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Transcript
For educational and institutional use. This test bank is licensed for noncommercial, educational in-
house or online educational course use only in educational and corporate institutions. Any broadcast,
duplication, circulation, public viewing, conference viewing or Internet posting of this product is
strictly prohibited. Purchase of the product constitutes an agreement to these terms. In return for the
licensed use, the Licensee hereby releases, and waives any and all claims and/or liabilities that may
arise against ASRT as a result of the product and its licensing.
1. The Spine Welcome to Module 5 of Sectional Anatomy Essentials – The Neck. This module was written by Michael A. Manders, B.S., R.R.A., R.T.(R), and Jeffrey D. Houston, MD.
2. License Agreement and Disclaimer
3. Objectives After completing this module, you will be able to:
Describe the features of the larynx.
Locate and describe the features of the pharynx.
Discuss the relationship of the esophagus and trachea as they descend through the neck.
Locate and compare the relationships of the 3 sets of major salivary glands.
Discuss the major muscles of the neck and their functions.
Identify and locate the lymph nodes in the neck.
Describe the major arteries and veins of the neck.
4. Introduction Throughout the Sectional Anatomy Essentials series, we display most of the cross-sectional anatomy using multidetector computed tomography (CT) and magnetic resonance (MR) images to illustrate the three-dimensional relationship of the structures. Use the slider bar in this animation to scroll through the images. Because you can easily lose your frame of reference when viewing cross-sectional images, the location of the featured slice on many slides will be displayed on adjacent localizer images of the other 2 planes, like the image shown here. Click on the next button when you are ready to proceed.
5. Skeletal Anatomy The skeletal portion of the neck is made up of multiple vertebrae called the cervical spine. The cervical spine usually consists of 7 vertebrae and extends from the base of the skull to about the level of the top of the lungs. Cervical vertebrae 3 through 6, or C3 through C6, have a typical appearance, with each vertebra having a body, pedicles, laminae, transverse processes, articular processes and a vertebral foramen; however, C1, C2 and C7 are unique.
6. Skeletal Anatomy There are a few differences between the C1, C2, and C7 vertebrae and the regular C3 through C6 vertebrae. The first difference is that the C3 through C6 spinous processes are typically bifid, meaning that they split into two at the tip, like a snake’s tongue. The C1 through C6 vertebrae also have paired transverse foramina, one located within each transverse process. Each transverse foramen allows for the passage of the vertebral artery from its origin in the upper thorax into the head.
7. Skeletal Anatomy – C1 In contrast, C1, C2 and C7 are different from the regular cervical vertebrae. C1, also known as the atlas, is an osseous ring that supports the head. It has no body and no spinous process, but instead has large superior articular processes that articulate with the occipital condyles of the skull.
The front portion of the ring is called the anterior arch, and the rear portion is called the posterior arch. The paired lateral masses, the most bulky parts of the atlas, are located on the sides of the vertebra between the superior and inferior articular processes.
8. Skeletal Anatomy – C2 C2, called the axis, also has a peculiar appearance. The odontoid process, also known as the dens, arises from the superior border of the body. The odontoid process is a dense bony projection that extends superiorly and articulates with the posterior border of the anterior arch of the atlas. The superior articular facets, which articulate with the inferior articular facets of the atlas, are located on each side of the odontoid process. These 3 articulations allow the skull to rotate. Another notable detail of C2 is its diminutive spinous process. An easy way to remember the arrangement of the atlas and axis is that they are in alphabetical order from superior to inferior.
9. Skeletal Anatomy – C7 The third unique cervical vertebra is C7, also called the vertebral prominens because of its prominent spinous process. Typically, this spinous process is not bifid like the other cervical vertebrae. Although rare, C7 may articulate with a pair of abnormal small, or hypoplastic, ribs called cervical ribs.
10. Skeletal Anatomy – Hyoid Bone The last bone of the neck we’ll mention is the hyoid bone. The hyoid is an arch-shaped bone that is located inferior to the posterior mandibular body and anterior to approximately the C3 or C4 vertebrae. The hyoid bone is made up of 3 parts: the body and the paired lesser and greater cornu. The hyoid bone functions as an attachment point for multiple muscles of the anterior triangle of the neck, which we’ll discuss later in this module.
11. Knowledge Check Answer the following question.
12. Knowledge Check Answer the following question.
13. Organs of the Neck
Multiple organs exist in the neck, primarily in the anterior to middle portion. These structures include the pharynx, larynx, esophagus, trachea, thyroid gland and salivary glands. Let’s discuss the specific location and function of each of these organs.
14. The Pharynx The pharynx is a hollow organ that extends from the nasal cavity to the base of the tongue. It typically is divided into 3 sections: the nasopharynx, the oropharynx and the laryngopharynx. The pharynx is a primary tool of both the digestive and respiratory systems.
