Neck: Blood Vessels and Lymphatics

Introduction

• The head and neck receive major blood supply from

1. Carotid arteries: Common, internal, and external carotid arteries

2. Subclavian arteries

SUBCLAVIAN ARTERY

• The right and left subclavian arteries supply the upper limbs and contribute to the blood supply of the neck and brain.
• They are named subclavian arteries because they pass deep to the clavicles.

Beginning

• Right subclavian artery: It arises from the brachiocephalic trunk behind the right sternoclavicular joint.
• Left subclavian artery: It arises directly from the arch of aorta and ascends through the superior mediastinum towards the root of the neck.

Course

• Each artery follows an arched course with upward convexity, passing laterally towards the first rib.
• The artery passes between scalenus anterior and scalenus medius muscles.

Termination

– Each subclavian artery continues as the axillary artery at the lateral border of the first rib.

Parts of subclavian artery

– The scalenus anterior divides the subclavian artery into three parts:

1. First part: It extends from the origin of the artery to the medial border of scalenus anterior.
2. Second part: It lies posterior to scalenus anterior.
3. Third part: It extends from the lateral border of scalenus anterior to the lateral border of the first rib.

Relations of subclavian artery

Relations of 1st part

Anteriorly

– The following structures lie anterior to the first part, with some variations between the two sides:

1. Skin, superficial fascia, and platysma.
2. Sternocleidomastoid enclosed by investing cervical fascia.
3. Anterior jugular vein.
4. Sternohyoid and sternothyroid muscles.
5. Common carotid artery.
6. Internal jugular vein.
7. Vagus nerve.
8. Vertebral vein.

Posteriorly and inferiorly

• Suprapleural membrane.
• Cervical pleura.
• Apex of lung.

Relations of 2nd part

Anteriorly

1. Skin, superficial fascia, and platysma.
2. Sternocleidomastoid and investing cervical fascia.
3. Subclavian vein.
4. Scalenus anterior.
5. Phrenic nerve, which descends on the anterior surface of scalenus anterior and crosses anterior to the artery.

Posteriorly

1. Scalenus medius.
2. Lower trunk of brachial plexus.

Inferiorly

– Suprapleural membrane, cervical pleura, and apex of lung.

Relations of 3rd part

– The third part lies in the supraclavicular triangle, the lower subdivision of the posterior triangle of the neck.

Anteriorly

1. Middle third of clavicle.
2. Subclavian vein.
3. External jugular vein.
4. Transverse cervical and suprascapular vessels.
5. Anterior jugular venous connections.

Posteriorly

1. Lower trunk of brachial plexus.
2. Scalenus medius.

Superiorly

– Upper and middle trunks of brachial plexus.

Inferiorly

1. First rib.
2. Cervical pleura and apex of lung, protected by the suprapleural membrane.

Branches of Subclavian Artery

Branches of First Part

1. Vertebral artery: It ascends towards the cranial cavity and contributes to the blood supply of the brain.
2. Internal thoracic artery: It descends into the thorax along the inner aspect of the anterior chest wall.
3. Thyrocervical trunk: It usually gives three main branches:
   • Inferior thyroid artery.
   • Transverse cervical artery.
   • Suprascapular artery.
4. Costocervical trunk: It usually arises from the first part on the left side and divides into:
   • Supreme (superior) intercostal artery.
   • Deep cervical artery.

Branches of Second Part

– The costocervical trunk usually arises from the second part of the right subclavian artery.

Branches of Third Part

• The dorsal scapular artery may arise from the third part.
• When present as a direct branch, it commonly replaces the deep branch of the transverse cervical artery.

Note: The branches of the subclavian artery show considerable anatomical variation.

DEVELOPMENT OF SUBCLAVIAN ARTERY

Right Subclavian Artery

– It develops from three embryological components:

1. Right fourth aortic arch.
2. Proximal part of right dorsal aorta.
3. Right seventh intersegmental artery.

Left Subclavian Artery

– It develops mainly from the left seventh intersegmental artery.

VERTEBRAL ARTERY

– The vertebral artery is a major artery supplying the brainstem, cerebellum, posterior part of the brain, and spinal cord.

