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8.2.3: Markings of the Cranium

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    53619
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    Markings of the Cranium

    Recall from Chapter 7: Introduction to the Skeletal System, that bones have markings including holes, passageways, basins, and projections. Before examining the specific markings of the cranium, review the pertinent types of markings we will see when we examine the cranium markings:

    Type of Bone Marking

    Description of Bone Marking Type

    canal

    Passageway through a bone.

    Example: optic canal

    condyle

    Refers to a large rounded prominence which often provides structural support to the overlying hyaline cartilage.

    Examples: femoral lateral and medial condyles; tibial lateral and medial condyles; occipital condyles articulate with atlas (C1)

    foramen

    (pl. foramina)

    A hole in a bone through which nerves and blood vessels pass.

    Examples: foramen magnum; supraorbital foramen; infraorbital foramen; mental foramen

    fossa (pl. fossae)

    A shallow depression in a bone surface.

    Examples: trochlear fossa; posterior, middle, and anterior cranial fossae

    meatus

    (pl. meatuses)

    A tube-like channel that extends within the bone, which may provide passage and protection to nerves, vessels, and sound.

    Examples: external acoustic meatus; internal auditory meatus

    process

    (pl. processes)

    Bony projection, allow for muscle attachment.

    Examples: spinous process, acromial process, radial styloid process

    protuberance

    A bump or outgrowth on a bone.

    Example: external occipital protuberance

    Markings of the inferior cranium

    Above: Markings of the cranium viewing the skull from the inferior view.

    Markings of the internal cranium

    Above: Markings of the cranium viewing the skull from the superior view of the cranial cavity.

    Marking

    Bone Marking is Part of

    Location

    Function

    carotid canal

    (2, one right & one left)

    temporal bones

    inferior skull

    provides passage for the right and left internal carotid arteries

    cribriform plate

    (2, one right & one left)

    ethmoid bone

    cranial cavity

    forms the superior aspect of the nasal cavities; forms part of the anterior cranial fossa; plate contains olfactory foramina where sensory neurons carrying scent information pass through from the nasal cavities towards the brain

    crista galli

    ethmoid bone

    cranial cavity

    located between the cribriform plates; attaches to the dura mater, one of the meninges surrounding the brain

    external acoustic meatus

    (2, one right & one left)

    temporal bones

    lateral skull

    passageways (right and left) form canals to the middle ears

    external occipital protuberance

    occipital bone

    posterior skull

    a minor projection on the posterior of the skull

    foramen lacerum

    (2, one right & one left)

    temporal bones

    inferior skull & cranial cavity

    mostly blocked by cartilage, but some blood vessels and nerves pass through

    foramen magnum

    occipital bone

    inferior skull & cranial cavity

    this is the largest foramen of the skull; provides passage for the spinal cord to attach to the brain stem

    foramen ovale

    (2, one right & one left)

    sphenoid bone

    inferior skull & cranial cavity

    these provide passage for branches of the paired (right and left) C.N. V trigeminal nerves

    foramen spinosum

    (2, one right & one left)

    sphenoid bone

    inferior skull & cranial cavity

    these provide passage for the middle meningeal arteries (right and left) which supplies blood to the dura mater of the brain

    hypoglossal canal

    (2, one right & one left)

    occipital bone

    cranial cavity

    provide passage for the pair (right and left) of C.N. XII hypoglossal nerves

    hypophyseal fossa

    sphenoid bone

    cranial cavity

    this fossa is the "seat" of the saddle-like sella turcica where the pituitary gland is positioned (another name for the pituitary gland is hypophysis)

    internal acoustic meatus

    (2, one right & one left)

    temporal bones

    cranial cavity

    provide passage for the right and left C.N. VIII vestibulocochlear nerves transmitting sensory information including auditory information

    jugular foramen

    (2, one right & one left)

    temporal bones

    inferior skull & cranial cavity

    provides passage for paired internal jugular veins (right and left) and right and left pairs of cranial nerves (C.N. IX, X, and XI)

    mandibular fossa

    (2, one right & one left)

    temporal bones

    inferior skull

    locations where the mandible articulates with the temporal bone creating hinges between the jaw and the rest of the skull; the condylar processes of the mandible (right and left) are positioned in these fossae

    mastoid process

    (2, one right & one left)

    temporal bones

    inferior skull & lateral skull

    location where neck muscles attach including the right and left sternocleidomastoid muscles

    middle nasal concha

    (2, one right & one left)

    ethmoid bone

    anterior skull, nasal cavities

    create passages for airflow through right and left nasal cavities

    occipital condyle

    (2, one right & one left)

    occipital bone

    inferior skull

    this pair of condyles is where the skull articulates with C1, the first cervical vertebra, also known as atlas

    olfactory foramina or cribriform foramina

    (many, found in right & left cribriform plates)

    ethmoid bone

    cranial cavity

    provides passage for axons of olfactory sensory neurons from the nasal cavities to the olfactory cranial nerves (C.N. I) in the cranial cavity; enables transmission of scent information to the brain

    optic canal

    (2, one right & one left)

    sphenoid bone

    anterior skull, posterior orbits & cranial cavity

    these provide passage for the paired C.N. II optic nerves (right and left) to pass from the eyes to the brain carrying sight information

    perpendicular plate

    ethmoid bone

    anterior skull, superior nasal septum

    creates the superior part of the nasal septum separating the nasal cavities into right and left

    pterygoid process

    (2, one right & one left)

    sphenoid bone

    inferior skull

    pterygoid muscles attach to these processes connecting with the mandible to move the mandible for chewing

    sella turcica

    sphenoid bone

    cranial cavity

    a saddle-like structure creating a basin (fossa) where the pituitary gland is located; the "seat" of the sella turcica saddle is called the hypophyseal fossa (another name for the pituitary gland is hypophysis)

    styloid process

    (2, one right & one left)

    temporal bones

    inferior skull & lateral skull

    thin and narrow inferior-pointing projections (right and left) where neck muscles and ligaments attach

    stylomastoid foramen

    (2, one right & one left)

    temporal bones

    inferior skull

    provides passage for the right and left C.N. VII; each of these foramina are located between the styloid process and the mastoid process on that side of the skull

    superior nasal concha

    (2, one right & one left)

    ethmoid bone

    inside the superior nasal cavities

    create passages for airflow through right and left nasal cavities

    superior orbital fissure

    (2, one right & one left)

    sphenoid bone

    anterior skull, posterior aspect of the orbits

    paired cranial nerves (right and left) pass through to control eye movements (C.N.III, IV, part of V, and VI)

    supraorbital notch/foramen

    (2, one right & one left)

    frontal bone

    anterior skull, superior to orbits

    passage for blood vessels and nerves

    zygomatic process

    (of temporal bones)

    (2, one right & one left)

    temporal bones

    lateral skull & inferior skull

    creates a bridge-like structure that connects the temporal bone with the zygomatic bone forming part of the zygomatic arch

    Markings of the anterior and lateral skull

    Rotating image of a skull

    Above: Markings of the cranium with the following views: (A) anterior view, (B) lateral view of the left side of the skull, (C) posterior view, and (D) lateral view of the right side of the skull.

    Attributions (All Skull Sections)


    This page titled 8.2.3: Markings of the Cranium is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Rosanna Hartline.

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