Erector spinae (back muscles)

Summary

This educational video script delves into the complex anatomy of the back muscles, breaking them down into layers: superficial, intermediate, and deep. It explains the functions of these muscles, particularly the erector spinae, which is crucial for back extension and rotation. The script also touches on the deeper transverse spinal muscles, hinting at their role in back pain and spasms.

Takeaways

• 📚 The script discusses the anatomy of the back muscles, focusing on their complexity and layers.
• 💪 The muscles of the back are categorized into superficial, intermediate, and deep layers, each with specific functions.
• 🤔 The main challenge for students is to understand the various muscles and their functions, as well as how to locate them.
• 🏋️‍♂️ The superficial muscles, such as the trapezius and latissimus dorsi, are primarily involved in moving the upper limb.
• 🌟 The intermediate layer includes muscles like serratus posterior inferior, which assists in respiration by bracing and pulling down the ribs.
• 🔍 The deep muscles, also known as intrinsic muscles, are crucial for back extension and include the erector spinae group.
• 🧍‍♂️ The erector spinae muscles are responsible for extending the vertebral column when standing up from a bent position.
• 🔑 The deep muscles are further divided into spinalis, longissimus, and iliocostalis, based on their attachment points on the spine.
• 📐 These muscles are also categorized by the region of the spine they affect: lumbar, thoracic, cervical, and capitis for those attaching to the head.
• 🌀 The splenius muscles, part of the deep layer, attach to the head and are involved in neck rotation and extension.
• 🔬 There is an even deeper layer of muscles called the transversospinales, which are involved in back pain and spasms and will be discussed in a subsequent session.

Q & A

What is the main focus of the video script?

The main focus of the video script is to explain the muscles of the back, breaking them down into layers and discussing their functions.

What are the superficial muscles of the back?

The superficial muscles of the back include the trapezius, latissimus dorsi, and rhomboids. These muscles are primarily involved in moving the upper limb.

What is the role of the serratus posterior inferior muscle?

The serratus posterior inferior muscle helps in respiration by bracing and pulling the ribs down.

What are the intermediate layer muscles of the back?

The intermediate layer muscles include the serratus posterior inferior and serratus posterior superior. These muscles are involved in elevating and bracing the ribs.

What is the primary function of the deep muscles of the back?

The primary function of the deep muscles of the back, also known as the intrinsic muscles, is to extend the vertebral column, helping to stand up straight from a bent position.

What is the term used to collectively refer to the deep group of intrinsic muscles of the back?

The deep group of intrinsic muscles of the back are collectively referred to as the erector spinae.

How are the muscles of the back categorized based on their location?

The muscles of the back are categorized based on their location as spinalis, longissimus, and iliocostalis, which run from medial to lateral.

What are the three groups of muscles that make up the erector spinae?

The three groups of muscles that make up the erector spinae are spinalis, longissimus, and iliocostalis.

What is the function of the splenius muscles in the neck?

The splenius muscles in the neck, specifically the splenius capitis and splenius cervicis, help in extending the neck and rotating the head.

What is the significance of the erector spinae in everyday movements?

The erector spinae play a crucial role in everyday movements such as flexion and extension of the back, lateral flexion, and rotation.

What is the deeper layer of muscles in the back that is mentioned in the script?

The deeper layer of muscles in the back mentioned in the script is the transversospinalis muscles, which are involved in back pain and spasms.

Outlines

00:00

📚 Introduction and Overview of the Back Muscles

The introduction of the video acknowledges the complexity of the back muscles. The speaker mentions the challenge students face in understanding the different layers and functions of the back muscles. They propose breaking the information down into manageable chunks to make it easier to comprehend. The introduction also highlights the importance of understanding these muscles for proper anatomical knowledge.

05:02

🔍 Superficial and Intermediate Muscles of the Back

The speaker discusses the superficial muscles of the back, including trapezius and latissimus dorsi, which are mainly involved in moving the upper limb. They also introduce the intermediate muscles like serratus posterior inferior and superior, which assist in respiration by bracing and moving the ribs. These muscles are described as extrinsic muscles of the back, which will be set aside for the focus on deeper layers.

10:04

🏋️ Deep Muscles and Their Functions

The focus shifts to the deep, or intrinsic, muscles of the back, which are primarily responsible for extending and stabilizing the vertebral column. The erector spinae group is introduced, consisting of spinalis, longissimus, and iliocostalis muscles. These muscles work to extend the back and provide lateral flexion and rotation. The importance of understanding these muscle groups and their anatomical positions is emphasized.

15:05

🔎 Specific Deep Muscle Groups and Their Roles

The detailed anatomy of the erector spinae group is explored, with emphasis on their divisions based on regions of the spine: lumborum, thoracis, cervicis, and capitis. The speaker explains how these muscles interact and their specific roles in movements and stability of the spine. The video highlights the complexity of these muscle groups and their importance in maintaining posture and facilitating various movements.

