Anatomy
Written By EZmed
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Introduction
The skull is made up of 22 bones that articulate with each other - 8 cranial bones and 14 facial bones.
The remaining 7 bones in the head (6 auditory ossicles and 1 hyoid bone) do not articulate with the rest of the skull, and they are often referred to as accessory bones of the skull as a result.
In this post, we will discuss the cranial bones and sutures along with their anatomy and landmarks using labeled diagrams.
By definition, the cranial bones form the surrounding cranium that encloses and protects the brain.
Every EZmed post is filled with simple tricks to learn the material, and today we will use an easy mnemonic to remember the cranial bone names and anatomy.
Make sure to also check out the EZmed facial bone mnemonic which will help you remember the names and anatomy of the facial bones as well!
Let’s get started!
Cranial Bone Mnemonic
The skull has 8 cranial bones as mentioned above.
The cranial bones are attached to one another by sutures, which are fibrous bands of tissue that connect the bones to form the cranium around the cerebrum, cerebellum, and brainstem.
The names of the cranial bones can be remembered using the following mnemonic:
“Eight Osseous Parts Form The Skull”
Eight = Ethmoid Bone
Osseous = Occipital Bone
Parts = Parietal Bones (2)
Form = Frontal Bone
The = Temporal Bones (2)
Skull = Sphenoid Bone
This mnemonic not only helps you remember the cranial bone names, but also that there are 8 cranial bones (osseous parts) that form the skull.
We are now going to discuss the anatomy and important features of each cranial bone in the order of the mnemonic.
Ethmoid Bone
We will start with the ethmoid bone shown in red on the diagram below.
Since the ethmoid bone is obscured by other bones, let’s look at an inside sagittal view of the skull to understand its shape and location.
You can see the ethmoid bone shown in green and yellow on the 2 images below.
The ethmoid bone sits at the roof of the nose between the 2 orbits or eye sockets, and it makes up the medial aspect of each orbit.
The ethmoid bone separates the nasal cavity from the brain, and it articulates with the frontal bone and sphenoid bone.
The skull contains several different sinuses or cavities within the bones of the face and cranium.
One of these sinuses is called the ethmoid sinus, and it is located in the ethmoid bone as the name suggests.
The ethmoid bone has 2 important features - the cribriform plate and the crista galli.
The cribriform plate is where the olfactory nerves travel through.
The olfactory nerves are involved in smell, so it makes sense they will need to travel through the ethmoid bone which sits at the roof of the nose and separates the nasal cavity from the brain.
The crista galli is a sail-like projection located at the top/superior portion of the ethmoid bone.
The crista galli is where the membrane around the brain attaches, thereby preventing the brain from moving around in the skull.
It essentially serves as an anchor point for the brain.
Occipital Bone
The occipital bone is next in the mnemonic.
The occipital bone is located at the back of the skull and protects the underlying cerebellum, brainstem, and occipital lobe of the cerebrum.
There are several important features to know about the occipital bone.
First, the lambdoid suture connects the occipital bone to both parietal bones.
As mentioned above, sutures are fibrous bands of tissues that attach the cranial bones to one another.
The lambdoid suture is easy to remember because it is shaped like the lambdoid symbol as shown below.
The next important feature to know about the occipital bone is the external occipital protuberance (EOP).
The EOP is the “bump” you can feel at the back of your skull, and it serves as an attachment point for some of the neck muscles.
Third, the occipital condyles are protuberances located at the base of the occipital bone, and they articulate with the 1st cervical vertebra (C1) or the atlas.
The final important feature to know about the occipital bone is called the foramen magnum.
The foramen magnum is a large hole at the base of the occipital bone where the brainstem travels through and connects the brain to the spinal cord.
Parietal Bones
The parietal bones are next as we continue through the mnemonic.
There are 2 parietal bones, one located on either side of the skull, shown in blue.
The parietal bones are surrounded by several different sutures.
The most anterior suture is the coronal suture which connects the parietal bones to the frontal bone.
The coronal suture is easy to remember because it travels along the coronal plane.
Next, the inferior suture is called the squamous suture and it attaches the parietal bones to the temporal bones.
