Foramen magnum - wikipedia Foramen magnum This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. ( January 2013 ) Foraman magnum Upper surface of base of the skull. The hole indicated by an arrow is the foramen magnum Occipital bone. Inner surface. Details Identifiers Latin Foraman magnum MeSH A02. 835.232. 781.572. 434 TA A02. 1.04. 002 FMA 75306 Anatomical terms of bone ( edit on Wikidata ) The foramen magnum ( Latin : great hole ) is a large oval opening ( foramen ) in the occipital bone of the skull in humans and various other animals. It is one of the several oval or circular openings ( foramina ) in the base of the skull. The spinal cord, an extension of the medulla, passes through the foramen magnum as it exits the cranial cavity. Apart from the transmission of the medulla oblongata and its membranes, the foramen magnum transmits the vertebral arteries, the anterior and posterior spinal arteries, the tectorial membranes and alar ligaments. It also transmits the spinal component of the accessory nerve into the skull. The opisthion is the midpoint on the posterior margin of the foramen magnum and is a cephalometric landmark. Another landmark is the basion located at the midpoint on the anterior margin of the foramen magnum. The foramen magnum is a very important feature in bipedal mammals. One of the attributes of a bipedal animal 's foramen magnum is a forward shift of the anterior border ; this is caused by the shortening of the cranial base. Studies on the foramen magnum position have shown a connection to the functional influences of both posture and locomotion. The forward shift of the foramen magnum is apparent in bipedal hominins, including modern humans, Australopithecus africanus, and Paranthropus boisei. This common feature of bipedal hominins is the driving argument used by Michel Brunet that Sahelanthropus tchadensis was also bipedal, and may be the earliest known bipedal ape. The discovery of this feature has given scientists another form of identifying bipedal mammals. Contents 1 Compartments 2 Other animals 3 Additional images 4 See also 5 References 6 External links Compartments The alar ligament which is attached on each side to the tubercle of occipital condyle on each side of Foramen magnum divides it into anterior smaller compartment and posterior larger compartment ; Structures passing through anterior compartment ( osseo - ligamentous compartment ) are Apical ligament and tip of dens Upper band of Cruciate ligament Membrana tectoria Structures passing through posterior compartment ( Neuro - vascular compartment ) are Lower end of Medulla Oblongata with meninges Fourth part of vertebral artery surrounded by sympathetic plexus of nerves Spinal roots of accessory nerves Anterior and posterior spinal arteries Tonsil of cerebellum ( occasionally ) Other animals In humans, the foramen magnum is farther underneath the head than in the other great apes. Thus, in humans, the neck muscles ( including the occipitofrontalis muscle ) do not need to be as robust in order to hold the head upright. Comparisons of the position of the foramen magnum in early hominid species are useful to determine how comfortable a particular species was when walking on two limbs ( bipedalism ) rather than four ( quadrupedalism ). Additional images Skull seen from below. The hole through which the medulla ( shown in red ) is passing is foramen magnum. Occipital bone. Foramen magnum shown in red. Human brain with dura mater intact. The foramen magnum is visible as the large hole in the centre. Opisthion shown in red Occipital bone inner surface ( basion shown in red ) See also Posterior cranial fossa References This article incorporates text in the public domain from the 20th edition of Gray 's Anatomy ( 1918 ) Jump up ^ Russo, Gabrielle A. ; Kirk, Christopher E. ( November 2013 ). `` Foramen magnum position in bipedal mammals ''. Journal of Human Evolution. 65 ( 5 ) : 656 -- 670. PMID 24055116. doi : 10.1016 / j. jhevol. 2013.07. 007. Retrieved 12 March 2015. Jump up ^ Dutta, Asim Kumar ( 2013 ). Essentials of Human Anatomy Head & Neck. kolkata : Current books international. pp. 56 -- 57. ISBN 81 - 86793 - 79 - 8. External links Wikimedia Commons has media related to Foramen magnum. `` Anatomy diagram : 34257.000 - 1 ''. Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014 - 01 - 01. Diagram 1 Diagram 2 3D animation showing position of basion on YouTube The neurocranium of the skull Occipital Squamous part external Inion / External occipital protuberance External occipital crest Nuchal lines planes Occipital Nuchal internal Cruciform eminence Internal occipital protuberance Internal occipital crest Groove for transverse sinus Lateral parts Condyle Condyloid fossa Condylar canal Hypoglossal canal jugular Jugular process Jugular tubercle Basilar part Pharyngeal tubercle Clivus Other Foramen magnum Basion Opisthion Parietal Parietal eminence Temporal line Parietal foramen Sagittal sulcus Frontal Squamous part Frontal suture Frontal eminence external Superciliary arches Glabella foramina Supraorbital Cecum Zygomatic process internal Sagittal sulcus Frontal crest Orbital part Ethmoidal notch Fossa for lacrimal gland Trochlear fovea Frontal sinus Frontonasal duct Temporal Squamous part Articular tubercle Suprameatal triangle Mandibular fossa Petrotympanic fissure Zygomatic process Mastoid part Mastoid foramen Mastoid process ( Mastoid cells ) Mastoid notch Occipital groove Sigmoid sulcus Mastoid antrum ( Aditus ) Petrous part Carotid canal Facial canal Hiatus Internal auditory meatus Cochlear aqueduct Stylomastoid foramen fossae Subarcuate fossa Jugular fossa canaliculi Inferior tympanic Mastoid Styloid process Petrosquamous suture ( note : ossicles in petrous part, but not part of temporal bone ) Tympanic part Suprameatal spine Sphenoid Surfaces Superior surface : Sella turcica Dorsum sellae Tuberculum sellae Hypophysial fossa Posterior clinoid processes Ethmoidal spine Chiasmatic groove Middle clinoid process Petrosal process Clivus Lateral surface : Carotid groove Sphenoidal lingula Anterior surface : Sphenoidal sinuses Great wings foramina Rotundum Ovale Vesalii Spinosum Spine Infratemporal crest Sulcus of auditory tube Small wings Superior orbital fissure Anterior clinoid process Optic canal Pterygoid processes fossae Pterygoid Scaphoid pterygoid plates Lateral Medial Pterygoid canal Hamulus Other Body Sphenoidal conchae Ethmoid Plates Cribriform plate Crista galli Olfactory foramina Perpendicular plate Surfaces Lateral surface Orbital lamina Uncinate process Medial surface Supreme nasal concha Superior nasal concha Superior meatus Middle nasal concha Middle meatus Labyrinth Ethmoid sinus ethmoidal foramina Posterior Anterior Foramina of the skull ( and canals, fissures, meatus, and hiatus ) Anterior cranial fossa to Orbit : ethmoidal foramina anterior posterior to Nasal cavity : olfactory foramina ( CN - I ) foramen cecum Middle cranial fossa to Orbit : optic canal ( CN - II ) superior orbital fissure ( CN - III, IV, V1, VI ) to Pterygopalatine fossa : foramen rotundum ( CN - V2 ) pterygoid canal to Infratemporal fossa : foramen ovale ( CN - V3 ) foramen spinosum / carotid canal other : foramen lacerum hiatus for greater petrosal nerve hiatus for lesser petrosal nerve sphenoidal emissary foramen Posterior cranial fossa internal auditory meatus / facial canal / stylomastoid foramen ( CN - VII, VIII ) jugular foramen ( CN - IX, X, XI ) foramen magnum ( CN - XI ) hypoglossal canal ( CN - XII ) condylar canal mastoid foramen Orbit to Nasal cavity : nasolacrimal canal to face : supraorbital notch foramen infraorbital foramen groove zygomatic foramen - facial - temporal to Pterygopalatine fossa : inferior orbital fissure other : Inferior orbital fissure Fossa for lacrimal sac Pterygopalatine fossa to Nasal cavity : sphenopalatine foramen to Oral cavity : greater palatine canal foramen lesser palatine canals foramina to Infratemporal fossa : pterygomaxillary fissure to Nasopharynx : palatovaginal canal to oral cavity : incisive canals incisive foramen to nasal cavity : Foramen vomerinum Meatus vomerinus Fissura vomerina Hiatus vomerinus Other external acoustic meatus mandibular foramen mental foramen parietal foramen petrotympanic fissure semilunar hiatus Retrieved from `` https://en.wikipedia.org/w/index.php?title=Foramen_magnum&oldid=801640660 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Foramina of the skull Hidden categories : Articles lacking in - text citations from January 2013 All articles lacking in - text citations Medicine infobox template using GraySubject or GrayPage Articles containing Latin - language text Talk Contents About Wikipedia Català Čeština Dansk Deutsch Español فارسی Galego Italiano Magyar Nederlands 日本 語 Norsk Norsk nynorsk Polski Português Română Simple English Slovenčina Suomi Svenska ไทย Türkçe Edit links This page was last edited on 20 September 2017, at 22 : 39. 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Question: the foramen magnus is a big hole in which of the following bones
Answer: the occipital bone of the skull