Anatomy of the Carotid ArteriesThe carotid arteries lie in the anterior region of the neck and consist of the

common carotid artery and its braches, as well as the internal and external carotid arteries. On either side of the neck, the common carotid artery travels with the internal jugular vein and vagus nerve within the carotid sheath to the superior border of the thyroid cartilage. The common carotid ends where it divides into the internal and external carotid arteries – the external carotid artery continues to branch in the neck region; however, the internal carotid artery does not branch in the neck region and instead moves up into the head.

The external carotid arteries supply blood to most of the structures that are external to the cranium, with few exceptions. The artery runs posterosuperiorly to the region between the neck of the mandible and the lobe of the ear, where it terminates as the maxillary artery and superficial temporal artery. Other important branches of the external carotid artery include

(1) ascending pharyngeal artery (supplies blood to the pharynx, prevertebral muscles, middle ear, and cranial meninges);(2) occipital artery (supplies blood to the muscles in the suboccipital region of the posterior portion of the neck);(3) posterior auricular artery (supplies blood to the parotid gland, structures in the temporal bone, auricle, and scalp);(4) superior thyroid artery (supplies blood to the thyroid gland and gives off branches that supply the infrahyoid and sternocleidomastoid muscles);(5) lingual artery (supplies blood to the tongue); and(6) facial artery (supplies blood to most of the muscles of facial expression).

Looking at the vast number of structures that are supplied by the external carotid arteries and its branches, it is clear that it is an essential structure within the human body. A diagram of some of the branches of the external carotid is shown below.

Carotid StenosisCarotid stenosis is the narrowing of the carotid arteries, causing a decrease in

the blood flow to the structures mentioned previously as being supplied by the carotid arteries and their subsequent branches. Carotid stenosis is also referred to as carotid artery disease, and is caused by a buildup of plaque inside the walls of the walls (atherosclerosis). The presence of this plaque buildup in the carotid arteries can increase an individual’s chances of having a stroke, as the carotid arteries are also a major supplier of blood to the brain. Plaque often builds up in the carotid bifurcation – the point at which the common carotid splits into the internal and external carotid arteries, as seen in the diagram below.

Carotid stenosis actually increases the risk of stroke in three different ways:- plaque deposits can grow and eventually occlude the artery,- plaque deposits can roughen and deform the walls of the artery causing the formation of blood clots, and- plaque deposits can break away and travel to a smaller artery, where they lodge and block blood to the brain.

In general, there are no symptoms of carotid stenosis until the condition becomes severe, at which time individuals often suffer a transient ischemic attack, or “mini-stroke”.

For individuals with carotid stenosis, treatment is often aimed at reducing the risk of stroke, often through medication. These medications include antiplatelet drugs to

thin the blood and reduce the occurrace of clot formation, cholesterol-lowering drugs to reduce plaque formation, and antihypertensive drugs to lower and regulate blood pressure. In extreme cases, or in individuals that have experienced a stroke, surgery may be considered to clear the plaque and enlarge the inner lumen of the artery.

Anatomy of the EsophagusThe esophagus is the muscular tube that connects the pharynx to the stomach.

The upper third of the esophagus contains voluntary striated muscle, whereas the lower third contains involuntary smooth muscle. The middle third of the esophagus contains a mixture of the two muscle types. When the esophagus is empty, it appears as a slit-like lumen; however, when a bolus of food passes through it, it expands, which causes peristalsis to occur in the lower portions of the esophagus. Within the region of the neck, the cervical esophagus lies between the larynx anteriorly and the cervical spine posteriorly. In this region, it is innervated by the recurrent laryngeal nerves, and branches of the inferior thyroid arteries supply blood.

Esophageal StrictureEsophageal stricture is the narrowing of the esophagus, which can occur in three

general ways:(1) intrinsic diseases that narrow the esophagus itself by inflammation, fibrosis, or neoplasia;(2) extrinsic diseases that compromise the esophagus by invasion or lymph node enlargement; or(3) diseases that disrupt peristalsis and/or the lower esophageal sphincter.

