Cervical spinal nerves and sympathetic trunk

Question 1

Cervical spinal nerves

Answer 1

• There are 8 pairs of cervical spinal nerves.
• Spinal nerves C1 – C7 emerge superior to the correspondingly numbered vertebrae
• Nerve C8 emerges inferiorly to vertebra C7 (below this area, all remaining nerves emerge inferior to the correspondingly numbered vertebrae)
• Spinal nerves divide into posterior and anterior primary ramus

Question 2

posterior rami of cervial spinal nerves

supply?

include?

Answer 2

• supply muscles, skin, and scalp on back of head and neck.
• Include:
  
  • Suboccipital n. (C1)
  • Greater occipital n. (C2)
  • Third (least) occipital nerve (C3)
  • Posterior rami n. (C3-C7)

Question 3

Suboccipital nerve (C1)

Answer 3

• Origin: posterior ramus of spinal nerve C1
• Course: exits spinal cord between cranium and C1 and lies within the suboccipital triangle
• Supply : muscles of the suboccipital triangle

Question 4

Greater occipital nerve (C2)

Answer 4

• Origin: posterior ramus of spinal nerve C2
• Course: emerges inferior to obliquus capitis inferior -> pierces semispinalis capitis during its ascend to posterior scalp
• Supply: scalp of greater occipital region, and semispinalis capitis m.

Question 5

Third (Least) occipital nerve (C3)

Answer 5

• Origin: posterior ramus of spinal nerve C3
• Course: pierces trapezius m. and ascends along posterior midline of neck
• Supply: scalp of lower occipital and suboccipital region

Question 6

Posterior rami, nerves C3 – C7

Answer 6

• Origin: posterior rami of spinal nerves C3 – C7
• Course: pass segmentally to muscles and skin of posterior neck region
• Supply: intrinsic mm. of back and overlying skin

Question 7

*Posterior rami of cervical spinal nerves

Question 8

Anterior rami of cervial spinal nerves (CERVICAL PLEXUS)

supply:

origin:

sensory & motor branches:

components:

Answer 8

• Supply skin and muscle on anterolateral region of neck, extending into head, shoulder girdle, and upper limb
• Origin: deep to SCM, comprised by the anterior rami of spinal nerves C1 – C4, which form the roots of the cervical plexus
• Ascending and descending branches of adjacent anterior rami unite to form loops from where the branches emerge
• Cutaneous (sensory) branches: originate from the posterior border of the SCM
• Motor branches: arise from the anterior border of the SCM
• Components
  
  • Ansa cervicalis
  • Phrenic nerve
  • Cutaneous branches
  • Deep motor branches
  • Contributions to accessory nerve (CN XI)

Question 9

*Anterior rami of cervical spinal nerves (cervical plexus)

Answer 9

Question 10

ansa cervicalis

Answer 10

• part of the cervical plexus
• Superior root
  
  • Origen: between loop of C1 – C2
  • Course: initially runs anteriorly with the hypoglossal nerve -> then turns inferiorly to join the inferior root
• Inferior root
  
  • Origen: between loop of C2 – C3
  • Course: runs inferiorly to join the superior root
• Branches of ansa cervicalis
  
  • Omohyoid m.
  • Sternothyroid m.
  • Sternohyoid m.
  • Geniohyoid and Thyrohyoid mm. (just before the superior root turns inferiorly there are 2 branches running anteriorly)

{Infrahyoid mm inn by ansa cervicalis except: Geniohyoid & thryohyoid mm inn by root of C1 and travels momentarily with the hypoglossal nerve}

Question 11

phrenic nerve

Answer 11

• part of the cervical plexus
• Origin: mostly C4, but also C3 & C5
• Course: descends with the IJV across the anterior scalene m. in the neck, superficially to anterior scalene -> through the thorax -> to diaphragm
• Supply: motor and sensation (medial part only) to diaphragm

Question 12

*phrenic nerve

Question 13

cutaneous branches of the cervical plexus include:

Answer 13

• lesser occipital n (C2)
• great auricular n (C2-C3)
• transverse cervical or anterior cutaneous (C2-C3)
• Supraclavicular (C3-C4)

Question 14

lesser occipital nerve (C2)

Answer 14

• cutaneous branch of the cervical plexus
• Course: runs superiorly and posteriorly (parallel to posterior border of SCM)
• Supply: skin of neck and scalp posterosuperior to auricle

Question 15

Great auricular nerve (C2 – C3)

Answer 15

• cutaneous branch of the cervical plexus
• Course: ascends across the SCM to inferior pole of parotid gland where it divides
• Supply
• Parotid gland
• Auricle
• Area over mastoid process

Question 16

Transverse cervical or anterior cutaneous (C2 – C3)

Answer 16

• cutaneous branch of the cervical plexus
• Course: curves around the posterior border of SCM and passes anteriorly superficial to the SCM and deep to the EJV
• Supply: skin of anterior cervical region (on top of the infrahyoid mm)

Question 17

Supraclavicular (C3 – C4)

Answer 17

• cutaneous branch of the cervical plexus
• Course: descend deep to SCM towards the shoulder region
• Supply:
• Medial: skin over base of neck and upper sternum
• Intermediate: skin over superior portion of pectoralis major m.
• Lateral: skin over superior 1/3rd of deltoid muscle

Question 18

*cutaneous branches of cervical plexus

Question 19

deep motor branches

Answer 19

• part of the cervical plexus
• Branches supply prevertebral muscles (e.g. middle scalene, longus colli and capitis m.)
• Contributions to accessory nerve (C2 – C4): C2 – C3 & C3 – C4

Question 20

anterior rami of cervical spinal nerves (roots of BRACHIAL PLEXUS)

Answer 20

• Anterior rami of C5 – C8 and T1
• Appear between anterior and middle scalene mm.
• Course: descends inferolaterally through lateral cervical region -> passes between 1st rib, clavicle, and superior border of scapula to enter axilla
• Supply: most of upper limb

Question 21

cervical sympathetic trunk

Answer 21

• Superior continuation of thoracic sympathetic trunk that extends superiorly into the neck
• Presynaptic sympathetic fibers emerging from C8 – T2
• Location: anterolateral to transverse processes of cervical vertebrae
• Ganglia
  
  • Superior cervical ganglion
  • Middle cervical ganglion
  • Inferior cervical ganglion: in about 80% of humans it fuses with 1st thoracic ganglion to form the cervicothoracic ganglion (stellate ganglion)

Question 22

*cervical sympathetic trunk

Question 23

Superior cervical ganglion

Answer 23

• Location: at the level of C1 and C2 vertebrae
• Branches
  
  • Internal carotid artery branch: branches following the internal carotid artery. Innervates structures supplied by branches of the internal carotid artery
  • External carotid artery branch: branches that ride on the external carotid artery following it, and innervating the structures supplied by it
  • Superior cervical cardiac nerve: runs inferiorly towards the cardiac plexus
  • Visceral branches: pharynx, larynx, thyroid

Question 24

Middle cervical ganglion

Answer 24

• Location: smallest of the 3 ganglia, lies anterior to the cricoid cartilage, at the level of C6 vertebra
• Branches
  
  • Middle cervical cardiac nerve: runs inferiorly towards cardiac plexus
  • Arterial branches: runs anteriorly towards the thyroid gland

Question 25

Inferior cervical ganglion

Answer 25

• Location: lies at the level of C7 vertebra
• Branches
  
  • Inferior cervical cardiac nerve: runs inferiorly along the trachea to the deep cardiac plexus
  • Arterial branches: run along the vertebral artery into the cranial cavity