The cervical plexus- teachmeanatomy

Question 1

what is the cervical plexus

Answer 1

a network of nerve fibres that supplies innervation to some of the structures in the neck and trunk.

Question 2

where is the cervical plexus found

Answer 2

It is located in the posterior triangle of the neck, halfway up the sternocleidomastoid muscle, and within the prevertebral layer of cervical fascia.

Question 4

what forms the cervical plexus

Answer 4

The plexus is formed by the anterior rami (divisions) of cervical spinal nerves C1-C4.

Question 5

At each vertebral level (C1-C4), paired spinal nerves leave the spinal cord via the ……………. ……………… of the vertebral column.

Answer 5

intervertebral foramina

Question 6

Each nerve then divides into

Answer 6

anterior and posterior nerve fibres.

Question 7

The cervical plexus begins as ….. …….. ……..of the spinal nerves C1, C2, C3 and C4.

Answer 7

the anterior fibres

These fibres combine with each other to form the branches of the cervical plexus.

Question 8

The cervical plexus gives rise to numerous branches which supply structures in the head and neck. They can broadly be divided into two groups –

Answer 8

muscular branches and sensory branches.

Question 9

muscular branches are loacted …….. to the sensory branches

Answer 9

deep to the sensory branches

Question 10

muscular branhces supply

Answer 10

some of the muscles of the neck, back and diaphragm

Question 11

After arising from the cervical plexus, the muscular branches tend to travel initially in an …………….direction. This is in contrast to the cutaneous branches, which travel posteriorly.

Answer 11

anteromedial

Question 12

main nerves of the muscular branche

Answer 12

phrenic nerve

nerve to geniohyoid and thryohydoid

ansa cervicalis

Question 13

the phrenic nerve arses fromt he anteiror rami of

Answer 13

C3-5- providing motor innervation tot he diphragm

C3,C4, C5 keeps the diaphragm alive

Question 14

journey of the phrenic nerve

Answer 14

After arising from the cervical plexus, the nerve travels down the surface of the anterior scalene muscle and enters the thorax. In the thoracic cavity, the nerve descends anteriorly to the root of the lung to reach the diaphragm.

Question 15

Nerves to Geniohyoid and Thyrohyroid

Answer 15

The C1 spinal nerve gives rise to nerves to the geniohyoid and the thyrohyoid

Question 16

function of geniohyoid

Answer 16

moves the hyoid bone anteriorly and upwards, expanding the airway

Question 17

function of thyrohyoid

Answer 17

which depresses the hyoid bone and elevates the larynx

Question 18

journey of the Nerves to Geniohyoid and Thyrohyroid

Answer 18

These nerves travel with the hypoglossal nerve to reach their respective muscles.

Question 19

Ansa Cervicalis

Answer 19

The ansa cervicalis is a loop of nerves, formed by nerve roots C1-C3. It gives off four muscular branches:

• Superior belly of the omohyoid muscle
• Inferior belly of omohyoid muscle
• Sternohyoid
• Sternothyroid

Question 20

function of the ansa cervicalis

Answer 20

These muscles (the infrahyoids) act to depress the hyoid bone; an important function for swallowing and speech.

Question 21

Other Muscular Branches

Several other minor branches arise from the nerve roots to supply muscles of the neck and back:

C1-C2: Rectus capitis anterior and lateralis

C1-C3: Longus capitis

C2-C3: Prevertebral muscles and sternocleidomastoid

C3-C4: Levator scapulae, trapezius and scalenus medius

The middle and anterior scalenus muscles also receive innervation directly from the cervical plexus.

Question 22

Sensory Branches

Answer 22

The cutaneous branches of the cervical plexus supply the skin of the neck, upper thorax, scalp and ear. These nerves all enter the skin at the middle of the posterior border of the sternocleidomastoid.

Question 23

cutaneous branches of the cervical plexus (sensory) is known as

Answer 23

as the nerve point of the neck (Erb’s point), and is utilised when performing a cervical plexus nerve block.

Question 24

sensory branches

Answer 24

Greater Auricular Nerve

transverse cervical nerve

lesser occipital nerve

supraclavicular nerve

Question 25

Greater Auricular Nerve is formed from by

Answer 25

from C2 and C3 roots.

Question 26

greater auricular nerves provides

Answer 26

It provides sensation to the external ear and the skin over the parotid gland. It is the largest ascending branch of the plexus.

The nerve also communicates with the auricular branch of the vagus nerve and the posterior auricular branch of the facial nerve (which innervates some small muscles around the ear).

Question 27

Transverse Cervical Nerve is formed by

Answer 27

The transverse cervical nerve is also formed by fibres from C2 and C3.

Question 28

route of the transverse cervical nerve

Answer 28

It curves around the posterior aspect of the sternocleidomastoid, and supplies sensation to the anterior neck. The nerve then pierces the deep cervical fascia and then gives branches that pass superiorly and inferiorly to supply the anterolateral skin of the neck and upper sternum.

Question 29

Lesser Occipital Nerve derived from the

Answer 29

the C2 root, with a contribution from C3 in some individuals.

Question 30

lesser occipital nerve supplies

Answer 30

It supplies cutaneous sensation to the posterosuperior scalp, and commonly communicates with the posterior branch of the greater auricular nerve.

Question 31

journey of the lesser occipital enrve

Answer 31

After its formation, the nerve curves around the accessory nerve, and passes superiorly, close to the posterior border of the sternocleidomastoid.

Question 32

The supraclavicular nerves are a group of nerves formed from

Answer 32

the C3 and C4 roots.

Question 33

supraclavicular nerves journey

Answer 33

They arise from the behind the posterior border of sternocleidomastoid, and provide sensation to the skin overlying the supraclavicular fossa and upper thoracic region and sternoclavicular joint.

Question 34

Cervical Plexus Block

Answer 34

A cervical plexus block is used to provide regional anaesthesia, usually for surgery in the neck region – such as carotid endarterectomy, thyroidectomy and cervical lymph node excision.

The anaesthetist inserts the needle containing the local anaesthetic, midway up the posterior border of the sternocleidomastoid (the nerve point of the neck). They then proceed to inject three times in a fan like fashion, with the needle pointing cranially, caudally and then anteriorly.

Note: as this procedure can also affect the phrenic nerve, it is usually not performed on those with co-existing cardiac or respiratory disease.

Question 35

The cervical plexus is made up of the anterior rami of which spinal nerves?

Answer 35

C1-C4

Question 36

Where do the sensory branches of the cervical plexus enter the skin?

Answer 36

middle of the posterior border oft he sternocleidomastoid

This is known as Erb’s area, and is a useful landmark when performing cervical plexus block

Question 37

sign of erbs palsy

Answer 37

The signs of Erb’s palsy include loss of sensation in the arm and paralysis and atrophy of the deltoid, biceps, and brachialis muscles. “The position of the limb, under such conditions, is characteristic: the arm hangs by the side and is rotated medially; the forearm is extended and pronated.

• waitors tip

Question 38

Which is the largest ascending branch of the cervical plexus, which provides sensation to the external ear

Answer 38

greater auricular nerve