15. The Nasopharynx The most cephalic portion of the pharynx is called the nasopharynx. The nasopharynx allows air to travel from the nose to the trachea. An extension of the internal nares, the nasopharynx stretches posteriorly, bordered by the soft palate inferiorly and the base of the skull superiorly. It follows the posteroinferior curve of the soft palate and ends at the uvula, a conical process that extends posteroinferiorly in the midline from the back of the soft palate.
16. The Palate The palate divides the nasal cavity from the oral cavity. As you may recall, the hard palate is a plate of bone formed by the palatine process of the maxilla and the horizontal plate of the palatine bone. The soft palate is primarily composed of muscle and extends inferiorly and posteriorly from the hard palate. It makes up the posterior portion of the roof of the mouth.
17. The Uvula As we mentioned previously, the uvula is a soft tissue process extending posteroinferiorly from the back of the soft palate. It takes its name from Latin for “little grape,” and you can easily see the grape-like appearance of the structure by looking directly through an open mouth. The uvula has 2 primary roles: the articulation of human speech and sealing off the nasopharynx during swallowing.
18. The Uvula The uvula works with the palate and the back of the throat, in conjunction with air from the lungs, to assist in the production of speech by altering air flow. During a swallow maneuver, it works with the soft palate to close off the nasopharynx from the oropharynx. This action prevents nasopharyngeal reflux, that is, the regurgitation of oral contents into the nasal cavity.
19. The Pharyngeal Tonsils The pharyngeal tonsils are located along the posterior wall of the nasopharynx. These small mounds of lymphatic tissue help the immune system by filtering bacteria and viruses. They often are referred to as the adenoids and are sometimes removed, a procedure known as an adenoidectomy.
20. Pharyngeal Ostia The pharyngeal ostia are situated bilaterally along the posterolateral walls of the nasopharynx. These triangular holes indicate the exit of the Eustachian, or auditory, tube into the nasopharynx. The Eustachian tubes equalize middle ear pressure with the atmosphere and drain mucus from the middle ear. The tube can become inflamed and obstructed when trapped fluid creates an environment that promotes bacterial growth that can cause an ear infection.
21. Torus Tubarius Creating an upside down “U” around each pharyngeal ostium is a raised mound of mucosa called the torus tubarius, or Eustachian cushion. The cushion is formed by the cartilage of the Eustachian tube pushing from directly under the mucosal membrane. Extending inferiorly, the posterior vertical portion of the upside down U is prominent and called the salpingopharyngeal fold. It contains the salpingopharyngeus muscle, which raises the pharynx and larynx during swallowing. The anterior and nonprominent portion of the U is called the salpingopalantine fold. It contains the levator veli palatine muscle, which raises the soft
palate, helping to close the nasopharynx during swallowing and preventing nasopharyngeal reflux.
22. Oropharynx The portion of the pharynx that extends inferiorly from the uvula to the level of the hyoid bone is called the oropharynx. The oropharynx contains a few structures we think are important to discuss: the valleculae, the palatine tonsils and the lingual tonsils.
23. The Valleculae The valleculae are located on the anterior wall of the oropharynx between the inferior border of the tongue and the superior border of the epiglottis. They serve as a fluid trap, catching saliva so that it doesn’t prematurely trigger the swallowing mechanism. The images on this slide are from a video fluoroscopic swallowing exam and show barium pooling in the valleculae. The valleculae are also a common place for foreign bodies to become lodged. Anatomically, the valleculae serve as a landmark for the placement of the blade tip of a laryngoscope during tracheal intubation.
24. The Palatine and Lingual Tonsils The palatine and lingual tonsils are paired lymphatic structures located in the oropharynx. The palatine tonsils are found on the lateral walls of the oropharynx, posterior to the base of the tongue. The lingual tonsils are located on the anterior wall of the oropharynx at the base of the tongue. Because these lymphatic structures are the first line of defense against outside materials entering the body through the upper respiratory and gastrointestinal tracts, they can easily become infected. Sometimes, the tonsils may be surgically removed because of tonsillar infection, termed tonsillitis, or tonsillar enlargement, called hypertrophy. This procedure is called a tonsillectomy.
25. The Hypopharynx The hypopharynx, also called the laryngopharynx, extends from the level of the hyoid bone to the inferior border of the cricoid cartilage at the approximate level of C6. At this level, the alimentary tract continues as a tube known as the esophagus, allowing food to travel from the pharynx to the stomach.
26. The Esophagus The esophagus is a muscular tube that extends from the inferior margin of the hypopharynx to the lower esophageal sphincter. It permits food and drink to pass from the oral cavity to the stomach. The esophagus consists of 3 parts: cervical, thoracic and abdominal, although we’ll only discuss the cervical portion in this module.
