In the neck, we find the beginning of the digestive system, the beginning of the respiratory system, and many sense organs: eye – ear – olfaction – taste.
The bony palate is made up of the bones: upper jaw + palatine, horizontal blade, we represent the severed mandible. The hyoid bone is cut.
The mandible is connected to the hyoid bone by muscles that appear on the floor of the mouth: the genio-hyoid muscles. On it, the muscle mass of the tongue is supported. Behind the base of the tongue, there is a cartilaginous lamella: the epiglottis. The wall of the esophagus continues up to the base of the skull through the pharyngeal wall.
2. Respiratory System
It is made up of the nasal cavities, above the oral cavity, separated by the bony palate in front and behind by the soft palate: the uvula, uvula. Around them, there are the pneumatic cavities of the face: the paranasal sinuses which do not belong to the respiratory tract but which are annexed.
The inspired air enters through the nostrils. Behind the nasal cavities, it descends into the pharynx and then enters the larynx before descending into the trachea and into the bronchi.
3. Digestive system
The oral cavity is the first part of the digestive tract. Back, food enters the pharynx and below it, it descends into the esophagus.
The pharynx is an aerodigestive crossroads.
The airways project back onto the sphenoid. The oral cavity projects back onto C1 and C2.
4. Digestive Viscera / Oral Cavity
The upper jaw has an alveolar dental arch for implanting the teeth. Towards the rear, it is extended by the horizontal blade of the palatine. The genio-hyoid muscle belongs to the constitution of the floor of the mouth.
The upper part is formed by the bony palate extended behind by the soft palate: the soft palate. On the midline, there is a growth: the uvula or uvula.
The oral cavity is occupied by the muscle mass of the tongue.
Above the oral cavity, we find the sinuses of the upper jaw, and on either side of the midline, the nasal cavities. Towards the bottom, the oral cavity is limited by a muscle which fits into the internal face of the mandible, an even muscle: the mylohyoid muscle.
It is roughly shaped like a horseshoe, like the hyoid bone. The mylohyoid muscle is stretched from the inside of the mandible to the midline and back to the body of the hyoid bone. On the midline, the two mylohyoid muscles meet. There is therefore a raphe of the floor of the mouth. These muscles wall down the oral cavity.
Below the mylohyoid muscles, there are the two digastric muscles, small muscles with two small bodies.
On the outer face of the jawbones, there are the buccinator muscles, of the cheeks, and in the oral cavity, we find the muscle mass of the tongue.
Limits of the oral cavity:
above: the bony palate = upper jaw + soft palate.
bottom: floor of mouth = mylohyoid muscle
laterally: two parts: outside, the alveolo-dental arches, and inside the cheeks, there is the vestibule, lined on the bone by a mucous membrane: the gum. At the level of the lips, the mucosa continues through the skin covering. The lips have a muscular apparatus: the orbicularis muscle of the lips.
lower = muscle limit.
The oral cavity is lined inside by a mucous membrane which is inserted at the tooth / bone junction, in continuity with that of the tongue. At the level of the soft palate, it continues with that which lines the nasal cavities.
Anterior opening = labial opening.
Posterior orifice, it is orifice which connects the oral cavity and the pharynx, it is the throat isthmus. It is limited above by the soft palate and below by the base of the tongue and laterally by the pillars of the veil.
The oral cavity contains the teeth at the level of the dental arch, ie: 2 incisors, 1 canine, 2 premolars, 3 molars.
5. The Tooth
It is inserted into the bone and has three parts:
– emerging = the crown
– in the bone = the root
– crown – root junction is the collar.
It is essentially made up of dentin or called ivory. Ivory is covered at the level of the crown by the hardest substance in the body: enamel. At the root level, the enamel is covered by the cementum. In the root is the pulp cavity: there are vessels, and the nerve.
The area that connects the tooth to the bone proper is the periodontium.
Periodontium + cementum = periodontium.
It has a double function: sensory-sensory organ and motor organ. There is a muscle mass, it is involved in chewing, swallowing, and also in phonation.
It is made up of 17 muscles, the main one being the genio-glosse muscle, which is inserted on the mandible on the superior geni process above the genio-hyoid muscle. It is an even muscle. It radiates like a fan in the language. Between the two genio-gloss muscles is the lingual septum, a fibrous skeleton for the tongue. Below the tongue there is the genio-hyoid muscle.
Innervation: the XIIth cranial nerve = nerve or large hypoglossal.
Sensory function = burns, stings, function provided by the lingual nerve, branch of the 5th cranial or trigeminal nerves.
Sensory function = taste role, thanks to the presence of the papillae, and role provided by the nerve which innervates the region of the lingual papillae, the glosso-pharyngeal nerve known as the IXth cranial nerve.
It has one end: the tip, two lateral edges and a root: implantation on the floor of the mouth, and a base, posterior part. The upper side is the back. On him, we notice a series of 9 papillae in V: the lingual V. These are the largest papillae, called goblet papillae.
