Bones of the skull and more skull anatomy

Summary

This educational video script delves into the intricacies of the human skull, focusing on sutures and bony landmarks. It explains the purpose of sutures like the coronal, sagittal, and lambdoid, and highlights features such as fontanels, which allow for brain growth and ease of childbirth. The script also covers various bony processes and fossae, emphasizing their roles in muscle attachment and housing blood vessels and nerves. The goal is to familiarize viewers with anatomical terms and structures, enhancing their understanding of the skull's complex architecture.

Takeaways

• 💀 The video discusses the anatomy of the human skull, focusing on sutures and bony landmarks.
• 🔍 The sutures are the seams between the bones of the skull, including the coronal, sagittal, lambdoid, and squamosal sutures.
• 👶 Fontanels are soft spots in the skull of infants, allowing for brain growth and facilitating birth.
• 🦴 The skull has various bony processes, such as the mastoid process and the zygomatic process of the temporal bone, which are important for muscle and ligament attachments.
• 👂 The external acoustic meatus is the opening for the ear, located near the mastoid process.
• 👁️ The sphenoid bone is a key part of the skull, with various sutures connecting it to other bones, such as the frontal and parietal bones.
• 🦷 The mandible articulates with the temporal bone at the mandibular fossa, with the condylar process being the articulating part.
• 🧠 The cranial fossae are depressions in the skull that house different parts of the brain, including the anterior, middle, and posterior cranial fossae.
• 🩺 The internal structures of the skull, such as the sella turcica, are important for the location of the pituitary gland and passage of blood vessels.
• 🦷 The palate is formed by the maxilla, palatine bones, and the sphenoid bone, with the hard palate being a significant structure.
• 🕳️ Foramina in the skull, such as the greater and lesser palatine foramina, are passageways for nerves and blood vessels.

Q & A

What is the main focus of the video script?

The main focus of the video script is to discuss the anatomy of the skull, specifically the sutures and various bony landmarks, as well as the anatomical terms associated with them.

What are sutures in the context of the skull?

Sutures are the fibrous joints between the bones of the skull that allow for growth and provide protection to the brain. They are immovable and have a tight interdigitated structure.

What does the term 'coronal suture' refer to?

The coronal suture is the suture that separates the frontal bone from the two parietal bones and lies in the coronal plane.

What is the sagittal suture, and what does its name signify?

The sagittal suture is the suture that separates the two parietal bones in the midline. Its name comes from 'Sagittarius the Archer,' symbolizing the straight path of an arrow, which is similar to the suture's direction.

What is the significance of the lambda and bregma in the skull?

Lambda is the point where the lambdoid suture meets and forms a Y-shape, while bregma is where the sagittal suture meets the coronal suture, forming a T-shape. These points are important anatomical landmarks on the skull.

What are fontanels, and why are they important in infants and fetuses?

Fontanels are large spaces between the bones of the skull in infants and fetuses, allowing for the rapidly expanding brain to grow without the bones impeding its growth. They also facilitate the molding of the skull during birth for easier passage through the birth canal.

What is the function of the mastoid process and the styloid process in the skull?

The mastoid process is a bony projection from the temporal bone, and the styloid process is a thin, elongated projection that serves as an attachment point for various muscles and ligaments, including the stylohyoid ligament to the hyoid bone.

What is the purpose of the sphenoid bone in the skull?

The sphenoid bone is a central bone in the skull that forms part of the眼眶 and the base of the skull. It also houses the pituitary gland and provides attachment points for various structures, including the tentorium cerebelli.

What are the anterior and posterior cranial fossae, and what do they contain?

The anterior cranial fossa is the space above the sphenoid bone, housing the frontal lobes of the brain. The posterior cranial fossa is located at the back of the skull, containing the cerebellum and brainstem.

What is the function of the pterygoid plates in the skull?

The pterygoid plates are parts of the sphenoid bone that serve as attachment points for the muscles of mastication, including the lateral and medial pterygoid muscles.

What are the ethmoid bone and its significance in the skull?