Symptoms of esophageal stricture include heartburn, dysphagia, odynophagia, food impaction, weight loss, and chest pain. Treatment often includes mechanical dilation of the esophagus, and surgical options can be considered if necessary. An example of a normally dilated esophagus is shown below on the left, with an example of esophageal stricture shown on the right.

Anatomy of the LarynxThe larynx is composed of nine cartilages – paired cuniform, corniculate, and

arytenoid cartilages, and single thyroid, cricoid, and epiglottic cartilages. The larynx contains the vocal cords, which are responsible for the production of sound by utilizing several laryngeal muscles. Of particular importance to the production of sound is the vocal ligament and the vocalis muscle. The larynx is closely associated with the hyoid bone, though it does not actually articulate with it. The larynx is supplied with blood by the superior laryngeal artery, as well as the inferior laryngeal artery and the cricothyroid artery. It is innervated by the superior laryngeal nerve, a branch of the vagus nerve (cranial nerve ten, CNX). The general structure of the larynx is shown below.

Posterior View of the Larynx and its Structures

Sagittal View of the Larynx and its Structures

In general, the larynx functions in breathing, swallowing, and of course, the production of sound, or phonation.

Fractures of the LarnyxA laryngeal fracture can occur as a result of trauma, either from a blow received

from a sport, such as kick boxing or hockey, or as the result of compression, such as during a car accident. This injury can be particularly dangerous, as airway obstruction could occur in more serious cases. The exact type of injury is dependent upon the cause of the injury, but there is always the possibility of skeletal injury as well, with cricothyroid and cricoarytenoid dislocations being the most likely. Furthermore, laryngeal fractures can vary by anatomical location, each of which has its own possible complications. These locations include

(1) supraglottis – traumatic forces cause horizontal fractures and subsequent superior posterior displacement of the epiglottis;(2) glottis – traumatic forces cause fractures of the thyroid cartilage;(3) subglottis – crushing forces to the cricoid cartilage may cause vocal cord paralysis due to recurrent laryngeal nerve damage;(4) hyoid bone – more common in women and tends to occur in the center of

the bone;(5) cricoarytenoid joint – traumatic forces that often result in cricoarytenoid dislocation, usually unilaterally;(6) cricotyroid joint – traumatic force causes the thyroid cartilage to be displaced posteriorly to the cricoid cartilage, limiting muscle function and pitch control.

Regardless of the cause or location of the injury, laryngeal fracture often presents with symptoms including subcutaneous emphysema, hemoptysis, hematoma, laryngeal tenderness, vocal cord immobility, and loss of anatomical landmarks, among others.

Treatment methods for individuals with laryngeal fractures are dependent upon the severity of the injury. In minor cases, individuals are often treated without surgery, and invasive methods to protect the airway, such as a tracheotomy, are often not needed. In more severe cases, surgical repair is sometimes needed, in which the fracture is reduced and repaired, often with the use of wires (shown on the left) or metal plates (shown on the right).

The overall goal of any treatment option is to restore the three functions of the larynx, which include breathing, speaking, and swallowing.

References

1.) Moore text2.) http://medmnemonics.files.wordpress.com/2012/02/external_carotid_artery.png? w=150&h=1383.) http://www.mayfieldclinic.com/PE-CarotidStenosis.htm4.) http://emedicine.medscape.com/article/175098-overview5.) http://emedicine.medscape.com/article/175098-clinical6.) http://emedicine.medscape.com/article/175098-treatment7.) http://duckskull.org/DMI%2063/1%20Digestive%20system%20biliary/Pics%20for%20 gi/AP%20esophagus%20single%20cont.%20x-ray.jpg8.) http://radiographics.rsna.org/content/23/4/897/F19.large.jpg9.) http://emedicine.medscape.com/article/865277-overview#a0410.) http://emedicine.medscape.com/article/865277-overview11.) http://emedicine.medscape.com/article/865277-treatment 12.) http://emedicine.medscape.com/article/865277-treatment#a1128