Posterior Triangle 7 part 2

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    The first exam is delayed to Sun. 18/03/12 and the second exam

    to Tus. 17/4/12.

    there will be a review lec. of the skull and the neck next week

    Tus. 28/02/12 so plz study well in the weekend to be prepared.

    In the previous lecture :

    the muscles in the neck are divided according to its function and location into3 groups:

    The reference and superficial group: - 3 muscles (the superficial is the platezis,and the reference are 2 the trapezius and SCM)

    Hyoid related group :( 4 supra and 4 infra hyoid) we call the infra hyoid groupthe strap muscles ( (

    The final group is related to the vertebral column (cervical vertebral muscles):consist of three groups:

    -The anterior have 2 muscles (longus cavities and longus coli).

    -Posterior group another 3 muscles (levator scapulae, splenius capitis and

    semispinalis capitis) => just names.

    -The lateral group have 3 scalenus muscles (scalenus anterior, medius, and

    posterior) => we must know all details about them according the vertebral.

    Posterior Triangle of The Neck

    (Lateral Cervical Region)

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    NOW, we will talk about the posterior triangle of the neck; we call it pos. Because

    its behind the SCM but its actually representing at the lateral cervical region.

    -GUYS, when we speak about any region in anatomy we look to the boundaries,

    roof, floor and the contents of that area.

    Lets start with boundaries:

    Pos. triangle located behind the SCM so the first border which is the anterior

    border of the triangle is SCM (sternocleidomastoid muscle) and the posterior

    border is the trapezius muscle. Inferiorly you have the mid. third of the clavicle -

    because the medial third is providing an attachment to SCM and the lateral third

    of the clavicle is providing an attachment for trapezius ,and the mid. third which

    is the inferior border of the posterior triangle.

    The roof: is made by skin and fascia (superficial fascia, and the investing layer of

    the deep fascia).

    The floor: is made by prevertebral muscles (specifically the lateral and posterior

    group) and the prevertebral fascia that cover them.

    ; the contents of posterior triangle are between the prevertebral fascia andinvesting fascia.

    -The prevertebral muscles which are the lateral and posterior group. The lateral

    group which is:

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    The anterior scalenus,medius scalenus, posterior scalenus

    -Between the anterior and medial scalene there is opening called scalene

    hyeetus subclavian artery and brachial plexus pass through it.

    So the floor starts from down up:

    1- Anterior scalene.

    2- Medius scalene.

    3- Posterior scalene.

    4- Elevator scapulae then the bandage ( )the first one in posterior group

    5- Splenius capitis.

    6-semispinales capitis (we can see small of semispinalis at the apex of pos.

    triangle).NOW; we can divide the pos. triangle to two smaller triangles to simplify studying

    it by a specific muscle which isinferior belly of omohyoid

    Omohyoid have superior and inferior belly and its call like that because the

    omohyoid is one of the strap muscles it descend from the body of hyoid bone insuperior belly, it goes posterior to SCM since there is Intermediate tendon,

    omohyoid inter these tendon => these called the anterior belly in anterior triangle

    then the inferior belly goes posterior and attach to the upper border of the

    scapulathats why called omo =>>omo means shoulder

    As Inferior belly goes to pos. triangle we take an advantage to subdivide the

    posterior triangle into two triangles:

    The smaller one bellow the inferior belly of omohyoid called

    omoclavicular or supraclavicular triangle another name forthis triangle subcalvian triangle because in its corner within

    these triangle we can see the subclavian artery and vein.

    3

    Soomoclavicular trianglecuz its boundaries

    Supraclavicular triangle

    cuz its location; superior to

    scapula

    Subcalvian triangle cuz its

    contents

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    The other triangle which is the very larger one and above the omohyoid muscle

    we call it occipital triangle >>why occipital?

    Because its closer to occipital bone.

    The contents of pos.triangle

    The contents of pos.triangle are artery, vein and nerve.

    There are four important artery:

    occipital arterytransverse cervical arterysuprascapular arterythird part of

    subclavian artery.

