Fascial_Planes_of_the_Neck_Ford_2023_SV.pptx

Fascial Planes of the Neck Bonny Ford, PhD RESP-I: Fall 2023 Image credit: Navegatium; Cervicothoracic Spine MRI Aliza; DICOM viewer LEARNING OBJECTIVES After completing your study of the fascial planes of the neck, you should be able to: 1. Name and identify the fascial layers of the neck. For...

Fascial Planes of the Neck Bonny Ford, PhD RESP-I: Fall 2023 Image credit: Navegatium; Cervicothoracic Spine MRI Aliza; DICOM viewer LEARNING OBJECTIVES After completing your study of the fascial planes of the neck, you should be able to: 1. Name and identify the fascial layers of the neck. For each layer, identify the boundaries and contents. Include: superficial cervical fascia, investing layer of deep cervical fascia, muscular layer, visceral layer (pretracheal and buccopharyngeal layers), prevertebral layer of deep cervical fascia, carotid sheath, and alar fascia. 2. Name and identify the formation and boundaries of the suprasternal space, retropharyngeal space, and danger space. 3. Integrate your knowledge of the triangles of the neck with the fascial layers. Integrate Your Material This lecture ties together information from MSK, CVS, and RESP, so make sure you are getting your anatomical bearings as we go through this. • • • • Hyoid bone: C3 Notch in Thyroid Cartilage: C4 Isthmus of Thyroid Cartilage: C4-C5 Cricoid Cartilage: C6 The inferior border of the cricoid is an important landmark for LOTS of things: • Junction of larynx with trachea • Junction of pharynx with the esophagus • Level where superior belly of omohyoid crosses the carotid sheath • Level where vertebral artery enters the transverse foramen (C6) • Level of middle cervical sympathetic ganglion • Level where carotid artery can be compressed against the carotid tubercle (transverse process of C6) Start Big Picture Basically, the neck has four main components that will get wrapped differently in fascia: • Posteriorly: The main structural element of the neck, the cervical spine, and its supporting struts of muscle. • Centrally: A large, visceral column; contains digestive and respiratory passageways and the thyroid gland. • Lateral to the Visceral Column: Neurovascular elements pass between the head and the thorax, contained within the carotid sheath. • Protecting the visceral and neurovascular elements: Strong, flat muscles (trapezius and SCM). Anatomic Exposures in Vascular Surgery, 4e, 2021 Copyright © Wolters Kluwer Is this really clinically relevant??? • Patient has a lump in the neck – the surgical approach is dependent on separating fascial layers and stitching layers back up in a way that will heal best. This is much easier if you know the fascial layers and the landmarks for defining them. • Patient presents with an abscess that has spread all the way from the level of their pharynx, just posterior to it, down to their mediastinum, because of having advanced tuberculosis of the cervical spine. How did the abscess spread that far? It used the spaces in between the fascial layers of the neck (and possibly eroded a layer…). • The neck has a whole lot of fascia and people are pretty good at injuring their neck. OMM is an amazing treatment tool to have in your toolbox, but you have to know the fascial planes well enough to localize the restrictions and treat fascial restrictions properly. • Collapse of alveolar walls (such as when the increased pressure of mechanical ventilation, together with underlying lung pathology causes alveolar rupture, which can cause leaking of air into the mediastinum). Because soft tissue compartments are continuous, and cervical fascial planes connect to the mediastinum, free mediastinal air can travel to the retroperitoneal space (posterior to the abdominal cavity) and many other areas of the body. Objective 1 and 2 • Name and identify the fascial layers of the neck. For each layer, identify the boundaries and contents. Include: superficial cervical fascia, investing layer of deep cervical fascia, muscular layer, visceral layer (pretracheal and buccopharyngeal layers), prevertebral layer of deep cervical fascia, carotid sheath, and alar fascia. • Name and identify the formation and boundaries of the suprasternal space, retropharyngeal space, and danger space. Fascial Layers/Spaces of the Neck Superficial Cervical Fascia Deep Cervical Fascia (has 5 layers) 1. Investing layer (also called superficial layer of the deep cervical fascia) 2. Muscular/Infrahyoid layer 3. Visceral layer – Pretracheal fascia 4. Visceral layer – Buccopharyngeal fascia 5. Prevertebral layer 1. Alar layer 2. Carotid sheath (composed of more than just prevertebral layer fascia) 3. Axillary sheath Spaces Retropharyngeal space Danger space Suprasternal space (of Burns) Superficial Cervical Fascia contains cutaneous nerves, blood and lymphatic vessels, lymph nodes, fat, and the platysma muscle. Platysma is a very thin sheet of muscle innervated by the facial nerve (CN VII) that covers the anterolateral aspect of the neck, separating along its medial border as it descends to the clavicle. This muscle is not hugely important in humans, but you see it prominently in