The perivertebral space (PVS) lies deep within the neck surrounding the vertebral column,
extending from the skull base to the mediastinum.
The PVS is covered by the deep layer of the deep cervical fascia (DLDCF) and contains different tissue types,
including muscles,
bones,
nerves,
and vascular structures.
Physical examination is of limited use in evaluating this space because is deeply located.
Therefore,
imaging is very essential.
Normal anatomy
The PVS comprises the cervical soft tissues surrounding the vertebral column,
extending from the skull base to the D4 level.
The DLDCF divides the PVS into an anterior prevertebral space and posterior paraspinal space.
The PVS borders in the suprahyoid and infrahyoid neck with the retropharyngeal space (RPS) anteriorly,
carotid space laterally,
and the posterior cervical space posterolaterally Fig. 1.
Fascial layers
The deep cervical fascia can be divided into superficial,
middle,
and deep layers.
Within the suprahyoid neck,
the superficial layer of the deep cervical fascia (SLDCF) delineates the masticator space,
parotid space,
as well as a portion of the carotid sheath.
Within the infrahyoid neck,
the SLDCF encases the trapezius muscles,
strap muscles and sternocleidomastoid muscles Fig. 2.
In the suprahyoid neck,
the middle layer of the deep cervical fascia (MLDCF) defines the deep margin of the pharyngeal mucosa and gives contributions to the carotid sheath.
The infrahyoid components of the MLDCF surround the visceral space.
The DLDCF enfolds the PVS and contributes to the carotid sheath.
It has lateral openings for the brachial plexus nerve roots.
The anterior portion of the DLDCF is located in front of the prevertebral muscles,
extending to the transverse processes laterally.
This anterior part functions as a barrier to infection,
extending anteriorly from the spine into the retropharyngeal space.
The posterior part arches over the paraspinal muscles,
attaching to the ligamentum nuchae.
A unique portion of the DLDCF is the alar fascia.
This slip of fascia separates the danger space from the more anterior RPS,
forms their lateral walls,
and provides a portion of the carotid sheath.
The DLDCF divides the PVS into an anterior prevertebral space and posterior paraspinal space.
Prevertebral space
Muscles include most of the prevertebral space.
Two major muscles of neck flexion are the longus capitis and longus colli (longus capitis/colli complex).
The longus capitis defines the anterior prevertebral space.
Besides,
there are anterior and lateral rectus muscles that lie deep to the superior aspect of the longus capitis.
Along with the longus capitis/colli complex,
the anterior,
middle,
and posterior scalene muscles also exist in the prevertebral space.
Important anatomic features include its location between the subclavian vein and artery and anterior position relative to the brachial plexus nerve roots.
Multiples nerves cross the prevertebral space en route to their respective end organs,
such as phrenic nerve,
dorsal scapular nerve,
long thoracic nerve and the brachial plexus nerve roots.
The vertebral arteries and veins are the major tributaries of the posterior circulation and travel in the transverse foramina of the vertebral bodies.
Paraspinal space
Paraspinal space is composed of muscle tissue.
The paraspinal muscle groups are made up of multiple smaller individual muscles in an array of symmetric pairs separated by the spinous processes,
interspinales muscles and ligamentum nuchae.
The major extensors of the head and neck are the splenius capitis,
semispinalis capitis,
and longissimus capitis.
More centrally located and smaller in size are the levator scapulae,
multifidus,
and interspinales muscles.
The SLDCF involve the trapezius muscles,
which are part of the posterior cervical musculature and are separated from the paraspinal muscles by fat.
Images through the midcervical level show the longissimus capitis and cervicis and the more medial multifidi and semispinalis cervicis osseous structures.