Coclia: Deep Space Neck Infections: 1. Describe the anatomy of the cervical fascia. AL - From Cummings b Investing-----~="HI layer Muscularportion,------~'**~~ """"~~~r==~~'""::-~~,-----prevertebral pretracheallayer Visceralportion,---~~~{!kjj~~--~~=----=> pretracheallayer layer E Fascial relationships in the neck b Left lateral view. Midsagittal section showing the prevertebrallayer.
The two main fascial divisions of the neck are the superficial cervical fascia and the deep cervical fascia, which further divides into three layers. Superficial Cervical Fascia -The superficial cervical fascia, deep to the dermis, envelops the platysma and muscles of facial expression. It incorporates the superficial muscu- loaponeurotic system and extends from the zygoma to the axillae, clavicles, and deltopectoral region. Deep to the platysma, a potential space separates the superficial and deep cervical fasciae. This space houses adipose tissue, sensory nerves, and blood vessels, such as the anterior and external jugular veins, and facilitates free movement of the skin. Deep Cervical Fascia -The deep cervical fascia is divided into three layers: the superficial, middle, and deep. The superficial layer of deep cervical fascia, or invest- ing fascia, surrounds the neck. Posteriorly it attaches to the superior nuchal line, the ligamentum nuchae of the cervical vertebrae, and the mastoid process. As it transmits anteriorly, it splits and re-fuses to sur- round the trapezius and sternocleidomastoid muscles. Anterosuperi- orly, this layer attaches to the inferior zygomatic arch. As it proceeds inferiorly, it splits to enclose the parotid gland, forming the parotid fascia superficially, and extends along the temporal bone to the carotid canal deeply. It envelops the muscles of mastication and covers the submandibular gland. This layer also forms the stylomandibular liga- ment, which separates the parotid from the submandibular gland. Infe- riorly the investing fascia attaches to the hyoid, clavicle, acromion, and spine of the scapula, but first splits to encompass the intermediate tendon of the omohyoid and form the suprasternal space. The super- ficial layer of deep cervical fascia contributes to the lateral aspect of the carotid sheath. The middle layer of deep cervical fascia, or visceral fascia, is com- posed of a muscular and visceral division. The muscular division sur- rounds the strap muscles (sternohyoid, sternothyroid, thyrohyoid, omohyoid). The visceral division surrounds the buccinator, pharyngeal constrictor muscles, larynx, trachea, esophagus, thyroid, and parathy- roid glands. The visceral division forms a pretracheal fascia that overlies the trachea. The visceral division also contributes the buccopharyngeal fascia posterior to the esophagus, which separates the esophagus from the deep layer of deep cervical fascia and forms the anterior border of the retropharyngeal space. The buccopharyngeal fascia forms two raphae: (1) one in the posterior midline that adheres to the alar layer of the deep layer, and (2) the pterygomandibular raphe of the lateral pharynx. The middle layer also contributes to the medial aspect of the carotid sheath. The deep layer of deep cervical fascia, or prevertebral fascia, divides into two layers: the prevertebral and alar layers. The prevertebral layer envelops the paraspinous muscles and cervical vertebrae, lying anterior to the vertebral bodies from the skull base to the coccyx, and attaching laterally to the transverse processes. It covers the scalene muscles and forms the floor of the posterior triangle. As it courses anteromedially, it contributes to the posterior carotid sheath and splits to form the alar layer. The alar layer lies between the prevertebral layer and the buccopharyngeal fascia of the visceral middle layer. The alar fascia separates the retropharyngeal and danger spaces and covers the cervical sympathetic trunk. The carotid sheath extends from the skull base to the thorax, and is a confluence of each layer of deep fascia. The sheath contains the common carotid artery, internal jugular vein, vagus nerve, and ansa cervicalis.
