 Welcome back to OMFS lecture series. We shall continue with orophacial and neck infections. This lecture will cover the classification of facial spaces, the anatomy and infections of submental, sublingual and submandibular spaces. We had seen in the previous lecture that fascia is a band or sheet of connective tissue, primarily made up of collagen and it is found beneath the skin that attaches, stabilizes, encloses and separates muscles and other internal organs. We had also discussed that facial spaces are potential spaces that exist between the fascia and underlying organs. They are separated from each other by barriers which may be muscle, bone or fascia. How exactly does a space get infected? Here you need to understand that no such space exists unless pus gets accumulated in these specific regions referred to as tissue spaces. Some of these potential spaces are compartments which contain structures like submandibular salivary glands, buccal pad of fat or a group of lymph nodes. So normally these structures are surrounded by loose connective tissue and this connective tissue is thin and very fragile and it is easy to strip off these tissues using finger. The pus which is formed within these spaces will destroy the loose connective tissue around it and it separates the anatomical boundaries of the compartment as it increases in its volume. Thus an abscess cavity is created which is bounded by muscles and tissues. So it is now understood that over facial infections do not spread haphazardly through the loose connective tissue but they tend to accumulate in these potential spaces around the jaws. Many of these spaces also communicate with each other. Therefore a detailed knowledge of the surgical anatomy, the boundaries and the related anatomical structures is important as it facilitates planning of proper surgical drainage. Coming to the classification of spaces, Grodinski and Holiok used numbers to indicate the various deep neck spaces. Space 1, it lies superficial to the superficial fascia here and this is synonymous with the subcutaneous space. Space 2 is a group of spaces surrounding the cervical scrap muscles. The scrap muscles are the sternothyroid, thyrohyoid, sternohyoid and omohyoid. Therefore space 2 surrounds the cervical scrap muscles. Space 3 is the potential anatomical space which is superficial to the visceral division of pre-trochial layer. It was discussed in the previous lecture that the pre-trochial layer of the deep cervical fascia is divided again into visceral and muscular divisions. Therefore space 3 is related to the visceral division of the pre-trochial layer and space 3a. Space 3a is the carotid sheet. Here is the carotid sheet. Space 4 is the potential space that lies between the lr fascia and the pre-vertibule fascia. This is the pre-vertibule fascia which lies just in front of the vertebral column and here is the lr fascia. Therefore danger space or space 4 is lying between the lr fascia and the pre-vertibule fascia. Space 4a this is associated with the posterior triangle and it lies posterior to the carotid fascia or the carotid sheet. Space 5 is pre-vertibule space and space 5a is enclosed by the pre-vertibule fascia which is posterior to the transverse process. If this is the vertebrae and this is the transverse process space 5a is formed by the pre-vertibule fascia which lies in the posterior aspect of the vertebrae surrounding the scalene muscles. We had seen the cross-sectional image of the neck at the level of C7 vertebrae. Here is the sagittal section. You can see that the buccal pharyngeal fascia is separated from the pre-vertibule fascia by retro-pharyngeal space. What is danger space? It is the potential space between the lr fascia and the pre-vertibule fascia and it extends from the base of the skull to the posterior medial stenum as far as the diaphragm. The lr fascia fuses with the retro-pharyngeal fascia at a variable level between the sixth cervical vertebrae and the fourth thoracic vertebrae. That means the lr fascia and the retro-pharyngeal fascia fuses in between somewhere in between C6 and T4. So this fusion forms the base of the retro-pharyngeal space somewhere over here. Infections of the retro-pharyngeal space can rupture the lr fascia thus entering the danger space which is continuous with the posterior medial stenum. So this is the significance of danger space. If there is an infection of the retro-pharyngeal space it will rupture or tear the lr fascia thus entering the danger space which extends up till the posterior medial stenum. Let us see how these facial spaces are classified. Facial spaces can also be divided based on its mode of involvement to the nidus of infection. It is divided into primary space or spaces with direct involvement and secondary spaces or those with indirect involvement. Spaces involved in autotogenic infections can again be classified into primary maxillary spaces that means those spaces associated with the upper jaw or maxilla. Primary mandible are spaces those involved in lower jaw infections and secondary facial spaces. All these spaces will be discussed in detail individually. Based on clinical significance facial spaces are classified into those present on face in the supra-hioid region in the infrahioid