Beginning

– It usually arises from the superior aspect of the first part of the subclavian artery.

Course

• It ascends through the root of the neck and enters the transverse foramen of the C6 vertebra.
• It passes upwards through the transverse foramina of the cervical vertebrae.
• After emerging from the transverse foramen of the atlas (C1), it curves backwards around the lateral mass and passes over the posterior arch of the atlas.
• It enters the cranial cavity through the foramen magnum and ascends along the medulla oblongata.

Termination

– The right and left vertebral arteries unite near the lower border of the pons to form the basilar artery.

Parts of vertebral artery

The artery is divided into four parts:

1. First part (V1, prevertebral): It extends from the subclavian artery to the transverse foramen of C6.
2. Second part (V2, foraminal): It ascends through the transverse foramina from C6 to C2.
3. Third part (V3, suboccipital): It extends from the transverse foramen of C2, passes through that of C1, and curves over the posterior arch of the atlas before piercing the dura mater.
4. Fourth part (V4, intracranial): It extends from the dural entry near the foramen magnum to the junction with the opposite vertebral artery at the lower border of the pons.

Important Anatomical Features

• The first part lies within the scalenovertebral triangle.
• The second part is accompanied by vertebral veins and a sympathetic plexus.
• The curved course of the third part accommodates movements of the head and neck without excessive stretching of the artery.
• The third part passes through the suboccipital triangle, where it lies in a groove on the superior surface of the posterior arch of the atlas.

Practical Note: Reflection of semispinalis capitis exposes the third part of the vertebral artery in the suboccipital triangle.

Branches of vertebral artery

Branches in the Neck

1. Spinal branches: They enter the vertebral canal through the intervertebral foramina and supply the cervical spinal cord, meninges, and adjoining structures.
2. Muscular branches: They supply deep muscles of the neck, particularly those surrounding the suboccipital triangle.

Intracranial Branches

The fourth part gives rise to the following branches:

1. Meningeal branches.
2. Posterior spinal artery, commonly arising from the vertebral artery or posterior inferior cerebellar artery.
3. Anterior spinal artery, formed by the union of branches from both vertebral arteries.
4. Posterior inferior cerebellar artery (PICA).
5. Medullary branches.

Development of vertebral artery

– The vertebral artery develops from the cervical intersegmental arteries and their longitudinal anastomoses.

1. First part: It develops from the dorsal branch of the seventh cervical intersegmental artery.
2. Second part: It develops from the longitudinal postcostal anastomoses connecting the upper cervical intersegmental arteries.
3. Third part: Its atlantal portion develops mainly from the spinal branch of the first cervical intersegmental artery.
4. Fourth part: It develops from the neural branches of the upper cervical intersegmental arteries and their preneural anastomoses.

INTERNAL THORACIC ARTERY

– The internal thoracic artery, also called the internal mammary artery, is a branch of the subclavian artery.

Beginning

– It arises from the inferior aspect of the first part of the subclavian artery, usually opposite the thyrocervical trunk.

Course

• It descends medially, anterior to the cervical pleura, and enters the thorax behind the sternoclavicular joint.
• It continues downwards approximately 1.25 cm lateral to the sternum, reaching the sixth intercostal space.

Termination

– At the sixth intercostal space, it divides into two terminal branches:

1. Musculophrenic artery.
2. Superior epigastric artery.

Branches

1. Pericardiophrenic artery.
2. Mediastinal branches.
3. Pericardial branches.
4. Sternal branches.
5. Anterior intercostal arteries.
6. Musculophrenic artery.
7. Superior epigastric artery.

THYROCERVICAL TRUNK

– The thyrocervical trunk is a short, wide artery arising from the first part of the subclavian artery.

Beginning

– It arises from the superior surface of the first part of the subclavian artery, near the medial border of scalenus anterior.

Branches

– It usually divides into three main branches:

1. Inferior thyroid artery.
2. Transverse cervical artery.
3. Suprascapular artery.

Inferior Thyroid Artery

• Origin: It arises from the thyrocervical trunk.
• Course: It ascends near the medial border of scalenus anterior and turns medially below the transverse process of C6.
• It passes behind the carotid sheath and anterior to the vertebral artery towards the lower pole of the thyroid gland.
• On the left side, the thoracic duct may cross anterior to the artery.
• Near the thyroid gland, it is closely related to the recurrent laryngeal nerve.

