Posterior Triangle

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Posterior Triangle of the Neck
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Cervical Fascia Interfascial layers of the Neck

• Allow for the free movement of the different
  components of the neck
• Serves as a barrier to the spread of infection
  and may direct the spread of infection from one
  region to another

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Cervical Fascia
Consists of 1- superficial fascia
2- deep cervical fascia
a. superfiscial (investing) layer
b. pretracheal layer
c. prevertebral layer
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Superficial Cervical Fascia -
immediately deep to the skin of the neck -
encloses the platysma muscle - is continuous
with that of the head and thorax - It
contains A. cutaneous nerves,
B. superficial LN, C.
superficial vessels, D. fat
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Deep cervical fascia
1- investing fascia -surrounds all structures
in the neck - b/w superficial fascia and the
muscles - Attachment (ECA or BRS)
-splits superiorly to enclose the parotid and
submandibular glands
-splits inferiorly to enclose the trapezius and
SCM muscles
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• Suprasternal Space
• space b/w the 2 layers of deep fascia just above
  the manubrium which encloses
• sternal head of SCMs
• Inf. end of the anterior jugular veins
• jugular venous arch
• fat
• few LNs

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2-pretracheal fascia
- limited to the anterior part of the neck
- completely surrounds the thyroid gland -
forming a sheath for the thyroid gland -
binds the gland to the larynx
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pretracheal fascia (cont)

• encloses the parathyroid glands, trachea,
  pharynx, esophagus and Infrahyoid muscles
• inferiorly blends with the fibrous pericardium
• laterally with the carotid sheath
• superiorly attaches to the thyroid cartilage and
  hyoid bone

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3-Prevertebral fascia

• tubular sheath for the vertebral column and its
  related muscle
• from base of the skull to T3, where it fuses with
  the anterior longitudinal ligament of the
  thoracic vertebrae
• extends laterally as the axillary sheath

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• Danger Space
• between the two layers on the front of the
  vertebral column that may facilitate the spread
  of infection from the deep neck into the thorax

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Retropharyngeal Space
-the largest and most important interfascial
space in the neck -It is a potential space
consisting of loose CT -Between 1-prevetabral
fascia, and 2-Bucchopharyngeal fascia ( covers
the pharynx superficially and the buccinator
muscle) -Closed superiorly by the base of the
skull -Opens inferiorly into the superior
mediastinum -Permits the movements of the
pharynx, larynx, esophagus, and trachea during
the swallowing
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Clinical Correlation
Investing layer of cervical fascia prevents the
spread of abscess Pus from an abscess posterior
to the prevertebral layer may extend later in the
neck and form a swelling posterior to the SCM
-Pus may perforate the investing layer and enter
the retopharyngeal space producing a bulge in the
pharynx (retropharyngeal abscess) which causes
difficulty in the swallowing and speaking
-Infection in the retropharyngeal space may
extend inferiorly into the Superior mediastinum
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Posterior triangle of the neck
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Triangles of the neck
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SCM divides the neck Into 2 triangles
1-anterior 2-posterior
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PosteriorTriangles of the Neck
Bounders Base intermediate 1/3
of the clavicle Apex meeting of
the anterior and posterior border Anterior
border posterior border of the SCM Posterior
border anterior border of the trapezius muscle
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Roof 1-skin 2-the superficial fascia which
contains a) platysma b) external jugular
vein c) cutaneous branches
of the cervical plexus 3-the deep fascia
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Floor 1- splenius capitis 2- levator scapula
3- scalenus posterior 4- scalenus medius 5-
scalenus anterior All covered by the
prevertebral fascia
Small part of the semispinalis muscle may appear
at the apex of the triangle
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subdivided by the inferior belly of the omohyoid
muscle Into 1-occipital 2- subclavian
triangles (supraclavicular)
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Contents A-Muscles? the inferior belly of the
omohyoid m
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B-nerves Accessory nerve Descends on
the surface of the levator scapulae Nerves to
the levator scapulae from the ventral rami of C3
and C4 Cutaneous branches of the cervical
plexus
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B-nerves Roots and trunks of the
brachial plexus Supraclavicular
nerve Suprascapular nerve Dorsal scapular nerve
Long thoracic nerve Emerging through the
scalenus medius muscle nerve to subclavius
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arteries -Transverse cervical vessels -Suprascapu
lar vessels -Subclavian artery crossing the
first rib veins External jugular vein
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Platysma muscle Origin deep fascia that covers
the pec major and deltoid ms Insertion into the
lowerr border of the mandible some fibers to
the Face and blend with the muscle at the angle
of the mouth Nerve supply cervical branch of
facial nerve Action -depresses the mandible
-drawers down the lower lib
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Omohyoid muscle Origin Inferior belly upper
margin of the scapula medial to suprascapular
lig. Superior belly lower border of body of
hyoid bone Insertion intermediate tendon (
clavicle and 1st rib by facial sling) Nerve
supply Ansa Cervicalis (C1,2 and 3) Action
depresses hyoid bone
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Sternocledomastoid(SCM) Origin manubrium and
medial 1/3 of the clavicle (sternal head and
Clavicular head)) Insertion mastoid processes of
temporal bone and occipital bone Nerve
supply 1-spinal part of the accessory nerve
(motor) 2-C2 and C3 (sensory) Action -two
muscles acting together extend the head and flex
the neck -one muscle rotates head to opposite
side
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What is torticollis?

