Frontal
Because your forehead needs a sturdy frame for all those expressive moments.
Parietal
Brain helmets.
Temporal
Ensuring your brain doesn’t get too loud for your ears.
Occipital
Watching your back since day one.
Sphenoid
The skull’s missing puzzle piece.
Sutures
The skull’s missing puzzle piece.
Frontal Bone
The frontalForehead bone; forms the front part of the skull and roof of the orbits. Smooth and curved., or forehead bone is what you use to give someone a head-butt.
The skull is complicated if you don’t approach it one thing at a time. Always begin with the flat bones of the skull. Look at the suturesImmovable joints between skull bones; zigzag or wavy seams. that connect them. This method is a great way to start. Before getting started, note that there are two structures within the skull. The cranial vault is where your brain is. Then there are your facial bones, where your brain isn’t.
The flat bones of the skull are named for the parts of the brain they overlie. Tap your forehead. This is the frontal bone and under it is the frontal lobeThe brain region responsible for decision-making, personality, and voluntary movements. of your brain where your personality sits. The frontal bone also forms the superior borderTop edge of the scapula; shortest of the three borders. of your eye socket. The eye socket is a wonderfully complex structure, much like the arch of your foot. Similar to the arch of your foot, if one of those bones is weakened, the entire structure is weakened.
The frontal bone is sutured to both the parietal bones by the coronal sutureRuns across top of skull between frontal and parietal bones (like a headband).. The word corona means crown and so it is fitting that this suture runs almost from ear to ear. The frontal bone also articulates with the sphenoidButterfly-shaped bone in the middle cranial floor; unites cranial and facial bones. bone just a little bit behind your temples. That suture, like many of the other sutures in the skull, is named for the two adjoining bones. It is called the spheno-frontal suture.
Ethmoid Bone
The ethmoidLight, spongy bone between the eyes; forms nasal septum and medial orbit walls. bone is nestled deepAway from the surface of the body. within your skull. It has a fascinating shape. The features of this shape have names from a faraway land.
- Crista galli
- Cribriform plate
The ethmoid bone is just so hard to visualize. The ethmoid bone is described as occupying the mid-facial region. Now, you might be thinking about the nose area and you are not wrong. The ethmoid bone is located deep inside the facial region near the nose. It forms the medial-inferior curvature of your eye socket or orbit. Looking at the ethmoid bone from a transverse view, it has a ridge along its midline called the crista galliSharp ridge projecting upward from ethmoid; anchor point for brain’s meninges.. The term refers to a cock’s comb (rooster head-thingy). Just lateralAway from the midline of the body. to the crista galli are the cribriform plates. These two plates can be identified by the numerous foramina that are in them. The olfactory nerve has dendritesBranch-like extensions from a neuron that receive signals from other neurons. that extend through these holes and invade the nasal cavityThe internal space behind the nose that filters, warms, and humidifies incoming air..
Occipital Bone
The back of your headRounded proximal end that fits into the acetabulum of the hip bone. is covered by the occipitalPosterior and base of the skull; curves under to form the back of the head. bone. This makes it easy to remember that the area in your brain managing sight is back there too.
- Foramen magnum
- Occipital condyles
The skull is complicated if you don’t approach it one thing at a time. A great way to start is to examine the flat bones of the skull. Then, look at the sutures that connect them to each other. Before getting started, note that there are two structures within the skull. The cranial vault is where your brain is. Then, there are your facial bones, where your brain isn’t.
The occipital bone forms part of the posterior wall of the cranium and the inferiorBelow or toward the lower part of the body. surface of the skull. It articulates with each of the parietal bones at the lambdoid sutureInverted “V” shape between occipital and parietal bones on the back of skull.. It also articulates with the temporal boneBones on the sides of the skull near the ears; house structures of hearing and balance. at the occipito-mastoid suture.
The hole in the middle of the occipital bone is where the spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae. punches through and connects to the brain. This is called the spine hole. No, it’s called the magnum foramen, meaning large hole. I just once had a class that kept calling it the spine hole.
The two occipital condylesSmooth, oval projections beside the foramen magnum; articulate with the atlas vertebra. are lateral to the magnum foramen. You are thinking that these can’t be condyles. We know condyles as knubby ends of bones like the femurThigh bone; longest and strongest bone in the body; has a large round head and prominent trochanters. Well, this applies here, kinda. These are little nubs, sticking out from the flatness of the bone. These nubs sit on the atlasFirst cervical vertebra; ring-shaped, no body; supports the skull at the occipital condyles (“yes, which is C1, or the most superiorAbove or toward the upper part of the body. vertebra. Atlas was a Titan who held the weight of the world on his shoulders. The atlas has structures that cradle these condyles allowing you to nod your head yes. Go ahead and nod your head. As you do, these occipital condyles rock on the atlas. They move back and forth like a rocking chair does on the floor. We’ll talk about shaking your head no when we go over vertebrae.