Branches

1. Ascending cervical artery: It ascends along the cervical transverse processes, medial to the phrenic nerve. Its spinal branches enter the vertebral canal and supply the spinal cord, meninges, and vertebrae.
2. Inferior laryngeal artery: It accompanies the recurrent laryngeal nerve in the tracheoesophageal groove and enters the larynx beneath the inferior constrictor.
3. Pharyngeal branches: They supply the lower pharynx.
4. Oesophageal branches: They supply the cervical oesophagus.
5. Tracheal branches: They supply the cervical trachea.
6. Glandular branches: They supply the thyroid and parathyroid glands.

Transverse Cervical Artery

• It arises from the thyrocervical trunk and passes laterally across the root of the neck.
• It usually divides into superficial and deep branches.

Superficial cervical branch

• It passes laterally across scalenus anterior, phrenic nerve, and brachial plexus.
• It enters the posterior triangle behind sternocleidomastoid and runs towards trapezius.
• It supplies trapezius and anastomoses with the descending branch of the occipital artery.

Deep branch (dorsal scapular artery)

• It passes deep to levator scapulae and descends along the medial border of scapula.
• It supplies levator scapulae and rhomboid muscles and participates in the scapular anastomosis.

Note: The dorsal scapular artery may arise independently from the third part of the subclavian artery instead of arising from the transverse cervical artery.

Suprascapular Artery

• It usually arises from the thyrocervical trunk.
• Course: It passes laterally across scalenus anterior and the phrenic nerve, deep to sternocleidomastoid.
• It crosses anterior to the subclavian artery and brachial plexus and passes behind the clavicle.
• It reaches the supraspinous fossa by passing above the superior transverse scapular ligament.
• Distribution: It supplies supraspinatus and infraspinatus and contributes to the scapular arterial anastomosis.

COSTOCERVICAL TRUNK

– The costocervical trunk arises from the posterior aspect of the subclavian artery.

Origin

• Right side: It usually arises from the second part of the subclavian artery.
• Left side: It usually arises from the first part of the subclavian artery.

Course

– It passes backwards above the cervical pleura towards the neck of the first rib.

Termination

– It divides near the neck of the first rib into:

1. Deep cervical artery.
2. Supreme (highest) intercostal artery.

Deep Cervical Artery

• It passes backwards above the C8 spinal nerve, between the neck of the first rib and transverse process of C7.
• It ascends through the deep posterior cervical region towards the C2 level.
• Distribution: It supplies the deep neck muscles, cervical vertebrae, meninges, and spinal cord through its branches.
• Supreme (Highest) Intercostal Artery
• It descends anterior to the necks of the upper ribs.
• It usually gives rise to the first and second posterior intercostal arteries.

DORSAL SCAPULAR ARTERY

Origin

– It commonly arises from the third part of the subclavian artery, although it may arise as the deep branch of the transverse cervical artery.

Course

• It passes laterally, often between the trunks of the brachial plexus.
• It runs deep to levator scapulae and descends along the medial border of scapula, accompanying the dorsal scapular nerve.

Distribution

• It supplies levator scapulae and the rhomboid muscles.
• It participates in the scapular arterial anastomosis.

COMMON CAROTID ARTERY

– The right and left common carotid arteries are the principal arteries supplying the head and neck.

Beginning

• Right common carotid artery: It arises from the brachiocephalic trunk behind the right sternoclavicular joint.
• Left common carotid artery: It arises directly from the arch of aorta and ascends through the superior mediastinum to enter the neck.

Course

• Both arteries follow a similar course in the neck, ascending towards the upper border of the thyroid cartilage.
• Each artery lies within the carotid sheath, medial to the internal jugular vein.

Termination

– Each common carotid artery divides into the external and internal carotid arteries at approximately the C3–C4 level, near the upper border of the thyroid cartilage.

Relations

• Laterally: Internal jugular vein.
• Posteriorly: Vagus nerve, lying between the artery and internal jugular vein.
• Superficially: Sternocleidomastoid muscle overlaps the artery, particularly in the lower neck.

