Cervical plexus

Cervical plexusAnatomy and function of the cervical plexus
~ 8 min

In this note, we are going to discuss the anatomy of the cervical plexus (plexus cervicalis), which provides innervation to the head and neck.

Cervical plexus (plexus cervicalis)
Cervical plexus (plexus cervicalis)

This plexus is located in the neck region deep to the sternocleidomastoid muscle, and anterolateral to the levator scapulae.

Plexus location between muscles
Plexus location between muscles

It is formed by the anterior rami of the four upper cervical spinal nerves (C1-C4).

Cervical plexus (plexus cervicalis)
Cervical plexus (plexus cervicalis)
Anterior ramus of the spinal nerve (ramus anterior)
Anterior ramus of the spinal nerve (ramus anterior)

The C5 is sometimes also considered as part of the plexus, due to its contribution in the formation of one of the deep branches of the cervical plexus, the phrenic nerve.

The cervical nerves within this plexus are intertwined with each other in such a way that each inferior nerve receives fibers from the superior one. For example, C3 receives fibers from C2, C4 receives fibers from C3, and so on. These communicating fibers are branches of the sympathetic trunk (truncus sympathicus)

Sympathetic trunk (truncus sympathicus)
Sympathetic trunk (truncus sympathicus)

and are also called gray rami communicantes (rami communicantes grisei).

Gray ramus communicans (r. communicans griseus)
Gray ramus communicans (r. communicans griseus)

Each of the cervical nerves, except for the first one (C1), splits into two branches: ascending (r. ascendens) and descending (r. descendens). They subsequently connect with the branches of adjacent cervical nerves, forming loops. These loops contribute to the formation of the cervical plexus.

The cervical plexus has two types of branches:

  • Deep or muscular or anterior branches (rr. musculares), which are motor branches that innervate muscles of the neck.
  • Superficial or cutaneous or posterior branches (rr. cutanei), which are sensory branches that supply the skin.
Cutaneous / posterior branches (rr. cutanei)
Cutaneous / posterior branches (rr. cutanei)

Let’s start with the sensory branches.

The loop between C2 and C3 gives off:

  • The lesser occipital nerve (n. occipitalis minor), which contains fibers from C2, and innervates the skin of the neck and the skin of the scalp (posterosuperior to the auricle)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve (n. occipitalis minor)
Lesser occipital nerve - area of innervation
Lesser occipital nerve - area of  innervation
  • The great auricular nerve (n. auricularis magnus), which contains fibers from C2 and C3, ascends across the sternocleidomastoid muscle, and divides into two branches at the inferior pole of the parotid gland.
Greater auricular nerve (n. auricularis magnus)
Greater auricular nerve (n. auricularis magnus)
Greater auricular nerve (n. auricularis magnus)
Greater auricular nerve (n. auricularis magnus)

These are the posterior (r. posterior) and anterior (r. anterior) branches.

Anterior and posterior branches of greater auricular nerve
Anterior and posterior branches of greater auricular nerve

It innervates the skin over the gland, the posteroinferior aspect of the auricle, and the area between the angle of the mandible and the mastoid process.

Greater auricular nerve - area of innervation
Greater auricular nerve - area of  innervation
  • The transverse cervical nerve (n. transversus colli) contains fibers from C2 and C3, it curves around the posterior border of the sternocleidomastoid muscle, passing deep to the platysma.
Transverse cervical nerve (n. transversus colli)
Transverse cervical nerve (n. transversus colli)
Transverse cervical nerve (n. transversus colli)
Transverse cervical nerve (n. transversus colli)

It innervates the skin covering the anterior triangle of the neck (trigonum cervicalis anterius).