• Torticollis (wry neck) is a congenital or
  acquired condition of limited neck motion in
  which the child will hold the head to one side
  with the chin pointing to the opposite side.
• It is the result of the shortening of the
  sternocleidomastoid (neck) muscle.
• In early infancy, a firm, non-tender mass may be
  felt in the midportion of the muscle. The mass
  will go away and be replaced with fibrous tissue.
  
• If untreated, there can be permanent limitation
  of neck movement. There may be flattening of the
  head and face on the affected side.

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The veins A.The subclavian vein (which lies on
the scalenus anterior muscle) B. Two veins
which end in the external jugular vein 1- the
transverse cervical vein 2- the
suprascapular vein
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C-External jugular vein
-begins just behind the angle of the
mandible -lies on a line joining the angle of
the mandible to the middle of the clavicle -deep
to the platysma muscle -is formed by union of
1-Posterior Auricular vein 2-Post. Division of
the Retromandibular v. - descends obliquely
across the SCM - just above the clavicle in the
poster triangle pierces the deep fascia - drain
into the subclavian vein /- the internal jugular
vein
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• Retromandibular vein
• Is formed by ?the superficial temporal and
  maxillary veins
• Divides into
• an anterior branch, which joins the facial vein
  to form? the common facial vein, and
• a posterior branch, which joins the posterior
  auricular vein to form? the external jugular vein

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C-External jugular vein
-begins just behind the angle of the
mandible -lies on a line joining the angle of
the mandible to the middle of the clavicle -deep
to the platysma muscle -is formed by union of
1-Posterior Auricular vein 2-Post. Division of
the Retromandibular v. - descends obliquely
across the SCM - just above the clavicle in the
poster triangle pierces the deep fascia - drain
into the subclavian vein /- the internal jugular
vein
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Tributaries . Posterior auricular vein .
Post.division of the Retromandibular vein .
transverse cervical vein, . suprascapular vein .
anterior jug.vein
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Superficial cervical LN -lie along the external
jugular vein in the posterior triangle, and along
the anterior jugular vein in the anterior
triangle -superficial to the SCM -Drains into
deep cervical LN -Receives Lymoh vessels from
the occipital and mastoid LNs
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Subclavian artery Grooves the first rib as it
passes between - scalenus anterior -
scalenus medius muscles Is divided into 3 parts
by the scalenus anterior muscle
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Subclavian artery Is a branch of the
brachiocephalic trunk on the right but arises
from directly from the arch of aorta on the
left 1-first part a. vertebral artery b.
thyrocervical trunk c. internal thoracic
artery 2-second part costocervical trunk
a. deep cervical artery b. superior
intercostal artery first 2
post.intercostal artery 3-third part dorsal
scapular artery when it is present it replaces
the deep branch of the transverse cervical
artery
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• thyrocervical trunk
• arises from the first part of subclavian artery
• at the medial border of the scalenus anterior
  muscle
• short trunk that give rise
• to the
• 1-inferior thyroid artery
• 2-transverse cervical artery
• 3-suprascapular artery