region and spaces of total neck. First facial space we are going to discuss is the submental space which is a potential primary space related to the mandible. In this image we are viewing the submental space from below. Imagine you are standing at the hyoid bone level and looking up to see the submental space. Here you can see that the space is bounded laterally by the lower border of mandible and anterior bellies of digastric muscle. Superiorly is the mylo-hioid muscle which forms the floor of the mouth. Inferiorly is the investing layer of deep cervical fascia. Superiorly you have the mylo-hioid muscle. Inferiorly the investing layer of deep cervical fascia and laterally the lower border of mandible and the anterior bellies of digastric muscle. The submental space contains submental lymph nodes and anterior jugular veins. Submental space is involved most frequently by the infections originating from the six anterior mandibular teeth. Infected skin wounds or anterior mandibular fractures can also cause infections of the submental space. How does an autogenic infection in the anterior mandible cause infection of the submental space? For the space to get infected the infection has to first perforate the cortical plate and this perforation is just below the attachments of the mentalis muscle, lebeli and mylo-hioid muscle, linguali. If the perforation of the cortical plate is below the attachments of these muscles then that will result in submental space infection. Extroval findings of submental space infection is distinct firm swelling in the midline beneath the chin as you can see in the diagram here. The skin overlying the swelling is hard and taut. Fluctuation may be present. Intraoral findings include the anterior teeth which are either non-vital, fractured or garrious. The offending tooth may exhibit tenderness to percussion and it may also show mobility. The patient will also experience considerable discomfort on swallowing. This diagram shows the incision needed for drainage of a submental space infection or a submental abscess. The drainage is performed by making a transverse incision in the skin just below the symphysis of the mandible. A blunt dissection is carried out by inserting a sinus forceps through this incision in upward and backward direction. Later a small piece of corrugated rubber drain is inserted into the abscess cavity and is secured to one of the margins of the wound using a suture. The next potential primary space associated with the mandible is the sublingual space. This space is v-shaped and it lies lateral to the muscles of tongue. The teeth which frequently gets involved in sublingual space infection are the mandibular incisors, canines, premolars and sometimes the first molars. The epises of these teeth are superior to the myelohyroid muscle. Therefore the autogenic infections from these teeth are confined to the sublingual space whereas if the root epises extends beyond the myelohyroid muscle then the infection will spread into the submandibular space which lies just beneath the sublingual space. The boundaries of the sublingual space are the mucosa of the flow of the mouth which is just superior to the sublingual space. So above the sublingual space it is only the mucosa of the flow of the mouth which is present. Inferiorly is the myelohyroid muscle. Laterally there is medial side of the mandible above the myelohyroid muscle. Medially is the tongue muscles, all the hyoglosses, genioglosses and geniohyroid muscles and posteriorly is the hyoid bone. So this is the sublingual space bounded by the mucosa of the flow of the mouth, superiorly, inferiorly by the myelohyroid muscle, laterally by the medial side of the mandible just above the myelohyroid muscle, the tongue muscles medially and posteriorly by the hyoid bone. Then so of the sublingual space include the tongue muscles, also deep part of the submandibular salivary gland and its duct, sublingual salivary gland, the lingual nerve and the hypoglossal nerve. Exteriorly there is little or no swelling. The lymph nodes may be enlarged and may be tender. Pain and discomfort is experienced by the patient on deglutition. Speech also may be affected. Introwerly a firm painful swelling is seen in the flow of the mouth on the affected side. The flow of the mouth may be raised and the tongue may be pushed superiorly. Elevation of the tongue is the clinical hallmark of the sublingual space infection. This will bring about airway obstruction if the tongue and the flow of the mouth is raised that can cause airway obstruction. The ability to protrude the tongue beyond the vermilion border of the upper lip is also an important sign in sublingual space infection. Surgical drainage of sublingual axis can be performed both intra and extraorally. Intraorally an incision is made close to the lingual cortical plate lateral to the sublingual plica. The important structures to be taken care here are the lingual nerve, the water duct and the sublingual vessels. Extraoral approach is preferred when both the submental and sublingual spaces contain pus and it can be drained via skin incision placed in the submental region. Similarly when submanupla space is also involved a sublingual space abscess can be approached and drained