The most posterior suture is the lambdoid suture, and it connects the parietal bones to the occipital bone as mentioned above.
The final suture is called the sagittal suture, and it connects the 2 parietal bones together at the top of the skull.
The sagittal suture is easy to remember because it travels along the sagittal plane.
Frontal Bone
Next is the frontal bone shown in yellow below.
The frontal bone is the forehead, and it connects to the parietal bones via the coronal suture as discussed above.
The frontal bone makes up the superior aspect of each orbit.
There is a foramen (hole in the skull) located above each orbit, known as the supraorbital foramen, in which the supraorbital nerve travels through.
Temporal Bones
The temporal bones are next in the mnemonic, and one of them is shown in orange below.
There are 2 temporal bones, one located on either side of the skull in the “temple” region.
There are several features to know about the temporal bones.
First, the squamous suture connects the temporal bones to the parietal bones as discussed above.
Next, there is an anterior projection coming off the temporal bone called the zygomatic process.
The zygomatic process joins with the zygomatic bone, specifically the temporal process of the zygomatic bone, to form the zygomatic arch which is the cheek bone you can feel on the side of your face.
The zygomatic bone is one of the facial bones discussed in the EZmed facial bone blog.
Third, the auditory meatus is a canal that travels through the temporal bone and connects to the inner ear.
Next is the mastoid process, and it serves as an attachment point for some of the neck muscles.
Fifth, the styloid process is an inferior projection where some of the tongue and larynx muscles attach.
Lastly, the mandibular fossa is the point of articulation between the mandible and temporal bone.
Pterion
The region on the side of the skull where the frontal, temporal, parietal, and sphenoid bones join together is known as the pterion.
This part of the skull is thin, and the middle meningeal artery travels underneath it.
Blunt trauma to the area can cause damage to the middle meningeal artery and subsequent epidural hematoma formation.
Sphenoid Bone
The final cranial bone is the sphenoid bone shown in light purple/pink below.
It is the only cranial bone that articulates with all of the other cranial bones.
The sphenoid bone is difficult to see on the side view of the skull, but it is actually shaped like a butterfly
Let’s look at other slices of the skull to better understand the shape.
The sphenoid bone has a depression in it, called the sella turcica, in which the pituitary gland sits.
There are several anatomical features of the sphenoid bone including the greater wing, lesser wing, pterygoid process, and body.
Conclusion
Hopefully this mnemonic and overview helped you better understand the anatomy and important features of each cranial bone.
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FAQs
What are the 22 bones of the skull? ›
- Inferior nasal concha -2x.
- Lacrimal -2x.
- Mandible -1x.
- Maxilla -2x.
- Nasal -2x.
- Platine -2x.
- Vomer -1x.
- Zygomatic -2x.
- Take the first letter or a key word of the item to remember and write it down.
- Repeat for all items.
- Create a sentence. ...
- Write the sentence out a few times while saying the words that the acronym refers to.
- Practice reciting the items and the created sentence together until you've got it memorized!
- On old Olympus's towering top, a Finn and German viewed some hops.
- Ooh, ooh, ooh to touch and feel very good velvet. Such heaven!
- Read before you go to class.
- Show up to class and take good notes.
- Rote memorization for definitions. ...
- Make sure to repeat them out loud. ...
- Print diagrams and complete them over and over again. ...
- Incorporate things you've learned into your daily conversations.
We'll turn our attention to the eight bones that form it: the ethmoid bone, the sphenoid bone, the frontal bone, the occipital bone, two parietal bones, and two temporal bones.
What are the 17 sutures of the skull? ›- Coronal suture: Located between the frontal and parietal bones.
- Lambdoid suture: Located between the parietal, temporal and occipital bones.
- Occipitomastoid suture.
- Parietomastoid suture.
- Sphenofrontal suture.
- Sphenoparietal suture.
- Sphenosquamosal suture.
- Sphenozygomatic suture.
The main sutures of the skull are the coronal, sagittal, lambdoid and squamosal sutures. The metopic suture (or frontal suture) is variably present in adults.
What are the 6 sutures of the skull? ›c, coronal suture; s, sagittal suture; l, lambda suture; f, frontal suture; pf, posterior frontal suture.