    -occipital artery: its abranch of exernal carotid artery(ECA) in the apex of pos.triangle, it pass over the holl pos. aspect of the head broviding the blood supply to

    pos. half of the skull

    Note:the main blood supply into the head and neck region comes fromcommon carotid artery .

    The common carotid at the level of adams apple divides into two arteries one

    continue to the brain calledinternal carotid the other one leaves the carotidsheet to provide blood supply to most of the structures outside the skull

    external carotid one of the branches of external carotid is the occipital.

    The other two important arterys we will see them running transversely through

    the triangle; the superior one usually call ittransverse cervicalartery the other

    The posterior triangle is subdivided by inf. belly of omohyoid muscle to two

    triangles:

    1Omoclavicular triangle

    2Occipital triangle

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    name is superfacial cervical artery defferent names depends on its story; the

    transverse cervical arise from subclavian artery, as it arise it goes and inter to pos.triangle posteriorly providing blood supply to superfascial structure in

    superfacial fascia and any structure there, then it disapper by getting deep to

    trapezius muscle then it desend down to medine border of scapula, there its namebecome dorsal scapular artery- it provides blood supply to romboid muscle-;now in other cases the dorsal scapula artery will arise directly from another

    origin of the subclavian and go all the way across the medine border of the

    scapula so its name dorsal scapula as it arise ,and the transverse cervical just arise

    passing through pos. triangle and terminate deep to the trapezius in these case no

    longer called transverse cervical; since its providing blood supply to superfacial

    part of the neck => we call it superfacial cervical artery ,and if its continue to

    become dorsal scapular we will name it transverse cervical artery , superfacial

    cervical artery.

    ones it arises it will pass superfacialy to the most of the structure there ;when it

    arise anteriorty to phrenic nerve and scalenus anterior muscle then it will pass

    above the trunks of bracial plexus all the way to disapper deep to the trapezius

    muscle .

    suprascapulaer artery always inferior the transverse cervical also passtransversly all the way to the posterior aspect, in the posterior aspect it will go to

    posterior surface of the scapula it pass through suprascapular notch => all the

    way to the back to pos. surface of the scapula since there is two muscles(

    supraspinatus and infraspinatus) providing blood supply to these.

    Another branch from subclavian artery in the anteroinf. angle of the triangle is

    the third part of subclavian artery

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    And now since we talk about it we have to know the story of

    subclavian artery:

    firstly the subclavian artery divides into different parts Once it's

    originate from its origin it will go to the superior thoracic openingthrough the scalene hiatus behind the scalenus anterior muscle

    arching over the first rip on the outer border of the 1st rip it

    becomes the axillary artery and on the lower border of teres

    major becomes the brachial artery so this is the subclavian from

    its origin - brachiocephalic- to the outer border of the 1st rip.

    the subclavian artery divides into 3 parts based on thescalenus anterior

    musclethe 1st part

    is from its origin to the medial border of

    scalenus anterior the 2nd part is the one that located behind the

    scalenus anterior "which we can't see in the drawing" the 3rd

    part from the lateral surface of scalenus anterior to the outer

    border of the first rip.

    THE BRANCHES

    1st --> 3 brances , 2nd --> 1 branch & 3rd --> no branches orsometimes it gives one branch which is "dorsalscapular artery"

    WHEN dorsalscapular artery is there the transverse cervical

    artery b9er 2smo super facial cervical artery BUT when there is

    no branches from the 3rd part "there is no dorsalscapular artery"

    bekon 2smo transvers servical artery most commonly there are

    no branches from the 3rd part

    First part branches:

    Remember them in a clock wise manner

    the 1st the most medial goes superiorly "vertebral artery" it

    goes between the scalenus anterior and longus colli (longus

    surfaces) then inter into the transverse foramina of C6 - C1 then

    Where does the

    subclavian artery

    originate from?

    the right subclavian from

    the brachiocephalicbehind the

    sternoclavicular joint

    while the left one from

    the arch of the aorta

    directly

    So the subclavian is

    three parts :

