Fascia and spaces of the neck

Transcript

The structures found in the neck are surrounded by a layer of subcutaneous tissue called the superficial fascia, while there are also layers of deep cervical fascia which distribute the structures in the neck into different compartments.

These fascial layers create different anatomical spaces in the neck, and dictate where an infection may spread if it starts in one of these compartments.

So, let’s take a look at the different fascia layers of the neck. You can think of fascia as a pair of thin stockings made of connective tissue that support and bind together different parts of the body, including the neck.

Now, the neck actually has two pairs of stockings on top of each other: the superficial fascia, which sits right underneath our skin, and the deep fascia, which is deep to or beneath the superficial fascia, and it surrounds muscles and viscera organizing them into compartments.

Ok, so the superficial cervical fascia or the cervical subcutaneous tissue is a layer of fatty connective tissue that lies between the skin and the most superficial layer of deep cervical fascia.

This fascia is usually thinner than in other regions, especially anteriorly, and it contains cutaneous nerves, blood and lymphatic vessels, superficial lymph nodes and variable amounts of fat.

Anterolaterally, it contains the platysma, which is a thin sheet of muscle that covers the anterolateral portion of the neck. Inferiorly, the platysma attaches to the deep fascia that covers the superior parts of pectoralis major and deltoid muscles, with its fibers moving superomedially over the clavicle and attaching superiorly to the inferior border of the mandible, and skin and subcutaneous tissues of the lower face.

The anterior borders of the two platysma muscles join together over the chin and blend with the facial muscles but inferiorly, the fibers remain separated, leaving a gap anterior to the larynx and trachea.

Deep to the platysma, there are the main cutaneous nerves of the neck and the external jugular vein, which descends from the angle of the mandible to the middle of the clavicle.

The platysma is supplied by the cervical branch of the facial nerve, or cranial nerve VII, and it’s involved in facial expression.

Acting from its superior attachment, it tenses the skin producing vertical skin ridges and releasing pressure on the superficial veins. This action is often used when people shave their necks or ease a tight collar.

Acting from its inferior attachment, it depresses the lower jaw and it also draws down the lower lip and angle of the mouth in the expression of sadness and fright.

Moving on, the deep cervical fascia consists of three fascial layers or sheaths called the investing, pretracheal and prevertebral fascia which serve to support the cervical viscera, muscles, vessels and lymph nodes.

The deep cervical fascia also wraps around the common carotid arteries, internal jugular veins and vagus nerves to form the carotid sheath.

These fascial layers form natural cleavage planes through which tissues may be separated during surgery and they limit the spread of abscesses that can result from infections.

Also, they allow the structures in the neck to move and pass over one another without difficulty, such as when swallowing or turning the head and neck.

Ok so, let’s begin with the investing layer of the deep cervical fascia which is the most superficial deep fascial layer. This layer surrounds the entire neck deep to the skin and subcutaneous tissue, investing the trapezius and sternocleidomastoid (SCM) muscles.

Superiorly, it attaches to the superior nuchal lines of the occipital bone, to the mastoid processes of the temporal bones, the zygomatic arches, the inferior border of the mandible, the hyoid bone and the spinous processes of the cervical vertebrae.

Just inferior to its attachment to the mandible, the investing layer splits to enclose the submandibular gland and posterior to the mandible, it splits to form the fibrous capsule of the parotid gland, both of which are salivary glands.

Inferiorly, the investing layer attaches to the manubrium of the sternum, clavicles and acromions, and spines of the scapulae.

Posteriorly, the investing layer continues with the periosteum that covers the C7 spinous process and with the nuchal ligament, which is a triangular membrane that forms a median septum between the muscles of the two sides of the neck.

Inferiorly between the sternal heads of the sternocleidomastoid muscle and just superior to the manubrium, the investing layer remains divided into two layers to enclose the SCM: one layer attaches to the anterior and the other to the posterior surface of the manubrium to form a space called the suprasternal space.

Here, the inferior ends of the anterior jugular veins, the jugular venous arch, fat and a few deep lymph nodes can be found.