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Transverse Cervical a. -across the scalenus
anterior m Phrenic n and trunks of the Br
plexus -across the post.Triangle of the Neck
A-superficial branch deep surface of the
trapezius with the accessory nerve B-deep
branch deep surface of the rhomboid m with
dorsal scapular nerve

• Suprascapular artery
• across the scalenus anterior m and the Br.plexus
• Across the post.triangle of the neck
• Behind the clavicle
• Deep surface of the supraspinatus m Joins the
  suprascapular nerve

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The brachial plexus and subclavian artery may be
compressed in the neck by

• a rudimentary cervical rib
• a tight fibrous band
• first thoracic rib
• a tight scalenus anterior muscle
• giving rise to sensory,
• motor
• vascular symptoms
• in one or both upper extremities.

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cervical rib

• Pressure in the region of a cervical rib will
  give rise
• to local pain as well as pain referred to the
  hand and arm particularly in the ulnar portion of
  the hand and forearm since it is the lower trunk
  of the brachial plexus which is involved (C8,T1).
  There is muscular weakness of the small hand
  muscles.

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Scalenus anticus syndrome

• Coldness and blueness of the hand and diminished
  pulsation in radial and ulnar arteries occur
  because of compression of the subclavian
  artery.Scalenus anticus syndrome is also
  characterized by pain in the arm, shoulder and
  neck and is associated with atrophy of the small
  hand muscles and numbness of the hand on the
  ulnar side. It is caused by compression of the
  subclavian artery and the lower trunk of the
  brachial plexus by the scalenus anterior muscle.

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In the normal plexus, the cervical spinal nerves
and trunks of the brachial plexus follow a
straight trajectory with even spacing.
Scalene syndrome is demonstrated by a gentle
deformation of the course of the nerve elements
and loss of space between them. In patients with
pain only there is usually no nerve
hyperintensity
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Nerves A-The Accessory nerve B-The
branches of the Cervical Plexus
C-The Roots and the Trunks
of the Brachial Plexus (b/w
Scalenus Anterior Medius)
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Nerves
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• cranial portion CN IX
• -arises from the side of the medulla
• -joins the spinal root before leaving the skull
• -Out side the skull separates from
• the spinal root to join the vagus nerve
• below the inferior vagal ganglion
• -Is distributed primarily with the
• external and inferior laryngeal nerve
• Contains only
• Special visceral efferent (SVE) fibers
• from the cell body the Nucleus Ambiguus
• Supplies the muscle of the larynx

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Cranial root of IX
Spinal root of IX nerve
IX
Jugular framen
Vagus nerve Inferior ganglion
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spinal portion of IX -From lateral side of the
C1-C5 segments -Ascends through the foramen
Magnum -To join the cranial root before
leaving the skull -Descends in the neck deep to
the SCM (/-through it) -Across the post.triangle
of the neck on the levator scapulae -Deep
surface of the trapezius m Contains only General
somatic efferent (GSE) fibers From cell bodies
in the accessory nucleus Supplies SCM and
Trapezius m
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accessory nerve injury

• The spinal accessory nerve injury can cause
  drooping shoulder, muscle atrophy, weakened or
  limited elevation of the arm/shoulder, shoulder
  pain and scapula (shoulder blade) winging.

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• The spinal accessory nerve is superficial, and is
  adjacent to cervical lymph nodes.

• sometimes nerve injury occurs because the surgeon
  is unaware of theproximity of the nerve, even
  surgeons who know the nerve is in the surgical
  field may damage it, either by section or
  retraction.

