Evaluation and Management of Penetrating Neck Injuries

Extends between the clavicle and sternal notch inferiorly to a horizontal plane passing through the cricoid cartilage superiorly

Structures

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  Proximal common carotid arteries

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  Vertebral and subclavian arteries

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  Subclavian, innominate, and jugular veins

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  Trachea

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  Recurrent laryngeal nerves

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  Vagus nerves

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  Brachial plexus

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  Esophagus

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  Thoracic duct (left-sided injury)

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  Thymus

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  Thyroid gland

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  Parathyroid gland

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  Spinal cord

Extends between a horizontal plane passing through the cricoid cartilage inferiorly to a horizontal plane passing through the angle of the mandible superiorly

Structures

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  Common carotid artery

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  Internal and external carotid arteries

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  Jugular and vertebral veins

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  Pharynx

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  Larynx

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  Recurrent laryngeal nerves

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  Vagus nerve

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  Spinal cord

Extends between the horizontal plane passing through the angle of the mandible inferiorly to the base of the skull superiorly

Structures

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  Extracranial internal carotid arteries

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  Vertebral arteries

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  Jugular veins

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  Cranial nerves IX–XII

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  Sympathetic trunk

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  Spinal cord

The larynx and the trachea are the most anterior structures in the neck.

Larynx

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  Three paired cartilages

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    Arytenoid

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    Corniculate

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    Cuneiform

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  Three unpaired cartilages

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    Thyroid

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    Cricoid

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    Epiglottis

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  Thyrohyoid membrane: fibrous tissue that connects thyroid cartilage to the hyoid bone

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  Cricothyroid membrane: membranous tissue that connects the cricoid cartilage to the thyroid cartilage

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  Trachea begins at the cricoid cartilage.

Trachea

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  Extends from the cricoid cartilage to the carina, which corresponds to C6–T5

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  Approximately10–12 cm long

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  1.5–2.5 cm in transverse diameter

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  Extends into the superior mediastinum and divides into right and left branches at the carina, which corresponds to the fifth thoracic vertebrae level and sternal angle

  

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  Has 16 to 20 C-shaped incomplete cartilaginous rings on the anterolateral surface.

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  Posterior wall composed of muscle and fibrous tissue

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  Relations of the trachea

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    Anterior

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      Platysma

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      Paired strap muscles: sternohyoid, sternothyroid, and thyrohyoid

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      Thyroid isthmus

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  Lateral

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    Sternocleidomastoid muscle

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    Carotid sheath containing common carotid artery, internal jugular vein, and vagus nerve

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    Thyroid lobes

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    Recurrent laryngeal nerves lie in the tracheoesophageal groove.

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  Posterior

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    The esophagus is posterior to the trachea.

Subclavian artery

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  Right subclavian originates from the innominate (brachiocephalic) artery on the left.

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  Left subclavian artery originates from the aortic arch.

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  Courses laterally, passing between the anterior and middle scalene muscles

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  Three parts

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    First part: from the origin to the medial border of the anterior scalene muscle, deep to the sternocleidomastoid and strap muscles

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    Second part: posterior to the anterior scalene muscle and superficial to the upper and middle trunks of the brachial plexus

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    Third part: lateral to the anterior scalene muscle and superficial to the lower trunk of the brachial plexus

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  Continues as axillary artery at the level of the inferior border of the middle third of the clavicle

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  Branches of subclavian artery

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    First part

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      Vertebral artery

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      Internal thoracic artery (internal mammary artery)

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      Thyrocervical trunk and branches

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        Inferior thyroid artery

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        Ascending cervical artery

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        Suprascapular artery

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    Second part

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      Costocervical trunk and branches

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        Deep cervical artery

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        Superior (supreme) intercostal artery

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    Third part

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      Dorsal scapular artery

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        May arise from the first or second part of the cervical artery

Common carotid artery

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  Right common carotid artery is a branch from the innominate (Brachiocephalic) artery. Brachiocephalic artery is also called brachiocephalic trunk.

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  Left common carotid artery originates directly from the aortic arch in the superior mediastinum.

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  Common carotid artery divides into internal and external carotid arteries at the level of the superior border of the thyroid cartilage.