animals. http://aclandanatomy.com/MultimediaPlayer.aspx?multimediaid=10528465 Deep Cervical Fascia Muscular layer Investing Layer of Deep Cervical Fascia contains 2 muscles (trapezius and SCM) and 2 glands (submandibular and parotid). This is really a tube of fascia that wraps around the neck, just deep to the platysma muscle. The tube splits to encompass the trapezius and SCM muscles (both of which are innervated by the spinal accessory nerve, CN XI). Also forms a fibrous capsule around the parotid gland (which means that if you get a swollen parotid gland, you’re in a world of hurt because that fibrous capsule is stiff and restrictive). Attachments Superiorly: zygomatic arches of the jaw Posteriorly: superior nuchal line of the occipital bone Anteriorly: mastoid process and inferior border of the mandible Anchor points: hyoid bone, spinous processes of cervical vertebrae Inferiorly: manubrium, clavicles, acromion and spines of the scapulae http://plasticsurgerykey.com/wp-content/uploads/2016/06/9781626230927_c021_f006.jpg Investing Layer of Deep Cervical Fascia Investing layer of (deep) cervical fascia Plate 51. Fascial layers of neck. Netter, Frank H. Netter Atlas of Human Anatomy, 8th Edition. Elsevier, Inc., 10/27/2022. When this layer gets to the manubrium, it splits into an anterior and posterior portion in order to envelop the inserting heads of the bilateral SCMs. These anterior and posterior portions of the investing layer attach to the anterior and posterior aspects of the manubrium at the midline – creating a space in between them called the Suprasternal Space (of Burns). Investing Layer of Deep Cervical Fascia Suprasternal Space (of Burns) contents: • Sternal heads of SCM • Anterior jugular vein anastomoses • Lymph nodes • Interclavicular ligament Muscular/Infrahyoid Layer of Deep Cervical Fascia contains the infrahyoid muscles. Muscular layer of deep cervical fascia This layer also creates thickened loops/tethers for muscles that have dual muscle bellies with intervening tendons (omohyoid and digastric). At the hyoid bone, there is a loop that projects superiorly to the hyoid bone and wraps around the tendinous portion of the digastric muscle. Plate 53. Cervical fasciae. Netter, Frank H. Netter Atlas of Human Anatomy, 8th Edition. Elsevier, Inc., 10/27/2022. At the clavicle, there is a thickened loop that wraps around the tendinous portion of the omohyoid muscle. Visceral Layer of Deep Cervical Fascia is divided into 2 layers dependent on whether the fascia is anterior or posterior to the trachea. Pretracheal fascia contains the trachea and thyroid gland. When this fascia gets to the thyroid gland, it splits to encompass the gland. Superiorly, this fascia is anchored to the hyoid bone and inferiorly it merges with the fibrous pericardium of the heart. • This creates a route through which infection can spread from the neck to the mediastinum. Buccopharyngeal fascia contains the pharynx and pharyngeal constrictors (it’s the continuation of the pretracheal layer that wraps around posterior to the trachea). This fascia extends all the way up to the buccinator muscle in the face. http://plasticsurgerykey.com/wp-content/uploads/2016/06/9781626230927_c021_f006.jpg Plate 51. Fascial layers of neck. Netter, Frank H. Netter Atlas of Human Anatomy, 8th Edition. Elsevier, Inc., 10/27/2022. Prevertebral layer of deep cervical fascia Plate 51. Fascial layers of neck. Netter, Frank H. Netter Atlas of Human Anatomy, 8th Edition. Elsevier, Inc., 10/27/2022. Prevertebral Layer of Deep Cervical Fascia contains vertebral column, longus colli, longus capitis, scalene muscles, deep cervical muscles, and the cervical portion of the sympathetic chain. Extends from the skull base to the coccyx, fused with the ALL and enveloping vertebral bodies and associated muscles. Laterally, it is fused to the transverse processes of the vertebrae. Superiorly, the prevertebral layer will cover the scalene muscles and form the floor of the posterior triangle. Prevertebral Layer of Deep Cervical Fascia This layer contributes to the formation of the carotid sheath and then divides into a continuation of the prevertebral layer and an alar layer. The prevertebral layer ultimately continues into the upper extremity and is renamed the axillary sheath (contains the axillary vessels and the brachial plexus). Figure 7-6 Chila, Anthony. Foundations of Osteopathic Medicine, 3rd Edition. Lippincott Williams & Wilkins, 102010. VitalBook file. Retropharyngeal Space The retropharyngeal space is formed between the alar fascia and the fascia of the pharyngeal constrictors and extends from the base of the skull to ~T1/2 (very variable). At ~T1/T2, the alar fascia fuses with the buccopharyngeal fascia, creating the inferior border of the retropharyngeal space. The retropharyngeal space contains fat and lymph nodes that drain the pharynx, nasal cavity, paranasal sinuses, and middle ears. The retropharyngeal space is what allows the necessary movements of the pharynx, esophagus, larynx, and trachea during swallowing/phonation/respiration/etc. https://www.researchgate.net/publication/ 51501348_Nonvascular_Nontraumatic_Mediastinal_Emergencies_in_Adults_A_Comprehensive_Review_of_Imaging_Findings