INTERNAL CAROTID ARTERY (ICA)

– The internal carotid artery is a major source of blood supply to the brain and eye.

Beginning

– It arises from the common carotid artery near the upper border of the thyroid cartilage, approximately at the C3–C4 level.

Parts

The internal carotid artery is conventionally divided into four parts:

1. Cervical part: It ascends through the neck.
2. Petrous part: It passes through the carotid canal of the temporal bone.
3. Cavernous part: It courses through the cavernous sinus.
4. Cerebral part: It lies at the base of the brain.

Termination

– The cerebral part terminates by dividing into the anterior and middle cerebral arteries near the anterior perforated substance.

Branches

1. Cervical part

– It gives no branches in the neck.

2. Petrous part

• Caroticotympanic branches.
• Pterygoid (Vidian) branch, when present.

3. Cavernous part

• Cavernous branches, including the meningohypophyseal and inferolateral trunks.
• Inferior hypophyseal artery, usually arising from the meningohypophyseal trunk.

4. Cerebral part

1. Ophthalmic artery.
2. Superior hypophyseal arteries.
3. Posterior communicating artery.
4. Anterior choroidal artery.
5. Anterior cerebral artery.
6. Middle cerebral artery.

Course Of Internal Carotid Artery

Cervical Part

• It ascends within the carotid sheath from the carotid bifurcation to the carotid canal at the skull base.
• Lower part: It lies superficially within the carotid triangle.
• Upper part: It passes deep to the posterior belly of digastric, styloid process, and its attached muscles.
• Branches: It gives no branches in the neck.

Petrous Part

• It runs within the carotid canal of the petrous temporal bone.
• Course: It initially ascends and then curves forwards and medially towards the foramen lacerum.
• It passes over the superior aspect of the foramen lacerum before continuing towards the cavernous sinus.

Branches

• Caroticotympanic arteries: They enter the middle ear through small canaliculi and anastomose with other tympanic arteries.
• Pterygoid branch: When present, it communicates with vessels passing through the pterygoid canal.

Cavernous Part

• It passes through the cavernous sinus along the lateral aspect of the body of sphenoid.
• Course: It ascends, turns forwards alongside the sella turcica, and curves upwards near the anterior clinoid process.
• It subsequently pierces the dural roof of the cavernous sinus to reach the cerebral region.

Branches

• Cavernous branches: They supply the dura mater and adjoining cranial nerves, including structures related to the trigeminal ganglion.
• Inferior hypophyseal artery: It supplies the posterior part of the pituitary gland.

Cerebral Part

• It lies at the base of the brain after emerging from the cavernous sinus.
• Course: It passes near the optic nerve and curves backwards along the lateral side of the optic chiasma.
• It gives rise to the ophthalmic, superior hypophyseal, posterior communicating, and anterior choroidal arteries.
• Termination: It divides into the anterior and middle cerebral arteries near the anterior perforated substance.

Carotid Siphon

• The carotid siphon is an S-shaped curvature formed by the intracranial course of the internal carotid artery, mainly involving its cavernous and adjoining segments.
• Its curved course is an important anatomical feature in cerebral angiography and endovascular procedures.

SUBCLAVIAN VEIN

Beginning

– The subclavian vein begins as a continuation of the axillary vein at the lateral border of the first rib.

Course

• It extends medially from the lateral border of the first rib towards the medial border of scalenus anterior.
• It passes anterior to scalenus anterior and arches over the cervical pleura.

Termination

• – It joins the internal jugular vein behind the sternoclavicular joint to form the brachiocephalic vein.

Relations

• Anteriorly: It is related to the clavicle and subclavius muscle.
• Posteriorly: It is related to scalenus anterior, phrenic nerve, and subclavian artery.
• Inferiorly: It is related to the first rib and cervical pleura.

Tributaries

• The principal tributary is the external jugular vein.
• Other variable tributaries include:
  • Dorsal scapular vein.
  • Anterior jugular vein.
  • Occasionally, the cephalic vein.

Note: The thoracic duct on the left and right lymphatic duct on the right usually open near the junction of the subclavian and internal jugular veins.

