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Sphenoid Bone

It is an unpaired bone situated at the base of the skull. Its resemblance is of the shape of a butterfly or bat with outstretched wings.

Interactive Anatomical Interface

Highlight
Frontal
parietal
Temporal
Sphenoid
Zygomatic
maxilla
Nasal
Lateral cartilage
greater alar cartilage
Mandbile
thyrohyoid membrane
thyroid cartilage
cricoid cartilage
cricotracheal ligament
ANterior longitudinal ligament
teeth
cervical vertabrae
first rib
second rib

Highlight
Frontal
parietal
Temporal
Sphenoid
Zygomatic
maxilla
Nasal
Lateral cartilage
greater alar cartilage
Mandbile

Highlight
thyrohyoid membrane
thyroid cartilage
cricoid cartilage
cricotracheal ligament
ANterior longitudinal ligament
teeth
cervical vertabrae
first rib
second rib
Highlight
frontal
Parietal
Sphenoid
temporal
Zygomatic
Maxilla
stylomandibular ligament
Lateral cartilage
posterior atlantoaxial ligament
lateral ligament
greater alar cartilage
teeth
mandible
hyoid
occipital bone
first rib
posterior atlanto-occipital memebrane
thyrohyoid membrane
thyroid cartilage
ricothyroid membrane and ligament
cricoid cartilage
cricotracheal ligament
t1 vertebra
stylohyoid ligament
joint capsule
Anterior longitudinal ligamnent
nuchal ligament
Cervical Vertebra
lacrimal

Highlight
frontal
Parietal
Sphenoid
temporal
Zygomatic
Maxilla
Lateral cartilage
greater alar cartilage
mandible
hyoid
thyrohyoid membrane
thyroid cartilage
ricothyroid membrane and ligament
cricoid cartilage
lateral ligament
cricotracheal ligament

Highlight
stylohyoid ligament
Anterior longitudinal ligamnent
nuchal ligament
Cervical Vertebra
first rib
t1 vertebra
lacrimal
occipital bone
teeth
posterior atlanto-occipital memebrane
posterior atlantoaxial ligament
joint capsule
stylomandibular ligament
-
Highlight
nasal
temporal bone
occipital bone
Internal auditory meatus
Stylomastoid foramen
Temporal
sphenoid
ethmoid
zygomatic bone
zygomatic bone
lacrimal bone
perpendicular plate
lacrimal bone
nasal cartilage
vomer
Nasal concha
Mandible
tectorial membrane of atlanto-axial joint
foramen magnum
tectorial membrane
c1 atlas
crista galli
ethmoidal sinuses
cribriform plate
foramen rotundum
optic foramen
superior orbital fissure
palatine
nuchal ligament
c01 atlas
posterior atlantoaxial ligament
c2 axis
c03 vertebrae
c04 vertebrae
C5 vertebrae

Highlight
nasal
temporal bone
occipital bone
Stylomastoid foramen
Temporal
sphenoid
ethmoid
zygomatic bone
zygomatic bone
lacrimal bone
perpendicular plate
posterior atlantoaxial ligament
nasal cartilage
vomer
Nasal concha
palatine
tectorial membrane of atlanto-axial joint

Highlight
foramen magnum
tectorial membrane
c1 atlas
crista galli
lacrimal bone
Mandible
ethmoidal sinuses
cribriform plate
foramen rotundum
Internal auditory meatus
optic foramen
superior orbital fissure
nuchal ligament
c01 atlas
c2 axis
c03 vertebrae
c04 vertebrae
C5 vertebrae
-

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Sphenoid Bone

Sphenoid Bone

Parts

It is composed of the following 7 parts:

  • A body.
  • 2 lesser wings.
  • 2 greater wings.
  • 2 pterygoid processes.
  • 2 pterygoid processes represent the legs of the bat.

Body

It includes a pair of sphenoidal air sinuses and is cuboidal in shape. The body presents 6 surfaces: superior, inferior, anterior, posterior and left and right lateral surfaces.

1. The superior surface presents the subsequent featuresfrom before backwards:

  • A triangular projection between the 2 lesser wings called Ethmoidal spine. It articulates together with the posterior margin of the cribriform plate.
  • A flattened plate of bone behind the ethmoidal spine called Jugum sphenoidale.
  • A shallow transverse groove, which leads on every side into optic canal called Sulcus chiasmaticus.
  • A horizontal elevation creating posterior limit of sulcus chiasmaticus called Tuberculum sellae. On every side it presents small conical projections, the middle clinoid process.
  • Hypophyseal fossa, a deep depression which lodges pituitary gland
  • Dorsum sellae, a square plate of bone which projects upwards and presents a conical projection on every side referred to as posterior clinoid process.
  • Sella turcica is combined name given to tuberculum sellae, hypophyseal fossa and dorsum sellae. It resembles a Turkish saddle.

2. Inferior surface presents the following three features:

  • Sphenoidal rostrum, a median ridge projecting downward. It inhabits the groove between the alae of Vomer.
  • Sphenoidal concha, a triangular plate of bone on every side of rostrum which articulates with the alae of Vomer.
  • Vaginal process, a triangular bony ledge projecting downwards and medially from the base of every medial pterygoid plate. It will help create vomerovaginal and palatovaginal canals.

3. Anterior surface presents these features:

  • Sphenoidal crest.
  • A vertical median ridge which articulates with all the posterior border of the perpendicular plate of ethmoid to create part of nasal septum. On every side of the sphenoid crest is located the opening of sphenoidal air sinuses.
  • Upper vertical parts of sphenoidal conchae, it is located on every side of the crest.

4. Posterior surface is quadrilateral in shape and articulates by a plate of hyaline cartilage with the basiocciput.

5. Every lateral surface of the body joins with the greater wing of sphenoid (projecting laterally) and the pterygoid process (going downwards). The lateral surface presents a groove named carotid sulcus generated by the internal carotid artery.

Lesser Wings

Every lesser wing appears from the anterior part of the body of sphenoid by 2 roots. Between these 2 roots is located the optic canal. The projecting medial ends of the lesser wings are termed anterior clinoid processes.

Greater Wings

Every greater wing spans outside laterally from the side of the body creating the floor of the middle cranial fossa.

The greater wing has the following 3 surfaces:

Upper surface: It is located in the middle cranial fossa.

Lateral (temple) surface: It’s split into temporal and infratemporal surfaces by the temple crest.

Anterior (orbital) surface: It is located at the lateral wall of the orbit and divides the superior orbital fissure from the inferior orbital fissure.

Clinical Significance

The craniopharyngeal canal sometimes exists in the floor of the pituitary fossa. It symbolizes the remnant of Rathke’s pouch which creates the anterior lobe of the pituitary gland

The observation of sella turcica in radiographs of skull is of great clinical importance because pathological changes in it represent intracranial space-occupying lesions like pituitary tumor.


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By | 2018-02-13T10:08:04+00:00 July 24th, 2017|Anatomy, Bones, Head|0 Comments