Fasciae of the Neck

Overview

Deep Cervical Fascia

The deep cervical fascia lies deep to the superficial fascia and platysma muscle.  This fascia is organised into several layers (superficial to deep):

Investing Layer

The investing layer is the most superficial of the deep cervical fascia and surrounds all the structures in the neck (splits in two where it meets the trapezius and sternocleidomastoid muscles). The investing fascia can be thought of as a tube with; superior, anterior, inferior and posterior attachments:

• Superior – attaches to the external occipital protuberance and the superior nuchal line of the skull.
• Anteriorly – attaches to the hyoid bone and courses further superiorly to enclose the submandibular gland, attaching to the inferior surface of the mandible
• Inferiorly – attaches to the spine and acromion of the scapula, the clavicle, and the manubrium of the sternum
• Posterior – attaches along the nuchal ligament of the vertebral column

Pretracheal Layer

The pretracheal layer of fascia is situated in the anterior neck, spanning between the hyoid bone superiorly and the thorax inferiorly (where it fuses with the pericardium). It is divided into two parts and encloses several structures:

• Muscular part – encloses the infrahyoid muscles
• Visceral part – encloses the thyroid gland, trachea and oesophagus

The posterior aspect of the visceral fascia is formed by contributions from the buccopharyngeal fascia (a fascial covering of the pharynx).

Prevertebral Layer

The prevertebral fascia surrounds the vertebral column and its associated muscles; scalene muscles, prevertebral muscles, and the deep muscles of the back. It has attachments along the antero-posterior and supero-inferior axes:

• Superior attachment – base of the skull
• Anterior attachment – transverse processes and vertebral bodies of the vertebral column
• Posterior attachment – along the nuchal ligament of the vertebral column
• Inferior attachment – fusion with the endothoracic fascia of the ribcage

The anterolateral portion of prevertebral fascia forms the floor of the posterior triangle of the neck. It also surrounds the brachial plexus as it leaves the neck and subclavian artery as it passes through the lower neck region – in doing so, it forms the axillary sheath.

Carotid Sheath

The carotid sheaths are paired column-like structures on either side of the neck, that run between the skull base to the thoracic mediastinum. It is formed by contributions from the pretracheal, prevertebral, and investing fascia layers. They enclose an important neurovascular bundle of the neck which includes:

• Common carotid artery – bifurcates within the sheath into the internal carotid artery and external carotid artery
• Internal jugular vein
• Vagus nerve
• Accompanying cervical lymph nodes