Nerves

Cranial Nerves.

The cranial nerves are as follows:

Use roman numerals or English names when designating cranial nerves:

Cranial nerves III, IV, and VI are responsible for ocular movement.

The oculomotor, trochlear, and abducens nerves are responsible for ocular movement.

Use ordinals when the numeric adjectival form is used:

The third, fourth, and sixth cranial nerves are responsible for ocular movement.

Vertebrae, Spinal Nerves, Spinal Levels, Dermatomes, and Somites.

These entities share a common nomenclature, deriving from spinal anatomic regions: cervical (neck), thoracic (trunk), lumbar (lower back), sacral (pelvis), and coccygeal (coccyx or tailbone).

Spinal nerves C1 through C7 are named for the vertebrae above which they emerge, while T1 through S5 are named for the vertebrae below which they emerge. Spinal nerve C8 emerges below vertebra C7; there is no C8 vertebra.

Vertebrae and spinal nerves are as follows.

The alphanumeric terms need not be expanded and, when clear in context, “vertebra” and “nerve” need not be repeated:

The first cervical vertebra is also known as the atlas, C2 as the axis, and C7 as the vertebra prominens.

Portions of a vertebra may be referred to as follows, ie, without the term vertebra:

C5 spinous process

L3 lamina

T12 transverse process

Hyphens are used for intervertebral spaces (including neural foramina) and intervertebral disks, as follows:

(Note: Terminologia Anatomica uses disc, not disk. See also 11.0, Correct and Preferred Usage.)

The sacrum, because its vertebrae are fused, does not contain intervertebral spaces. Its 4 paired foramina are commonly referred to as the first sacral foramen (or S1 foramen), second sacral foramen (or S2 foramen), etc.

Ranges of vertebrae are expressed as in the following examples; use letters for both the first and last vertebra in the indicated range:

Ranges of vertebrae when used as modifiers have one or more hyphens, eg:

C1-C3 arthrodesis

C2-T1 spinous processes

C4-T3 fusion

L1-L2-L3 motion segments

L1-L4 bone mass density

L2-S1 canal stenosis

L3-L4-L5 fusion

L4-L5 laminectomy

erosion of T9-T12 vertebrae

The same abbreviations are used for spinal segments or levels, spinal dermatomes, and somites. Text should indicate which is being referred to, eg, vertebra, spinal nerve (or root, radiculopathy, or distribution), spinal level, dermatome, or somite. Within a clear context, as noted above, the words vertebra, nerve, etc, need not be repeated.

Serious injury of the cervical cord at the level of the C2-C5 vertebrae causes respiratory paralysis due to injury of spinal nerves C3 through C5.

The first patient had herpes zoster in the T9 dermatomal distribution, the second patient in the C5 distribution.

L1-S2 radiculopathy

L3-L4-L5 periradicular infiltration