Anterior triangle of the neck (trigonum cervicalis anterius)
Anterior triangle of the neck (trigonum cervicalis anterius)
Transverse cervical nerve - area of innervation
Transverse cervical nerve - area of  innervation
  • Supraclavicular nerves (nn. supraclaviculares) arise from the loop between C3 and C4,
Supraclavicular nerves (nn. supraclaviculares)
Supraclavicular nerves (nn. supraclaviculares)
Supraclavicular nerves (nn. supraclaviculares)
Supraclavicular nerves (nn. supraclaviculares)

they contain fibers from C3 and C4, and pass as a common trunk under the sternocleidomastoid muscle. This trunk then divides into medial supraclavicular nerves (nn. supraclaviculares mediales),

Medial supraclavicular nerves (nn. supraclaviculares mediales)
Medial supraclavicular nerves (nn. supraclaviculares mediales)

intermediate supraclavicular nerves (nn. supraclaviculares intermedii),

Intermediate supraclavicular nerves (nn. supraclaviculares intermedii)
Intermediate supraclavicular nerves (nn. supraclaviculares intermedii)

and lateral supraclavicular nerves (nn. supraclaviculares laterales).

Lateral supraclavicular nerves (nn. supraclaviculares laterales)
Lateral supraclavicular nerves (nn. supraclaviculares laterales)

These branches innervate the skin of the neck region and the skin over the shoulder.

Supraclavicular nerves - area of innervation
Supraclavicular nerves - area of  innervation

There is a commonly used mnemonic to memorize the sensory branches of the cervical plexus: Let’s Go To Spain!

Muscular branches

Now let’s discuss motor (or muscular) branches of the cervical plexus.

These are the so-called ansa cervicalis (ansa cervicalis), the phrenic nerve (nervus phrenicus), and several smaller muscular branches.

The ansa cervicalis is a loop, formed by two roots: the superior (radix superior) and inferior (radix inferior), which is composed of fibers from nerves C1 to C3.

Ansa cervicalis (ansa cervicalis)
Ansa cervicalis (ansa cervicalis)
Superior root(radix superior)
Superior root(radix superior)
Inferior root (radix inferior)
Inferior root (radix inferior)

The ansa cervicalis gives rise to several branches to the corresponding muscles:

  • The sternohyoid branch (r. sternohyoideus) – C1 – C3
Sternohyoid branch (r. sternohyoideus)
Sternohyoid branch (r. sternohyoideus)
Sternohyoid branch (m. sternohyoideus)
Sternohyoid branch (m. sternohyoideus)
  • The sternothyroid branch (r. sternothyreoideus) – C1 – C3
Sternothyroid branch (r. sternothyroideus)
Sternothyroid branch (r. sternothyroideus)
Sternothyroid muscle (m. sternothyroideus)
Sternothyroid muscle (m. sternothyroideus)
  • The geniohyoid branch (r. geniohyoideus) – C1, passes with the hypoglossal nerve
Geniohyoid branch (r. geniohyoideus)
Geniohyoid branch (r. geniohyoideus)
Geniohyoid muscle (r. geniohyoideus)
Geniohyoid muscle (r. geniohyoideus)
Hypoglossal nerve passing along the ansa cervicalis
Hypoglossal nerve passing along the ansa cervicalis
  • The omohyoid branch (r. omohyoideus) – C1 – C3
Omohyoid branch (r. omohyoideus)
Omohyoid branch (r. omohyoideus)
Omohyoid muscle (m. omohyoideus) - superior belly
Omohyoid muscle (m. omohyoideus) - superior belly
Omohyoid muscle (m. omohyoideus) - inferior belly
Omohyoid muscle (m. omohyoideus) - inferior belly
  • The thyrohyoid branch (r. thyrohyoideus) – C1, passes with the hypoglossal nerve
Thyrohyoid branch (r. thyrohyoideus)
Thyrohyoid branch (r. thyrohyoideus)
Thyrohyoid muscle (m. thyrohyoideus)
Thyrohyoid muscle (m. thyrohyoideus)
Hypoglossal nerve passing along the ansa cervicalis
Hypoglossal nerve passing along the ansa cervicalis

The branches of the ansa cervicalis provide innervation to the mentioned infrahyoid muscles.

You can use the following mnemonic to memorize the nerves, that form the ansa cervicalis: Stephen Stole The Golden Orange

The phrenic nerve receives most of its fibers from C4, with small contributions from C3 and C5 nerves.

Phrenic nerve (nervus phrenicus)
Phrenic nerve (nervus phrenicus)
Phrenic nerve (nervus phrenicus)
Phrenic nerve (nervus phrenicus)

The nerve is formed in the area of the lateral part of the anterior scalene muscle at the level of the superior border of the thyroid cartilage. It descends with the internal jugular vein (vena jugularis interna) obliquely along the anterior scalenus muscle.