27. The Cervical Esophagus The cervical esophagus is relatively short, extending from the pharyngoesophageal junction at the approximate level of C5 and C6 to the thoracic inlet at roughly the T1 level.
28. The Larynx The larynx arises anteroinferiorly from the hypopharynx at about the level of C3. In addition to containing many important structures for creating sounds, the larynx provides a pathway for air to travel from the pharynx to the lungs. The larynx has a cartilaginous frame made up of 3 single major cartilages and 3 sets of paired minor cartilages. The 3 single cartilages are the epiglottic, thyroid and cricoid. The paired cartilages are the arytenoid, corniculate and the cuneiform. We’ll cover several laryngeal structures, including the epiglottis and other laryngeal cartilages, vestibular folds, vocal folds, aryepiglottic folds and piriform sinuses.
29. The Epiglottis The epiglottis is made up of elastic cartilage and is responsible for sealing off the airway during swallowing to prevent food or liquid from entering the lungs, a pathologic process called aspiration. The epiglottis is normally directed superiorly, creating an open airway. During swallowing, the hyoid bone elevates, causing the epiglottis to flip downward, closing off the larynx and forcing food and liquid down the esophagus to the stomach.
30. The Thyroid Cartilage The largest of the laryngeal cartilages is the thyroid cartilage. The thyroid cartilage is made up of left and right shield-like plates that unite anteriorly at the midline. This union creates a prominent ridge called the laryngeal prominence, otherwise known as the Adam’s apple. As you may know, this ridge is more prominent in men than in women secondary to the degree of the angle at the union. The angle is approximately 90 degrees in men and 120 degrees in women. Superiorly, the laryngeal prominence contains a depression called the superior thyroid notch.
31. Cricoid Cartilage Scroll through this animation as we describe the cricoid cartilage. The cricoid cartilage, located just inferior to the thyroid cartilage, is the only complete ring of cartilage in the trachea. This structure functions as an attachment point for many muscles, cartilages and ligaments that open and close the airway. It also is useful during tracheal intubation, as the practitioner may push posteriorly on the cricoid cartilage to effectively close the esophagus and prevent passage of material that could be refluxed from the stomach.
32. The Arytenoid Cartilages The 3 paired laryngeal cartilages are considered minor cartilages. The largest are the bilateral arytenoid cartilages, which are pyramidal in shape and arise from the posterosuperior aspect of the cricoid cartilage. They are significant in that they provide attachment points for the true vocal cords.
33. The Corniculate and Cuneiform Cartilages The other minor cartilages are the corniculate and cuneiform cartilages, which are made up of yellow elastic cartilage. The paired corniculate cartilages arise from the tops of their respective arytenoid cartilages and help to extend the backward and medial movement of each arytenoid cartilage. The paired cuneiform cartilages are located on either side of the aryepiglottic folds.
34. The Vestibular and Vocal Folds Two pairs of thick mucous membrane folds are located within the cartilaginous frame of the larynx. The superior pair is called the vestibular folds, or false vocal cords. A vestibular, or ventricular, ligament runs through each of these folds. Anteriorly, the vestibular folds attach to the thyroid cartilage inferior to the attachment of the epiglottis; posteriorly, the vestibular folds attach to the arytenoid cartilages. Although they have a minimal role in normal speech, the false vocal cords play a large role in keeping food and fluid out of the airway.
35. Vocal Folds The vocal folds, or true vocal cords, are located inferior to the vestibular folds and are responsible for speech. During quiet respiration, these thick folds of mucous membrane relax and allow air to pass between them without vibration. The space between the folds is called the glottis. During speech, the folds tighten and move closer to each other, which builds pressure beneath the glottis. When the pressure is released through the glottis, the folds vibrate, creating sound in much the same way as a tight guitar string.
36. Aryepiglottic Folds The aryepiglottic folds are another pair of mucous membrane folds. They extend bilaterally from the lateral border of the epiglottis to the respective apex of each arytenoid cartilage, forming the lateral borders of the opening of the larynx. More important are the piriform sinuses, which are paired spaces lateral to each aryepiglottic fold. These sinuses help to divert food away from the larynx and guide the food down the esophagus.
37. The Trachea The trachea extends inferiorly from the larynx although some sources consider the larynx part of the trachea. The trachea, or windpipe, is made up of pseudostratified columnar epithelial cells and mucus-producing goblet cells. Multiple cilia, or tiny finger-like projections, line the inside of the trachea. As inhaled foreign bodies such as dust and other airborne particles get stuck in the mucus, the cilia move them upward, until they can be swallowed or coughed up. The trachea extends inferiorly until bifurcating into the right and left mainstem bronchi, which then distribute air throughout the lungs. This bifurcation is called the carina and is an easily recognizable structure on chest radiographs. The framework of the trachea is provided by 15 to 20 C-shaped cartilaginous rings, with the opening of the C located posteriorly. The opening serves 2 main purposes: to allow expansion of the posteriorly located esophagus and to permit luminal constriction of the trachea. As food travels down the esophagus, the tube stretches to accommodate the bolus of food. Because the trachea is located directly anterior to the esophagus, the food could get caught on the cartilaginous rings if there were no openings. Also, when we cough, the trachealis muscle pulls the ends of the incomplete rings together to effectively narrow the tracheal diameter, increasing air pressure and allowing for a stronger cough.