    1st one Extension isfrom its origin to the

    scalenus anterior

    2nd one extension isposterior to scalenus

    anterior

    3rd one extension isfrom scalenus anterir to

    the outer border of the

    first rip

    Branches from the first

    part of the subclavian

    artery :

    vertebral artery

    superiorly to the brain thyrocervical trunkanteriorly to the thyroid

    & structures of the neck

    internal thoracic arteryto the thorax

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    inter the foramen magnum to supply the brain the inferior

    posterior part of it 'hai Rabe3 mrra bne7keha !!' .

    the 2nd one is more lateral goes anteriorly it's short but wide so

    it's "thyrocervical trunk" cuz it gives arteries to the thyroid and

    the structures of the neck.

    it gives three main branches the first and largest one that goes

    superiorly to the thyroid gland it is the inferior thyroid artery cuz

    it reaches the thyroid gland from inf. the remaining two arteries

    goes transversely cross the posterior triangle to the back the

    upper on is the transverse cervical artery "2smo eltaney

    superficial depending on the 3rd part branches!!" and the lower

    is the supra scapular artery 'that the ones we just spoke about :)'

    the 3rd one the most lateral goes inferior to the thorax along

    with the sternum gives the anterior intercostals arteries we will

    name it "internal thoracic artery" which descends down passing

    along the margins of the sternum providing the anterior

    intercostals arteries for the upper 6 spaces then it divides into

    two arteries superior epigastric to the abdomen the other goes

    with the costal margin the musculophrenic which provide the

    remaining intercostals spaces."u've studied it the last sem. so its

    good to know just the internal thoracic"

    NOW the subclavian artery goes behind the SCM so now we are

    in the Second part of the subclavian.

    Second part branches:

    from the second part there is one branch only this time it arising

    : what is the largest

    branch from

    thyrocervical trunk ?

    ans. : inferior thyroid

    the transverse cervical

    artery and the supra

    scapularartery arise

    from the thyrocervicaltrunk which is from the

    first part of subclavian

    Notice the order of the

    branches the 1st branch

    of the first part goes

    sup. then the 2nd

    branch goes ant. thenthe 3rd goes inf. and

    now the second part

    branch goes post.

    "clock wise manner":D

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    posteriorly "the costocervical trunk" cuz its a large artery divides

    above the neck of the first rip and gives two branches :

    1- Deep cervical artery : go superiorly to supply the deep muscles

    of the posterior neck "Semispinalis, Splenius, Levator Scapulae".

    2-Superior intercostals artery : go inferiorly gives the posterior

    intercostals arteries of the first two intercostals spaces.

    We have 11 intercostals spaces the first 2 spaces get blood

    supply from the Superior intercostals artery which come from the

    costocervical trunk which arise from subclavian and the

    remaining spaces get blood supply from the descending thoracic

    aorta which was a Q in the previous term ;)

    Third part :

    the third part of subclavian has no branches But SOMETIMES the

    dorsalscapular artery arise from it , if that happened the

    transverse cervical artery becomes superficial cervical. so it

    depending on the presence or absence of the dorsal scapular

    artery.

    To remember:

    the costocervical trunk

    arise from the posterior

    aspect of the second

    part of the subclavian !!

    you have to know about the subclavian branches but When we are talking about the posterior

    triangle you have to know exactly what arteries are present which is the 3rd part only cuz the 1st is

    medial to the Scalenus anterior and the 2nd is behind the scalenus anteriorso only the 3rd part

    present in the posterior triangle

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    So till now we have 4 arteries we will go to the veins which are 5

    veins :

    Veins in Post. Triangle

    the veins are two systems :deep and superficial ,the deep ones

    are the same as the deep arteries we've studied later Occipital

    v., Transverse cervical v., Suprascapular v. & Subclavian v.

    The superficial vein within the posterior triangle is called

    external jugular vein (EJV) it is usually formed at the angle of the

    mandible by the union of two veins( posterior oracular vein &posterior division of retromandibular vein) now its superficial or

    external to the SCM then it descend down, when it reach deeper

    it will appear in the posterior triangle within the superficial facia

    its deep to the platysma muscle and superficial to the SCM,

    after leaving the SCM it will get into the lower part of the

    posterior trianglein the subclavian triangle (omoclavicular

    triangle), now it tears the investing layer deep facia and go deep

    to drain into the deep veins whether the EJV or the subclavian

    vein.