Who have 213 bones? ›There are typically around 270 bones in human infants, which fuse to become 206 to 213 bones in the human adult.
What are the 29 bones of the skull? ›Head bones: The 29 head bones consist of 8 cranial bones, 14 facial bones, the hyoid bone, and 6 auditory (ear) bones. The 8 cranial bones are the frontal, 2 parietal, occipital, 2 temporal, sphenoid, and ethmoid bones.
What are the 206 bones called? ›
The axial skeleton, comprising the spine, chest and head, contains 80 bones. The appendicular skeleton, comprising the arms and legs, including the shoulder and pelvic girdles, contains 126 bones, bringing the total for the entire skeleton to 206 bones.
What is the fastest way to memorize answers? ›- Try to understand the information first. Information that is organized and makes sense to you is easier to memorize. ...
- Link it. ...
- Sleep on it. ...
- Self-test. ...
- Use distributed practice. ...
- Write it out. ...
- Create meaningful groups. ...
- Use mnemonics.
...
Peg Method Mnemonics
- one = bun.
- two = shoe.
- three= tree.
- four = door.
- five = hive.
- six = sticks.
- seven = heaven.
- eight = gate.
ROY G. BIV = colors of the spectrum (Red, Orange, Yellow, Green, Blue, Indigo, Violet.) This is by far the most popularly used mnemonic. To make an Expression or Word mnemonic, the first letter of each item in a list is arranged to form a phrase or word.
What are the 12 cranial nerves and functions quizlet? ›- Olfactory. sensory; sense of smell.
- Optic. sensory; sense of sight.
- Oculomotor. motor; eye movement.
- Trochlear. motor; eye movement.
- Trigeminal. sensory and motor; sensory impulses in the skin, jaw movement.
- Abducens. motor; eye movement.
- Facial. ...
- Vestibulocochlear.
The skull (22 bones) is divisible into two parts: (1) the cranium, which lodges and protects the brain, consists of eight bones (Occipital, Two Parietals, Frontal, Two Temporals, Sphenoidal, Ethmoidal) and the skeleton of the face, of fourteen (Two Nasals, Two Maxillae, Two Lacrimals, Two Zygomatics, Two Palatines, Two ...
How do you remember the bones of the foot mnemonic? ›The different foot bones can be remembered with the acronym "Tiger Cubs Need MILC," representing the Talus, Calcaneous, Navicular, Medial Cuneiform, Intermediate Cuneiform, Lateral Cuneiform and the Cuboid bones.
How to memorize anatomy med school? ›- Develop good study habits. ...
- Create a glossary. ...
- Break down your studies into sections. ...
- Use study aids. ...
- Think about function. ...
- Test your knowledge regularly. ...
- Get a study partner or join a study group.
- Change up your environment. ...
- Associate words with visuals. ...
- Memorize with the help of repetition. ...
- To-do List Applications. ...
- Use mnemonic devices. ...
- Make use of your senses. ...
- Don't wait until the last minute. ...
- Use time recording software.
The total number of bones found in the human skull is 29. Eight cranial bones and fourteen facial skeleton bones. In the neurocranium these are the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones.
What are the 26 vertebrae called? ›
What are the 26 bones of the spine called? The 26 bones of the spine are called vertebrae. The first 5 bones of the spine are known as the cervical vertebrae, the next 12 bones are known as the thoracic vertebrae followed by 5 lumbar vertebrae and then one fused sacral and a coccyx at the last.
What are the 3 main suture marks on a skull? ›The sutures are a type of fibrous joint, found in between many of the bones that make up the skull. Today we're going to take a look at three sutures; the coronal suture, the sagittal suture and the lambdoid suture.
What are the 3 types of sutures? ›Suture material
Nylon: Nylon creates a type of natural monofilament suture. Polypropylene (Prolene): This material creates a monofilament suture. Silk: Silk sutures are typically braided and made naturally.
- Anterior Fontanelle. The anterior fontanelle is the largest of the six fontanelles, and it resembles a diamond-shape ranging in size from 0.6 cm to 3.6 cm with a mean of 2.1 cm. ...