Behind the V, there is the base of the tongue. It is raised by small nipples which also lift the mucous membrane: these are lymphoid organs, the lingual tonsil.
Innervation: the anterior 2/3 of the tongue are innervated by the 7th bis cranial nerve: the intermediate Wrisberg nerve.
7. The Annex Glands
These are the salivary glands which appeared in the species coming out of the water. Role: humidification of the oral cavity. They are not located in the oral cavity, but around.
There are three main salivary glands:
• the most voluminous, the parotid gland which is placed in front of the external auditory canal behind the ascending branch of the mandible. It has an excretory canal which opens in the oral cavity at the level of the cheek opposite the second upper molar: the Sténon canal
• the submandibular gland, which is located on the internal face of the angle of the mandible, but often extends beyond it. Its excretory duct, Wharton’s duct, is located below the floor of the mouth on the inner side of the mandible, and opens into the oral cavity down anterior to the root of the tongue.
• the sublingual gland, located on the inner side of the mandible under the lining of the floor of the mouth. This gland has a lot of ducts.
These three glands are aligned from front to back about at the level of C3. Be careful, there are not only 6 salivary glands, these are the main ones. The inner surfaces of the lips contain a lot of it, and small sizes.
In the fetus, the stomodeum is the future oral cavity.
8. Temporo-Mandibular Joint
It is placed in front of the external auditory canal and comprises two elements: the glenoid cavity of the temporal just in front of the external auditory canal and the temporal condyle, articulated with the mandibular condyle. These are two convex surfaces. The glenoid intervenes little. This joint has a meniscus which improves the congruence of surfaces.
There is a joint capsule adhering to the external face of the meniscus plus internal and external ligaments which will strengthen this joint.
This joint is mobilized by 4 masticatory muscles:
– masseter muscle
– lateral pterygoid muscle
– medial pterygoid muscle
All are innervated by the motor branch of the 5th cranial nerve.
Behind the oral cavity, the digestive system is extended by the pharynx.
9. The Pharynx
It is a musculo-membranous organ in the form of a gutter open towards the front. It is made up of flat muscles open towards the front. It contains two types of muscles: the constrictors and the elevator.
– The lower constrictor muscle is inserted on the cricoid cartilage
– The middle constrictor muscle is inserted on the small and large horns of the hyoid bone.
– The superior constrictor muscle is inserted on the inner wing of the pterygoid bone.
These muscles are covered on the outside by the peripharyngeal fascia.
Inside the pharynx, there is a mucous membrane.
Just behind the pharynx are the vertebral bodies of the cervical spine, lined by the prevertebral muscles, covered by the deep cervical aponeurosis. Sagittal laminae unite the pharynx to this deep cervical aponeurosis. : there is therefore a space, called avascular, retro pharyngeal.
The pharynx is about 15 cm high, it extends from the base of the skull to the lower edge of C6. It is a median organ. In C6, it opens forward in the larynx and behind it continues through the esophagus.
Just below the base of the skull, the lining of the pharynx is lifted by the pharyngeal tonsil. We can see the choanae, the posterior opening of the nasal cavities. There, the pharynx communicates with the nasal cavities: it is the nasopharynx or nasopharynx, the upper part of the pharynx. Below the rhino pharynx, there is the soft palate which separates the nasal cavity from the throat isthmus; we also see the base of the language. The veil separates the nasopharynx from the oropharynx. The oropharynx stops below at the level of a relief raised by a cartilaginous lamella, this is the epiglottis. It marks the entrance to the third part: the laryngopharynx.
On each side of the laryngopharynx, the wall of the pharynx forms a vertical gutter into which food enters, the laryngopharyngeal gutter or piriformis recess.
The hyoid bone is connected to the epiglottis by the hyoepiglottic membrane. We cut the floor of the nasal cavity.
– the nasopharynx projects back onto the sphenoid;
– the oropharynx on C1 and C2;
– the laryngopharynx on C3 to C6.
The posterolateral wall is occupied by an orifice which places the oropharynx and the eardrum in communication: the tubal orifice, or orifice of the Eustachian tube.
Below, there are two reliefs at the level of the oropharynx: on the lateral wall: one anterior, the other posterior. These are the pillars of the tonsillar lodge, lodge in which is the palatal amygdala.
Under the lining of the base of the tongue is the lingual tonsil.
The respiratory system begins at the level of the nasal passages.
10. The Nasal Pits
They are located above the oral cavity, below the base of the skull between the orbital cavities and the maxillary sinuses.
They have several parts:
– upper wall, narrow, formed by the horizontal blade of the ethmoid, screened blade;
– middle wall: separates the right nasal fossa from the left, formed by the perpendicular blade of the ethmoid, the vomer and cartilages;
– lateral wall, the most complex, formed by six bones: upper maxilla, unguis or lacrimal bone, ethmoid or lateral masses, lower horn, palatine, sphenoid.
This wall has reliefs: the cones.