38. The Salivary Glands Multiple glands surround the oral cavity. These glands produce saliva along with amylase, an enzyme that helps to break down starches. Salivary glands are exocrine glands that release their product directly to the external environment via ducts. Although there are hundreds of minor
salivary glands scattered throughout the submucosa of the mouth, we’ll focus on 3 primary paired glands: the parotid, the submandibular and the sublingual.
39. The Parotid Glands The parotid glands are found bilaterally between the ramus of the mandible and the sternocleidomastoid muscle. The parotid glands extend from about the level of the cheek down to the angle of the mandible. They excrete saliva and alpha-amylase into the oral cavity via the Stensen ducts, also called parotid ducts, to aid in mastication, swallowing and the initial breakdown of starches.
40. The Submandibular Glands The second largest paired saliva glands are the submandibular glands, located subjacent to the posterior body of the mandible and extending from the angle of the mandible to the hyoid bone. Their secretions are delivered to the oral cavity via Wharton ducts, also called the submandibular ducts.
41. The Sublingual Glands The third primary salivary glands are the paired sublingual glands, located in the oral submucosa underneath the tongue and anterior to the submandibular gland. Their secretions drain bilaterally into the submandibular ducts via the ducts of Bartholin, or the major sublingual ducts. Secretions from the sublingual glands also drain directly into the mouth through multiple smaller ducts known as the ducts of Rivinus.
42. The Thyroid Gland The neck also contains one of the largest endocrine glands, the thyroid gland. Scroll through this animation as we discuss the thyroid gland. Endocrine glands, unlike exocrine glands, release their secretions into the bloodstream. The bi-lobed thyroid gland is located just inferior to the thyroid cartilage and flanks the trachea anteriorly. The thyroid lobes are connected by a thin band of tissue called the isthmus. The thyroid gland performs 3 important functions: It secretes hormones that control the body’s metabolism, controls which proteins to make and regulates how the body should react to other hormones.
43. Parathyroid Glands Other endocrine glands located in the neck are the parathyroid glands. Typically 4 in number, these glands are most commonly located on the posterior surface of the thyroid gland. Rarely, they are found within the thyroid and sometimes in the chest. They control the amount of calcium the body maintains in the blood and bones.
44. Knowledge Check Answer the following question.
45. Knowledge Check Answer the following question.
46. Knowledge Check Answer the following question.
47. Major Muscles of the Neck Next, we’ll discuss the major muscles located in the neck and their functions. Two pairs of muscles that extend over the length of the neck are the platysma and the sternocleidomastoid muscles. Compartmentalized neck muscle groups include the suprahyoid, infrahyoid, lateral vertebral, anterior vertebral and posterior triangle muscles, and the muscles of mastication. We will further discuss the compartmentalized neck muscle groups shortly.
48. The Platysma Muscles The paired platysma are broad sheet-like muscles that originate from the fascia overlying the pectoralis major muscle of the chest and the deltoid muscle of the shoulder. These superficial muscles extend superiorly were they insert at the base of the mandible and adjacent structures. They are responsible for depressing the lower jaw and also for pulling the corners of the mouth inferiorly, like when a person frowns.
49. The Sternocleidomastoid Muscles The paired sternocleidomastoid muscles have 2 origins. The rounded medial, or sternal, heads originate from the superior portion of the sternum, called the manubrium. The flattened lateral, or clavicular, heads originate from the medial clavicles. The heads of the muscles are initially separated by a triangular space, but the fibers blend together to form a thick rope-like muscle that extends superiorly to insert at the mastoid process of the temporal bone. The sternocleidomastoid muscles are located deep to the platysma. They are individually responsible for flexion of the neck to the ipsilateral, or same, side and rotation of the neck to the contralateral, or opposite, side. When they work together, they flex the entire head and neck, as in touching your chin to your chest.
50. Muscles of the Suprahyoid Region The suprahyoid region of the neck encompasses the area above the hyoid bone and consists of 4 paired muscles: the digastric, the stylohyoid, the mylohyoid and the geniohyoid muscles.