Keywords

💡Muscles of the back

The muscles of the back are a complex group of muscles that provide support, movement, and stability to the spine. In the video, the muscles of the back are the central theme, with a focus on differentiating between superficial, intermediate, and deep layers, and understanding their roles in movement and posture.

💡Trapezius

The trapezius is a large, superficial muscle that extends from the back of the head to the shoulder blades. It plays a crucial role in moving the shoulder blades and upper limbs, as mentioned in the script when discussing the superficial muscles of the back.

💡Latissimus dorsi

The latissimus dorsi is a large muscle that covers most of the back, playing a key role in pulling movements of the upper limbs. It is also part of the superficial layer of back muscles, as identified in the script.

💡Serratus posterior inferior

Serratus posterior inferior is an intermediate muscle that helps in respiration by bracing and pulling down the ribs. It is a counterpart to the more well-known serratus anterior, which is associated with the upper limbs, as the script explains.

💡Erector spinae

The erector spinae is a collective term for the deep muscles of the back, which are responsible for extension of the vertebral column. The script describes these muscles as essential for movements such as standing up straight from a bent-over position.

💡Spinalis

Spinalis, or spinalis thoracis, is the most medial of the three groups of erector spinae muscles, running between the spinous processes of the vertebrae. It contributes to the extension of the back, as detailed in the video script.

💡Longissimus

Longissimus is a muscle of the erector spinae group that is situated more laterally than spinalis and runs between the transverse processes of the vertebrae. It plays a role in extending and stabilizing the spine, as mentioned in the script.

💡Iliocostalis

Iliocostalis is the most lateral of the three main erector spinae muscle groups, originating from the iliac crest and sacrum and attaching to the ribs. It assists in both extension and lateral flexion of the back, as described in the video.

💡Splenius

The splenius muscles are deep muscles of the back that attach to the head and play a role in neck rotation and extension. The script distinguishes between splenius cervicis and splenius capitis, indicating their different attachments and functions.

💡Intrinsic and extrinsic muscles

Intrinsic muscles are those that are native to a specific region, in this case, the deep muscles of the back. Extrinsic muscles, such as the trapezius and latissimus dorsi, originate elsewhere but have an impact on the movement of the back. The script uses these terms to categorize the muscles based on their origin and function.

💡Lumbar, thoracic, cervical, and capitis regions

These terms refer to specific regions of the vertebral column and are used to classify different sections of the erector spinae muscles. The script explains that muscles are named according to the region they are in or their attachment points, such as iliocostalis thoracis or spinalis cervicis.

Highlights

Introduction to the complexity of the back muscles and the approach to understanding their structure and function.

Explanation of the superficial muscles of the back, including the trapezius and latissimus dorsi, and their role in moving the upper limb.

Identification of the nuchal ligament covering the spinous processes and its relevance to the muscles discussed last week.

Introduction to the intermediate layer of back muscles, including serratus posterior inferior and its function in respiration.

Description of the deep muscles of the back, also known as intrinsic muscles, and their primary function in extension of the vertebral column.

The role of deep muscles in lateral flexion and rotation of the back, with a focus on the quadratus lumborum.

Overview of the erector spinae muscle group, which includes various muscles responsible for the extension of the back.

Differentiation of the three medial to lateral groups within the erector spinae: spinalis, longissimus, and iliocostalis.

Regional classification of the erector spinae muscles based on their attachment to different regions of the vertebral column.

Introduction to the splenius muscles, which are part of the deep layer and attach to the head, contributing to neck rotation and extension.

The importance of understanding the functional units of the back muscles in relation to the vertebral column and their movements.

Discussion on the complexity of the back muscles and the strategy to break down this complexity into manageable parts.

Mention of the even deeper layer of muscles, the transversospinal muscles, and their involvement in back pain and spasms.

Emphasis on the importance of not giving up when faced with the intricate anatomy of the back muscles.

Encouragement to stay engaged with the material, promising that understanding the back muscles will become clearer over time.

Summary of the key points covered in the session, including the anatomy and function of the back muscles and their layers.