The ethmoid bone is a light, spongy bone located in the orbit of the skull, forming the upper part of the nasal cavity and contributing to the formation of the eye socket.

Outlines

00:00

💀 Skull Anatomy and Sutures

This paragraph delves into the intricacies of the human skull, focusing on the sutures and bony landmarks. It begins with an introduction to the frontal, parietal, occipital, and temporal bones, highlighting the coronal, sagittal, and lambdoid sutures that interconnect them. The discussion includes the significance of fontanels in infants, which allow for brain growth and skull flexibility during birth. The paragraph also touches on the zygomatic arch, mastoid process, and styloid process, emphasizing their roles in the attachment of muscles and ligaments. The importance of sutures as protective, immovable joints for the skull's contents is underscored.

05:01

🦴 Exploring Skull Features and Landmarks

The second paragraph continues the exploration of the skull, identifying specific bony features such as the zygomatic process of the frontal bone, the frontal process of the zygomatic bone, and the ethmoid bone within the orbit. It discusses the sphenoid bone's position and the surrounding sutures, including the sphenofrontal and spheno parietal sutures. The paragraph also describes the external and internal occipital protuberances, the superior and inferior nuchal lines, and the attachment sites for neck muscles. The inner skull structures are highlighted, including the anterior, middle, and posterior cranial fossae, and the sphenoid bone's role in the skull's interior.

10:02

🗝️ Skull Sutures and Their Functional Significance

This paragraph examines the functional aspects of skull sutures, their variability among individuals, and their purpose in protecting the brain. It describes the external occipital protuberance and the nuchal lines, which serve as attachment points for muscles that support the head. The paragraph also details the internal structures of the skull, such as the anterior and posterior clinoid processes that form a groove for the internal carotid artery. It explains the importance of the sphenoid bone in the skull's interior, the presence of the pituitary gland in the hypophyseal fossa, and the role of the clivus and dorsum sellae in the skull's posterior wall.

15:03

🦷 Mandible and Skull's Bony Intersections

The final paragraph shifts focus to the mandible and its connection to the skull, specifically the mandibular fossa and the temporomandibular joint. It describes the condyloid process, coronoid process, and the body, angle, and ramus of the mandible. The paragraph also discusses the muscles of mastication, particularly the masseter muscle, and the structures passing through the mandibular foramen to the lower teeth. It concludes with a mention of the mental foramen and the mylohyoid muscle, emphasizing the complexity of the skull's bony intersections and the importance of understanding these anatomical details.

Keywords

💡Skull

The skull is the bony structure that forms the head of a vertebrate, providing protection for the brain and supporting structures for the face and jaws. In the video, the skull is the primary subject, with a focus on its various sutures and bony parts, highlighting its importance in understanding human anatomy and the attachment points for muscles and ligaments.

💡Sutures

Sutures are the fibrous connections between the bones of the skull, particularly in the cranium, which are immovable joints that protect the brain. The video discusses several types of sutures, such as the coronal, sagittal, and lambdoid sutures, and explains their anatomical locations and functions, like the sagittal suture separating the two parietal bones.

💡Fontanels

Fontanels are soft spots on an infant's skull, where the bones of the skull have not yet fused, allowing for brain growth and facilitating the passage of the head through the birth canal. The video mentions the anterior and posterior fontanels, emphasizing their role in the development and birthing process.

💡Bony Processes

Bony processes are projections or extensions from bones that serve various functions, such as providing attachment points for muscles or ligaments. The video describes several processes, including the zygomatic process of the temporal bone and the mastoid process, illustrating their anatomical significance and their role in the structure of the skull.

💡Zygomatic Arch

The zygomatic arch is a bony arch in the skull formed by the zygomatic process of the temporal bone and the zygomatic bone, creating a framework for the cheek area. The video explains the formation of the zygomatic arch and its components, which is crucial for understanding facial structure and muscle attachments.

💡Mastoid Process

The mastoid process is a bony projection behind the ear, part of the temporal bone, which is involved in the attachment of various muscles and the transmission of sound. The video points out the mastoid process and its associated structures like the external acoustic meatus, indicating its importance in both the auditory system and muscle attachment.

