Sphenoid bone - wikipedia Sphenoid bone Sphenoid bone Cranial Bones. Only the end of the wing of the sphenoid bone is visible Sphenoid bone, upper surface. Details Identifiers Latin os sphenoidale MeSH D013100 TA A02. 1.05. 001 FMA 52736 Anatomical terms of bone ( edit on Wikidata ) The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the temporal bone and the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended. Contents 1 Structure 1.1 Intrinsic ligaments of the sphenoid 1.2 Features 1.3 Articulations 2 Body of sphenoid 2.1 Superior or cerebral surface 2.2 Inferior surface 2.3 Anterior surface 2.4 Posterior surface 2.5 Lateral surface 3 Sphenoidal sinuses 4 Greater wings 4.1 Superior or cerebral surface 4.2 Lateral surface 4.3 Orbital surface 5 Lesser wings 5.1 Development 5.1. 1 Presphenoid 5.1. 2 Postsphenoid 6 Function 7 Other animals 8 Additional images 9 See also 10 Notes 11 References 12 External links Structure Seven bones articulate to form the orbit. The sphenoid bone is shown as pink ( directly in the middle of the orbital cavity ) Wedge - shaped sphenoid bone seen laterally It is divided into the following parts : a median portion, known as the body of sphenoid bone, containing the sella turcica, which houses the pituitary gland as well as the paired paranasal sinuses, the sphenoidal sinuses two greater wings on the lateral side of the body and two lesser wings from the anterior side. Pterygoid processes of the sphenoides, directed downwards from the junction of the body and the greater wings. Two sphenoidal conchae are situated at the anterior and inferior part of the body. Intrinsic ligaments of the sphenoid The more important of these are : the pterygospinous, stretching between the spina angularis and the lateral pterygoid plate see ( cervical fascia ) ; the interclinoid, a fibrous process joining the anterior to the posterior clinoid process ; and the caroticoclinoid, connecting the anterior to the middle clinoid process. These ligaments occasionally ossify. Features pterygoid notch pterygoid fossa scaphoid fossa pterygoid hamulus pterygoid canal pterygospinous process sella turcica Articulations The sphenoid articulates with the frontal, parietal, ethmoid, temporal, zygomatic, palatine, vomer, and occipital bones and helps to connect the neurocranium to the facial skeleton. Body of sphenoid Superior or cerebral surface Articulates with ethmoid bone anteriorly and basilar part of occipital bone posteriorly. It shows : Jugum sphenoidale Sulcus chiasmaticus Tuberculum sellae Sella turcica Dorsum sellae Clivus Inferior surface Rostrum of sphenoid Sphenoidal conchae Vaginal processes of medial pterygoid plate Anterior surface Sphenoidal crest articulates with the perpendicular plate of ethmoid leading to formation of a part of the septum of nose. Posterior surface Basilar part of occipital bone Lateral surface Carotid sulcus lodging cavernous sinus and internal carotid artery Sphenoidal sinuses These are asymmetrical air sinuses in the body of the sphenoid, closed by Sphenoidal conchae Greater wings Superior or cerebral surface This forms the floor of the middle cranial fossa. It presents ( starting from the front ) : Foramen rotundum Foramen ovale Emissary sphenoidale foramen Foramen spinosum Lateral surface This is divided into ( by infratemporal crest ) : Upper or temporal surface Lower or infratemporal surface Foramen pierce it : Foramen ovale Foramen spinosum Orbital surface This forms the posterior wall of the orbit Lesser wings These are two triangular wings projecting laterally from anterosuperior part of the body. Each consists of : A base forming medial end of the wing. Tip forming the lateral end of the wing. Superior surface forming floor of anterior cranial fossa. Inferior surface forming upper boundary of superior orbital fissure. Posterior surface projects into the Sylvian point. Medially, terminates in the anterior clinoid process. Development Figure 4 : Sphenoid bone at birth, posterior aspect. Until the seventh or eighth month of fetal development, the body of the sphenoid consists of two parts : one in front of the tuberculum sellæ, the presphenoid, with which the small wings are continuous ; the other, consisting of the sella turcica and dorsum sellae, the postsphenoid, with which are associated the great wings, and pterygoid processes. The greater part of the bone