2.Name the deep neck spaces. Be prepared to draw pictures to help us understand. AL 1 1 Anatomy ofthe Neck: General Considerations 509 Muscles I. Scalene group 2. Levator of the scapula 3. Splenius of the head 4. Semispinal of the head 5. Rhomboids 6. Prevertebral group Nerves I. Brachial plexus 2. Cervical plexus 3. Phrenic nerve THE FASCIAE OF THE NECK (FIG. 11.1) Superficial Fascia Comprises two layers: Supraplatysmal Infraplatysmal Superficial Space #4 Space of Middle Layer Deep Fascia (Anterior Visceral) Trachea
Esophagus Retropharyngeal Space #3 (Posterior Visceral) B uccopharyngeal Middle Layer Deep Prevertebral Space #5 Danger Space #4 Prevertebral Fascia Superficial Fascia Superficial Layer Deep Fascia Deep Layer Deep Fascia Lateral Pharyngeal Space
Visceral Vascular Space Space of Superficial Layer Deep Fascia Space of Deep Layer Deep Fascia A Fasciae Spaces FIG. 11.1. A,B: Fasciae and spaces of the neck. Neck Spaces The above fasciae and the structures within the neck form real and potential spaces. Many of these compartments openly communicate with each other, and some spaces are contiguous with distant regions of the body, offering a route of rapid transit for infections. The neck spaces can be organized by their location: the face (buccal, canine, masticator, parotid), suprahyoid neck (peritonsillar, submandibular, sublingual, parapharyngeal), infrahyoid neck (anterior visceral), and along the length of the neck (retropharyngeal, danger, prevertebral, carotid). Parapharyngeal Space Also called the lateral pharyngeal or pharyngomaxillary space, the para- pharyngeal space is an inverted pyramid with its superior base at the skull base and its inferior apex at the junction of the posterior belly of the digastric muscle and greater cornu of the hyoid bone. The pterygomandibular raphe and medial pterygoid muscle bound the space anteriorly, while the prevertebral fascia bounds it posteriorly. The supe- rior constrictor, tensor, and levator veli palatini muscles form the medial boundary, and the parotid gland, mandible, and lateral pterygoid muscle bound it laterally. The styloid process divides the space into two compartments: the prestyloid compartment, which is anterior to the styloid process, and the post-styloid compartment, which is posterior to the process. The prestyloid compartment contains fat, muscle (styloglossus and stylo- pharyngeus), lymph nodes, deep lobe of the parotid, internal maxillary artery, inferior alveolar, lingual, and auriculotemporal nerves. The post- styloid compartment contains neurovascular structures: carotid artery, internal jugular vein, sympathetic chain, and cranial nerves IX, X, XI, and XII. The parapharyngeal space provides a central connection for the major deep neck spaces. It connects posteromedially with the retropha- ryngeal space, inferiorly with the submandibular space, and laterally with the masticator space. The carotid sheath courses through the space into the mediastinum. Lateral extension from the peritonsillar space directly invades the parapharyngeal space.
Submandibular and Sublingual Spaces These two spaces are best discussed together, because they functionally comprise a single space. The mucosa of the floor of the mouth forms the superior border of the submandibular space, and the digastric muscle and hyoid bone form the inferior. Anteriorly, the mylohyoid muscle and anterior belly of digastric bound the submandibular space, with the posterior belly of the digastric and stylomandibular ligament serving as its posterior borders. The hyoglossus, mylohyoid, styloglos- sus, genioglossus, and geniohyoid muscles are medial, with the platysma and mandible being lateral. The mylohyoid muscle divides the submandibular space into a superior sublingual compartment and an inferior submaxillary com- partment. This sublingual compartment is also called the sublingual space, and contains the sublingual gland and Wharton s duct. The supramylohyoid sublingual space is lateral to the geniohyoid and gen- ioglossus muscles. The sublingual space openly connects to the sub- maxillary compartment around the free posterior edge of the mylohyoid. The inframylohyoid submaxillary compartment, sometimes itself called the submandibular space, connects to its corresponding space contralat- erally and contains the submandibular gland and lymph nodes. The relationship of the mylohyoid to the tooth apices, the mylo- hyoid line, determines the most likely route of odontogenic infectious spread. The teeth apices anterior to the second molar lie superior to the mylohyoid line and thus involve the sublingual space. Infections of the second and third molars initially involve the submandibular or para- pharyngeal space, because their roots extend below the mylohyoid line. Retropharyngeal Space The retropharyngeal space, extending from the skull base to the medi- astinum at the tracheal bifurcation, refers to the lymph node and con- nective tissue containing potential space between the middle and deep layers of deep cervical fasciae. The space lies anterior to the alar fascia of the deep layer and posterior to the buccopharyngeal fascia of the middle layer that lines the posterior pharynx and esophagus. The carotid sheath is lateral to the space. It typically becomes involved by direct spread from the parapharyngeal space, or lymphatic spread from the paranasal sinuses or nasopharyngeal region, primarily in children. Danger Space The danger space, so named because of the potential for rapid inferior spread of infection to the posterior mediastinum through its loose areolar tissue, extends from the skull base to the diaphragm. This poten- tial space lies between the retropharyngeal and prevertebral spaces. The deep layer of deep cervical fascia subdivisions bound this space. The alar layer forms its anterior border, and the prevertebral layer forms its posterior border. Laterally, the transverse processes of the vertebrae enclose the danger space. The sympathetic trunk courses through this space. Infectious infiltration from the retropharyngeal, parapharyngeal, or prevertebral spaces are the primary routes to the danger space.