💡Sphenoid Bone

The sphenoid bone is a butterfly-shaped bone located in the skull's central region, playing a key role in the structure of the face and the base of the skull. The video discusses the sphenoid bone's position and its sutures with other bones, such as the spheno-frontal suture, highlighting its complex and integral role in the skull's composition.

💡Occipital Bone

The occipital bone is the bone at the back of the skull, supporting the brain and forming part of the clivus and the foramen magnum. The video describes features of the occipital bone, including the external occipital protuberance and the nuchal lines, which are important for muscle attachment and understanding the skull's posterior aspect.

💡Cranial Fossae

Cranial fossae are depressions in the skull that house parts of the brain, divided into the anterior, middle, and posterior fossae. The video explains the location and contents of each fossa, such as the pituitary gland in the hypophyseal fossa, showing their importance in neuroanatomy.

💡Dura Mater

The dura mater is the thickest and outermost of the three layers of the meninges, the protective membranes surrounding the brain and spinal cord. The video mentions the dura mater in the context of its attachment points, such as the clinoid processes, and its role in supporting and protecting the brain.

💡Styloid Process

The styloid process is a long, slender projection from the temporal bone, involved in the attachment of muscles and ligaments, including the stylohyoid ligament. The video notes the styloid process's vulnerability to breakage and its anatomical landmarks, emphasizing its role in the skull's structural integrity.

💡Mandible

The mandible, or lower jaw, is the largest, strongest, and lowest bone in the face, forming the lower part of the oral and digestive tracts. The video describes the mandible's features, such as the condyloid process and the mental foramen, and its articulation with the temporal bone, illustrating its function in mastication and facial structure.

Highlights

Introduction to the anatomy of the skull, focusing on sutures and bony landmarks.

Explanation of the coronal suture and its position on the skull.

Description of the sagittal suture and its significance in the midline of the skull.

Identification of the lambdoid suture and its Y-shaped structure at the back of the skull.

Discussion on lambda, bregma, and fontanels in the context of skull development.

Mention of the sphenoid bone and its role in the skull's structure.

Explanation of the squamosal suture and its relation to the temporal bone.

Description of the zygomatic arch and its formation by the zygomatic and temporal bones.

Identification of the mastoid process and its anatomical landmarks.

Discussion on the external and internal occipital protuberances and their significance.

Overview of the cranial fossae and their locations within the skull.

Explanation of the sphenoid bone's role in the middle cranial fossa and its surrounding structures.

Identification of the ethmoid bone and its position within the skull.

Discussion on the importance of sutures in protecting the brain and their individual characteristics.

Description of the attachment points for muscles and ligaments on the skull.

Explanation of the styloid process and its associated structures.

Identification of the pterygoid processes and their relation to the muscles of mastication.

Overview of the mandible's anatomy, including the mandibular fossa and its articulation points.

Conclusion summarizing the importance of understanding skull anatomy for medical and educational purposes.

Transcripts

[Music]