Internal carotid artery

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  Does not have any extracranial branches

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  Enters the carotid canal behind the styloid process

External carotid artery

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  Lies medial to the internal carotid artery

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  Branches

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    Superior thyroid artery: first branch near the carotid bifurcation

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    Lingual artery

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  Ascending pharyngeal artery

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  Facial artery

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  Occipital artery

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  Posterior auricular artery

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  Superficial temporal artery: terminal branch

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  Maxillary artery: terminal branch

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  Terminates in the parotid gland and divides into the superficial temporal and maxillary arteries

Carotid sheath: contents

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  Common and internal carotid arteries medially

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  Internal jugular vein laterally

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  Vagus nerve posteriorly between the arteries and the vein

Vertebral artery

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  First cephalad branch from the first part of the subclavian artery.

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  Enters the foramen transversarium of C6 at the cricoid level and continues in the vertebral canal up to the C1 level

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  Enters the base of the skull through the foramen magnum

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  Joins the opposite vertebral artery to form the basilar artery

Important relations

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  Hypoglossal nerve (cranial nerve XII): crosses superficially to the external carotid arteries at the level of the angle of mandible.

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  Glossopharyngeal nerve (cranial nerve IX): located in front of the internal carotid artery above the hypoglossal nerve

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  Posterior belly of digastric muscle: crosses the external carotid artery at the level of the angle of the mandible

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  Facial vein: crosses the carotid sheath superficially to enter the internal jugular vein at the level of the carotid bifurcation

External jugular veins

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  Formed by retromandibular vein and posterior auricular vein

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  Start at the level of the angle of the mouth in the parotid gland, run along the posterior border of the sternocleidomastoid muscle, and join the subclavian vein

Internal jugular veins

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  Begin at the sigmoid sinus and enter the neck through the jugular foramen at the base of the skull

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  Join the subclavian veins and form brachiocephalic veins

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  Branches

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    Facial veins

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    Lingual veins

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    Pharyngeal veins

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    Superior and middle thyroid veins

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  The left thoracic duct drains at the junction of the left subclavian vein and the internal jugular vein.

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  In the carotid sheath, the internal jugular vein lies lateral and superficial to the common carotid artery and the vagus nerve.

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  The facial veins cross the carotid sheaths superficially to enter the internal jugular veins at the level of the carotid bifurcation.

Subclavian veins

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  Continuation of the axillary vein at the level of the outer border of the first rib

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  Situated anterior to the anterior scalene muscles

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  Connect to the internal jugular veins at the medial border of the anterior scalene muscles

Brachiocephalic veins

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  Formed from the union of the subclavian veins with the internal jugular veins

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  The left and right brachiocephalic veins join to form the superior vena cava.

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  The thoracic duct drains into the left subclavian vein at its junction with the left internal jugular vein.

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  The right lymphatic duct (right thoracic duct) drains into the junction of the right subclavian vein and right internal jugular vein.

Vagus nerves

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  Situated in the carotid sheaths posterior to the common carotids medially and internal jugular veins laterally

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  Right vagus nerve

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    Located on the anterior surface of the first part of the right subclavian artery medial to the internal mammary (internal thoracic) artery

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  Left vagus nerve

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    Located between the left common carotid and the subclavian arteries medial to the internal mammary (internal thoracic) artery

Recurrent laryngeal nerve

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  Right recurrent laryngeal nerve

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    Branches from the right vagus nerve as it crosses the right subclavian artery

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    Loops behind the right subclavian artery and ascends posterior to the carotid artery into the tracheoesophageal groove

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  Left recurrent laryngeal nerve

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    Branches from the left vagus nerve at it crosses the aortic arch

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    Loops around the aortic arch and ascends into the tracheoesophageal groove

Phrenic nerves

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  Located on the anterior surface of the anterior scalene muscles

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  Situated lateral to the internal mammary (internal thoracic) arteries

Brachial plexus

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  Located between the anterior and middle scalene muscles

Begins at the pharyngoesophageal junction, which corresponds to the level of the cricoid cartilage, and the sixth cervical vertebral body

On esophagoscopy, the pharyngoesophageal junction is approximately 15 cm from the incisor teeth.

The esophagus is approximately 25 cm long and terminates in the stomach at the level of T11–12.

Descends through the superior and posterior mediastinum and terminates in the cardia of the stomach

Divided into three main anatomical regions: cervical, thoracic, and intraabdominal esophagus

Layers of the esophagus: mucosa, submucosa, muscularis propria, and adventitia

Muscularis propria is critical to esophageal structure and function. It is composed of two layers: inner circular layer and outer longitudinal layer.

Relations of the cervical esophagus

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  Anterior: Trachea

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  Posterior: Cervical spine

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  Lateral: Carotid sheath containing common carotid artery, internal jugular vein, and vagus nerve bilaterally

Arterial supply: Inferior thyroid artery

Venous drainage: Inferior thyroid vein.