SKULL

HUMAN SKULL Consists of 22 bones 8 of these bones make up the cranium 14 form the facial skeleton. (also 6 tiny bones in the middle ear)

PARTS OF THE SKULL CRANIUM The cranium encloses and protect the brain, and its surface provides attachments for muscles that make chewing and head movements possible. There are 8 bones that make up the cranium. Frontal Bone Parietal Bones (2) Occipital Bone Temporal Bones (2) Sphenoid Bone Ethmoid Bone

FRONTAL BONE Forms the anterior portion of the skull above the eyes, including the forehead, the roof of the nasal cavity and roof of the orbits of the eyes.

Parietal Bones The parietal bones (2) form, by their union, the sides and roof of the cranium. Each bone is irregularly quadrilateral in form, and has two surfaces, four borders, and four angles.

Occipital Bone The occipital bone joins the parietal bones. It forms the back of the skull and the base of the cranium. A large opening on its lower surface houses nerve fibers from the brain that pass to the spinal cord.

Temporal Bones A Temporal bones (2) on each side of the skull joins the parietal bone along a squamosal suture. Forms the sides and the base of the cranium. House the internal ear. Notice how far it goes around the face before it meets the zygomatic bone “cheek”

Temporal Bones

Sphenoid Bones The sphenoid bone is wedged between several other bones in the anterior portion of the cranium. Helps form the base of the cranium, the sides of the skull and the floors and sides of the orbits. This bone really has three different views… Laterial—anterior to the temporal bone Anterior- the back of the eye sockets Inferior- looks like a butterfly.

Sphenoid Bones This bone really has three different views… Lateral—anterior to the temporal bone Anterior- the back of the eye sockets Inferior- looks like a butterfly.

Sphenoid Bones (Inferior View)

Ethmoid Bone Located in front of the sphenoid bone. Forms part of roof and walls of nasal cavity. Floor of cranium, and walls of orbits. In the back of the orbital cavity…longer bone

Ethmoid Bone

Facial Skeleton The facial skeleton consists of 13 immovable bones and a movable lower jaw bone. These bones provide basic shape of the face Attachments for muscles that move the jaw and control facial expressions.

MANDIBLE Lower jaw bone A moveable bone held to the cranium by ligaments. Horseshoe-shaped body with a flat ramus projecting upward at each end

MANDIBLE

MAXILLARY BONES They form the upper jaw. Together the form the keystone of the face. They form anterior roof of mouth, floors of orbits, and floor of nasal cavity. Contains aleveolar process, maxillary sinuses, palatine process.

Palatine Bones The L-shaped palatine bones are located behind the maxillae. The horizontal portions form the posterior section of the hard palate and the floor of the nasal cavity. The perpendicular portions help form the lateral walls of the nasal cavity. This is easier too see from the bottom view of the skull.

ZYGOMATIC BONES Responsible for the prominences of the cheeks below and to the sides of the eyes. Help form the lateral walls and the floors of the orbits. Again notice where it meets the temporal bone…called the Zygomatic Arch or the Zygomatic process of the Temporal

Lacrimal Bones A thin, scalelike structure located in the medial wall of each orbit between the ethmoid bone and the maxilla. A groove in its anterior portion leads from the orbit to the nasal cavity, providing a pathway for a channel that carries tears from the eye to the nasal cavity.

NASAL BONES The nasal bones are long, thin, and nearly rectangular. They lie side by side and are fused at the midline, where they form the bridge of the nose. These bones are attachments for the cartilaginous tissue that forms the shape of the nose.

Vomer bone The thin, flat vomer bone is located along the midline within the nasal cavity. Posteriorly, it joins the perpendicular plate of the ethmoid bone Together they form the nasal septon.

Inferior Nasal Cavity The inferior nasal conchae are fragile, scroll-shaped bones attached to the lateral walls of the nasal cavity. Positioned below the superior and middle nasal conchae of the ethmoid bone.

Foramen Foramen- An opening through a bone that usually serves as a passageway for blood vessels, nerves, or ligaments. You need to be able to identify the following… Mental Foramen, Supraorbital Foramen Infraorbital Foramen, Foramen Magnum

Foramen Supraorbital foramen (notch) Infraorbital foramen Mental

Foramen Foramen magnum

Sutures Suture- an interlocking line of union between bones You need to be familiar with the following sutures…. Coronal Suture, Lambdoidal Suture Squamosal Suture Sagittal Suture

Sutures Coronal suture Squamous suture Lambdoid suture

Sutures Sagittal suture Lambdoid suture

Process Process- a prominent projection on a bone You need to familiar with the following… Styloid Process Mastoid Process Coronoid Process

Process Mastoid process Styloid process Coronoid process

Condyle Condyle- is a rounded process that usually articulates with another bone You need to be familiar with the following… Mandibular Condyle Occipital Condyle

Condyle Mandibular condyle

Condyle Occipital condyle

Inferior View Palatine bone Zygomatic bone Sphenoid bone Vomer

For Your Information Zygomatic process (Aka zygomatic arch External acoustic canal

Ear Bones Malleus (2)- means hammer- shape of the bone Incus(2)- means anvil- shape of bone Stapes (2) means stirrup- shape of the bone Don’t worry about identification of these on the skull…you cannot see them. Just recognize the names as bones of the inner ear.

What have we learned so far?? Coronal Suture Frontal Bone Sphenoid Bone Parietal Bone Ethmoid Bone Temporal Bone Lacrimal Bones Lamboid suture Squamous suture Nasal Bone Occipital bone Zygomatic Bone Maxilla External Auditory Canal Mastoid Process Mandible Styloid Process Mandibular condyle Mental Foramen Coronoid process 42