NERVES OF THE NECK

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NERVESOFTHE NECK
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Main Nerves of the neck

1. Vagus nerve.
2. Accessory nerve.
3. Hypoglossal nerve.
4. Cervical part of sympathetic trunk.
5. Cervical plexus.
6. Phrenic nerve.

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Vagus Nerve

• It is a mixed nerve, it leaves the skull through
  the jugular foramen.
• It has two sensory ganglia (superior and inferior
  ganglia).
• At its beginning, it is joined by the cranial
  part of accessory nerve (having motor fibers to
  pharynx and palate).
• It descends in the neck within the carotid sheath
  in between carotid artery and internal jugular
  vein.
• It descends in front of the 1st part of
  subclavian artery, then enters the thorax.

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Branches of Vagus Nerve

1. Meningeal branch for posterior cranial fossa.
2. Auricular branch sensory for the medial surface
   of auricle, floor of external auditory meatus and
   adjacent parts of outer surface of tympanic
   membrane.
3. Pharyngeal branch (its fibers come from cranial
   part of accessory nerve). It passes between ext.
   and int. carotid arteries, and shares in
   pharyngeal plexus around the wall of pharynx. It
   supplies all muscles of palate (except tensor
   palati) and all muscles of pharynx (except
   stylopharyngeus).

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Branches of Vagus Nerve

• Superior laryngeal nerve Descends toward the
  larynx and divides into
• External laryngeal nerve that accompanies the
  superior thyroid artery then deep to the thyroid
  gland to supplies the cricothyroid muscle.
• Internal laryngeal nerve that pierces the
  thyrohyoid membrane and supplies the mucosa of
  the piriform fossa of pharynx and mucosa of
  larynx above the level of vocal fold.
• Cardiac branches 2-3 nerves that share in
  formation of cardiac plexus.

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Branches of Vagus Nerve

1. Right recurrent laryngeal nerve arises from the
   right vagus as it crosses the first part of the
   subclavian artery. It hooks backward and upward
   behind the artery, then ascends in the groove
   between the trachea and esophagus. It passes deep
   the thyroid gland with accompany of inferior
   thyroid artery. It enters the larynx and supplies
   all its intrinsic muscles (except cricothyroid)
   and mucosa of the larynx below the level of the
   vocal folds and upper part of trachea. (left
   recurrent laryngeal nerve begins in the thorax).

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Accessory Nerve

• It is a motor nerve and consists of cranial and
  spinal (upper 5 cervical segments) parts.
• It leaves the skull through the jugular foramen,
  then the two parts separate again, the cranial
  part joins the vagus nerve at its inferior
  ganglion and it is distributed through it (mainly
  in the pharyngeal plexus and recurrent laryngeal
  nerve).
• The spinal part runs downward and laterally,
  crosses the internal jugular vein, enters deep to
  sternocleidomastoid, then crosses the posterior
  triangle (on the levator scapulae muscle) and
  enters deep to the trapezius muscle. It supplies
  sternocleidomastoid and trapezius muscles.

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Hypoglossal Nerve

• It is a motor nerve that supplies all muscles of
  the tongue (except palatoglossus).
• It leaves the skull through the hypoglossal
  canal, then it has a short course in the carotid
  sheath (with internal carotid artery, internal
  jugular vein, glossopharyngeal, vagus and
  accessory nerves).
• It passes between the internal carotid artery and
  internal jugular vein (covered by the posterior
  belly of digastric). It then curves up and
  anteriorly crossing the first part of lingual
  artery and is distributed to the lingual muscles.
• At its beginning, it is joined by branch from the
  cervical plexus (containing fibers from C1) which
  supplies some muscles.

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Branches of Hypoglossal Nerve

1. Meningeal branch for posterior cranial fossa.
2. Descending branch Containing C1 fibers. It is
   also called (descendens hypoglossi) and form the
   superior root of ansa cervicalis.
3. Nerve to thyrohyoid also contains C1 fibers and
   supplies the thyrohyoid muscle.
4. Nerve to geniohyoid also contains C1 fibers and
   supplies the geniohyoid muscle.
5. Muscular branches of the tongue supplies all
   intrinsic and extrinsic muscles of the tongue
   except palatoglossus (from pharyngeal plexus).

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Cervical sympathetic trunk

• It extends upward till the base of the skull and
  below to the neck of the first rib where it
  continues in the thorax.
• It lies behind the common and internal carotid
  arteries (posterior to the carotid sheath).
• It possesses three ganglia superior, middle and
  inferior.
• Superior ganglion is the larger and longer and
  lies just below the skull.
• Middle ganglion lies at the level of the cricoid
  cartilage (6th cervical vertebra).
• Inferior ganglion may fuse with 1st thoracic to
  form stellate ganglion and it lies in front of
  the neck of the 1st rib.

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Branches of superior ganglion

1. Internal carotid nerve accompanies the internal
   carotid artery and enters the carotid canal and
   form the plexus around the artery.
2. Gray rami communicantes to upper four anterior
   rami of the cervical nerves.
3. Arterial branches with form plexus around the
   common and external carotid arteries and are
   distributed with them.
4. Branches to the cranial nerves join the
   glossopharyngeal, vagus and hypoglossal nerves.
5. Pharyngeal branches to the pharyngeal plexus.
6. Superior cardiac branch to the cardiac plexus in
   thorax.

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Branches of middle ganglion

1. Gray rami communicantes to the anterior rami of
   the 5th and 6th cervical nerves.
2. Arterial branches with form plexus around the
   inferior thyroid artery to be distributed to the
   thyroid gland.
3. Middle cardiac branch to the cardiac plexus in
   thorax.
4. Ansa subclavia descends in front of the first
   part of subclavian artery then rotates around it
   and ascends again to join the inferior cervical
   (or stellate) ganglion.

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Branches of inferior ganglion

1. Gray rami communicantes to the anterior rami of
   the 7th and 8th cervical nerves.
2. Arterial branches with form plexus around the
   subclavian and vertebral arteries to be
   distributed along them.
3. Inferior cardiac branch to the cardiac plexus in
   thorax.
4. Ansa subclavia mentioned before.

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Cervical plexus

• Formed by the anterior rami of the upper cervical
  nerves.
• Lies in front of the origin of levator scapulae
  and scalenus medius muscles.
• It is covered by the prevertebral fascia.
• Branches
• Cutaneous branches lesser occipital, great
  auricular, transverse cervical and
  supraclavicular nerves.
• Muscular branches to prevertebral muscles,
  sternocleidomastoid trapezius (proprioceptive),
  levator scapulae, geniohyoid thyrohyoid
  (through C1 fibers that join hypoglossal nerve
  and infrahyoid muscle (through ansa cervicalis).
• Phrenic nerve to the diaphragm.

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Phrenic nerve

• It is the only motor nerve supply to the
  diaphragm.
• It also contains sensory and sympathetic nerves.
• It supplies the pleura and peritoneum on both
  surfaces of diaphragm, mediastinal pleura,
  pericardium and proprioceptive sensation of the
  diaphragm.
• It arises from C3,4,5 and runs over the scalenus
  anterior muscle (from its lateral to medial
  borders) and covered by prevertebral fascia and
  enters the thorax by passing in front of the
  subclavian artery.

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