Parietal Bones
The parietal bones are the big bones covering the most of your head. They form the vault of the cranium.
- parietal bone(s)
The skull is complicated if you don’t approach it one thing at a time. It is always great to begin with the flat bones of the skull. Next, examine the sutures that connect them to each other. Before getting started, note that there are two structures within the skull. One is the cranial vault, where your brain is. The other is your facial bones (where your brain isn’t).
The flat bones of the skull are named for the parts of the brain they overlie. The parietal bones cover the top, sides, and back of the brain. Many students forget that there are two parietal bones: left and right. This is different than the other unpaired bones of the skull such as the frontal and occipital. The parietal bones are large in relation to the other skull bones. They cover the top, some of the sides, and the superior portion of the posterior skull. Basically, they are your brain hat.
Both parietal bones articulate with the front or forehead bone. That suture, running almost from ear to ear, is called the coronal suture. The parietal boneLarge, flat bones forming the top and sides of the skull; meet at the sagittal suture. covers a large portion of the cranium. It has more than a few sutures where it meets the other skull bones. The parietals meet the occipital bone at the posterior of your skull. They are sutured by the lambdoid suture (lambdoid means “soft”).
Just above the ear, the parietal bones articulate with the temporal bone. The suture binding them together is called the squamosal suture. Finally, the parietals articulate with the sphenoid bone. It could be considered part of the cranium but actually occupies more space of the face than the cranium. The suture binding the parietal bones and the sphenoid bone is called the spheno-parietal bone.
Sphenoid bone
The sphenoid bone articulates with almost all your cranial bones and forms the outside of your eye socket.
- Sella turcica
- Optic foramen
The skull is complicated if you don’t approach it one thing at a time. Begin with the flat bones of the skull. Then proceed with the sutures that connect them to each other. This method is always a great way to start. Another important point is that there are two structures within the skull. One is the cranial vault where your brain is. The other is your facial bones (where your brain isn’t).
The sphenoid bone fits with the temporal, frontal, occipital, and parietal bones. Touch the side of your eye socket, and find the rim of the socket. Move back or posterior just a little bit, that is the sphenoid bone. The small patch visible from the outside does not show how large the sphenoid bone really is. If we turn the skull over, we can see the spread of the sphenoid bone more clearly. It becomes apparent when we look at the inferior face. We can see it articulate more clearly with the occipital bone. It also connects with the vomerThin, flat bone forming the lower portion of the nasal septum. and palatineL-shaped bones forming posterior part of hard palate and floor of nasal cavity. bones on the roof of the mouthThe opening of the digestive tract where food enters and mastication begins.. The sphenoid and ethmoid bones both have structures that have a lot of twists and turns…literally.
The special features of the sphenoid bone that interest us are only viewable from the inside of the skull. These can be seen from a mid-sagittal section A cut or slice of the body or an organ for study., which cuts the skull into left and right. Alternatively, view them from a transverse section, cutting it into top and bottom.
The term sella turcicaSaddle-like depression in sphenoid that holds the pituitary gland. means “turk’s saddle.” This curved structure cradles the pituitary glandEndocrine gland at the brain’s base controlling many hormones.. The gland dangles down from what seems like the exact center of your brain. When they swab you for COVID, it’s like they are trying to swab your pituitary gland. The optic foramenRound opening in sphenoid for the optic nerve; visible inside orbit. is the canal through which cranial nerve II or the optic nerve threads. After passing through the sphenoid bone, the optic nerves cross. The pituitary, still cradled in the sella turcica, is located just inferior to that crossing.
Temporal Bone
Get to know the temporal bone. Many important features and attachment points are on this bone.
- Zygomatic process
- Mandibular fossa
- External auditory meatus
- Styloid process
- Mastoid process
The skull is complicated if you don’t approach it one thing at a time. Start by examining the flat bones of the skull. Then, look at the sutures that connect them to each other. This is always a great way to begin. Note that before getting started, there are two structures within the skull. The cranial vault is where your brain is. Then, there are your facial bones, where your brain isn’t.
There are many features of the temporal bone. The first I already mentioned is the ear hole or the external acoustic meatus. Sometimes this is called an auditory meatus. You also have an internal acoustic meatus, but you can’t see that from this side of the skull.
