Anatomy Lab 8

Anterior, middle nad posterior cranial fossae. 

In the fossae completely enclosed by the calvaria. 

Eight bones make up the cranium - 1. Frontal Bone 2.  (2) Parietal bone 3. (2) Temporal bone 4. Occiptal bone 5. Sphenoid Bone 6. Ethmoid bone

Anterior portion of the cranium; forms the forehead, superior part of the orbit, and floor of the anterior cranial fossa. 

Cranium -- Frontal bone -- opening above each orbit allowing blood vessels and nerves to pass. 

Skeleton -- axial skeleton -- Skull -- Cranium -- frontal bone -- Smooth area between the eyes. 

Skeleton -- axial --- skull; posterolateral to the frontal bone, forming sides of the cranium. 

Skeleton -- axial --- skull -- Parietal bone; Midline articulation point of the two parietal bones. 

Skeleton -- axial --- skull -- parietal bone; point of articulation of parietals with frontal bone. 

Inferior to the parietal bone on the lateral skull. 

1. The squamous part - borders the parietals

2. Tympanic part - surrounds the external ear opening

3. Petrous part - form the lateral portion of the skull base and contains the mastoid process. 

Skeleton -- axial --- skull -- temporal bone -- squamous part; point of articulation of the temporal bone with the parietal bone

Skeleton -- axial --- skull -- temporal bone -- squamous part; A bridgelike projection joining the zygomatic bone (cheekbone) anteriorly. Together these two bones form the zygomatic arch. 

Skeleton -- axial --- skull --- temporal bone -- squamous part; rounded depression on the inferior surface of the zygomatic process (anterior to the ear); forms the condylar process of the mandible, the point where the mandible (lower jaw) joins the cranium. 

Skeleton -- axial --- skull - temporal - squamous part: Squamous suture; zygomatic process; mandibular fossa. 

External acoustic meatus, styloid process

Skeleton -- axial --- skull -- temporal bone -- tympanic part; Canal leading to eardrum and middle ear. 

Skeleton -- axial --- skull  -- temporal bone -- tympanic part; Needle-like projection inferior to external acoustic meatus; attachment point for muscles and ligaments of the neck. This process is often broken off demonstration skulls. 

Jugular foramen, carotid canal, internal acoustic meatus, foramen lacerum, stylomastoid foramen, mastoid process. 

Skeleton -- axial --- skull -- temporal bone -- petrous part; Opening medial to the styloid process through which the internal jugular vein and the cranial nerves IX, X, and XI pass. 

Skeleton -- axial --- skull -- temporal bone -- petrous part; Opening medial to the styloid process through which the internal carotid artery passes into the cranial cavity. 

Skeleton -- axial --- skull -- temporal bone -- petrous part; Opening on posterior aspect (petrous part) of the temporal bone allowing passage of cranial nerves VII and VIII. 

Skeleton -- axial --- skull -- temporal bone -- petrous part; A jagged opening between the petrous temporal bone and the sphenoid providing passage for a number of small nerves and for the internal carotid artery to enter the middle cranial fossa (after ipasses through part of the temporal bone). 

Skeleton -- axial --- skull  -- temporal bone -- petrous part; Tiny openings between the mastoid and the styloid process through which cranial nerve VII leaves the cranium. 

Skeleton -- axial --- skull -- temporal bone -- petrous part; Rough projection inferior and posterior to the external acoustic meatus; attachment site for muscles. 

The mastoid process, full of air cavities and so close to the middle ear - a trouble spot for infections - often becomes infected too, a condition refered to as mastoiditis. Because the mastoid area is separated from the brain by only a thin layer of bone, an ear infection that has spread to the mastoid process can infalme the brain coverings, or the meninges. The latter condition is known as MENINGITIS. 

Skeleton -- axial --- skull; Most posterior bone of the cranium - forms floor and back wall. Joins sphenoid bone anteriorly via its narrow basilar part. 

Skeleton -- axial --- skull -- occiptal bone; Site of articulation of acciptal bone and parietal bones. 

Skeleton -- axial --- skull -- occiptal bone; Large opening in base of occipital bone, which allows the spinal cord to join with the brain. 

Skeleton -- axial --- skull -- Occipital; Rounded projections lateral to the foramen magnum that articulate with the first cervical vertebra (atlas). 

Skeleton - axial - skull - occipital bone; Opening medial and superior to the occipital condyle through which the hypoglossal nerve (cranial nerve XII) passes

Skeleton - axial - skull -  occipital bone; Midline prominences posterior to the foramen magnum. 

Skeleton - axial - skull - sphenoid bone; Bat-shaped bone forming the anterior plateau of the middle cranial fossa across the width of the skull. The sphenoid boen is the keystone of the cranium because it articulates with all other cranial bones. 

Skeleton - axial - skull - sphenoid bone; Portions of the sphenoid seen exteriorly anterior to the temporal and forming a part of the eye orbits.