Lecture 1- Cervical fascial planes Flashcards
the neck extends from the
lower margin of the mandible to the suprasternal notch of the manubrium and upper border of the clavicle
structues int he neck are compartmentalised by layers called
cervical fascia
types of cervical fascia
- 1 superifical cervical fascial layer (just below the skin)
- 3 deep cervical fascial layers
The superficial cervical fascial layer is a
loose connective tissue largely containing adipose. Within this layer lie superficial blood vessels e.g. anterior and external jugular veins, cutaneous nerves, superficial lymph nodes and the platysma muscle.
name the three layers of deep cervical fascia from the most superficial to deep
- investing layer
- pretracheal layer
- prevertebral layer
the carotid sheath is a
ourth deep cervical fascia layer that is essentially formed by parts of all three layers of deep cervical fascia
what does the carotid sheath encircle
internal jugular, com mon caroitd and vagus nerve
the investing layer
- most superificial of the deep cervical fasciae
- surround entire neck like a collar
- supeiror amrign is attached on each side to the lower border of the mandible
- , the mastoid process, the superior nuchal like and the external occipital protuberance of the posteiror midline
- also attaches to spinous processes of the vertebrae and ligamentum nuchae posteirorly
- inferiorly the investing layer attaches to the upper border of the manubrium, the upper surface of the clavicle, acromion and spine of the scapula
the investing layer encloses
sternocleidomastoid and trapezius muscles, and the submandibular and parotid salivary glands.
pretracheal layer
- is thin and limited to the anterior and lateral part of the neck (this makes more sense when viewing the cross-sectional view below).
- Superiorly and anteriorly it is attached to the hyoid bone and inferiorly it extends into the thorax where it blends with the fibrous pericardium.
pretracheal layer encloses
the infrahyoid muscles (not shown on the image below) and a visceral layer, which encloses the thyroid gland (splitting around this to form a false capsule), trachea and oesophagus (shown on image below, ‘peeled’ open).
pretracheal layer as it contines posteriroly to invest the muscles of the pharynx and oesophagus is know as the
buccopharyngeal fascia, (fascia associated with the pharynx and oesophagus).
buccopharyngeal fascia
runs from the base of the skull superiorly, to the diaphragm inferiorly.
The carotid sheath is a
tubular, fibrous structure that extends from the base of the skull through the root of the neck to the arch of aorta. It contains a number of structures including but not limited to the common carotid artery, internal jugular vein and the cranial nerve [CN], the vagus nerve (CN X).
The deepest (or innermost) layer of the deep cervical fascia (prevertebral layer) forms a sheath for the
vertebral column and muscles associated with it.
location of the pretvertebral fascia
This layer extends from the base of the cranium to the 3rd thoracic vertebra and extendslaterally as the axillary sheath that surrounds the axillary vessels and the brachial plexus of nerves running into the upper limb.
Clinical Correlate: Deep Cervical Fasciae and Infection
The layers of deep cervical fascia form natural cleavage planes that not only allow structures to move and pass over one another with ease but allow easy separation of tissues during surgery. These facial layers also determine the direction and
extent to which any infection occurring within the neck may spread.
The fascial compartmentalisation of structures in the neck gives rise to
potential spaces between fascial planes. These deep neck spaces contain a loose connective tissue, so they are not technically “empty” spaces. However, infection or an abscess can arise between the fascial planes causing these “spaces” to distend (deep neck space infections). The infective source often originates in the teeth, tissues of the pharynx, sinuses or middle ear, and spreads. Although deep neck space infections are thankfully rare, they pose significant risk to life. It is important therefore, that doctors are aware of how deep neck space infections present and the risks they pose.
Retropharyngeal Space Infections
Infection in the retropharyngeal space is usually secondary to an upper respiratory tract infection (e.g. nasal cavity, nasopharynx, oropharynx) and is most commonly seen in children, usually under the age of 5 years. Infection in this space may
develop into an abscess.
A retropharyngeal abscess can present with a variety of signs and symptoms including a visible bulge on inspection of the oropharynx, sore throat, difficulty swallowing, stridor, reluctance to move their neck and a high temperature. It is important to recognise and treat early.
Clinical Correlates: Lumps in the Thyroid Gland and Retrosternal Goitres
Diseases affecting the thyroid gland can cause enlargement of the gland or discrete lumps to appear. Asking a patient with a swelling or lump in their neck to swallow and observing whether it moves, can help localise pathology to the thyroid gland. This is because the thyroid gland is enclosed by pre-tracheal fascia, which is attached to the hyoid bone. The hyoid bone and larynx move up with swallowing, as such so too will the thyroid gland, and any swelling or lump involving this gland.
An enlarged thyroid gland (goitre) can sometimes extend retrosternally (behind the
sternum), through the root of the neck because the lower limit of the pre- tracheal fascia extends into the thorax. Retrosternal extension of a goitre can lead to compression of other structures running through the root of the neck (thoracic inlet) such as the trachea and venous blood vessels. This can lead to symptoms such as breathlessness and stridor due to tracheal compression, and facial oedema from the compression impeding venous drainage from the head and neck.