all

look at that these hands are coming out

really nicely

now but I don't actually want to talk

about the hand today I'm going to go

back to the

skull right um so we were talking about

the skull so I thought I'd do a little

bit more about the skull but um talk

about the sutures just go over the

sutures and some of the Bony bits the

protuberances the lumpy bits that we see

um cuz they often get emitted often we

use the names the terms pop up we talk

about muscles attaching to this and

ligaments attaching to that and I'll try

not to give you an exhaustive list of

what attaches to things I'll just try to

point out the Bony bits um so that when

you come across those terms you know

what people are talking about all right

cuz there's quite a lot going on in here

all right I got I got a skull that's got

colored bones which is very helpful and

I've got a decent quality skull

got my skeleton they're always taller

than me these

skeletons so let's use this skull with a

different colored Bones on it cuz it's

quite easy to see where the sutures are

generally right so here's the frontal

bone here are the two pretal

bones here's the occipital bone and

here's the temporal bone here's the

Magilla

mandible zygoma and in red here we've

got the sphenoid bone

um and here are the nasal bones here and

so on so

here separating the frontal bone from

the pital bones is the coronal suture

this is the coronal plane right

separating here in the midline

separating the two uh parial bones is

the sagittal suture Sagittarius the

Archer firing arrows right this is the

sagittal plane um and if we look at the

back of the

skull so between so here's the parial

bone here's the occipital bone this is

the lamboid suture now

lamboid means y-shaped and if we look

here where these sutures meet we get a y

shape this is known as Lambda um so this

gets called the lamboid suture where

these sutures meet here kind of forming

a t this gets known as the bregma and uh

in infants and in the fetus we find two

fontanels here right so the bone Bon we

have these large spaces between the

bones and there's also another suture

here the frontal suture in the fetal

skull which disappears in the adult this

is the anterior

Fontanel and this is the posterior

Fontanel and what the fontanels do is

they allow the

uh the rapidly expanding brain to grow

uh and the bone doesn't get in the way

and it keeps up also during birth

there's a little bit of you you can of

molding of the the bones can move around

a little bit so the head can pass

through the birth canal but yeah those

fontanels there between the parietal

bone and the temporal bone we have the

sosal suture

here this is the squamous the

flat part of the temporal bones this is

the squamous part of the temporal bone

and look at this process here if we're

going to talk about processes in a

moment this is the zygomatic process of

the temporal

bone uh and here's the zyg zygoma here

and together they're forming the

zygomatic Arch this being the zyg this

gets called the temporal arch of the

zygomatic bone and they meet now down

here this is an example of why it's

useful to know the parts the Bony Parts

this here is the mastoid process can you

see that so so here that hole there is

the external acoustic

meatus where we find the

external the opening of the external ear

there the external acoustic meatus or

the external auditory meatus and here

see this bony Point here this this is

the styloid

process and this is then the mastoid

process so if this is the occipital bone

here and this is the mastoid process

here this gets called this suture here

the joint between the two gets called

the excip mastoid suture a little

awkwardly maybe this is the squamous

part of the temporal bone and this meets

the sphenoid bone here and this gets

called the spheno squa suture here and

there's see that little suture there so

here's the prial bone here's the the

sphenoid bone and there's a there's a

little short suture there um so this is

the spheno parietal suture in there so

then here of course here's the frontal

bone here's the sphenoid bone this is

the spheno frontal suture here and we

can also see look we've got these other

bony lumps

here which there we go that's a bit

better

unfortunately this is yellow this is

kind of a a mustard yellow but we got

these two colors next to each other so

it's not super clear but here's the

zygoma here's the frontal bone so this

is the zygomatic process here of the

frontal

bone and this is the frontal process of

the zygomatic bone if you wanted to talk

about the magila you could do similarly

so you see this process

here this process of the Magilla passing

to the zygoma would be the zygomatic

process of the Magilla and this process

here extending up to the frontal

bone this would be the frontal

process of the Magilla now we've talked

about these bones here we uh within the

orbit so we've talked about the bones

there's another video about the bones of

the nasal cavity in here to include

these bits the laal bone and the nasal

bones but if we go deeper inside the

orbit we've got another yellow bone in

there do you see how this this is

mustard so this is the frontal bone this

is the the zygoma and in here can you

see there's that other yellow bone it's

not very helpful is it they could have

could have picked more

colors but it's it's this bone here hang

