An Introduction to the Axial An Introduction to the Axial Skeleton Terms: Structures of Bones ......

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  • Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    An Introduction to the Axial Skeleton

  •  Terms: Structures of Bones

     Articulations: Contacts with other bones

     Landmarks (Bone Markings; Marks): Areas

    of muscle and ligament attachment

     Foramina: Openings for nerves and blood


  •  All bones possess distinctive landmarks that are

    designed for specific functions, e.g. certain

    landmarks are used as articulating surfaces to form

    a joint (an articulation) with another bone on the


     Examples of these include condyles, heads, and


     A complete list of bony landmarks is shown in your

    activities packet pg 89 Table 7.1

     In your lab activities study sheet, it is suggested that

    you create online study cards using “Quizlet”

  • The Axial Skeleton

  •  The axial skeleton Has 80 bones & forms the vertical axis of

    the body. It can be divided into three parts: the skull, the

    vertebral column, & the bony thorax.

     The skull: 8 cranial bones & 14 facial bones

    – Bones associated with skull: 6 auditory ossicles & hyoid bone

     The vertebral column: 24 vertebrae (singular = vertebra),

    The sacrum, & The


     The thoracic cage:

    24 ribs & The sternum

  • The axial skeleton forms the vertical

    axis of the body

  •  Functions of the Axial Skeleton

     Supports and protects organs in body cavities

     Attaches to muscles of:

     Head, neck, &


     Respiration

     Appendicular


  • The Skull

  •  The skull is composed of two sets of bones:

     8 cranial bones:

     Forms the walls and floor of the cranial cavity

     Most of the bones are flat or slightly curved

     14 facial bones:

     Have irregular shapes. These bones form the face & the walls of orbital

    and nasal cavities and provide bony sockets for the teeth.

  •  Learning the bones of the skull can be challenging, thus you

    must examine it’s 3-D. In addition to your drawings, note your

    3-D paper skull and the iPad App.

     All but one of the bones of the skull are joined by interlocking

    joints called sutures. Only the mandible, or lower jawbone, is

    attached to the rest of the skull by a freely moveable joint.

  • Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    The Skull

    Figure 7–2 Cranial and Facial Subdivisions of the Skull.

  • Terminology Aids

  •  Sinuses

     Cavities that decrease the weight of the skull

     Lined with mucous membranes

     Protect the entrances of the respiratory system

     Sutures

     The immovable joints of the skull

     The four major sutures

     Lambdoid suture

     Coronal suture

     Sagittal suture

     Squamous suture

  •  For a suture, compare the uniting of two skull

    bones with fibrous connective tissue to the

    sewing together of two pieces of fabric with a

    zigzag stitch. The word suture comes from

    sutura, Latin for seam.

  •  imagine the ethmoid as a capital letter “T.” (Make a “T” with

    your hands, as you would if signaling a time-out.)

  •  The knuckles of the hand that form the cross bar of the “T”

    are analogous to the crista galli, which can only be viewed

    from inside the cranial cavity.

     Crista galli = rooster’s comb

  •  The term ethmoid derives from “sieve-like”

    and numerous ethmoid sinuses of the

    ethmoid bone. Cribriform may remind

    students of a corncrib.

  •  Functions of the


     Forms floor of the


     Roof of the nasal cavity

     Part of the nasal

    septum and medial

    orbital wall

     Contains ethmoidal air

    cells (network of


  •  Three Parts of the


     The cribriform plate

     Roof of the nasal


     Contains the crista


     The two lateral


     Ethmoidal labyrinth

    (ethmoidal air cells)

     The perpendicular


     Part of the nasal


  •  Foramina of the


     Olfactory


     In the cribriform


     For olfactory


  •  If the perpendicular plate of the ethmoid bone

    is displaced from its medial position narrowing

    the nasal cavity (deviated septum), the result

    can be chronic sinus problems

  •  Associate the Latin adjective magnum with

    the word magnify to indicate that this foramen

    is BIG.

  •  The parietal bones get their name because

    they form the wall of the cranium, just as a

    parietal membrane covers the wall of a body


  •  The squamous portion of a bone refers to the

    flattened region, just as squamous epithelium

    refers to flattened cells.

  •  Sphenoid means “wedge-shaped.” The

    sphenoid bone is “wedged” between the

    cranial and facial bones. Trace the outline of

    the “bat with wings” that the sphenoid


  •  The pituitary gland “rides” protected in its

    sella turcica, literally, “Turkish saddle.”

  •  Marks of Temporal Bones

     Mandibular fossa: articulates with the mandible

     Zygomatic process

     Articulates with temporal process of zygomatic bone

     Forms zygomatic

     arch (cheekbone)

  •  Marks of Temporal Bones

     Mastoid process: For muscle attachment Contains mastoid

    air cells connected to middle ear

     the word mastoid (mastos), referring to a breast-like shape

    (recall mastectomy, removal of the breast).

  •  Marks of the Temporal Bones

     Styloid (stylo = stake) process

     attach tendons and ligaments of the hyoid, tongue, and pharynx

     Auditory ossicles

     Three tiny bones in tympanic cavity (middle ear)

     Transfer sound from tympanic membrane (eardrum) to inner ear

  •  Coronoid comes from the word corona, a

    crown. Imagine this process as the point in a

    king’s crown. The word coronation is related.

  •  The word mental pertains to the chin. Recall

    Rodin’s The Thinker.

  •  Functions of the hyoid


     Supports the larynx

     Attaches muscles

    of the larynx,

    pharynx, and


     Articulations of the

    hyoid bone

     Connects lesser

    horns to styloid

    processes of

    temporal bones

  •  The hyoid bone “hides” behind the mandible.

     Not really counted as a skull bone, located in


  •  The hyoid bone is the only bone in the body

    that doesn’t articulate with another bone. The

    space between the muscular base of the

    tongue and the soft tissue above the thyroid

    cartilage (hyoid bone).

  •  The vomer is probably the least famous skull

    bone. It means plowshare (from its shape).

  •  the zygomatic process is on the zygomatic

    bone. Note the color coded diagram, that

    demonstrates that this feature also belongs to

    the temporal bone.

  •  The maxilla holds the upper teeth, but it also

    composes much of the face, including the

    floor of the orbit and the roof of the mouth.

  •  Andre the Giant (Andre Rene Roussimoff), world-renowned

    professional wrestler and actor, suffered from pituitary

    gigantism and acromegaly. Acromegaly develops in those for

    whom hypersecretion of growth hormone continues past

    epiphyseal closure. After closure, elongation of endochondral

    bones is over, but appositional growth of these bones and

    intramembranous bones continues. This leads to deformity of

    the face, skull, and mandible; a coarsening of facial features;

    and thickening of fingers and toes.

  • The Infant Skull

  •  The Infant Skull Grows rapidly, Is large compared to the body

     It Has many ossification centers

     Fusion is not complete at birth

  •  Fontanel (fountain or spring)

     Are areas of fibrous connective tissue (soft spots—pulse

    can be felt, especially anterior)

     Cover unfused sutures in the infant skull

     Allows the skull to flex during birth