Anatomy of the Cervical Spine:
Upper Limb Tension Test

The clinical test known as the Upper Limb Tension Test (ULTT) is presently utilized to distinguish between pain arising from neuromeningeal tissue and pain arising from other structures in the upper limb.

Elvey (1980) initially described the test as a blend of passive shoulder girdle depression, glenohumeral abduction beyond the coronal plane, forearm supination, and wrist extension.

The fundamental test position can be enhanced by incorporating cervical side flexion. If the patient’s symptoms are replicated upon assuming the ULTT position, it suggests involvement of the neuromeningeal tissue.

A positive ULTT result can be confirmed if the symptoms decrease with ipsilateral wrist flexion or worsen with contralateral cervical side-flexion.

The relationship between the biomechanics of the ULTT and the replication of the patient’s symptoms remains ambiguous. Determining the exact source of the patient’s symptoms, such as the cervical spinal nerve, dura, or cords of the brachial plexus, based on the ULTT alone is challenging.

According to literature, the test generates a growing tension in the peripheral nerves that is conveyed to the sheaths of the cervical nerve roots. The C5 and C6 roots of the brachial plexus are the most susceptible to experiencing tensile stresses.

In some cases, When performed with a contralateral limb flexion (CLF), the ULTT induces greater strain in the lateral cord and certain segments of the subclavian artery compared to an ipsilateral limb flexion (ILF).

Anatomy

The interpretation of the impact of forces generated by the ULTT on the cervical spine and brachial plexus based on anatomical studies of cervical nerves may differ between literature, but most of it agrees that the anterior and posterior roots of a nerve emerge from the dura mater independently, each enclosed within its own dural sleeve.

The dura mater is dorsally covered by delicate epidural tissue that spreads laterally to form part of the coverings of the spinal nerves. The fascia of the posterior longitudinal ligament (PLL) spreads outward to connect with the dural root sleeves laterally. This fascia then contributes to the development of the spinal nerve covering.

There has been some uncertainty regarding the level of attachment of the cervical nerves to the adjacent zygapophyseal joints and intervertebral foramina. While literature suggests that nerves are connected to the walls of the foramina through connective tissue, others have argued that such attachments are nearly absent.

However, one researcher found that there may be some exchange of fibers between the nerve sheath and the capsule of the adjacent intervertebral joint, particularly in the anterior region (likely referring to the uncovertebral joint). It has been described that there is a strong connection between the cervical nerves and their adjacent zygapophyseal joints.

The transverse processes’ gutters provide an anchor for the cervical nerves. The connections between the transverse processes and the fifth, sixth, and seventh cervical nerves are referred to as “fibrous slips,” “fibrous attachments,” or specialized “semiconic ligaments.”

The primary anatomical structure that prevents the avulsion of cervical nerve roots is the specialized attachment between the cervical nerves and the transverse process. The dural root pouch is attached to a fascial extension of the posterior longitudinal ligament, which then extends through the intervertebral foramina (IVF) to contribute to the formation of the periradicular covering.

The superficial layer of the posterior longitudinal ligament is the only part that extends laterally as a connective tissue membrane to enclose the nerves, and then it transitions into the connective tissue membrane that surrounds the spinal nerves as they exit the intervertebral foramina.

Gross Anatomy

Essentially, the path and connections of the CS, C6, and C7 within the IVF and the transverse processes of the cervical spine are the same. Dense white fibrous tissue connects much of the circumference of CS, C6, and C7 to the bony margins of their respective IVFs, including the posterior zygapophyseal joint capsule, as these three nerves emerged from the IVF.

The lower surfaces of the nerves do not have this dense attachment of connective tissue. The nerves are only loosely connected to the pedicle below and, for CS and C6, to the transverse process’s gutter floor.

The anterior aspects of the nerves are blended into the epineurium by a thick fascia that extends laterally through the IVF from the posterior longitudinal ligament (PLL). The nerves flattened anteroposteriorly and pass behind the vertebral artery as they exit the IVF. Dense irregular connective tissue fibers can be observed between the nerves and the vertebral artery.

The nerves have a relationship with the vertebral artery in which on its inner side, the vertebral artery is attached by narrow pieces of dense and irregular connective tissue from its outer layer not only to the C5, C6, and C7 cervical vertebrae but also to the intervertebral discs located between C5 and C6, and C6 and C7.

The adventitial coat of the vertebral artery on its lateral side is connected to the anterior surface of the nerves C5, C6, and C7 by connective tissue fibers. The lateral movement of the vertebral artery can be induced by pulling the nerves in a lateral direction.

The displacement of the artery laterally seems to be restricted by the attachments of the artery’s medial side to the periosteum of the vertebral bodies of C5 and C6, and the intervertebral disc of C5 and C6.

As the nerves C5 and C6 travel towards the periphery within the gutter, they are attached to the anterior and posterior edges of the gutter of the transverse processes by bundles of connective tissue. These bands are distinct clusters of tightly-packed connective tissue.

The connective tissue bundles are primarily found on the posterior gutter wall, and their thickness is greatest at the medial end of the gutter. There exist only a limited number of fragile connective tissue strands linking the nerves and the floors of the bony gutters.

Histology

The histological findings reveal the connections of the lower cervical nerves as they exit the spinal cord and move towards the outer regions. Each nerve has its own dural sleeve that contains both its ventral and dorsal root, and the dura is penetrated separately by each of them.

The surrounding structures are connected to the dural sleeves. Anteriorly, there is a thick and dense connective tissue that stretches from the posterior longitudinal ligament (PLL) to the anterior aspect of the dura, particularly in the area where the roots emerge from their dural sleeves.

The layer of membranous tissue extending laterally from the ligament attaches to the posterior aspects of the vertebral bodies and intervertebral discs. The PLL’s lateral extensions pass underneath the ventral root and connect the nerve root to the intervertebral foramen’s floor.

The posterior aspect of the dura is blended with connective tissue fibers extending from the inferior pedicle. The dorsal root ganglion is situated posterior to the vertebral artery in a lateral direction. It is firmly attached to the artery by dense, irregularly arranged connective tissue.

The lower cervical nerves have multiple connections to innervated structures as they travel from the spinal cord to the outside of the spinal cord region:
The anterior surface of the dorsal root ganglion medial to the vertebral artery is attached to connective tissue fibers that extend from the PLL.

At the medial end of the foramina, the nerves attach to the periosteum of the inferior pedicles and the capsules of the zygapophyseal joints by dense connective tissue, posteriorly. The PLL extends laterally to attach the nerves to the vertebral bodies and intervertebral discs anteriorly.

The extensive attachment of the lower cervical nerves to their surrounding structures implies that pain caused by an ULTT is unlikely to be solely derived from neuromeningeal tissue. The lower cervical nerves are attached to many innervated structures.

The sinuvertebral nerve is a composite nerve, consisting of a somatic root from a ventral ramus and an autonomic root from a gray ramus communicantes. The intervertebral discs, PLL, and the periosteum of the ventrolateral spinal canal are all innervated by the sinuvertebral nerve. The cervical dorsal ramus splits into a medial branch which supplies the zygapophyseal joints.

The Atlas (Top Bone in the Cervical Spine) Illustrated