on there you go and my lighting could be

a bit better but you might be able to

hear the pter patter of rain outside

it's dark I've left this a bit late but

you see this bone here so that's the

ethoid bone

and at the back of the orbit we can see

the red of the sphenoid

bone so these sutures are I mean they're

not very Wiggly on this

skull but on this skull and other skulls

you look at the sutures

are see on this SC the sutures are very

torturous they vary between people but

the purpose of the suture is to form a

tight a very tight kind of inter

digitated joint between the bone of the

skull then these are joints that don't

move um so they're protecting the

contents inside so if we turn the skull

around there are a few features on the

occipital bone as well hopefully you can

see some of the lumps and bumps here um

back here and you can you can usually

palpate it on the back of your head

you've got a lump and this is the

external occipital protuberance

here and there are a couple of lines

there are superior nucle lines and

inferior nucle lines

um difficult to see in 2D but there's

the lump there so there's an external

occipital protuberance and often a Crest

running from it and you can see can you

see these lines here and there are lines

here and these are obviously attachment

sides for structures in the neck which

lift your head up and support your head

and that sort of thing of course if

there's an external oipal protuberance

there's going to be an

internal acal protuberance and if we

open up and look inside

here occipital protuberance in there

just again another

lump and of course if we're inside the

skull here we should probably talk about

some of the shapes in here can you see

how we've got a fosser here we have a

fosser here and we have a fosser here so

up here this is the anterior CR anterior

cranial fosser here we have the middle

cranial fosser on either side and back

here is the posterior cranial fosser and

in here we find the sphenoid bone

um don't really so you can see the

sphenoid bone there in red in the middle

so here's forum and

Magnum

so here and if you study a skull you'll

see the

sutures surrounding the edge of the

sphenoid bone in here right in the

middle we talked about uh the CRI form

plate and the Crystal Galley up

here and we looked

at the internal cotted artery as it

appeared here now here this depression

is the cell Tura The Turk saddle this is

uh and the Deep part in here is the

hypop phesal fosser and this is where

the pituitary gland sits surrounded by

all of this bone um we have um kinoid

processes around

here so these two here are the anterior

kenid processes and you can see that

they're forming

this they're forming a

uh uh they're forming a Groove a tube

through which the internal coted artery

passes and pops up about here um we have

a middle kenid process kind of in here

and this is the posterior kenid proc

process here of the cell Tura we also

talk about the dorsum C as this wall

here the posterior wall is the dorsum

cell and the anterior wall is the uh

tuberculum Cellar so around here we have

there's the the optic Canal passes

through

there um you see this slope

here this slope here

we have a

slope and this is called the cleavus

cleavus literally from the words meaning

slope so we have this slope here and on

the cleavus this is where we find the

basil artery um giving off lots of

pontine arteries the ponds is here um so

blood vessels are coming in here towards

the circle of Willis from the for and

Magnum so there's cleavus um this we

talked about this lumpy part part of

bone here is the petus part of the

temporal bone so on the inside and the

petus part of the temporal bone in here

has the inner rear structures within it

remember that all of these grooves and

processes and lumps and bumps that we're

looking at here have a purpose and the

reason that they're there many of the

grooves are formed by blood vessels um

next to the Bone these melal arteries

and some of them like the the groove we

see formed by the internal cored artery

leave some lovely shapes and the holes

are there for blood vessels and cranial

nerves to pass through these other lumps

and bumps which might not be immediately

apparent what they do or why they're

there they're attachment points for um

for the duramater for the thick

connective coverings of the brain so

Mark was removing some brains from some

bodies this week and um one of the

things Mark has to do is is not just

remove the the skull cap the calvarium

but when he goes in he cuts the cranial

nerves as as close as he can um so he

have as much nerve on the brain as

possible but also he he needs to go deep

and find these edges and cut along here

along the edges of the reflections of

the of the thick connective tissues of

the um the duramater which are holding

the brain down so the tentorium cerebell

here holds down the

cerebellum beneath it and what have you

so that's why there are lumps and bumps

here that's what these Kleen oid

processes are for we have bits of

durometer attaching into them holding it

all in place and the durometer of course

supports the brain and the the Dural

Venus

sinuses I mentioned the the the styloid

process here and the number of

structures pass from it like the styo

hyoid ligament to that to the floating

hyoid bone here so Stylo hyoid ligament