There are three processes on the temporal bone, two are easy to identify, one is confusing. Touch behind your ear. Move your jaw in a chewing motion. You can feel where your chewing muscles attach. These muscles connect the mandibleLower jawbone; only movable bone of the skull; U-shaped and largest facial bone. or the lower jaw to the skull. This is the mastoid processLarge, rounded bump behind the ear; attachment for neck muscles.. The word masticate means to chew and this is where the word mastoid comes from.
Whereas the mastoid process is rounded, the styloid processThere are many styloid processes in the human body. All are pointed projections that serve as muscle is pointy. The word stylus means writing utensil, like a pencil. Many times when humans skulls are prepared from viewing, the styloid process easily breaks off. The zygomatic processProjection of the temporal bone that connects to the cheekbone (zygomatic bone). is the third process and can be hard to see on a lateral view of the skull.
There are three processes on the temporal bone, two are easy to identify, one is confusing. Touch behind your ear. Move your jaw in a chewing motion. You can feel where your chewing muscles attach. These muscles connect the mandible or the lower jaw to the skull. This is the mastoid process. The word masticate means to chew and this is where the word mastoid comes from.
Whereas the mastoid process is rounded, the styloid process is pointy. The word stylus means writing utensil, like a pencil. Many times when humans skulls are prepared from viewing, the styloid process easily breaks off. The zygomaticCheekbones; form lateral walls of orbits and connect to temporal bones via zygomatic process. process is the third process and can be hard to see on a lateral view of the skull.
The zygomatic process, comes off the temporal bone and connects with your zygomatic bone, or the cheek bone. The process is not named for the bone from which it originates. It is named for the bone with which it articulates or connects. I recommend looking at the description of the zygomatic bone right now to see how these two processes articulate.
Zygomatic bone
The prefix zygo- means “pouch.” Your cheeks are the pouches (this is the cheek bone).
- Temporal process
The skull is complicated if you don’t approach it one thing at a time. Begin with the flat bones of the skull. Then, examine the sutures that connect them to each other. This is always a great way to start. Another thing to note before getting started is that there are two structures within the skull. The cranial vault holds your brain. Your facial bones are where your brain isn’t.
The zygomatic bone is the cheek bone. We saw this before because a few of the other bones we’ve discussed articulate with the zygomatic bone. We are concerned with the temporal processProjection of zygomatic bone that connects with temporal bone’s zygomatic process to form the zygo, which is on the zygomatic bone and juts out to the posterior. This is a feature that’s hard to relate to in person. It is even more difficult to recognize and explain in a virtual class like this.
If we turn a skull over and look at the inferior face of it (where the spine hole or foramen magnumLarge hole at base of skull for spinal cord to pass through. is), it looks like the skull has handles on the side. These handles are called the zygomatic arches and are actually made of of projections from two bones, not one. This arch includes part of a projection from the zygomatic bone, which is called the temporal process. It also includes part of a projection from the temporal bone, known as the zygomatic process. Note that each process is NOT named for the bone it is part of. Instead, it is named for the bone with which it articulates.
Put your finger on the point of your cheek bone. You are on the temporal process. Move your finger posteriorly toward your ear. You are moving over the zygomatic arch (which, again, is made of BOTH the zygomatic process AND the temporal process). Right in front of your ear, you pass the suture line of the zygomatic and temporal bones. You then end up touching the zygomatic process of the temporal bone.
The zygomatic process, comes off the temporal bone and connects with your zygomatic bone, or the cheek bone. The process is not named for the bone from which it originates. Instead, it is named for the bone with which it articulates or connects. I recommend looking at the description of the zygomatic bone right now to see how these two processes articulate.
Identify More Bones
Link to more Bone Identification
Long Bones
Stick Bones
Hands and Feet
Pectoral Girdle
Pelvic Girdle
Skull Bone
Facial Bones
Vertebrae & Ribs
Odds and Ends
List of terms
- frontal
- sutures
- frontal lobe
- superior border
- coronal suture
- sphenoid
- ethmoid
- deep
- crista galli
- lateral
- dendrites
- nasal cavity
- head
- occipital
- inferior
- lambdoid suture
- temporal bone
- spine
- occipital condyles
- femur
- atlas
- superior
- parietal bone
- vomer
- palatine
- mouth
- section
- sella turcica
- pituitary gland
- optic foramen
- mandible
- mastoid process
- styloid process
- zygomatic process
- zygomatic
- temporal process
- foramen magnum