INTERNAL JUGULAR VEIN (IJV)

Beginning

– The internal jugular vein begins at the jugular foramen as a continuation of the sigmoid dural venous sinus.

Course

• It descends through the neck within the carotid sheath, lateral to the internal and common carotid arteries.
• The vagus nerve lies posteriorly between the artery and vein.

Termination

– It joins the subclavian vein behind the medial end of the clavicle to form the brachiocephalic vein.

Important Features

• Superior bulb: It is a dilatation at the origin of the vein, situated within the jugular fossa of temporal bone.
• Inferior bulb: It is a dilatation near its termination, behind the medial end of the clavicle.
• Right internal jugular vein: It is commonly larger than the left because the right-sided dural venous sinuses are frequently dominant.
• Carotid sheath: It encloses the internal jugular vein, carotid arteries, and vagus nerve.
• Deep cervical lymph nodes: They lie along the course of the internal jugular vein.
• Jugulosubclavian junction: The thoracic duct usually drains at the left venous angle, while the right lymphatic duct commonly drains at the right venous angle.

Relations of IJV

Superficial Relations

– The following structures are related to the superficial aspect of the vein at different levels:

1. Sternocleidomastoid.
2. Anterior jugular vein and its connections.
3. Superior belly of omohyoid.
4. Ansa cervicalis and its branches.
5. Occipital artery.
6. Posterior belly of digastric.
7. Posterior auricular artery.
8. Styloid process and its attached muscles.
9. Spinal accessory nerve near the upper part of the vein.

Posterior Relations

– The following structures lie posterior to the vein at different levels, from above downwards:

1. Rectus capitis lateralis.
2. Transverse process of atlas.
3. Levator scapulae.
4. Scalenus medius.
5. Scalenus anterior.
6. Phrenic nerve.
7. Thyrocervical trunk and vertebral artery.
8. First part of subclavian artery.
9. Terminal part of thoracic duct on the left side.

Medial Relations

• Internal carotid artery: It lies medial to the upper part of the vein.
• Common carotid artery: It lies medial to the lower part.
• Glossopharyngeal, vagus, and accessory nerves: They are related to the upper part of the vein.
• Vagus nerve: It descends within the carotid sheath, between and posterior to the artery and vein.

Tributaries

– The internal jugular vein receives the following tributaries:

1. Inferior petrosal sinus.
2. Common facial vein.
3. Lingual vein.
4. Pharyngeal veins.
5. Superior thyroid vein.
6. Middle thyroid vein.
7. Occipital vein, occasionally.
8. Communicating veins from the external jugular vein, occasionally.

Note: The thoracic duct and right lymphatic duct are lymphatic channels, not venous tributaries. They usually drain near the corresponding jugulosubclavian junctions.

BRACHIOCEPHALIC VEIN

• The right and left brachiocephalic veins drain venous blood from the head, neck, upper limbs, and parts of the thoracic wall.
• The right brachiocephalic vein is shorter and more vertical than the left.

Formation

– Each brachiocephalic vein is formed by the union of the internal jugular and subclavian veins behind the corresponding sternoclavicular joint.

Length

• Right brachiocephalic vein: Approximately 2.5 cm.
• Left brachiocephalic vein: Approximately 6 cm.

Course

• Right brachiocephalic vein: It descends almost vertically behind the right sternoclavicular joint.
• Left brachiocephalic vein: It passes obliquely downwards and towards the right, behind the manubrium.

Termination

– Both brachiocephalic veins unite behind the lower border of the right first costal cartilage to form the superior vena cava.

Tributaries

Right Brachiocephalic Vein

– It commonly receives:

1. Right vertebral vein.
2. Right internal thoracic vein.
3. Inferior thyroid veins.
4. Right first posterior intercostal vein.
5. Small thymic and mediastinal veins.

Left Brachiocephalic Vein

– It commonly receives:

1. Left vertebral vein.
2. Left internal thoracic vein.
3. Inferior thyroid veins.
4. Left first posterior intercostal vein.
5. Left superior intercostal vein.
6. Thymic and pericardial veins.

LYMPHATIC DRAINAGE OF HEAD AND NECK

• The head and neck contain approximately 300 lymph nodes, representing a substantial proportion of the body’s lymph nodes.
• These nodes receive lymph from the head and neck and eventually drain into the deep cervical lymph nodes.