is ossified in cartilage. There are fourteen centers in all, six for the presphenoid and eight for the postsphenoid. Presphenoid By about the ninth week of fetal development an ossific center appears for each of the small wings ( orbito - sphenoids ) just lateral to the optic foramen ; this is followed by the appearance of two nuclei in the presphenoid part of the body. The sphenoidal conchae are each developed from a center that makes its appearance about the fifth month ; at birth they consist of small triangular laminae, and it is not until the third year that they become hollowed out and coneshaped ; about the fourth year they fuse with the labyrinths of the ethmoid bone, and between the ninth and twelfth years they unite with the sphenoid bone. Postsphenoid The first ossific nuclei are those for the great wings ( alisphenoids ). One makes its appearance in each wing between the foramen rotundum and foramen ovale about the eighth week. The orbital plate and that part of the sphenoid, which is found in the temporal fossa, as well as the lateral pterygoid plate, are ossified in membrane ( Fawcett ). Soon after, the centers for the postsphenoid part of the body appear, one on either side of the sella turcica, and become blended together about the middle of fetal life. Each medial pterygoid plate ( except its hamulus ) is ossified in membrane, and its center probably appears about the ninth or tenth week ; the hamulus becomes chondrified during the third month, and almost at once ossifies ( Fawcett ). The medial joins the lateral pterygoid plate about the sixth month. About the fourth month, a center appears for each lingula and speedily joins the rest of the bone. The presphenoid is united to the postsphenoid about the eighth month, and at birth the sphenoid is in three pieces ( Fig. 4 ) : a central, consisting of the body and small wings, and two lateral, each comprising a great wing and pterygoid process. In the first year after birth the great wings and body unite, and the small wings extend inward above the anterior part of the body, and, meeting with each other in the middle line, form an elevated smooth surface, termed the jugum sphenoidale. By the twenty - fifth year the sphenoid and occipital are completely fused. Between the pre - and postsphenoid there are occasionally seen the remains of a canal, the canalis cranio - pharyngeus, through which, in early fetal life, the hypophyseal diverticulum of the buccal ectoderm is transmitted. The sphenoidal sinuses are present as minute cavities at the time of birth ( Onodi ), but do not attain their full size until after puberty. Function This bone assists with the formation of the base and the sides of the skull, and the floors and walls of the orbits. It is the site of attachment for most of the muscles of mastication. Many foramina and fissures are located in the sphenoid that carry nerves and blood vessels of the head and neck, such as the superior orbital fissure ( with ophthalmic nerve ), foramen rotundum ( with maxillary nerve ) and foramen ovale ( with mandibular nerve ). Other animals The sphenoid bone of humans is homologous with a number of bones that are often separate in other animals, and have a somewhat complex arrangement. In the early lobe - finned fishes and tetrapods, the pterygoid bones were flat, wing - like bones forming the major part of the roof of the mouth. Above the pterygoids were the epipterygoid bones, which formed part of a flexible joint between the braincase and the palatal region, as well as extending a vertical bar of bone towards the roof of the skull. Between the pterygoids lay an elongated, narrow parasphenoid bone, which also spread over some of the lower surface of the braincase, and connected, at its forward end, with a sphenethmoid bone helping to protect the olfactory nerves. Finally, the basisphenoid bone formed part of the floor of the braincase and lay immediately above the parasphenoid. Aside from the loss of the flexible joint at the rear of the palate, this primitive pattern is broadly retained in reptiles, albeit with some individual modifications. In birds, the epipterygoids are absent and the pterygoids considerably reduced. Living amphibians have a relatively simplified skull in this region ; a broad parasphenoid forms the floor of the braincase, the pterygoids are relatively small, and all other related