Prevertebral Space The prevertebral space is enclosed by the prevertebral fascia, vertebral bodies and transverse processes, and extends from the clivus of the skull base to the coccyx. It is a compact potential space that contains dense areolar tissue and lies posterior to the danger space. In addition to the paraspinous, prevertebral, and scalene muscles, it contains the vertebral artery and vein, brachial plexus, and phrenic nerve. The main pathways of spread to the prevertebral space are from infection of the vertebral bodies and penetrating injuries. Tuberculosis of the spine may breach the space and form a Pott s abscess. Masticator Space The superficial layer of deep cervical fascia defines the masticator space upon splitting at the inferior border of the mandible to cover the medial pterygoid and masseter muscles. Next, the fascia continues superiorly to cover the inferior tendon of the temporalis muscle and incorporate with the superficial temporalis fascia. It contains the mandible and muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid). The masticator space also contains the third portion of the trigeminal nerve, which enters through the foramen ovale, the internal maxillary artery, and much of the buccal fat pad. This space occupies a position anterolateral to the parapharyngeal space. The masticator space is also further divided into subspaces: the masseteric space between the masseter muscle and ramus of mandible, the pterygoid space between the pterygoid muscles and ramus, the superficial temporal space between the superficial temporal fascia and temporalis muscle, and the deep temporal space between the deep temporal fascia and temporal bone. Transmission of infection into the masticator space is most commonly from the third mandibular molars. Peritonsillar Space The peritonsillar space consists of loose connective tissue between the capsule of the palatine tonsil and the superior constrictor muscle. The anterior and posterior tonsillar pillars contribute to its anterior and posterior borders, respectively. The posterior tongue forms the inferior boundary. Peritonsillar infections may readily spread to the parapha- ryngeal space. Parotid Space The superficial layer of deep cervical fascia forms the parotid space as it splits to surround the parotid gland. However, the fascia, which does not enclose the superomedial aspect of the gland, permits communica- tion with the prestyloid compartment of the parapharyngeal space. The space also contains the facial nerve, external carotid artery, and posterior facial vein. It occupies a position lateral to the parapharyngeal space. Carotid Space The carotid, or visceral vascular, space is the potential space within the carotid sheath containing the carotid artery, internal jugular vein, vagus nerve, and sympathetic plexus. Infection from the
surrounding para- pharyngeal space, penetrating trauma, or intravenous drug use may potentiate spread into this space. Anterior Visceral Space The visceral division of the middle layer of deep cervical fascia encloses the anterior visceral space, or pretracheal space, which lies immediately anterior to the trachea. It extends from the thyroid cartilage to the superior mediastinum. It contains the pharynx, esophagus, larynx, trachea, and thyroid gland. Perforation of the anterior esophageal wall by endoscopic instrumentation, foreign bodies, or trauma may intro- duce infection to this space. 3.Where is the Lincoln Highway and what is the importance? CB 4.Microbiology of deep neck infections. CB 5.Most common etiology of deep neck infections. Name some others. TT 6.You order a lateral neck film to rule out a retropharyngeal abscess. What are the radiographic criteria for widening of this space? AL Lateral neck films are useful for quickly evaluating the upper aerodiges- tive tract in cases of suspected retropharyngeal abscess or supraglottitis. Presence of an air-fluid level or greater than 5mm of thickening in a child or greater than 7 mm of thickening in an adult of the prevertebral tissue at C2 indicate retropharyngeal infection until proven otherwise. 7.Indications for surgical management of deep neck infections. CB 8.What is Ludwig s angina? TT 9.Your friend wants to get a cat, but is worried about possible infections. What can you tell her? CB 10.Scrofula vs. non tuberculosis infections of the neck. HH 11.A patient presents with a slow growing, painless submandibular mass. Biopsies reveal gram-positive anaerobic bacillus with sulfur granules. What is the diagnosis and how should it be treated? HH