- Posterior Fontanelle. ...
- Mastoid Fontanelle. ...
- Sphenoid Fontanelle. ...
- Third Fontanel.
The frontal suture connects the frontal bone to the two parietal bones. The sagittal suture connects the two parietal bones. The lambdoid connects the two parietal bones to the occipital bone. The squamous sutures connect the parietal bones to the temporal bones.
What are the 4 parts of the skull? ›The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone.
Which suture closes first? ›The posterior fontanelle usually closes by age 1 or 2 months. It may already be closed at birth. The anterior fontanelle usually closes sometime between 9 months and 18 months. The sutures and fontanelles are needed for the infant's brain growth and development.
Who has 300 bone? ›Slowly, as you grew older, everything became a bit bigger, including your bones. A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults have.
Are there 256 bones? ›The skeleton
The human skeleton is made up of 206 bones, including bones of the: Skull – including the jaw bone. Spine – cervical, thoracic and lumbar vertebrae, sacrum and tailbone (coccyx) Chest – ribs and breastbone (sternum)
There are 126 named bones of the appendicular skeleton (all bones exist in pairs) [1]: Upper Limb.
What are the 18 major bones? ›
- Head. Cranium.
- Jaw Bone. Mandible.
- Collar Bone. Clavicle.
- Shoulder Blade. Scapula.
- Ribs. Ribs.
- Breast Bone. Sternum.
- Spinal Column. Vertebra.
- Pelvis. Pelvis.
Long bones are found in the upper limbs (humerus, ulna, radius) and lower limbs (femur, tibia, fibula), as well as in the hands (metacarpals, phalanges) and feet (metatarsals, phalanges).
What are the 7 types of bones? ›The bones of the human skeleton are classified by their shape: long bones, short bones, flat bones, sutural bones, sesamoid bones, and irregular bones (Figure 1).
What are 22 bones made of? ›The Skull. The skull is made up of 22 bones: the cranium includes eight bones that surround and protect the brain and 14 bones that form the face. In adults, all but one of the skull bones are fused together by immovable joints called sutures.
What is the 5 word acronym or mnemonic device to help memorize the 5 layers of the epidermis? ›You can easily remember the layers of the epidermis using the acronym: Come, Let's Get Sun-Burned! Thin skin contains the same layers, except for the stratum lucidum, which is missing.
What's the best mnemonic device for remembering? ›ROY G. BIV = colors of the spectrum (Red, Orange, Yellow, Green, Blue, Indigo, Violet.) This is by far the most popularly used mnemonic. To make an Expression or Word mnemonic, the first letter of each item in a list is arranged to form a phrase or word.
What is the mnemonic that you can use to help you remember the order of the colors of the visible light spectrum? ›ROYGBIV (in reverse VIBGYOR) is commonly used to remember the order of colors in the visible light spectrum, as seen in a rainbow. (red, orange, yellow, green, blue, indigo, violet).
What is the acronym for remembering the parts of the brain? ›Use a “piranha” fish as your mnemonic. The piranha bites you on the top of the head (where the parietal lobe is located). That's a sensation the parietal lobe would process! The Occipital Lobe processes visual information.
What is mnemonic code short answer? ›Mnemonic codes are those codes that consist of alphabets or abbreviations as symbols for codifying a piece of information. E.g. HQ for headquarters, DLI for Delhi in train bookings.
What are the 9 types of mnemonic devices? ›The 9 basic types of mnemonics presented in this handout include Music, Name, Expression/Word, Model, Ode/Rhyme, Note Organization, Image, Connection, and Spelling Mnemonics.
What is the fastest way to memorize in 10 minutes? ›
- Change up your environment. ...
- Associate words with visuals. ...
- Memorize with the help of repetition. ...
- To-do List Applications. ...
- Use mnemonic devices. ...
- Make use of your senses. ...
- Don't wait until the last minute. ...
- Use time recording software.
A mnemonic is an instructional strategy designed to help students improve their memory of important information. This technique connects new learning to prior knowledge through the use of visual and/or acoustic cues. The basic types of mnemonic strategies rely on the use of key words, rhyming words, or acronyms.