Phrenic nerve (nervus phrenicus)
Phrenic nerve (nervus phrenicus)
Internal jugular vein (vena jugularis interna)
Internal jugular vein (vena jugularis interna)

It passes posteriorly to the subclavian vein (vena subclavia), anteriorly to the internal thoracic artery (a. thoracica interna), and enters the thoracic cavity.

Phrenic nerve (nervus phrenicus)
Phrenic nerve (nervus phrenicus)
Subclavian vein (vena subclavia)
Subclavian vein (vena subclavia)
Internal thoracic artery (a. thoracica interna)
Internal thoracic artery (a. thoracica interna)

The phrenic nerve contains not only motor but also sensory and sympathetic nerve fibers, which makes it a mixed nerve.

It provides the motor supply to the diaphragm as well as sensation to its central area.

Diaphragm (diaphragma)
Diaphragm  (diaphragma)
Branches of the phrenic nerve innervating the diaphragm
Branches of the phrenic nerve innervating the diaphragm

In the thoracic cavity, the nerve innervates the mediastinal pleura and pericardium.

Phrenic nerve in the superior mediastinum
Phrenic nerve in the superior mediastinum
Phrenic nerve in the lower mediastinum
Phrenic nerve in the lower mediastinum
Mediastinal pleura (pleura mediastinalis)
Mediastinal pleura (pleura mediastinalis)
Pericardium (pericardium)
Pericardium (pericardium)

The motor branches of the cervical plexus also include fibers to the levator scapulae muscle, the sternocleidomastoid muscle, and the prevertebral muscles.

Levator scapulae muscle (m. levator scapulae)
Levator scapulae muscle (m. levator scapulae)
Sternocleidomastoid muscle (m. sternocleidomastoideus)
Sternocleidomastoid muscle  (m. sternocleidomastoideus)
Intrinsic muscles of the back
Intrinsic muscles of the back
Dictionary

Cervical plexus

Cervical plexus
plexus cervicalis
Anterior branch
ramus anterior
Sympathetic trunc
truncus sympathicus
Gray rami communicantes
rami communicantes grisei
Ascending branch
ramus ascendens
Descending branch
ramus descendens
Muscular branches
rr. musculares
Cutaneous branches
rr. cutanei
Lesser occipital nerve
n. occipitalis minor
Great auricular nerve
n. auricularis magnus
Posterior branch
ramus posterior
Transverse cervical nerve
n. transversus colli
Anterior triangle of the neck
trigonum cervicalis anterius
Supraclavicular nerves
nn. supraclaviculares
Medial supraclavicular nerves
nn. supraclaviculares mediales
Intermediate supraclavicular nerves
nn. supraclaviculares intermedii
Lateral supraclavicular nerves
nn. supraclaviculares laterales
Ansa cervicalis
ansa cervicalis
Phrenic nerve
nervus phrenicus
Superior root
radix superior
Inferior root
radix inferior
Sternohyoid branch
r. sternohyoideus
Sternohyoideus muscle
m. sternohyoideus
Sternothyroid branch
r. sternothyroideus
Sternothyroideus muscle
m. sternothyroideus
Geniohyoid branch
r. geniohyoideus
Geniohyoideus muscle
m. geniohyoideus
Omohyoid branch
r. omohyoideus
Omohyoideus muscle
m. omohyoideus
Thyrohyoid branch
r. thyrohyoideus
Thyrohyoideus muscle
m. thyrohyoideus
Internal jugular vein
vena jugularis interna
Subclavian vein
vena subclavia
Internal thoracic artery
a. thoracica interna
Diaphragm
diaphragma
Mediastinal pleura
pleura mediastinalis
Pericardium
pericardium
Levator scapulae muscle
m. levator scapulae
Sternocleidomastideus muscle
m. sternocleidomastoideus
Main screen of the Easy Anatomy app

Download Easy Anatomy and try it for free

  • Anatomical atlas
  • Interactive notes
  • Videos on Anatomy
  • Flashcard tests

Easy Anatomy

Learn anatomy effectively

3.2K

Функция доступна в приложении

Download the app