passes from the styloid process to the

hyoid bone now the styloid process is um

bolstered a bit on these plastic skulls

because when skulls get dropped

that's the thing that usually breaks but

here's the styloid process here this

skull has been dropped and it's lost the

styloid process on the other side so

when you're looking at skulls watch out

for that

um but also down here we have a number

of interesting shapes around here right

so here's the nasal cavity opening

posteriorly

so you can see the coni in there you can

see those curves of bone um we've got

these look these Wing shaped bits of

bone here so these are the teroid

processes and there are two on either

side and teroid comes from the word

meaning Wings these are wings of bone

like the

pterodactyl um and there is a lateral

plate and a medial plate for each and if

you think about the muscles of

mastication the uh

the teroid the muscles that the lateral

medial teroid they they attach here oops

so what bone do the teroid plates come

from H let's have a look look you can

see how here's the sphenoid bone so the

teroid plates the teroid processes are

part of the sphenoid bone and you can

see vomer in there um and here's the for

and ovali so this is where you'll find

the the oot gangion just around here and

a whole bunch of nerves dropping out and

running around and then we've got the

muscles here's the pallet so up here

we've got the hard

palette and you can see that the purple

is the

Magilla but there's another red here and

that's not actually the sphenoid bone

this red this is this is a a Palatine

bone on either either side so we've got

the Magilla the and then we've got two

Palatine bones forming the hard pallet

and then we' got the sphenoid bone back

here so watch out for those and there

are a number of faram in

here you can see there's a larger hole

here and there's usually a couple of

smaller holes here and this is the

greater Palatine foran the bigger one

and the smaller ones the Lesser Palatine

foramina and you've got um nerves of the

palet and nasal cavity looping around a

blood vessels looping around here

through these holes um up here there's

another

foran in the pallet and that hole there

that's the incisive

fosser what we've got here are lots of

joins between the occipital bone the

sphenoid bone and the temporal bone

and the cracks of bone that we see here

um we have a a teroid canal that opens

near the teroid plates

um through various which various

structures pass through so these cracks

of bone here are the opening of the

teroid canal very difficult to see

they're there but it's very difficult to

actually see you know the entire Canal

or really parts of it just to know that

the openings are there if we take the

mandible

off of course on these skulls this is

the mandibular fosser so we have a

depression in here so but this

depression of course is filled with a

bit of bit of plastic in these models so

this is the the mandibular fosser you

see where we are so here's

the there's the masto process here's the

um zygomatic process of the temporal

bone and in here then that's the

mandibular

fosser

which the mandible is going to

articulate with so we've got the condil

process which is the articulating part

and then we've got the coronoid process

up here which the masseter muscle

inserts

into and um we have the body down here

the angle where it changes angle and

then the Ramos up here Ramos meaning

Branch but this flattened part and we

can see here on this model we've

got uh a nerve the inferior alviola

nerve and we've got blood

vessels passing into the mandibular

foran which are then going to run to the

lower teeth and then out here through

the mental

Forin

um which is this foran

here there's a Groove in here for the

Milo hyoid muscle which is forming the

floor

here and this notch in between the

condil process and the coronoid process

is the

uh the mandibular Notch so you guys know

the names of the bones we've looked at

the sutes and where the sutes meet oh

one thing I did mention is where these

sutures meet here we were talking about

right we have this all these sutures

coming together here this is the teron

PT r i o n

pan teron teroid we're talking about

wings again aren't we but that's the ter

in that space there so we've got that

weakness where the bone gets thin you

have all those sutures meeting um so

we've talked about the sutures talked

about the bones and I've talked about as

many lumpy bumpy bits on here as I can

think of and I didn't really want to

talk about what attaches to what or what

goes through what as we were talking

about it too much cuz then we'll go down

a rabbit hole and we'll never come out

um but I wanted to go over the terms CU

these terms often get thrown up and

students are blank you know what I don't

know what that means so if you've heard

the term and you've seen the term when

it gets brought up somewhere else you'll

know what we're talking about we're

talking about the cranial FY and all

these bits and Bobs in here right there

are other bits and Bobs on here but you

know that's already extending on what we

were talking about last time and what

we'll often talk about in teaching we

often don't go into that much detail um

but there's a bit more detail and you'll

find more detail if you study a skull um

so good luck spend some time with these

things