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Axial Skeleton Cranium.

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Presentation on theme: "Axial Skeleton Cranium."— Presentation transcript:

1 Axial Skeleton Cranium

2 Axial skeleton Major Divisions in the skeletal system:
Axial: Bones along the center axis (medial) of the body. Skull, Vertebral column, rib cage

3 The Skull The skull is formed by two sets of bones:
The cranium encloses and protects the fragile brain tissue ( 8 cranial bones: Frontal bone, 2 parietal bones, 2 temporal bones, the occipital bone, the spenoid bone, ethmoid bone) The facial bones hold the eyes in an anterior position (14 facial bones: 2 nasal bones, 2 maxillae, 2 zygomatic bones, the mandible, 2 lacrimal bones, 2 palatine bones, 2 inferior nasal conchae, vomer) All but one of the bones of the skull are joined together by sutures, which are interlocking, immovable joints

4 Frontal Bone Frontal Bone: Forms the forehead, the bony projections under the eyebrows, and the superior part of each eye orbit

5 Parietal Bones The paired parietal bones form most of the superior and lateral walls of the cranium They meet in the midline of the skull at the sagittal (front to back) suture, and form the coronal (up and down) suture where they meet the frontal bone

6 Temporal Bones The temporal bones lie inferior to the parietal bones
The temporal bones and parietal bones are joined at the squamous (sideways) sutures

7 Occipital Bone It is the most posterior bone of the cranium
It forms the floor and back wall of the skull The occipital bone joins the paretial bones anteriorly at the lambdoidal (along the back) suture

8 Sphenoid Bone The butterfly-shaped bone spans the width of the skull and forms part of the floor of the cranial cavity

9 Ethmoid Bone The ethmoid bone is very irregularly shaped and lies anterior to the sphenoid It forms the roof of the nasal cavity and part of the medial wall of the orbits(eye sockets)

10 Parietal Frontal Coronal suture Squamous suture Sphenoid Lambdoidal suture Ethmoid Occipital Temperal

11 Bone Surface Markings Bones have characteristic surface markings
Structural features adapted for specific functions There are two major types of surface markings: 1) Depressions and openings Allow the passage of blood vessels and nerves or form joints 2) Processes Projections or outgrowths that form joints or serve as attachment points for ligaments and tendons

12 Temporal Bones Markings
External auditory meatus: a canal that leads to the eardrum and the middle ear Styloid process: a sharp needle projection. Many neck muscles use the styloid process as an attachment point

13 Temporal Bones Markings
Zygomatic process: a thin bridge of bone that joins with the cheek bone Mastoid process: a rough projection posterior and inferior to the external auditory meatus, which is full of air cavities

14 Temporal Bones Markings
Jugular foramen (hole): the junction of the occipital and temporal bones, allows passage of the large jugular vein which drains the brain Just anterior to it is the carotid canal through which the carotid artery runs, supplying blood to most of the brain

15 Occipital Bone Markings
Foramen magnum (large hole): surrounds the lower part of the brain and allows the spinal cord to connect with the brain

16 Sphenoid Bone Markings
Sella turcica: holds the pituitary gland in place



19 Facial Bone 2 Maxillae or maxillary bones, fuse to form the upper jaw
All facial bones except the mandible join the maxillae, thus they are the main or keystone bones of the face The maxillae contains sinuses, which drain into the nasal passages: Paranasal sinuses

20 Palatine Bones The paired palatine bone are posterior to the palatine processes of the maxillae Failure of these results in cleft palate

21 Facial Bones Zygomatic bones: Are commonly referred to as the cheekbones Lacrimal Bones: fingernail size bones forming part of the medial wall to each orbit (eye socket)

22 Facial Bones Nasal Bones: The small rectangular bones forming the bridge of the nose (the lower part of the nose is made up of cartilage) Vomer Bone: The single bone in the median line of the nasal cavity

23 Facial Bones Inferior conchae: Thin curved bones projecting form the lateral walls of the nasal cavity Mandible: The lower jaw. The largest and strongest bone of the face

24 The Hyoid Bone Lies inferior to the mandible
It is the only bone with no direct articulation with any other bone Acts as a movable base for the tongue



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