Classification

The lymph nodes of the head and neck are divided into two major groups:

A. Peripheral lymph nodes

1. Outer group (pericervical collar):

• Submental nodes.
• Submandibular nodes.
• Superficial parotid (preauricular) nodes.
• Mastoid (posterior auricular) nodes.
• Occipital nodes.

2. Inner group (deep visceral nodes):

• Infrahyoid nodes.
• Prelaryngeal nodes.
• Pretracheal nodes.
• Paratracheal nodes.
• Retropharyngeal nodes.

B. Terminal (deep cervical) lymph nodes

1. Superior deep cervical nodes, including jugulodigastric nodes.
2. Inferior deep cervical nodes, including jugulo-omohyoid nodes.

PERIPHERAL LYMPH NODES

Outer Group (Cervical Collar)

• These nodes form a ring around the junction of the head and neck.
• They receive lymph from superficial structures of the scalp, face, and adjoining regions.

Inner Group

– These nodes lie deep to the investing layer of deep cervical fascia.

1. Infrahyoid Nodes

– They lie anterior to the thyrohyoid membrane.

2. Prelaryngeal Nodes

• They lie anterior to the cricothyroid membrane.
• They receive lymph from the larynx and adjoining thyroid region.

3. Pretracheal Nodes

• They lie anterior to the trachea, below the thyroid gland.
• They drain the thyroid isthmus, trachea, and adjoining parts of the larynx.

4. Paratracheal Nodes

• They lie along the lateral aspects of the trachea and oesophagus.
• They receive lymph from the trachea, cervical oesophagus, thyroid gland, and larynx.

5. Retropharyngeal Nodes

• They lie between the buccopharyngeal and prevertebral fasciae, posterior to the pharynx.
• They receive lymph from the pharynx, auditory tube, nasal cavity, and soft palate.

– The inner group ultimately drains into the deep cervical lymph nodes.

TERMINAL (DEEP CERVICAL) LYMPH NODES

• The deep cervical lymph nodes lie along the internal jugular vein.
• They receive lymph directly or indirectly from the peripheral lymph nodes.
• They are divided into superior and inferior groups.

Superior Deep Cervical Nodes

• They lie mainly above the level where omohyoid crosses the internal jugular vein.
• Jugulodigastric nodes are prominent members situated beneath the posterior belly of digastric, near the angle of mandible.
• They receive lymph particularly from the palatine tonsils and oropharynx.
• They are commonly called the tonsillar lymph nodes.

Inferior Deep Cervical Nodes

• They lie mainly below the omohyoid.
• Jugulo-omohyoid nodes are situated near the crossing of omohyoid and internal jugular vein.
• They receive lymph particularly from the tongue and are commonly called the principal lymph nodes of the tongue.

TERMINATION OF LYMPHATIC DRAINAGE

• Lymph from the deep cervical nodes enters the right and left jugular lymphatic trunks.
• Left jugular trunk: It usually drains into the thoracic duct or directly into the left venous angle.
• Right jugular trunk: It may join the right lymphatic duct or drain directly into the right venous angle.
• Thoracic duct: It is the largest lymphatic channel in the body and usually terminates near the junction of the left internal jugular and subclavian veins.
• Right lymphatic duct: When present, it receives the right jugular, subclavian, and bronchomediastinal lymphatic trunks and drains near the right venous angle.

SURGICAL CLASSIFICATION OF CERVICAL LYMPH NODES

– For surgical purposes, cervical lymph nodes are classified into seven levels.

Level Group and location I Submental (IA) and submandibular (IB) lymph nodes. II Upper jugular nodes, including jugulodigastric nodes, extending from the skull base to the hyoid bone. III Middle jugular nodes, extending from the hyoid bone to the lower border of cricoid cartilage. IV Lower jugular nodes, extending from the lower border of cricoid cartilage to the clavicle. V Posterior triangle nodes, mainly along the spinal accessory nerve and transverse cervical vessels. VI Anterior central compartment nodes, including prelaryngeal, pretracheal, and paratracheal nodes. VII Superior mediastinal lymph nodes below the suprasternal notch.