Glossary of Anatomy Chapter 7B: Cranial Bones
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- Cranial Vault/Calvaria
- Superior, lateral, and posterior walls of the skull
- Cranial Floor/Base
- Skull bottom.
- Frontal Bone (1)
- Anterior portion of the cranium. Forms the forehead, superior part of the orbits, and most of the floor of the anterior cranial fossa.
Contains the glabella, frontal sinuses, frontal squama, supraorbital margins, and supraorbital foramina.
Articulates with the sphenoid bone, zygomatic bone, parietal bones, ethmoid bone, lacrimal bones, nasal bone, and maxilla.
- Supraorbital Foramen (2)
- Opening above each orbit allowing supraorbital arteries and nerves to pass.
Located in frontal bone, in the region of the "eyebrow" (supraorbital margin)
- Smooth region between the eyes.
Located in the frontal bone.
- Coronal Suture
- Articulation point of the posterior portion of the frontal bone and the anterior portion of the paired parietal bones.
- Frontal Squama
- The most anterior part of the frontal bone. "Forehead."
- Supraorbital Margins
- The thickened superior margins of the orbits that lie under the eyebrows.
- Frontonasal Suture
- Articulation point of the frontal and nasal bones.
- Frontal Sinuses
- Internal sinuses riddling the areas lateral to the glabella in the frontal bone.
- Parietal Bones (2)
- Paired bones posteriolateral to the frontal bone, forming the lateral and superior aspects of the cranium.
Articulates with the frontal bone anteriorly at the coronal suture; with each other superiorly (at cranial midline) at the sagittal suture, with the occipital bone posteriorly at the lamboid suture; with the temporal bones on the lateral aspects of the skull at the squamous sutures; and antero-inferiorly with the sphenoid bone on the lateral aspects of the skull.
- Temporal Bones (2)
- Bones located inferior to the parietal bone on lateral skull.
Divided into the squamous, tympanic, mastoid, and petrous regions.
Contains the zygomatic process, zygomatic arch, mandibular fossa, external auditory meatus, styloid process, mastoid process, stylomastoid foramen, jugular foramen, carotid canal, internal acoutsic meatus, foramen lacernum
Articulates superiorly with the parietal bones at the squamous sutures; anteriorly with the sphenoid bone, anteriorly with the zygomatic bone via the zygomatic process, inferiorly with the mandible, and posteriorly with the occipital bone at the occipitomastoid suture
- Squamous Region
- Flaring, platelike superior region of the temporal bone which abuts the squamous suture
- Tympanic Region
- Region of the temporal bone surrounding the external acoustic meatus.
- Mastoid Region
- Region of the temporal bone posterior to the external acoustic meatus containing the mastoid process.
- Petrous Region
- Inferior region of the temporal bone which contributes to the cranial base. Looks like a miniature mountain ridge between the occipital bone posteriorly and the sphenoid bone anteriorly.
- Zygomatic Arch
- "Cheekbone." Located in the temporal bone, including the zygomatic process and the squamous region.
- Zygomatic Process
- Horizontal barlike structure jutting anteriorly from the temporal bone to articulate with the zygomatic bone. Helps to form the zygomatic arch.
- Mandibular Fossa
- Small, oval indentation on the inferior aspect of the temporal bone which serves as an articular point of the mandibular condyle.
- External Acoustic Meatus
- Canal leading from the external ear to the eardrum. Located in the tympanic region of the temporal bone.
- Styloid Process
- Sharply downward jutting needle-like process inferior to the external acoustic meatus. Attachment point for several tongue and neck muscles and for a ligament that secures the hyoid bone of the neck to the skull.
- Mastoid Process
- Finlike downward pointing projection of the mastoid region of the temporal bone. The "lump" just posterior to the ear. Anchoring site for several neck and tongue muscles.
- Stylomastoid Foramen
- Tiny round opening between the mastoid and styloid processes through which cranial nerve VII leaves the cranium
- Mastoid Sinuses
- Air cavities in the mastoid process of the temporal bone.
- Anterior Cranial Fossa
- Concave region of the cranium which supports the frontal lobes of the brain. Composed of the frontal bone, ethmoid bone, and lesser wings of the sphenoid bone.
- Middle Cranial Fossa
- Concave region of the interior of the cranium which supports the temporal lobes of the brain. Formed by the sphenoid bone and the petrous portions of the temporal bones.
- Sagittal Suture
- Articulation point where the parietal bones meet superiorly at the cranial midline.
- Lamboid Suture
- Articulation point where the parietal bones meet the occipital bone posteriorly.