Transcripts

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hello okay this is a challenging one

then last week we looked at vertical

bones and I said that we would next look

at the muscles of the back so I've got

lots of different models that show lots

of different bits of the back the trick

is that there are an awful lot of bits

of the back and lots of layers so

there's a student your difficulty is oh

my how do I untangle all of this how do

I work out what's what how do I manage

all of these structures and understand

what they do where they are is stuff

like that I mean I imagine the last you

just kind of look at the back and give

up so what we'll do is we'll break it

down into chunks into layers and it will

make sense right but the other trick

I've got is do I have enough things to

show the things that I want to talk

about don't know the thing applies they

forgot your skeleton here I can fit him

in and as I go in here I go wee man over

here

so we'll rotate around until we can do

right okay the muscles on the back then

see let's see this model here on this

side we see the superficial muscles of

the back so you can see trapezius up

here and we can see latissimus dorsi all

of these muscles of the back are very

very superficial you can see the spinous

processes covered by the nuchal ligament

here

we will talk about the spinous processes

of the vertebra last week and you can

palpate me on your own back on you and

these superficial muscles are actually

moving the upper limb really so we

talked about those when we're talking

about the shoulder on the upper limb so

that this is the most this is the

superficial layer of muscles of the back

today

we can ignore them these also known as a

layer of extrinsic muscles of the back

so trapezius that isthmus d'Orsay the

rhomboids all these guys think they're

gone in that first layer of the

superficial muscles of the back in the

next layer are the intermediate group

and there are only a couple of muscles

here right so do you see this this is

serratus posterior inferior hopefully

you remember serratus anterior as the

boxers muscle the sweetest anterior

muscle is passing from the ribs gives

you all those fingers so slips of muscle

you see and on the sides of super-heroes

massive chests and these pull length of

the scapula and they pull the scapular

anteriorly right which gives you that

reach give the box for some of the power

of their punch so that's the rate as

anterior that's not a muscle of the back

that's a muscle of the shoulder of the

upper limb but this is why this is

called serratus anterior because this is

serratus posterior and this is serratus

posterior inferior so laters could is

serrated serrated because it's a passion

to the ribs and it's going down to the

vertebra here we're doing all these

muscles today as well we talked about

these muscles when we talked about

respiration so

so eaters posterior inferior braces the

ribs and I'll pull the ribs down helping

with exploration right and if there's a

serratus posterior inferior and there

must be a straightest posterior superior

and there it is up here we can't see it

but these are the intermediate layers

which we just posterior superior there

are tears form underneath the rhomboid

and they're elevating the ribs and also

bracing the ribs that's going to need a

group of muscles of the back also

extremely muscles of the back also

something we're going to ignore today

and then we get down to the intrinsic

muscles of the back also known as the

deep muscles of the back this is the

deep group of the deep layer and they're

these muscles that you can see here now

we need to think about what the function

of these muscles is if these other

muscles we've been talking about moving

the upper limb and bracing the ribs and

that sort of thing

what do the deep group of muscles of the

back do women need our backs to do it's

one of the reasons there's always a

skeleton in my Amin frame is that he's

usually what I focus on so that when I

stand by it

I should be in focus he's more focused

on me she is focused on me okay so what

we do with our backs then well one of

the big things we do is that when we're

bent over we stand up straight again and

what we're doing here is all this is

them so this would be flexion of the

back of this way and then just stand up

again this would be extension of the

vertebral column or extension of the

back right so these deep muscles of the

back I mean one thing they're working

eccentrically to lower us like this and

then they're contracting working

concentric ly to extend the back and you

can extend further as well right

currently something else we can do is

because we can flex laterally and yes we

were also using the muscles of our core

here there are other muscles involved

just as there are pretty much in any

move we make there are other muscles

involved

but the muscles of the back will also

give some lateral flexion and a little

bit of rotation but we know you can do

these movements you can feel all these

other muscles and deep muscles like

quadratus lumborum all these other thing

these are also laterally flexing the

back and a probably more powerful at it

but the muscles of the think group of

the back can also do a better lateral

flexion but their main job is extension

right and this group of muscles then if

we look at if this is a series of

spinous processes here which you can

feel you can feel lateral to that on

either side a good chunk of muscle right

and it kind of it bulges out around here

and that's the deep group that we're

talking about and there are lots and

lots of muscles here and this is where

students can get lost but when you when

you do that and when you extend the back

you can feel those muscles you can feel

that bulge of muscles when you have your

back and that bulge of muscles if you

group all of those muscles together we

call those erector spinae alright so

we've got a lot of muscles in there lots

of different muscles lot of different

groups which we'll talk about in a

minute if we group all of those muscles

together all of that deep group of

intrinsic muscles of the back

we call them erector spinae an erector

spinae is main job then is extension of

the vertical column when you're bent

over that is also lower you you know

what I'm talking about

that's erector spinae these are the

muscles we're interested in today what

we need to do what we need to do next

then is is look at the groups within the

heck within that group

