The Anterior Triangle and Root of Neck

The Root of the Neck

 

  

Structures at the root of the neck

 

  • Brachio cephalic trunk
  • Subclavian artery and its branches
  • Subclavian vein
  • Termination of internal jugular vein
  • Thoracic duct
  • Apex of lung
  • Phrenic nerve
  • Vagus nerve

Contents:

 

1)The arteries:

 

•  The brachiocephalic trunk.

•  Right common carotid.

•  Right subclavian.

•  May also give thyroidea ima.

Left subclavian artery.  
 


Divided into 3 parts by scalenus anterior muscle.

Part 1:

Medial to the muscle and gives 3 branches:

•  Vertebral artery : Enters foramen transversarium at C6

•  Thyrocervical trunk : Inferior thyroid artery, transverse cervical artery and suprascapular artery.

•  Internal thoracic artery.

Part 2:

Posterior to the muscle and gives 1 branch, the costocervical trunk which gives superior intercostal and deep cervical arteries.

Part 3:

Lateral to the muscle, usually giving one branch (dorsal scapula). It may also occasionally give the suprascapular artery.

 

Fig 2.0: Variant branching of subclavian artery

Task: Identify the arteries labelled 1-6

Relevance of subclavian artery branches to respiration

Branch

Distribution relevant to respiration

Vertebral
  • Respiratory center in the midbrain
  • Cervical cord segments that give phrenic nerve

Internal thoracic
  • Intercostal muscles
  • Ribs and sternum
  • Thoracic diaphragm
  • Phrenic nerve
  • Abdominal wall

Supreme Intercostal
  • 1st two ribs

Inferior thyroid
  • Trachea
  • Larynx
  • Cervical portion of spinal cord

Transverse Cervical
  • Trapezium and Scapula muscles

Suprascapular artery
  • Clavicle and scapula to which accessory muscles are attached

2)The veins:

 

•  External jugular veins.

•  Anterior jugular veins: These either drain into the external jugular or subclavian vein.

The two veins are joined by the jugular venous arch, but could unite to form a single trunk in the midline of the neck. These veins have no valves.

•  The subclavian vein: A continuation of the axillary vein. This vein usually has only one named tributary, the external jugular vein. The veins that correspond to the arterial branches either drain into the external jugular or brachiocephalic vein.

•  The internal jugular vein, in the carotid sheath. The internal jugular vein and subclavian veins unite to from the brachiocephalic vein.

3)Nerves

 

The Vagus Nerve:

This is cranial nerve 10. Located between common carotid and the internal jugular vein. This nerve gives the following branches in the neck:

•  Meningeal nerve: Recurrent to the dura.

•  Auricular nerve: Anastomoses with similar branches from the glossopharyngeal and facial nerves and supplies the pinnae and external auditory meatus.

•  Pharyngeal nerves: Join the pharyngeal plexus.

•  Superior laryngeal nerve: Divides into internal laryngeal and external laryngeal.

•  Recurrent laryngeal nerve:

•  Cardiac branches: Cardiac plexus.

Full details on Vagus nerve

The Phrenic Nerve:(C3, 4, 5 )

Root value :

  • C3, C4, C5

Course

  • Descends obliquely on the anterior surface of scalenus anterior muscle
  • Crosses first part of sub clavian artery on the left
  • Crosses posterior to sub clavian vein on both sides
  • Lies anterior to the internal thoraci artery
  • Goes through thoracic inlet

Distribution

  • Parietal pericardium
  • Parietal pleura
  • Thoracic diaphragm
  • Biliary apparatus

 

4)Sympathetic Trunk:

 

From T1 to T4. There are 3 ganglia, lies on pre-vertebral fascia behind carotid sheath

Inferior cervical ganglion: At the level of the superior border of the neck of the first rib. It is commonly fused with the first thoracic ganglion to form cervicothoracic ganglion (Stellate ganglion).

Middle cervical ganglion: On the anterior aspect of the inferior thyroid artery , at the level of cricoid cartilage pm the posterior aspect of inferior thyroid.

Superior cervical ganglion: Located at the level of the axis and atlas / (C1/ C2) / angle of mandible.

From these ganglia, postganglionic fibres reach their targets in four principal ways:

  • Joining spinal nerves.
  • Joining cranial nerves.
  • Forming plexuses on blood vessels
  • Directly.

Provides secretomotor innervation to blood vessels and glands of the head and neck

Lymphatics

 

•  There are lymph nodes within the carotid sheath, along the internal jugular vein. Another group runs along the transverse cervical artery. These, deep cervical lymph nodes are divided into superior and inferior, relative to the omohyoid muscle.

•  The efferents drain into the jugular lymph trunk, which drains into the right lymphatic duct, or the thoracic duct. Both of these ducts enter the venous system, at the junction of the subclavian and the internal jugular veins.

Brachial Plexus

 

Apex of Lung and Pleura

  
Deep cervical
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