neck condensed grayscale slides

7/27/2019 Neck Condensed Grayscale Slides

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NeckNeckOral Biology

Alex ForrestAssoci ate Profess or of For ensic Od ontol ogyForensic Science Research & Innovation Centre, Griffith UniversityConsultant Forensic Odontologist,Queensland Health Forensic and Scientific Services,

39 Kessels Rd, Coopers Plains, Queensland, Australia 4108

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Learning GoalsLearning Goals

You should aim to achieve a good appreciation of the general

plan of the neck, with particular reference to the layout of the

major fascial sheets. You should be able to explain what afascia is, and describe its general purpose.

You should aim to gain a deeper appreciation of the posteriortriangle of the neck and be able to recognize the muscles in

its floor with the exceptions of splenius capitis and

semispinalis capitis.

You should be able to recognize and describe the superficial

cutaneous branches of the cervical plexus, and also the

phrenic nerve.

Learning GoalsLearning Goals


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ApproachApproach

When we discuss the neck, you should recall the session in

which we examined the way in which the head and neck

have been designed.

Ask yourself what are the functions of the neck, and how

are they reflected in its layout and shape, and how in turndo these determine the internal structure?

Only then will their structures make sense, and beintegrated into the plan you develop for the neck.

Finally, think in clinical terms

ApproachApproach

A good way to visualize the neck is to think of it in terms of

skeleton, muscles, fasciae and viscera.

Categorizing the contents in this way makes the plan easyto comprehend, and helps you to locate structures in a

simple way.

ApproachApproach SkeletonSkeleton

The skeleton of the neck is essentially the vertebral column,although the larynx has a cartilaginous skeleton of its own.


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Be able to identify thevertebral body, neural

arch, pedicles,

laminae, transverseforamina, spinous

processes, anteriorand posterior roots

and tubercles of thetransverse processes,articular surfaces and

the intervertebralforaminae.

SkeletonSkeleton

From Grays Anatomy, 35th Ed, Longman, London 1973, p. 236.

Intervertebral

foraminae are only

obvious when

adjacent vertebrae

are articulated.

SkeletonSkeleton

From Grays Anatomy, 35th Ed, Longman, London 1973, p. 237.

Be sure that you can draw the basic plan of a typicalcervical vertebra and label these features.

SkeletonSkeleton

Being able to draw

the fasciae of theneck provides a key

to the comprehension

of its overallstructure, so it is animportant piece of

understanding to

acquire.

FasciaeFasciae

Diagram A. Forrest 2008.


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In the diagram on the

right, note the

superficial fascia

which is colouredpink, and the deepfasciae which are

drawn in red.

FasciaeFasciae


The superficial fascialies immediately

beneath the skin and

is continuous with it.

One removes it when

one removes the skinin dissection.

Note that it contains

the platysma muscle.

FasciaeFasciae


The deep fascia is

designed to permit

easy movementbetween groups of

structures, and letsgroups of muscles

and viscera move

independently.

It essentially providesa layer betweenadjacent sliding

surfaces.

FasciaeFasciae


Layers of deep fascia

divide the neck into anumber of

compartments, and

leave the so-called

tissue spaces -potential spaces whichlie along the planes of

cleavage between the

layers.

These spaces are

important in the spreadof infection in the neck.

FasciaeFasciae



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The deep fasciaecomprise a number of

layers.

The most superficial

of these is called theinvesting layer of thedeep cervical fascia.

FasciaeFasciae


Sometimes it is misleadingly called the superficial investing

layer of deep cervical fascia, and this can be confusing

because the terms superficial and deep are used in the

same name to describe a layer of deep fascia in the neck.

For this reason, the term investing layer is preferred.

FasciaeFasciae

The investing layer lies deep

to the superficial fascia, andforms a continuous sheath

around the entire neck.

It splits to contain thetrapezius muscle and the

sternocleidomastoid muscle

on each side, and in betweenthe two muscles it forms a

sheet that acts as a roof overthe posterior triangle of the

neck.

FasciaeFasciae


The presence of thesternocleidomastoid andtrapezius in this layer gives

them mobility independent ofother muscles in the neck.

FasciaeFasciae



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The carotid sheath lies

deep to the investing layer,

and wraps the internaljugular vein, common

carotid artery and vagusnerve (X) in a bundle. As

we ascend in the neck, the

carotid sheath contains the

internal carotid arteryrather than the common

carotid after we pass

above the junction

between the two vessels.

FasciaeFasciae


The pre-vertebral fasciaseparates the larynx and

oesophagus from the

prevertebral muscles,

giving these viscerafreedom of movement in

this important area.

FasciaeFasciae


The potential space thatlies between the pharynx

and the prevertebral

muscles is called the

retropharyngeal space,and this is important fromthe point of view of

spread of infection, since

it communicates inferiorlywith the mediastinum, and

provides a pathway forinfection to spread into

this area.