    Nerves in Post. Triangle

    we can divide them into 3 groups :

    1- Cutaneous Nerves:

    they are four arising from the midpoint of posterior border ofSCM go through the investing layer of deep facia to the

    superficial facia from there they will go to the skin so they are

    sensory cutaneous nerves.

    lesser occipital nerve: from anterior ramous of C2

    Retromandibular vein

    descend behind the

    mandible at the angle of

    the mandible divide into:

    1- ant. division ofretromandibular vein: it

    will drain into the facia.

    2- post. division of retro

    mandibular vein: it will

    unite with the posterior

    oracular vein to form the

    EJV.

    To remember :

    EJV

    extension: from the

    angle of the mandible to

    the middle 3rd of the

    claviclemuscle relations : deep

    to the platysma muscle

    superficial to SCM.

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    the great auricular nerve : cuz there is no lesser only greatone, from the anterior ramie of C2,C3. innervate the skinover

    the angle of the mandible which is part of the face not the neck

    so in the facial surgeon after anesthetizing the sensation of the

    face from the trigeminal nerve (V) we have to anesthetize this

    location cuz it has a different nerve. andinnervate the skin

    over the parotid gland (the larges salivary gland ) then

    to the lower part of the auricle especially the lobule where U

    put the ear rings ;)

    transverse cervical or Cutaneous nerve to the anterior triangle

    supra clavicular nerve to the upper half of the shoulderandskin over the clavicle

    2- Brachial Plexus

    Roots and trunks arising from C5-T1 passing through the scalene

    hiatus btween scalenus anterior and scalenus medius to go to the

    axilla as it passing there you can see the trunks of the brachial

    plexus mainly the upper ,the middle and the lower trunks.

    3- Spinal accessory n.

    the eleventh cranial nerve (XI) arises from the spinal cord

    from the upper five segments it goes up and enter inside

    the skull through foramen magnum and get out from the jugular

    foramen as it leaves it is classify as cranial nerve. then it goes

    deep to the SCM it gives a branch to the SCM , after that it leaves

    the SCM to appears at the posterior triangle of the neck.then it

    goes deep to the trapezius muscle and innervate it.

    the accessory n. is a land mark it helps to know the muscle that

    located under it which is levator scapulae muscle

    You have to know those

    4 nerves , their origins

    and what area they give

    sensation to !!

    All of them have been

    discussed in previous

    lec. in details :)

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    so as a quick revision the posterior triangle contents are :

    4 arteries:

    3rd part of subclavian --> anteroinf. angle Transverse cervical a.(superficial cervical) Suprascapular a. --> inf. to transverse cervical Occipital a. --> at apex of triangle

    5 veins :

    EJV Occipital v. Transverse cervical v. Suprascapular v. Subclavian v.

    3 types of nerves :

    Cutaneous Nerves --> 4 nerves Spinal accessory n.( XI) Brachial Plexus THE END

    ,,

    Baraah Al-Salamat , Asmaa Al-Mawas

    If U find any mistake plz forgive us, but we will NOT if U dont tell us about it

    plz correct the name of the third group in the slides "slide #13" to become Spinal accessory n.

    instead of spinal division of accessory n. ,if u asked why?!

    previously we used to classify accessory n. ( the cranial nerve XI) into two parts one arising from

    the spinal cord "spinal root" and the other arising from the brain "cranial root" BUT in the

    recent years this is wrong bcuz the cranial root is now part of the vagus n. (X) so we dont have

    cranial and spinal we just name it accessory or spinal accessory.

    BTW , this nerve changed the definition of the cranial nerves they are NO more the nerves that

    arise from the brain because the XI arising from the spinal cord so to redefine the cranial nerves:

    Cranial nerves : any nerve passing through skull foramina or cranial openings