don't give up stay with me it's not so

bad okay

who should we look at so local women if

you're wise we men like that he means we

he's little so this is the erectus

Spinney muscle group here there's

serratus posterior inferior so imagine

that's not there much that's been

removed these are all the superficial

muscles forget them

it's this bulge here now we've got three

layers of muscles and we can think of

those three these three groups of

muscles from medial to lateral and the

most medial group of muscles are called

spinalis or spine eyeless and the spine

arles muscles or spin Arliss still Ali

sounds nicer than just buying spoilers

display nihilus muscles then are the

most medial and for them to be the most

medial then they're going to have to run

between the spinous processes of the

vertebrae so you can see how those

muscles running between the spinous

processes can help with extension of the

bat first spinalis

then we have a long isthmus so long

muscles and the long muscles then a

little bit more laterally and these are

running between the transverse processes

our vertebrae okay and then we have a

Yoko stylist now elio cost Dallas you

can break down any Oh ileum

so the ileal cost Arliss muscles are

coming from you can see these guys here

they're coming from the iliac crest and

the sacrum and they're running up to the

ribs costal right up to the ribs up here

like you can see here how they running

out to the ribs we have spinalis most

medially then Langham it long Isthmus

and then any across stylus over your

three groups that's almost it you have

to think about we have we have groups of

muscles kind of running across a number

of vertebrae alright they're not

attached to the vertebrae next to them

they're running across a few vertebrae

so we've got lots of groups of muscles

overlapping and running up the length of

the vertebral column so we then group

those muscles by whatever region Erin

lumborum if they're in the lumbar region

thoracis if then they're in the thoracic

region and services if they're in the

neck and if they go to the ahead and

head is coupled right home so if they go

to the head then they get called capitis

so we've got

spin analyst long is Imus iliocostalis

here we can see these iliocostalis

muscles so these would be in eco stylish

thoracis muscles do you see what I mean

now not all of these layers extend the

full length of the vertebral column the

longest immersed group for example don't

really go down into the London region so

they don't have a lumborum section so we

have long asommus thoracis long asommus

services and that's almost here that's

almost the whole picture

well spoilers there's more but not for

today's video we've also got some other

models up some other muscles up in up in

the head as I said cathetus which go to

the head right ok so now up in the neck

we can see this muscle here and this is

another muscle of the back and it's part

of that intrinsic group that do play as

you can see the superficial intermediate

and deep layers now do you remember when

we were looking at the half section of

head and we looked at the splendor of

the corpus callosum like and I said

splaining was a roller bandage well for

some reason these muscles get called

roller bandages as well why think anyway

this is a bandaged muscle splenius and

it's going to the head so it's capitis

can you see it's going to the mastoid

process here and you can feel your

masters young area here right and you

can feel your mastoid process here big

lump of muscle pretty important

anatomical landmark and that's where

splenius capitis is going for so you can

imagine the splenius capitis alright

then another muscle as well actually

deep to it it's under here and we can't

see it but there's also splenius

services so another splenius muscle

versus of isis or services because it's

just going between

cervical vertebrae little gap we're

looking through here that that may well

be it what's under there somewhere

and it's running between the vertebra at

about the t3 t4 level not so bad c1 so

it's covering this region here right and

then we have splenius capitis here which

is running from again c6 c7 t1 t2 t3

kind of down here maybe a little bit

higher and then that's running out to

the mastoid process of the head so you

can imagine then that these going

laterally is going to help with rotation

of the neck and head but also like other

like a rector spinae muscles it's also

extending if they work together on both

sides right it's going to extend the

neck as part of that extension of the

back that make sense plus chipiya start

a whole bunch of other muscles they're

all they're all acting together as they

always do but that's all those muscles

do okay so have that last week we looked

at the vertebrae you know all about the

spinous processes and the transverse

processes and allowing the pedicles and

things like that and today we've talked

about many of the deep muscles of the

back of the superficial intermediate and

deep muscles we've talked about the deep

muscles of the back and how those attach

to the vertebrae and work together as

erector spinae to extend the back the

other muscles we talked about in the

upper limb as I said now hopefully the

back doesn't seem too terrifying or too

complicated to you anymore

even if it did in the first place there

is a lot going on here but just think

about those functional units but

unfortunately there is more this is got

a block that comes out so there are also

there's an even deeper layer of the

muscles of the back now you might read

different descriptions and different

textbooks for Groovy's these groups of

muscles differently don't worry about

that we would you like to describe

things in different ways but while I was

talking about

erector spinning being part of the deep

muscles of the back which is one way of

describing them and being part of the

intrinsic group of muscles of the back

there's an even deeper layer of muscles

called the transverse Oh spinal muscles

and these guys are really really deep

and they run between the processes of

pretty much adjacent vertebrae and they

do a whole bunch of other things these

guys are involved in back pain back

spasms that sort of thing whole battle

will come back to those guys next week

to chunk by chunk by chunk and then

you'll understand the anatomy of the

musculature or the musculature at the

back all right well yeah there is a lot

here

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