then skips the skull through the jugular foramen, through which it passes, lying in the same sheath of dura mater as the vagus, but here it is being separated from it by a fold of the arachnoid.
Apical ligament of dens:
The apical ligament connects the apex of the dens to the anterior margin of the foramen magnum that is conceptually mentioned above. It is the weak, fibrous remnant of the notochord. On the other-side some describes it as like, it is the triangular interval between the alar ligaments is another fibrous cord ( a bone of spinal cord), the apical ligament of dens (apical odontoid ligament), which expands from the top of the odontoid procedure to the anterior margin of the foramen magnum, being intimately mixture with the deep dilate part of the anterior atlantooccipital membrane and superior crus of the transverse ligament of the atlas receptively. It is called as a rudimentary intervertebral fibrocartilage, and in it run to the ground of the notochord probably persist.
The mental artery is a terminal branch of the inferior alveolar artery which itself is a branch of the first part of the maxillary artery. It emerges onto the face from the mandibular canal at the mental foramen and supplies muscles and skin in the chin region. The mental artery anastomoses with the inferior labial and submental arteries.
The emissary veins are valveless and go through various cranial foramina to communicate the intra-cranial along with extra-cranial veins. Thereby they keep a balance of intra-cranial venous pressure. Clinically, emissary veins probably carry infected thrombus from the exterior to the interior of the cranial cavity. Some of the veins are continuity remain constant, while others all are variable.
The oculomotor nerve is the 3rd of 12 pairs of cranial nerves located in the brain. This nerve is accountable for eyeball movement. It gives the olfactory and optic nerves needy orders. The oculomotor nerve consist of a couple of separate portions, each of which has a unique function.