General organisation of H&N - fascial planes of neck Flashcards
what does the head consist of?
scalp, skull, brain & coverings (meninges) special sense organs muscles cranial nerves & branches glands blood vessels lymphatics
what do the structures of the head run through the neck in close relation to?
thyroid gland pharynx larynx trachea oesophagus cervical vertebrae
where does the next extend from to?
from lower margin of mandible
to suprasternal notch of manubrium & upper border of clavicle below
connects head to rest of body
how are structures in the neck compartmentalised?
by layers of cervical fascia
how many layers of cervical fascia are there?
superficial cervical fascia
3 deep cervical fascia layers
describe the superficial cervical layer
just below the skin
largely fatty tissue
what is within the superficial cervical layer?
superficial blood vessels within (external jugular vein, cutaneous nerves, superficial lymph nodes)
platysma muscle
what are the 3 layers of deep cervical fascia? (superficial to deep)
investing layer
pretracheal layer
prevertebral layer
what is formed by all 3 layers of deep cervical fascia?
carotid sheath
what does the carotid sheath create?
a compartment for a number of neurovascular structures running between the head and thorax
what does the investing layer (most superficial layer) of the deep cervical fascia surround?
the entire neck like a collar
where does the superior margin of the investing layer attach?
on each side to the entire lower border of the mandible (midline to angle)
the mastoid process, the superior nuchal line
external occipital protuberance in posterior midline
what does the investing layer attach to posteriorly?
spinous processes of the vertebrae
ligamentum nuchae
what does the investing layer attach to inferiorly?
upper border of the manubrium
upper surface of the clavicle
acromion
spine of scapula
what does the investing layer split to enclose?
sternocleidomastoid
trapezius muscle
submandibular + parotid salivary glands
describe the pretracheal layer (middle)? where it sits?
thin and limited to anterior part of the neck
what does the pretracheal layer attach to superiorly?
hyoid bone
what does the pretracheal layer attach to inferiorly?
extends into the thorax - blends with fibrous pericardium
what does the pretracheal layer consist of? what do they enclose?
muscular layer enclosing the infrahyoid muscles
visceral layer - encloses thyroid gland, trachea, oesophagus
what happens to the visceral layer as it encloses the thyroid gland?
splits around the thyroid gland to form a false capsule
what do diseases affected the thyroid gland cause?
enlargement of gland (goitre) / discrete lumps to appear
how can you localise pathology to the thyroid gland?
asking patient with a swelling or lump in their neck to swallow and observing whether it moves
why does the thyroid gland move when swallowing?
thyroid gland is enclosed by pre-tracheal fascia - which is attached to the hyoid bone (superiorly)
which level is the hyoid bone at?
C3
what moves up when swallowing?
hyoid bone and larynx (so will thyroid + any swelling / lump involved)
where can enlarged thyroid gland sometimes be extended to?
retrosternally, through the root of the neck
why can enlarged thyroid sometimes be extended retrosternally?
because lower limit of the pre-tracheal fascia (middle) extends into thorax
what can retrosternal extension of a goitre lead to?
compression of other structures running through the root of the neck (thoracic inlet) e.g. trachea + venous blood vessels
what symptoms can compression of other structures running through thoracic inlet via goitre lead to?
breathlessness + stridor - tracheal compression
facial oedema - compression impending venous drainage from head + neck
what is the carotid sheath?
a tubular, fibrous structure that extends from base of cranium through the root of neck to arch of aorta
what does the carotid sheath contain?
a number of structures including: common carotid artery internal jugular vein vagus nerve (CN X)
what does the prevertebral layer (innermost) of deep cervical fascia form?
a sheath for the vertebral column and muscles associated with it
where does the prevertebral layer extend?
from base of cranium to 3rd thoracic vertebra
what does the prevertebral layer extend laterally as? surrounding what?
as the axillary sheath that surrounds the axillary vessels and the brachial plexus of nerves running into the upper limb
what do the layers of deep cervical fascia form?
natural cleavage planes allowing structures to move pass one another with easy and easy separation of tissues during surgery
what do the fascial layers determine?
the direction and extent to which any infection occurring within the neck may spread
what do the fascial compartmentalisation of structures in the neck give rise to?
potential spaces between fascial planes
what is an important deep neck space?
the retropharyngeal space
where does the retropharyngeal space lie?
between prevertebral layer of fascia and fascia surrounding the pharynx
what is the fascia surrounding the pharynx? what is it a component of?
buccopharyngeal fascia - component of pre-tracheal (middle) fascia
what does the retropharyngeal space contain up until 3-4 years old?
lymph nodes
what is the retropharyngeal space helpful in?
allowing the pharynx to move freely on the vertebral column and expand during swallowing
can be space for infection to collect
where can an infection that develops in the retropharyngeal space potentially spread from? to? risking development of what?
neck into thorax as far down as the posterior mediastinum
risking development of mediastinitis (rare but life threatening)
what can an infection in the retropharyngeal space be secondary to? common age group?
throat infection
commonly in children under 5 years
what can infection in retropharyngeal space develop into?
an abscess (collection of pus)