Alar Layer and Danger Space The Alar Layer is a derivative of the prevertebral layer of deep cervical fascia and covers the cervical portion of the sympathetic chain. This layer also separates the retropharyngeal space from the danger space. Danger Space is a space formed between the prevertebral fascia and the alar fascia. It extends from the base of the skull all the way to the diaphragm and is continuous with the posterior mediastinum. Portions of the sympathetic chain travel in this space. This space is filled with loose connective tissue, which is great for allowing movement of neck tissues but presents very little resistance to the spread of infection through this area. https://www.researchgate.net/publication/51501348_Nonvascular_Nontraumatic_Mediastinal_Emergencies_in_Adults_A_Comprehensive_Review_of_Imaging_Findings Alar layer Visceral layer Retropharyngeal space Infections can actually be spread all the way from the nose/mouth/throat to the mediastinum if the infection degrades through the retropharyngeal space into the danger space. What layer of fascia would that infection also have to degrade through for this to occur? https://www.researchgate.net/publication/51501348_Nonvascular_Nontraumatic_Mediastinal_Emergencies_in_Adults_A_Comprehensive_Review_of_Imaging_Findings The Carotid Sheath is formed by fascial contributions from the prevertebral layer, pretracheal layer, and investing layer. This is a special, thickened, protective sheath that contains the common and internal carotid arteries, internal jugular vein, CN X, deep cervical lymph nodes, carotid sinus nerve, and some sympathetic nerve fibers. This sheath can also serve as an open pathway from the mediastinum into the skull that can spread infections and/or bleeds. https://www.researchgate.net/publication/51501348_Nonvascular_Nontraumatic_Mediastinal_Emergencies_in_Adults_A_Comprehensive_Review_of_Imaging_Findings I know this figure is overwhelming and can be disorienting…but if you just focus on the layers and the spaces, the nice thing is that it’s able to show a lot of things on one image. But, if it stresses you out more than it helps you, it’s ok to ignore it. You have what you need in the other figures I’ve provided, you’ll just need to visualize the 3dimensionality of it on your own. https://pocketdentistry.com/fascial-spaces-of-the-head-and-neck/ Cochard, Larry R., PhD, Netter's Introduction to Imaging, 8, 183-259 Copyright © 2012 Copyright © 2012 by Saunders, an imprint of Elsevier Inc. Objective 3 • Integrate your knowledge of the triangles of the neck with the fascial layers. Anterior Cervical Region/Anterior Triangle The roof of this triangle is the superficial cervical fascia, and the floor is the pharynx, larynx, and thyroid gland. Lateral Cervical Region/Posterior Triangle The roof of this triangle is the investing layer and the floor is the prevertebral layer of deep fascia. Posterior Cervical Region/Trapezius and SCM Region The trapezius muscle and the SCM (bilaterally) are enveloped in the investing layer of the deep cervical fascia. Cochard, Larry R., PhD, Netter's Introduction to Imaging, 8, 183-259 Copyright © 2012 Copyright © 2012 by Saunders, an imprint of Elsevier Inc. A 36-year-old woman complained of significant swelling in front of her right ear before and around mealtimes. This swelling was associated with considerable pain. On examination, she had tenderness around the right parotid region and a hard nodule was demonstrated in the buccal mucosa adjacent to the right upper molar teeth. A diagnosis of parotid duct calculus was made. What layer of cervical fascia surrounds the parotid gland thereby restricting its movement? A. B. C. D. E. Buccopharyngeal fascia Investing layer of deep cervical fascia Muscular layer of deep cervical fascia Pretracheal fascia Superficial cervical fascia **Case adapted from Gray’s Anatomy for Students, 4th edition by Drake et al.** An 18-year-old man presents to the Emergency Department with a threeday history of fever, malaise, and difficulty swallowing. Following physical examination, the patient is diagnosed with abscess involving the pharyngeal tonsil. The purulent fluid erodes through the buccopharyngeal fascia. What space would the purulent fluid now be found in? A. B. C. D. E. Carotid sheath Danger space Retropharyngeal space Suprasternal space Visceral space References 1.Dalley AF and Agur AMR. Moore’s Clinically Oriented Anatomy, 9th edition. Wolters Kluwer Health, Inc., 2022. https://meded-lwwhealthlibrary-com.ezproxy.ad.bcomnm.org/book.aspx?bookid=3187 Accessed July 12, 2022 2.Netter FH. Netter Atlas of Human Anatomy: Classic Regional Approach, 8th edition. Elsevier, Inc.; 2022. https://www-clinicalkey-com.ezproxy.ad.bcomnm.org/#!/browse/book/3-s2.0-C20180044345 Accessed July 15, 2022. 3.Rosse C and Gaddum-Rosse P. Hollinshead’s Textbook of Anatomy, 5th edition. Philadelphia: Lippincott-Raven, 1997. 4.Schuenke, M. Atlas of Anatomy: Head, Neck and Neuroanatomy, Vol. 3. 2nd Ed. New York: Theime Medical Publishers, 2016. http://www.thiemeteachingassistant.com.ezproxy.ad.bcomnm.org/Home/Collection/1. Accessed July 6, 2021