51. The Digastric Muscles Each of the bilaterally paired digastric muscles consists of 2 bellies, which accounts for the name “digastric.” Although similar in appearance and sharing the same name, the 2 bellies actually have separate embryological origins, different arterial blood supplies and are even innervated by different cranial nerves. Each anterior belly originates from the digastric fossa of the mandible, found in the midline of the chin. Each posterior belly originates from the mastoid process of the temporal bone, found just posterior to the ear. Both the anterior and posterior bellies terminate in an intermediate tendon, which then perforates another muscle, the stylohyoid, and inserts into the greater cornu and body of the hyoid bone. The digastric muscles elevate the hyoid bone to aid swallowing and, in some instances, opening the mouth.
52. The Stylohyoid Muscles The relatively long and slender stylohyoid muscles are located anterior and superior to the posterior belly of each digastric muscle. Each stylohyoid muscle originates from the styloid process of the temporal bone and extends inferiorly until it inserts into the body of the hyoid bone near the greater cornu. Like the digastric muscle, the stylohyoid muscles also elevate the hyoid bone. The stylohyoid ligament is a fibrous band attached to the tip of the styloid process and the lesser cornu of the hyoid bone. This ligament is radiologically significant because it frequently contains a small amount of central cartilage. Calcification of this cartilage is an occasional incidental finding on neck radiographs or CT scans. However, when the ligament becomes thickened and ossified, it can become symptomatic, causing facial pain, dysphagia and a foreign-body sensation in the throat. This condition is called Eagle syndrome.
53. The Mylohyoid Muscles Located just superior to the anterior bellies of the digastric muscles are the mylohyoid muscles. The name represents a combination of the muscle’s 2 attachments. “Mylo” represents the Greek word for “molar” and signifies the mandible, and “hyoid” denotes the hyoid bone. Each mylohyoid muscle originates from the inner surface of the body of the mandible along a line called the mylohyoid line. The posterior fibers of the mylohyoid muscle converge with the stylohyoid muscle and insert into the greater cornu of the hyoid. The anterior and middle fibers insert into a fibrous ridge that runs from the mid chin to the hyoid bone, a ridge called the median raphé. Collectively, the bilaterally located mylohyoid muscles form the floor of the oral cavity and help to depress the mandible and elevate the hyoid bone and floor of the oral cavity.
54. The Geniohyoid Muscles The final muscle of the suprahyoid region we’ll discuss is the geniohyoid muscle pair. The term “geniohyoid” also represents a conjunction of the muscle’s 2 attachments. “Genio” comes from the Greek word for “chin,” and “hyoid” represents the hyoid bone. The geniohyoid muscles originate from the mid chin and extend inferiorly and bilaterally until they attach to the anterior portion of the body of the hyoid bone. The geniohyoid muscles help to elevate the hyoid bone and tongue during swallowing and also assist in depressing the mandible.
55. Muscles of the Infrahyoid Region Just as the suprahyoid region encompasses the area above the hyoid bone, the infrahyoid region includes the area below the hyoid bone. The infrahyoid muscles are commonly referred to as the strap muscles because of their long, flat, strap-like shape. Four muscles are included in this area: the sternohyoid, the sternothyroid, the thyrohyoid and the omohyoid.
56. The Sternohyoid and Sternothyroid Muscles The paired sternohyoid muscles originate from the posterior medial border of the clavicle and the superior posterior border of the manubrium of the sternum. They extend superiorly and insert into the inferior border of the hyoid bone. The sternohyoid muscles help depress the hyoid bone during swallowing.
The paired sternothyroid muscles originate from the posterior border of the manubrium, below the origin of the sternohyoid muscles. They extend superiorly beneath the sternohyoid muscles until inserting into the oblique line of the lamina of the thyroid cartilage. The sternothyroid muscles help depress the larynx, as in yawning.
57. The Thyrohyoid Muscles The paired thyrohyoid muscles also originate from the oblique line of the lamina of the thyroid cartilage, anterior to the origin of the sternothyroid muscles. They extend superiorly until they insert into the lower border of the greater cornu of the hyoid bone. The thyrohyoid muscles help elevate the larynx and depress the hyoid bone during swallowing.
58. The Omohyoid Muscles The paired omohyoid muscles are unique relative to other infrahyoid muscles in that they consist of an inferior belly and a superior belly. The term “omohyoid” refers to the muscle’s 2 attachments, with “omos” representing the Greek word for “shoulder” and “hyoid” referring to the hyoid bone. The inferior belly originates from the superior border of the scapula and extends superomedially where it passes behind the sternocleidomastoid, becoming tendinous and taking a sharp angle superiorly. The superior belly arises from this tendinous angle and extends superiorly along the lateral border of the sternohyoid muscle until it inserts into the inferior border of the body of the hyoid bone. The omohyoid bone depresses the larynx and hyoid bone. The remaining muscles of the neck can be classified into lateral and anterior vertebral muscles.