FasciaeFasciae


Infection in this space can

cause problems withswallowing and with

respiration.

It communicates with theposterior triangle

posteriorly to the carotidsheath.

FasciaeFasciae



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The thyroid gland and

larynx are surrounded

anteriorly by the pre-

laryngeal fascia.

The paralaryngeal/

parapharyngeal spacelies between this, the

investing layer and the

carotid sheath.

FasciaeFasciae


This space provides a

pathway for infection tospread into the

retropharyngeal space.

Infection in this area canalso compromise

respiration to an extent.

FasciaeFasciae


Retropharyngeal

Space

TrianglesTriangles

For convenience, when

we describe the neck,we refer to a series of

imaginary lines drawn

on its surface whichcorrespond to important

anatomical structureswhich lie beneath.

Since these lines form a

series of triangularshapes on the neck

surface, we refer to

them as the triangles ofthe neck.


Note the posteriortriangle, shaded pink in

the diagram.

TrianglesTriangles



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The space between the

investing layer, the

carotid sheath and the

prevertebral fascia isknown as the posterior

triangle of the neck, and

it is here that many

important structures can

be found duringdissection.

TrianglesTriangles


If the investing layer,

which forms the roof ofthe triangle, is removed,

one looks down on the

carotid sheath (deep tosternocleidomastoid)

and many importantmuscles, as well as the

superficial branches of

the cervical plexus.

TrianglesTriangles

Clemente CD, Anatomy, A Regional Atlas of the Human

Body, Munich, Urban & Shwarzenberg, 1975, Diagram 429.

You should identify the

three scalene muscles,scalenus anterior,

medius and posterior,

levator scapulae, andsplenius capitis.

You should also identify

the accessory nerve (XI)

and the phrenic nerve.

TrianglesTriangles

Modified from: Clemente CD, Anatomy, A Regional Atlas of the

Human Body, Munich, Urban & Shwarzenberg, 1975, Diagram 427 .

The scalenus anterior

attaches to the anteriortubercles of the 3rd to

6th cervical vertebrae,

while scalenus mediusand posterior attach to

the posterior tuberclesof the lower 5 and 4th to

6th cervical vertebrae

respectively.

TrianglesTriangles




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This means that the

cervical and brachial

nerves emerge betweenthe scalenus anterior

muscle and thescalenus medius

muscle.

TrianglesTriangles



You will learn that the

accessory nerve, orcranial nerve (XI), is

the nerve that allows

us to shrug ourshoulders.

It is motor to the

sternocleidomastoidmuscle and to

trapezius.

NervesNerves



You will need toknow the branches of

the cervical plexus

later in your course,so now is a good

time to becomefamiliar with them.

The trunks of the

brachial plexus will

not be covered andneed not be known

.

NervesNerves



NervesNerves

The branches of the

cervical plexusemerge from the

posterior border of

thesternocleidomastoid

muscle, andtherefore they

emerge at the

anterior border of theposterior triangle.




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The lesser occipitalnerve hooks around

the accessory nerve

and runs along the

posterior border ofthe

sternocleidomastoidmuscle to supply

sensation to the back

of the neck and lowerpart of the back of

the head.

NervesNerves



The great auricular

nerve is a larger branch

which runs across the

belly of thesternocleidomastoid on

its way towards the

parotid gland and the

ear.

It supplies sensation tothe skin in the region of

the parotid gland and tomuch of the auricle of

the ear.

NervesNerves



The transverse cervical

nerve crosses thesternocleidomastoid

muscle as it passes

towards the front of theneck, and then divides

into superior andinferior branches which

supply common

sensation to the front ofthe neck from the chin

down to the upper partof the chest.

NervesNerves



The reason it is

important to dentists is

that it can sometimes

provide an accessorynerve supply to the

lower anterior teeth, and

this can prevent

conventional blockanaesthesia from being

successful in this area.

NervesNerves




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The supraclavicular

nerves divide into

three groups and

supply commonsensation to the skin

overlying the chestand shoulder.

NervesNerves



Since all of these

nerves are sensory,

and supply areas of

skin, they must passthrough the investing

layer of cervicalfascia to get there.

NervesNerves



The final branch is the

phrenic nerve. This

contains fibres from C3,

C4 and C5 and is the

motor nerve to the

diaphragm.

It is a deep branch of the

cervical plexus, and

crosses the belly of the

scalenus anterior muscle

and the lower anterior end

of the posterior triangle,

where it is accessible to

traumatic injury.

NervesNerves



SummarySummary

Examine thisdiagram now and

note its salientfeatures.

Can you use yourknowledge to label

this plan?

Diagram Alex Forrest 2008


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Become familiar

with this and use it

as a guide to theneck.

You can print it outfrom

learning@griffith.

SummarySummary

Diagram Alex Forrest 2008.

The End

neck condensed grayscale slides

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