- Squamous Sutures (2)
- Articulation points where the parietal and temporal bones meet on the lateral aspects of the skull.
- Occipitomastoid Suture (2)
- Articulation point of the occipital and temporal bones on the lateral aspects of the skull.
- Jugular Foramen (2)
- Large kidney-bean shaped holes at the junction of the occipital bone and the petrous regions of the temporal bones which allow passage of the internal jugular vein and cranial nerves IX, X, and XI.
- Carotid Canal (2)
- Large circular hole on the inferior aspect of the skull just anterior to the jugular foramen which transmits the internal carotid artery into the cranial cavity.
- Foramen Lacerum (2)
- Large, jagged opening between the petrous region of the temporal bones and the sphenoid bone. Provides passage for a number of small nerves and for the internal carotid artery to enter the middle cranial fossa.
- Internal Acoustic Meatus
- Opening on posterior aspect (petrous region) of temporal bone allowing passage of cranial nerves VII and VIII. Just anterior to the jugular foramena.
- Occipital Bone
- Most posterior bone of the cranium. Forms floor and back wall. Joins sphenoid bone anteriorly via its narrow basioccipital region. Forms the walls of the posterior cranial fossa.
Contains the foramen magnum, occipital condyles, hypoglossal canal, external occipital protuberance, external occipital crest, and external occipital protuberance
Articulates anteriorly with the paired parietal bones via the lamboid sutures and the temporal bones via the occipitomastoid sutures.
- Posterior Cranial Fossa
- Posterior concave region of the cranium which supports the cerebellum of the brain. Formed by the interior of the occipital bone.
- Foramen Magnum
- Large hole in the base of the occipital bone through which the inferior part of the brain connects with the spinal cord.
- Occipital Condyles
- Large, smooth, rounded projections flanking the foramen magnum on the inferior aspect of the occipital bone. Articulate with the first cervical vertebra (atlas).
- Hypoglossal Canal
- Openings medial and superior to the occipital condyles through which the hypoglossal nerve (cranial nerve XII) passes. Flank the foramen magnum.
- External Occipital Protuberance
- Knoblike projection on the posterior skull, just superior to the foramen magnum.
- External Occipital Crest
- Medial crest along the inferior aspect of the occipital bone.
- Inferior Nuchal Line
- Horizontal ridge just posterior to the foramen magnum on the occipital bone.
- Superior Nuchal Line
- Horizontal ridge just posterior to the inferior nuchal line on the occipital bone.
- Pharyngeal Tubercle
- Small bump just anterior to the foramen magnum, anterior and medial to the occipital condyles, on the occipital bone
- Sphenoid Bone (1)
- Bat/Crab/Moth shaped bone forming the anterior plateau of the middle cranial fossa across the width of the skull. Spans the width of the middle cranial fossa.
Articulates with ALL cranial bones, palatine bone, vomer, zygomatic bone, mandible, maxilla
Contains the greater wings, superior orbital fissures, sella turcica, hypophyseal fossa, dosum sellae, lesser wings, optic canals, foramen ovale, "body", sphenoid sinuses, pterygoid processes, and foramen spinosum
- Sphenoid Body
- Central structure of the sphenoid bone. The "face" of the crab from posterior view.
- Sphenoid Sinuses
- 2 large "caverns" in the interior of the sphenoid bone.
- Sella Turcica
- The "body" of the sphenoid bone's "moth" from a superior view. Saddle-shaped region in the sphenoid midline which nearly encloses the pituitary gland.
- Hypophyseal Fossa
- Snug concave portion of the sella turcica "saddle" in the sphenoid bone. Area on which the pituitary gland sits.
- Dorsum Sellae
- Posterior abuttment/ridge of the hypophyseal fossa portion of the sella turcica "saddle" of the sphenoid bone.
- Greater Wings
- Portions of the sphenoid bone seen exteriorly anterior to the temporal bones, forming a part of the eye orbits. Part of the middle cranial fossa.
- Lesser Wings
- Hornlike structures of the sphenoid bone which form part of the floor of the anterior cranial fossa and part of the medial walls of the orbits. "Antennae" of moth from superior view. "Antennae/Eye Stalks" of crab from posterior view. Situated anterior to the sella turcica.
- Pterygoid Processes
- Winglike protrusions projecting inferiorly from the junction of the body and greater wings of the sphenoid bone.
The "legs" of the sphenoid "crab" from posterior view.
- Pterygoid Plates
- Subdivided "lobes" or "fins" of the pterygoid process of the sphenoid bone.