59. The Lateral Vertebral Muscle Group
The lateral vertebral muscle group of the neck consists of the anterior, medius and posterior scalene muscles. Scalene originates from the Greek word “skalenos,” meaning “uneven.” Just as in a scalene triangle where all sides are different lengths, the scalene muscles are also different lengths. The 3 paired scalene muscles are unique in that they originate from multiple levels to form 1 muscle. The scalene muscles help to elevate the first and second ribs and to flex the neck on the same side as the muscle.
60. The Scalene Muscles The scalenus anterior muscles originate bilaterally from the transverse processes of the C3 through C6 vertebrae and insert into the inner and superior surfaces of the first ribs. The scalenus anterior muscles help the first rib elevate for respiration when the neck is fixed. When the first rib is fixed, they assist in flexion and rotation of the neck. The scalenus medius muscles originate bilaterally from the transverse processes of the C2 through C6 vertebrae and insert into the superior surfaces of the first ribs. The scalenus medius muscles help elevate the first rib for respiration. The scalenus posterior muscles, the smallest and deepest of the scalenus muscle group, originate bilaterally from the transverse processes of the C4 through C6 vertebrae and insert into the superior surface of the second ribs. The scalenus posterior muscles help elevate the second rib for respiration.
61. The Anterior Vertebral Muscle Group The anterior vertebral muscle group of the neck consists of 4 paired muscles: the longus colli, the longus capitis, the rectus capitis anterior and the rectus capitis lateralis. The muscles in this group are located between a layer of connective tissue in the anterior neck called the prevertebral fascia and the vertebral column. Each of these paired muscles primarily assists in the flexion of the head and neck.
62. The Longus Colli Muscles The longus colli muscles are further divided into 3 parts: the superior oblique, the inferior oblique and the vertical portions. “Longus” is a Latin term for “long” and “colli” comes from the Latin “collum” representing the neck, so these are the long muscles of the neck. The superior oblique portions of the longus colli originate bilaterally from the anterior tubercles of the transverse processes of the C3 through C5 vertebrae and extend superolaterally until they insert into the anterior arch of the atlas. The inferior oblique portions of the longus colli originate bilaterally from the anterior bodies of the T1 through T3 vertebral bodies and extend superolaterally until they insert into the anterior tubercles of the transverse processes of the C5 and C6 vertebrae. The vertical portions of the longus colli originate bilaterally from the anterior bodies of the C5 through T3 vertebrae and extend superiorly until they insert into the anterior bodies of the C2 through C4 vertebrae. These muscles assist in the flexion and rotation of the neck and are involved in traumatic whiplash injuries.
63. The Longus Capitis Muscles The longus capitis muscles originate bilaterally from the anterior tubercles of the transverse processes of the C3 through C6 vertebrae and extend superiorly until they insert into the inferior portion of the basilar part of the occipital bone. As with the longus colli, “longus” means “long,” and “capitis” comes from the Latin “caput” meaning “head”; therefore, these are the long muscles of the head. The longus capitis muscles also assist in the flexion of the neck and the atlantooccipital joint.
64. The Rectus Capitis Anterior and Lateralis Muscles The rectus capitis anterior muscles originate bilaterally from the anterior surface of the lateral masses of the atlas and extend superiorly until they insert into the inferior border of the basilar part of the occipital bone, anterior to the foramen magnum. “Rectus” is Latin for “straight,” and “capitis” means “head”; so these are the anterior straight muscles of the head. The rectus capitis anterior muscles assist in the flexion of the atlantooccipital joint. The rectus capitis lateralis muscles originate bilaterally from the transverse processes of the atlas and extend superiorly until they insert into the inferior border of the jugular processes of the occipital bone. As “lateralis” is Latin for “side,” the rectus capitis lateralis muscles are the straight muscles of the head at the side. These muscles assist in the lateral flexion of the atlantooccipital joint.
65. The Muscles of Mastication Now we’re going to discuss the muscles of mastication. These are the muscles that are responsible for the motions related to chewing. The muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid.
66. The Temporalis Muscles The paired temporalis muscles originate from the elliptical temporal fossae of the cranium and extend medial to the zygomatic arches until they insert into the coronoid processes of the mandible. Given that the temporalis muscles contain both horizontally and vertically running muscle fibers, they both elevate and retract the mandible. The movement of this muscle can be felt if you place your hand over the temporal bone and clench your teeth.
67. The Masseter Muscles The paired masseter muscles are located bilaterally. Each muscle is made up of a superficial part and a deep part. The superficial portion, the larger of the 2 parts, originates from the zygomatic process of the maxilla, as well as the anterior two-thirds of the inferior border of the zygomatic arch. The superficial masseter muscle extends inferiorly and posteriorly, inserting into the mandibular angle and inferolateral border of the mandibular ramus. The smaller, deep portion of the masseter muscle originates from the posterior third of the lower border and entire medial border of the zygomatic arch. This muscle continues inferiorly and anteriorly until it inserts into the superior mandibular ramus and the lateral coronoid process of the mandible. Like the temporalis muscle, the masseter is a muscle of mastication and with the medial pterygoid muscle is responsible for elevation and protrusion of the mandible.
