Posterior Triangle Flashcards
superior boundary of the neck
base of skull & inferior border of mandible
inferior boundary of neck
top of sternum, clavicle, acromion (anterior) & C7 (posterior)
what is fascia and why is it present
it is very thin connective tissue that surrounds compartments of the neck providing containment & protection for muscles / viscera & conduit for neurovascular structures
superficial fascia
cervical subcutaneous connective tissue
3 layers of deep fascia
pretracheal, investing and prevertebral
what do the 3 layers of deep fascia form?
carotid sheath
where is superficial fascia found
between the dermis and investing layer of deep fascia
what is in superficial fascia
contains cutaneous nerves, vessels, superficial lymph nodes, fat and platysma (anterolaterally)
investing layer purpose
encloses SCM & trapezius as well as parotid & submandibular glands
what pierces through investing layer
external & anterior jugular veins and nerves including cervical plexus
superior attachments of investing layer
- superior nuchal line of occipital bone
- mastoid processes of temporal bone
- zygomatic arches
- inferior border of mandible
inferior attachments of investing layer
- spine of scapula
- acromion
- clavicle
- manubrium
anterior attachments of investing layer
hyoid bone
posterior attachments of investing layer
- ligamentum nuchae
- periosteum of C7 spinous process
2 parts of pretracheal layer
- visceral part - encloses trachea, oesophagus & thyroid gland
- muscular part - encloses infrahyoid muscles / separates them from trachea & thyroid
where does the pretracheal layer extend from and to
extends from hyoid bone to upper thoracic cavity
what is pretracheal layer continuous with
posteriorly & superiorly continuous with buccopharyngeal fascia of pharynx
what pierces the pretracheal layer
thyroid vessels
what does pretracheal layer laterally fuse with?
alar fascia and carotid sheaths
prevertebral layer is pierced by
cutaneous branches of cervical plexus
superior, anterior and inferior connections of prevertebral layer
superiorly - fixed to cranial base
inferiorly - blends with endothoracic fascia peripherally
anteriorly - longitudinal ligament centrally (at T3/T4 level)
lateral extension of prevertebral fascia is to where?
laterally extends over the first rib to surround axillary vessels & brachial plexus as axillary sheath
how does carotid sheath connect to other fascia
anteriorly with investing + pretracheal
posteriorly with prevertebral layer
major vasculature found within carotid sheath
- common and interior carotid arteries
- IJV
- vagus nerve
boundaries of anterior triangle
inferior border of mandible
anterior border of SCM
midline of the neck
boundaries of posterior triangle
posterior border of SCM
middle 1/3 of clavicle
anterior border of trapezius
4 main regions in neck
- SCM region
- posterior cervical region
- lateral cervical region
- anterior cervical region
what is in the lateral cervical region
posterior triangle & omoclavicular triangle
what is in anterior cervical region
anterior triangle + submandibular, submental, carotid & muscular triangles
boundaries of posterior triangle
anterior - posterior border of SCM
posterior - anterior border of trapezius
inferior - middle 1/3 of clavicle
apex - superior nuchal line of occipital bone
SCM origin
sternal head attaches to manubrium
clavicular head attaches to superior surface of medial 1/3 of sternum
insertion of SCM
lateral surface of mastoid process & lateral half of superior nuchal line
action of SCM
- draws head forwards (bilaterally = both muscles acting)
- tilts head towards ipsilateral shoulder while turning face contralaterally
innervation of SCM
spinal accessory nerve CN XI (motor)
C2 and C3 nerves (pain & proprioception)
function of SCM in respiration
acts as an accessory muscle if head and neck are fixed; SCM elevates clavicles and manubrium
to test SCM
head is turned to opposite side against resistance
trapezius origin
- superior nuchal line
- external occipital protuberance
- ligamentum nuchae
- spinous processes (C7 - T12)
insertion of trapezius
lateral 1/3 of clavicle
acromion
spine of scapula
innervation of trapezius
spinal accessory nerve CN XI
action of trapezius
assists in rotating scapula during abduction of humerus; upper fibres elevate, middle adduct and lower depress scapula
to test trapezius
shoulder shrugged against resistance & superior border can be seen / palpated
cervical plexus
anterior rami of C1, C2-C4
muscular branches of cervical plexus
phrenic nerve C3, C4, C5
ansa cervicalis C1, C2, C3
cutaneous branches of cervical plexus
C2 - lesser occipital nerves
C2, C3 - great auricular & transverse cervical nerves
C3, C4 - supraclavicular nerves
where are cutaneous branches
superficial to prevertebral layer of fascia
where are muscular branches
deep to prevertebral layer of fascia
where is ansa cervicalis
anterior rami of C1-C3
function of ansa cervicalis
innervates infrahyoid muscles
where does external jugular vein drain
drains into subclavian vein
where does anterior jugular vein drain
drains into external jugular vein
what crosses the SCM
EJV
great auricular nerve
transverse cervical nerve
what crosses posterior triangle (superficial to prevertebral fascia)
spinal accessory nerve
EJV
lesser occipital nerve
transverse cervical artery + vein
supraclavicular nerves