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• Diagnosis of the injury is often delayed. The
  reasons for this delay can be poor medical
  knowledge or practices. The delay can also be
  caused by doctors attempting to avoid malpractice
  issues and claims. This delay is unfortunate
  because repair of the nerve should occur promptly
  after the injury. If too many months pass by so
  can the prospects of a successful repair. A
  neurosurgeon specializing in peripheral nerves is
  best suited to assess the possibility of repair.
  Read our story. . .

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• The cervical plexus
• -anterior primary rami of the upper four cervical
  nerves
• deep to the SCM
• Each nerve except the first divides into upper
  and lower branches

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The cervical plexus 4 Cutaneous Branches
1-lesser occipital nerve (neck and scalp
behind the ear) ventral ramus C2 Ascends
along the post. Border of the SCM 2-great
auricular nerve (over the auricle,parotid
gland) C2,C3 Ascends vertically on the SCM
toward the auricle parallels the EJV
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• 3-Transeverse cut. Nerve of the neck
• passes anteriorly across the SCM toward the
  midline skin of the anterior neck
• 4-Supraclavicular nerve
• skin over the clavicle and shoulder from the
  midline to the acromion

• May relay pain referred to the shoulder from the
  phrenic nerve
• Distribution Supplies the skin of thorax to the
  level of second rib

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The cervical plexus 4 muscular branches
a-prevertebral muscles C1-C4 b-levator
scapulae m C3,C4 c-Scalenus ant.,med.,
and posterior d-infrahyoid and
geniohyoid ms. C1,C2,C3
e-phrenic nerve C3,C4,C5
f-SCM C2,C3 Trapezius C3,C4
ONLY - Afferent (Propriception)
-
Sympathetic fibers
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• Phrenic nerve
• C3,4,and 5, Mainly C4
• At lateral and anterior border of the scalenus
  anterior m.undercover the SCM
• Deep to the prevertebral fascia
• Leaves the neck through the thoracic outlet b/w
  subclavian artery and vein
• Crossing in front the origin of the internal
  thoracic artery, where it joins the
  pericardiacophrenic branch of this artery

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1- motor innervation of the diaphragm 2-
Sensory A-pericardium B- mediastinal
pleura C- pleural and peritoneal And
coverings of the central part of the diaphragm
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• Accessory Phrenic n
• Arises as a contribution of C5 to the phrenic
  nerve or a branch of the nerve to the subclavius
  C5
• Descends lat to the phrenic nerve
• Post to the subclavian vein
• Joins the phrenic n below the first rib to supply
  the diaphragm

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• The Brachial plexus
• is formed by union of the anterior
• primary rami of C5-T1
• Passes between the anterior scalene
• and middle scalene m
• Its root gives rise to the
• Dorsal scapular n C5?dep to the levator scapulae
  and the rhomboid ms
• Long thoracic nerveC5-7?serratus anterior
• Its upper trunk gives rise to the
• Suprascapular n C5-6?throgh the scapular
  notch?supraspinatus and infraspinatus ms
• Nerve to subclavius m C5?in front the plexus
  behind the clavicle?subclavius

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• Injury to the brachial plexus at birth has
  probably always occurred. The first recorded
  mention of it is by William Smellie in a 1768
  publication on midwifery.

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• Prevalence (How common is Birth Brachial Plexus
  Palsy)?
• Total Prevalence 0.2 - 2.5 / 1,000 births
• Persistent Weakness 0.4 - 5.0 / 10,000 births

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Pathogenesis

• The brachial plexus is injured by traction on the
  shoulder during delivery. Infants affected are
  usually large, so that it is necessary to use
  force in pulling them from the birth canal. When
  the shoulder is forcibly pressed downward, the
  brachial plexus can be stretched or injured.

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Upper Brachial Plexus (Erb's) Palsy

• In this condition, the upper part of the nerve
  plexus is damaged. Along with total brachial
  plexus palsy, this is the most common form of the
  disorder. These infants cannot move the shoulder
  and keep their arms extended and turned inward,
  giving the appearance of the "waiter's tip hand."
  Often, these babies have no movement of the arm
  right after birth but begin to move the fingers
  and wrist within a few weeks. The weak shoulder
  and elbow movement remain persistent problems,
  however.

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