Organization of the Skeleton

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Organization of the Skeleton
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The Human Skeleton

• 206 bones
• Divided into two portions.
• Axial Skeleton- Contains the bones which are in
  the mid-vertical axis of the body.
• Appendicular Skeleton- Bones which are outside
  the mid-vertical axis, associated with the
  appendages.

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Axial Skeleton

• Skull
• Contains 22 bones.
• Bones of the skull include (8) cranial, (13)
  facial and the (1) mandible.
• Sutures- Connection between the bones of the
  skull.
• Sinus-Chamber- Located in the skull, are lined
  with mucous membranes, and filled with air.
• Connect with the nasal cavity to drain fluids and
  reduce the weight of the skull.

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Axial Skeleton

• Cranium (8) bones
• 1.Frontal Bone- Large bone forming the anterior
  part of the skull (forehead).
• Orbits Eye sockets, partially formed by the
  frontal bone.
• Supraorbital Foramen Hole above each orbital
  where blood vessels pass.

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Axial Skeleton

• Cranium
• 2.Parietial Bone(s)-Two bones which form most of
  the superior/lateral cranium.
• Meet at the top of the skull at the sagittal
  suture.
• Meet the frontal bone at the coronal suture.

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Axial Skeleton

• Cranium
• 3.Occipital Bone- Thick bone which forms the
  posterior wall and floor of the cranium.
• Meets the parietal bone at the lambdoid suture.
• Foramen Magnum- Opening for the spinal cord.
• Occipital Condyles- Processes that articulate
  with the first vertebrae, to allow head movement.

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Axial Skeleton

• Cranium
• 4.Temporal Bone(s)- Two bones on either side of
  the cranium, below the parietal bones.
• Meet the parietal bones at the squamous suture.
• Styloid Process- Serves as an anchor for muscles
  of the tongue and pharynx.

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Axial Skeleton

• Cranium
• 5. Sphenoid Bone- Butterfly shaped bone that
  forms the lower lateral walls and floor of the
  cranium, also the posterior walls of the orbits.
• Optic foramen- Location of the optic nerve
  passage.
• 6.Ethmoid Bone- Small bone anterior to the
  sphenoid bone.
• Forms sections of the cranial floor, orbital
  walls, and nasal cavity.

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Axial Skeleton

• Facial Bones
• Contains 13 immovable bones and a movable
  mandible.
• 1.Maxillary Bone(s)- Two bones on each side of
  the face that form the upper jaw.
• 2.Palatine Bone(s)- Two L-shaped bones that are
  posterior to the maxillary bones.
• Forms the roof of mouth and floor of the nasal
  cavity.

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Axial Skeleton

• Facial Bones
• 3.Zygomatic Bone(s)- Two bones on the side of the
  face that form the cheeks.
• 4.Nasal Bone(s)- Two small rectangular bones that
  meet to form the bridge of the nose.
• 5.Lacrimal Bone(s)- Two fingernail shaped bones,
  form part of the orbits medial walls.

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Axial Skeleton

• Facial Bones
• 6.Vomer- Single bone along the midline within the
  nasal cavity.
• Meets with ethmoid to form the nasal septum,
  divides the nasal cavity in half.
• 7.Inferior Nasal Concha- Two thin scroll-like
  bones attached to the lateral walls of the nasal
  cavity.
• Forms shelves to channeled air into the nasal
  cavity.

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Axial Skeleton

• Facial bones
• 8.Mandible-Single lower jaw bone, articulates
  with the temporal bones.
• Only movable bone of the skull.
• Forms TMJ (temporal-mandibular joint)
• Lock Jaw
• Dislocated Jaw

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Axial Skeleton

• Hyoid Bone
• Single bone that doesnt articulate with any
  other bones.
• Horse-shoe shaped
• supports the tongue and provides attachments for
  muscles.

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Axial Skeleton

• Vertebral Column
• Strong flexible rod that supports the trunk,
  while allowing for movement.
• Extends from the skull to the pelvis.
• Made of irregular bones known as vertebrae.
• Between each vertebrae is an intervertebral disc.
• The adult vertebral column contains 26 vertebrae
  (after fusion).

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Axial Skeleton

• Structure of typical vertebrae
• Body Thick, disc-shaped front portion, designed
  for supporting weight.
• Vertebral Arch Forms a ring to hold the spinal
  cord called the Vertebral Foramen.
• Seven processes arise from the vertebral arch and
  serve for joint formation or muscle attachment.

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Axial Skeleton

• Types of Vertebrae and their Structures.
• Cervical- (7) Vertebrae of the neck region, the
  support the head.
• Transverse foramen- small hole that permits the
  passage of arteries to the brain.
• Atlas- First cervical vertebrae that connects
  with the occipital condyles of the cranium.
  Allows for up and down movement of Skull.
• Axis- Second cervical vertebrae that contains a
  tooth like projection called the
• Odontoid process- It projects up through the
  rings of the atlas and allows for twisting of the
  head.

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Axial Skeleton

• Types of Vertebrae and their Structures.
• Thoracic- (12) Only vertebrae that articulate
  with the ribs. (middle of back)
• Lumbar- (5) Vertebrae that are large and thick,
  this is due to the increase in the body weight
  they support. (lower back).
• Sacrum- Large triangular bone that forms the
  posterior part of the pelvis made of (5)
  vertebrae fused together.
• Sacral Canal contains the spinal cord.
• Coccyx- 3-5 fused bones that is attached to the
  sacrum by ligaments. (tail bone)

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Axial Skeleton

• Thoracic Cage
• Formed by thoracic vertebrae, sternum, and the
  ribs.
• Conical, basket-shaped structure
• (cone shaped).
• Partially encloses the internal structures of the
  chest.
• Supports the upper limbs.

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Axial Skeleton

• Thoracic Cage
• Sternum- AKA breast bone, Its a flat, narrow
  bone at the center of the chest.
• Articulates with the clavicles on one end.
• Articulates with the ribs via the costal
  cartilage.
• Consists of three (3) parts
• Manubrium- Superior part
• Body- Large middle part
• Xiphoid Process- Small pointy inferior end.

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Axial Skeleton

• Thoracic Cage
• Ribs
• (12) sets in every individual.
• Attach to the thoracic vertebrae in the back and
  the sternum in the front.
• True Ribs- First seven (7) pair, connects
  directly to the sternum via the costal cartilage.
• False Ribs- Remaining five (5) pair, have an
  indirect connection or no connection at all to
  the sternum.
• Floating Ribs- Last two (2) or sometimes three
  (3) pairs of ribs, have no connection at all to
  the sternum.