- Optic Canals
- Oblong openings in the bases of the lesser wings of the sphenoid bone through which the optic nerves enter the orbits to serve the eyes.
Appear like eye holes in the "mask" formed by the lesser wings of the sphenoid in superior view.
Appear as small oval holes flanking the bridge of the nose when looking into the orbit anteriorly.
- Superior Orbital Fissures
- Jagged openings in the orbits providing passage for cranial nerves III, IV, V, and VI to enter the orbit. Long slit between the greater and lesser wings of the sphenoid bone.
Spaces between the "body" and the "claws" of the posterior-view sphenoid "crab."
Appears as a gash through the sphenoid bone, just lateral to the optic canal, when looking anteriorly into the orbit.
- Foramen Ovale
- Large, oval openings in the posterior ends of the greater wings of the sphenoid bones--posterior to the sella turcica. Allows passage of a branch of the cranial nerve V.
Appear like "spots" on the back part of the wings of the sphenoid "moth" from superior view. Highly visible holes flanking the "folds" of the sphenoid bone in inferior view.
- Foramen Spinosum
- Tiny round holes posterolateral to the foramen ovale in the greater wings of the sphenoid bone. Transmits the middle meningeal artery.
Small dots on the narrow ends of the "bottom wings" of the sphenoid "moth" from superior view.
- Chiasmatic Groove
- Runnel connecting the optic canals between the lesser wings of the sphenoid bone.
"Furrow" connecting the "eyes" of the "mask" formed by the lesser wings of the sphenoid bone in superior view.
- Foramen Rotundum
- Opening lateral to the sella turcica providing passage for a branch of cranial nerve V. Not visible on an inferior view of the skull.
Tiny dot where the "top" and "bottom" wings of the sphenoid "moth" in superior view would overlap.
- Ethmoid Bone
- Irregularly shaped bone anterior to the sphenoid. Forms the roof of the nasal cavity, upper nasal septum, and part of the medial orbit walls.
Articulates with the lacrimal bones anteriorly, the sphenoid bone posteriorly, the maxilla anteriorly, the vomer inferiorly, the frontal bone superiorly, and the nasal bone anteriorly.
Contains the cribiform plate, olfactory foramina, crisa galli, perpendicular plate, left/right lateral masses, ethmoid sinuses, superior/middle nasal conchae, and orbital plates.
- Cribiform Plate
- Superior surface of the ethmoid, riddled with tiny holes. Located lateral to the crista galli. Form the horizontal plate of the ethmoid bone, together with the crista galli.
- Olfactory Foramina
- Tiny holes riddling the cribiform plates of the ethmoid bone. Notable from superior view.
- Crista Galli
- "Cock's comb." Vertical projection of the ethmoid bone.
"Body" of the ethmoid "dragon" in anterior view. Prominent medial ridge in superior view.
- Perpendicular Plate
- Inferior projection of the ethmoid bone jutting downward from the cribiform plate to form the superior part of the nasal septum.
Long "neck" and "head" of the ethmoid "dragon" in anterior view.
- Left and Right Lateral Masses
- Irregularly shaped thin-walled bony regions flanking the perpendicular plate of the ethmoid bone laterally. Their lateral surfaces shape part of the medial orbit wall.
The "wings" of the ethmoid "dragon" in anterior view.
- Ethmoid Sinuses
- Irregularly shaped basins and infoldings of the lateral masses of the ethmoid bone.
"Folds" in the "wings" of the ethmoid "dragon" in anterior view.
- Superior and Middle Nasal Conchae
- Thin, delicately coiled plates of bone extending medially from the lateral masses of the ethmoid into the nasal cavity.
"Arms/hands" of the ethmoid "dragon" in anterior view.
- Orbital Plates
- Lateral surfaces of the ethmoid's lateral masses which contribute to the medial walls of the orbits.
Sides of the "wings" in the ethmoid "dragon" in anterior view.
- Wormian/Sutural Bones
- Tiny, irregularly shaped bones or bone clusters that appear within sutures, most often in the lamboid suture. Variable from skull to skull.
- Name the cranial bones.
- Frontal bone, parietal bones (2), temporal bones (2), occipital bone, sphenoid bone, ethmoid bone
- What passes through the carotid canal?
- internal carotid artery
- What passes through the foramen magnum?
- the spinal cord
- What passes through the foramen lacerum?
- small nerves and the internal carotid artery
- What passes through the Foramen Ovale?
- a branch of cranial nerve V
- What passes through the Jugular Foramen?
- the internal jugular vein and cranial nerves IX, X, and XI
- What passes through the Optic Canal?
- the optic nerves
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