68. The Lateral and Medial Pterygoid Muscles The last 2 muscles of mastication that we’ll discuss are the paired lateral and single medial pterygoid muscles. The function of the pterygoid muscles is to help open and close the jaw. The medial pterygoid muscle originates from the lateral pterygoid plate and inserts on the medial surface of the ramus and the angle of the mandible. The medial pterygoid muscle closes the jaw. The lateral pterygoid muscle has 2 heads. One head originates from the greater wing of the sphenoid and inserts onto the articular disc; the other head originates from the lateral surface of the lateral pterygoid plate and inserts under the condylar process of the mandible. The lateral pterygoid muscle opens the jaw.
69. Knowledge Check Answer the following question.
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71. Knowledge Check Answer the following question.
72. Knowledge Check Answer the following question.
73. Lymph Nodes Before we get into the complex system of cervical lymph nodes, let’s talk about what a lymph node is and what it does. Lymph nodes are small, oval or ball-shaped organs located throughout the body. They are part of the immune system, and each node is linked to another node by
lymphatic vessels. A lymph node can be thought of as a military fort that houses platoons of troops. The platoons are made up of B, T and other immune cells. When a lymphocyte, a type of white blood cell, encounters an infection, it identifies the type of infection and travels to a lymph node where it alerts the other immune cells. The appropriate immune cells then can be sent to fight the infection. Sometimes lymph nodes become enlarged. This consequence is secondary to the body’s response of creating more immune cells to fight the current infection.
74. Cervical Lymph Nodes Now let’s discuss the more than 300 cervical lymph nodes in the neck. Luckily, there is a system commonly used to classify the locations of the cervical nodes. The system consists of 7 levels, but it is not all inclusive in that it doesn’t incorporate nodes arising in the supraclavicular and retropharyngeal regions. However, we’ll discuss those nodes in this module as well.
75. Cervical Lymph Nodes – Level I Level I of the cervical lymph nodes is further broken down into 2 regions: the submental triangle and the submandibular triangle. Both of these areas are found inferior to the mylohyoid muscle, which makes up the floor of the mouth.
76. Cervical Lymph Nodes – Levels II, III, IV Level II consists of the upper internal jugular nodes. This area is found inferior to the external auditory meatus and behind the submandibular salivary gland. Level III consists of the middle jugular nodes. These nodes are located between the level of the inferior border of the body of the hyoid bone and the inferior border of the cricoid cartilage. Level IV is made up of the low jugular nodes. These nodes are located between the level of the posterior border of the cricoid cartilage and the level of the clavicle. The area is lateral to the carotid arteries, which we’ll discuss later.
77. Cervical Lymph Nodes – Level V Level V also is divided into 2 parts. Both subdivisions are called the posterior triangle nodes and are located posterior to the posterior border of the sternocleidomastoid muscle.
78. Cervical Lymph Nodes – Levels VI and VII Level VI includes the upper visceral nodes. They are located between the carotid arteries, from the level of the inferior border of the body of the hyoid bone to the level of the superior border of the manubrium. Level VII consists of the superior mediastinal nodes. They are located between the carotid arteries below the level of the superior border of the manubrium and above the branching of the superior vena cava, the primary blood return pathway of the upper body.
79. The Supraclavicular Nodes The supraclavicular nodes are located in a region at the level of or below the clavicle and lateral to the carotid arteries. A node in the left supraclavicular fossa is named the Virchow node after the German pathologist who first associated enlargement of the node with gastric carcinoma.
Because this node receives lymphatic drainage from the abdominal cavity, enlargement can be the first sign of metastatic disease from various abdominal malignancies.
80. The Retropharyngeal Lymph Nodes The retropharyngeal nodes are located behind the pharynx, medial to the internal carotid artery, from the skull base down to the level of the hyoid bone. The uppermost node of the retropharyngeal lymph nodes is called the node of Rouvière in honor of a French anatomist. This node also has a specific correlation with malignancy. Nasopharyngeal carcinoma arising in a deep groove known as the pharyngeal recess, or fossa of Rosenmüller, posterior to the Eustacian tube cushion, can easily escape diagnosis with endoscopy. The malignancy will spread first to the node of Rouvière.
81. Knowledge Check Answer the following question.
82. Knowledge Check Answer the following question.
83. Vessels of the Neck Next, we’ll discuss the arteries and veins of the neck, covering the following vessels: the common carotid arteries, the internal carotid arteries, the external carotid arteries, the vertebral arteries, the internal jugular veins, the external jugular veins, the retromandibular veins and the vertebral veins.