bones except the sphenethmoid are absent. In mammals, these various bones are often ( though not always ) fused into a single structure ; the sphenoid. The basisphenoid forms the posterior part of the base, while the pterygoid processes represent the pterygoid bones. The epipterygoids have extended into the wall of the cranium ; they are referred to as alisphenoids when separate in mammals, and form the greater wings of the sphenoid when fused into a larger structure. The sphenethmoid bone forms as three bones : the lesser wings and the anterior part of the base. These two parts of the sphenethmoid may be distinguished as orbitosphenoids and presphenoid, respectively, although there is often some degree of fusion. Only the parasphenoid appears to be entirely absent in mammals. In the dog the sphenoid is represented by 8 bones : basisphenoid, alisphenoids, presphenoid, orbitosphenoids, pterygoids. These bones remain separate and are the : 2 Alisphenoids : each greater wing 2 Orbitosphenoids : each lesser wing Basisphenoid : back part of body Presphenoid : front part of body 2 Pterygoids : medial pterygoid plate Additional images Position of sphenoid bone ( shown in green ). Animation. Seen from below ( mandible is removed ) Seen from above ( parietal bones are removed ) Shape of sphenoid bone. Facial bones. Lateral wall of nasal cavity, showing ethmoid bone in position. Base of skull. Inferior surface. Lateral view of the skull. Horizontal section of nasal and orbital cavities. Floor of the skull. Roof, floor, and lateral wall of left nasal cavity. The skull from the front. The sphenoid is labeled with yellow to the left of the picture, both in the orbit and behind the zygomatic process Sphenoid bone Sphenoid bone - anterior view Sphenoid bone superior view Sphenoid bone and temporal bones Tympanic cavity. Facial canal. Internal carotid artery. See also This article uses anatomical terminology ; for an overview, see Anatomical terminology. Wikimedia Commons has media related to Sphenoid bones. Sphenoidal sinus Pterygospinal ligament Basilar skull fracture Notes Jump up ^ According to most dictionaries, the word sphenoid ( / ˈsfiːnɔɪd / derives from Greek sphenoeides, `` wedgelike ''. Thieme Atlas of Anatomy disagrees and says that the sphenoid bone was originally called os sphecoidale, meaning `` bone resembling a wasp '', and that the word was later written ' sphenoidale ' by a transcription error. An anterior view of the bone resembles more the body of a wasp or a bat with wings than a wedge. References Jump up ^ OED 2nd edition, 1989. Jump up ^ Entry `` sphenoid '' in Merriam - Webster Online Dictionary. Jump up ^ Thieme Atlas of Anatomy, Head and Neuroanatomy 2011 ^ Jump up to : Chaurasia. Human Anatomy Volume Three. CBS Publishers & Distributors. pp. 43 -- 45. ISBN 978 - 81 - 239 - 2332 - 1. Jump up ^ Human Anatomy, Jacob, Elsevier, 2008, page 211 Jump up ^ Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 52. ^ Jump up to : Romer, Alfred Sherwood ; Parsons, Thomas S. ( 1977 ). The Vertebrate Body. Philadelphia, PA : Holt - Saunders International. pp. 220 -- 244. ISBN 0 - 03 - 910284 - X. This article incorporates text in the public domain from page 147 of the 20th edition of Gray 's Anatomy ( 1918 ) External links Anatomy figure : 22 : 01 - 06 at Human Anatomy Online, SUNY Downstate Medical Center - `` Lateral view of skull. '' 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 Anatomy portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Sphenoid_bone&oldid=825336493 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Bones of the head and neck Hidden categories : Pages with unresolved properties Talk Contents About Wikipedia Azərbaycanca Bân - lâm - gú Bosanski Brezhoneg Català Čeština Dansk Deutsch Español Esperanto Euskara فارسی Français Galego 한국어 Italiano עברית Қазақша Latina Latviešu Lietuvių Magyar Македонски Nederlands 日本 語 Norsk Norsk nynorsk Polski Português Română Русский Scots Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska ไทย Türkçe Українська 粵語 中文 35 more Edit links This page was last edited on 12 February 2018, at 20 : 42. 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Question: where is the pituitary gland located in the sphenoid bone
Answer: a median portion, known as the body of sphenoid bone, containing the sella turcica, which houses the pituitary gland