ACOS OBJ 6.) Identify Bones that compose the Skeletal
System
Introduction

The skull is made up of 22 bones total
 8 Cranial Bones
 13 Facial Bones
 The Mandible
 The Main function of the skull is to protect the
Brain
 Except for the lower jaw all bones in the skull
are interlocked along lines called sutures.
Cranium
Protects the Brain
 Provides attachment for muscles
 Contains air-filled sinuses to allow it to
be light weight.

Bones Located in the Cranium

1. Frontal Bone: Includes frontal
sinuses. One located above each eye.

2. Parietal Bones: 1 located on each
side of the skull just behind the frontal
bone.
 Fused at the sagittal suture
 Meets the frontal bone at the coronal suture

3. Occipital Bone: Joins Parietal Bones
along lambdoidal suture.
 Forms the back of the skull & the base of the
cranium.
 Contains a large opening (Foramen
Magnum) where the nerve fibers from the
brain pass through & enter the vertebral
canal to become part of the spinal cord.
 Occipital Condyles: Located on each side of
the foramen magnum.
○ Articulate w/ the first vertebra ( Atlas)

4. Temporal Bones: located on each
side of the skull.
 Joins parietal bone @ squamosal suture.
 Forms parts of the sides & base of the
cranium.
 Inferior margin: an opening (external
auditory meatus) that leads to the ear.
 Mandibular fossae articulate with condyles
of the mandible.

Below external auditory meatus are 2
projections.
 1. Rounded mastoid process- provides an
attachment for certain muscles of the neck.
 2. Styloid Process- anchors muscles
associated with the tongue & pharynx.
○ - Zygomatic Process: projects anteriorly from
the temporal bone.
 Joins zygomatic bone & helps form prominence of
the cheek.

5. Sphenoid Bone- Anterior portion of
the cranium.
 Composed of a central part & 2 wing like
structures
○ Helps form the base of the cranium, side of
the skull, & floors and sides of the orbits.
- Contains 2 sphenoidal sinuses
- Midline portion of bone indents to form saddle-
shaped Sella Turcica ( where pituitary gland is
located)

6. Ethmoid Bone- Located in front of the
Sphenoid bone.
 Consists of 2 masses (1 on each side of the
nasal cavity)
 2 masses are joined horizontally by
cribriform plates(form part of the roof of the
nasal cavity)
 Crista Galli- triangular process located
between cribriform plates & forms most of
the nasal septum.
 Superior & Middle Nasal Concha- Project
inward from lateral portions of the ethmoid
bone toward the perpendicular plate.
Facial Skeleton

1. Maxillae- Form the upper jaw.
-Portions of these bones make up the
anterior roof of the mouth ( Hard
Palate), floors of orbits, & sides and
floor of the nasal cavity.
- Contain sockets of the upper teeth
-dense connective tissue binds teeth
to bony sockets.
During Development the
Palatine Process grows
& fuses together to form
the anterior port of the
hard palate.

2. Palatine Bones- L shaped
 Located behind the maxillae
 Horizontal portions form the posterior
section of the hard palate & floors of the
nasal cavity.
 Perpendicular portions help form lateral
walls of the nasal cavity.

3. Zygomatic Bones- form prominences
of cheeks below & to the sides of the
eyes.
 Consists of temporal processes which join
zygomatic process and form the zygomatic
arch

4. Lacrimal Bones- Thin scale-like
structures located in the medial wall of
each orbit.
 Between the ethmoid bone & maxilla

5. Nasal Bones- Long, thin, and nearly
rectangular.
 Lie side by side and fused at the midline
where they form the bridge of the nose.

6. Vomer Bone- Thin, Flat, & located
along the midline within the nasal cavity.
 Posteriorly joins perpendicular plate of the
ethmoid bone (Together they form the nasal
septum)

7. Inferior Nasal Conchae
 Fragile, Scroll-shaped
 Attached to the lateral walls of the nasal
cavity
 Support mucous membranes within the
nasal cavity.

8. Mandible- Horseshoe shaped body
with a flat portion projecting upward at
each end.
 Divided into 2 processes:
○ 1. Posterior Mandibular Condyle: Articulate w/
mandibular fossae of temporal bones.
○ 2. Anterior Coronoid Process: Provides
attachments for muscles used in chewing.
○ Superior Border of Mandible (Alveolar Arch)Contains hollow sockets that bear the lower
teeth