through an incision in the skin overlying the submanupla space. The spread of infection from the sublingual to other spaces or region is possible. The infection always crosses the midline and it can affect the space on the opposite side. Infection from the posterior inferior part of the space can spread around the submandibular gland into the submandibular space. Similarly infection can also spread via lymphatics to the submendial or submandibular lymph nodes. The sublingual space is separated from the submendial space by myelohyoid muscle in the anterior region. Therefore the spread to the submandibular region occurs most often as a result of lymphatics spread to the submandibular lymph nodes. The diagram here shows that the sublingual space is evacuated. Incision was placed, drainage is performed and the space is evacuated following which a corrugated rubber grain is inserted into the space through the extraoral incision. So it passes the anterior belly of digastric, the myelohyoid muscle and it emerges into the sublingual space. So this is performed on either side, it is performed bilaterally through the same incision you can place two rubber grains into the submandibular space on either side. Moving on to submandibular space. The submandibular and submandibular spaces are quite distinct anatomically. Still they are considered as a single surgical unit because of their proximity and frequent dual involvement in autogenic infections. Let's have a look at the boundaries that form the submandibular space. Anteiromedially the floor of the submandibular space is formed by the myelohyoid muscle anteriorly and posterior medially the floor is formed by the hyoglossus muscle. So there are two muscles which form the medial extant of the submandibular space which are the myelohyoid and the hyoglossus muscle. Myelohyoid muscle also form the separation because between the sublingual and submandibular space. As you can see in this diagram this is the myelohyoid muscle which separates the submlingual space from the submandibular space. Supido laterally the medial surface of the mandible forms the limit. So if this is the mandible the medial aspect of this mandible below the myelohyoid ridge. It forms the supido lateral boundary of submandibular space. Postero superiorly is the anterior belly of digastric. Here is the anterior belly of digastric and posterior superiorly is the posterior belly of digastric. Laterally the space is covered by platysma and skin. The submandibular space contains the superficial lobe of submandibular salivary gland and the submandibular lymph nodes. It also contains facial, artery and vein. How do autotogenic infections extend to submandibular space? This space is involved most frequently by infections originating from mandibular molars. The pus perforates the lingual cortical plate of mandible inferior to the attachment of the myelohyoid muscle and the infection passes directly to the submandibular space. It was told earlier that the teeth responsible for sublingual space infections are the mandibular anterior teeth as well as premolars. It is because their teeth apices were confined superior to the myelohyoid muscle whereas the teeth apices of the mandibular molars extend beyond the myelohyoid muscle thus extending the infection to the submandibular space. The infection from the submandibular salivary gland may also pass through lymphatics to the submandibular region. The submandibular space infections can also be a result of infections originating from the middle third of the tongue and posterior part of the flow of the mouth. The diagnosis of submandibular space infection can be confirmed by the presence of firm swelling in submandibular region just below the inferior border of mandible. The patient will present with generalized constitutional symptoms like fever, lethargy and malaise. There will be some degree of tenderness present at the overlaying skin which will be erythematous or redding color. Intraoral findings include sensitive teeth which are tender on percussion, mobile teeth, dysphagia and moderate swissness. The surgical drainage of apices from the submandibular space can be performed by placing an incision of about 1.5 to 2 cm length, 2 cm below the lower border of mandible within the skin crease. The skin and subcutaneous tissues are incised, a sinus forcep is inserted through the incision in superior and posterior direction on the lingual side of the mandible below the myelohyold. This will release pus from submandibular space. Later, a corrugated rubber drain is inserted into the abscess cavity and is secured with a suture. Adversing can also be applied. Coming to the spread of infection from submandibular space. There are no major anatomic barriers between the two submandibular and submental spaces. Hence, infection can extend into the submental space as well as the contralateral submandibular space. The submandibular space also communicates with sublingual space around the posterior border of myelohyold muscle. Pediphenyl spaces can also get involved when there is a backward spread of infection. So that's all about the submental, sublingual and submandibular space infections. Rest of the facial spaces shall be explained in subsequent lectures. Thank you.