84. Common Carotid Arteries Paired common carotid arteries supply oxygenated blood to the head and neck. They follow roughly the same path bilaterally, with the exception of their origins. The left common carotid artery typically arises directly from the aorta as the second branch of the aortic arch in the thorax. The right common carotid artery usually originates in the neck from the brachiocephalic artery, which itself typically begins as the first branch of the aortic arch. The brachiocephalic artery is commonly known as the innominate artery, from the Latin term meaning “nameless.” Both common carotid arteries extend superiorly behind each sternoclavicular joint to the level of approximately C4, where they divide into the internal carotid arteries and the external carotid arteries. Interestingly, there are a number of anatomic variations in the origin of the common carotid arteries. For example, the right common carotid artery can arise directly from the aorta and the left common carotid artery can originate with or from the brachiocephalic artery. “Bovine arch” is a misnomer used to describe a frequent variant of the aortic arch in which the left common carotid artery origin is moved to the right and arises with the brachiocephalic artery. Contrary to the name, the variant does not actually reflect the typical aortic arch configuration in cattle or other bovines.
85. Internal Carotid Arteries An internal carotid artery arises from the bifurcation of each common carotid artery. More commonly known by the abbreviation ICA, these vessels are the major supplier of oxygenated blood to the brain. At the origins of the ICAs, there are dilated segments called the carotid bulbs, or carotid sinuses.
From the bifurcations of the common carotid arteries, the ICAs extend upward until they enter the cranium through the carotid canal in the petrous portion of the temporal bone. Each internal carotid artery travels anteromedially and passes through the cavernous sinus before supplying blood to the circle of Willis.
86. External Carotid Arteries An external carotid artery also arises from the bifurcation of each common carotid artery. Known by the abbreviation ECA, these vessels extend anteriorly and superiorly from the bifurcations and pass posterior to the neck of the mandible before branching to supply blood to the face
87. Vertebral Arteries
The last pair of arteries in the neck that we’ll discuss are the vertebral arteries. Each vertebral artery arises from the corresponding subclavian artery and enters the vertebral column at either C6 or C7. From that point, the artery travels superiorly within the transverse processes of the cervical vertebrae. At the inferior border of the pons, the right and left vertebral arteries merge to form the basilar artery. The basilar artery then continues superiorly and supplies oxygenated blood to the circle of Willis, a ring of arteries located at the base of the brain.
88. Review Scroll through these images to see the neck arteries we just discussed. As you scroll through the animation, watch the localizer images on the right-hand side. These views will help you recognize the location of the structures.
89. Internal Jugular Veins Next, we’ll focus on the veins in the neck. The bilateral internal jugular veins descend inferiorly from the convergence of the sigmoid and inferior petrosal sinuses at the base of the brain, in the posterior compartment of each jugular foramen. They continue inferiorly, lateral to first the internal carotid arteries and then to the common carotid arteries. The internal jugular veins receive deoxygenated blood from the brain and face and converge with each respective subclavian vein at the base of the neck to form the brachiocephalic, or innominate, veins. Unlike the brachiocephalic artery, which is normally found only on the left side, there are both right and left brachiocephalic veins.
90. External Jugular Veins The external jugular veins include the posterior portions of the retromandibular veins, which receive blood from the face, and the posterior auricular veins, which receive blood from the external cranium. The external jugular veins descend inferiorly from the level of the angle of the mandible and continue inferiorly until they drain into their respective subclavian veins.
91. Vertebral Veins The vertebral veins travel inferiorly through the transverse foramina and carry deoxygenated blood from the deep muscles of the back and neck to the brachiocephalic veins.
92. The Carotid Sheath Made up of fibrous connective tissue, the carotid sheath surrounds the common carotid artery, internal carotid artery and internal jugular veins. The carotid sheath is significant in radiology
because tumors can occur in small sensory organs that detect oxygen levels in arterial blood called the carotid bodies, which are located within the sheath. These highly vascular tumors can bleed uncontrollably if biopsied.
93. Knowledge Check Answer the following question.
94. Knowledge Check Answer the following question.
95. Knowledge Check
Answer the following question.
96. Conclusion This concludes Sectional Anatomy: Module 5 — The Neck. You should now be able to:
Describe the features of the larynx.
Locate and describe the features of the pharynx.
Discuss the relationship of the esophagus and trachea as they descend through the neck.
Locate and compare the relationships of the 3 sets of major salivary glands.
Discuss the major muscles of the neck and their functions.
Identify and locate the lymph nodes in the neck.
Describe the major arteries and veins of the neck.
97. Resources 98. Acknowledgements 99. Development Team 100. Module Completion