These are bony lamellae, there are three: upper, medium, lower. The upper and middle turbinates are dependent on the ethmoid. The inferior turbinate is an autonomous bone which is implanted on the lateral wall of the nasal cavities;
– floor, the lower wall, formed by the palatal process of the upper jaw and the horizontal blade of the palatine;
– anterior orifice: orifice of the nostrils, cartilaginous;
– posterior orifice: bony orifice formed on the midline by the posterior edge of the vomer and laterally by the pterygoid processes of the sphenoid.
Two functions: respiration, the first element of the upper airways and also, olfaction: the super-internal mucosa of the nasal cavities presents the receptors for olfaction.
Above the lower horn, the lacrimal duct is touched. Under the superior and middle turbinate, open the channels which put in communication the nasal cavities and the paranasal sinuses: these air cavities are represented above the orbit by the frontal sinus, the ethmoidal cells between the nasal cavities and the orbits, the maxillary sinuses in the upper jaw bone, one to the right, one to the left, and the sphenoid sinus. These cavities are filled with a mucous membrane, epithelium.
In the baby, there are no frontal sinuses, they develop with the face. These air cavities have a double role: 1- warm the inspired air, and 2- lighten the weight of the skull.
Behind the choanes, the upper airways enter the pharynx.
11. The Larynx
It is a cartilaginous musculo-aponeurotic organ, it is placed in front of the pharynx. It is palpable.
The larynx is separated from the mouth by the hyoid bone, located at the C4 level below the mandible, in the midline.
Below the hyoid bone begins the larynx: the first cartilage is the thyroid cartilage formed by a plate: the thyroid plate which continues at the top behind by the large horns of the thyroid cartilage and at the bottom behind by the small horns thyroid cartilage. On each side there is an oblique crest down medially where the subhyoid muscles attach. Below, the cricoid cartilage is less prominent than the thyroid cartilage. The cricoid cartilage is annular. Seen from the front, it is much higher in its anterior part than in its posterior part.
Below, the larynx ends with the trachea at the lower edge of C6.
The cricoid cartilage articulates with two small triangular cartilages: the arytenoid cartilages. They belong to the cartilages of the larynx, like the epiglottis. Thin lamella, concave in its upper part, and convex in its lower part which is placed behind the hyoid bone, behind the re-entrant angle of the thyroid cartilage, it rises above the hyoid bone.
These elements are joined together by a membrane: the thyro-hyoid membrane at the top, then crico-thyroid, then crico-tracheal, and finally, the tracheal membrane which closes the trachea behind.
The arytenoid cartilages are connected to the reentrant angle by muscles of the larynx which make the sound vibrate: the vocal muscles. The mucous membrane of the pharynx insinuates itself on each side of the larynx to form the laryngopharyngeal gutters or piriformis recess. The larynx is a respiratory organ and an organ of phonation. It is narrower, higher in women than in men, hence the higher-pitched voice.
The hyoid bone does not belong to these cartilages, but it is the boundary between the oral cavity and the larynx.
11.1. Thyroid cartilage
It’s a cartilage plate, the thyroid plate. Viewed in profile, it forms a re-entrant angle and a bony projection towards the front: the Adam’s apple. On this plate there is an oblique ridge with a tubercle at its end. On the lower slope of the ridge, insertion of the sternothyroid muscle and on the upper slope, insertion of the thyro-hyoid muscle. This plate also gives insertion on either side of the plate to the lower constrictor muscles of the larynx. The upper edge of the plate is extended upwards, by the upper horns or large horns. Down, ditto, we have the little horns. The small horns articulate with the cricoid cartilage.
11.2. Cricoid cartilage
It has a circular shape. It is a cartilaginous ring whose anterior part or anterior arch is relatively narrow, and the posterior or posterior arch is higher. It is the cricoid plate. Below the cricoid cartilage begins the trachea.
The crico-thyroid joint and the cricoarytenoid joint are united by membranes, notably the thyro-hyoid, which is thickened laterally by the lateral thyro-hyoid ligaments and medially by the medial thyrohyoid ligament. Towards the bottom, the lower edge of the thyroid cartilage is connected to the upper edge of the cricoid by the crico-thyroid membrane. Below, there is the cricotracheal membrane that connects the cricoid to the first tracheal ring. The epiglottis is connected to the re-entrant angle of the thyroid cartilage by a ligament. There is also a hyoepiglottic membrane.
The muscles surround these membranes, close the larynx and mobilize the joints.
There is a lining lining the inside of the larynx. There are three parts: upper, middle, lower which flares out. Under the mucous membrane, there is the elastic cone of the larynx: it is a membrane which gives a consistency. Surrounding the cone, the muscles.
The crico-thyroid muscle connects the cricoid cartilage and the thyroid. The upper part of the mucosa is the entrance to the larynx, very inclined downwards backwards, it has a funnel shape. There are two glosso-epiglottic dimples. This upper part is called the laryngeal vestibule.
In the middle part, the glottis narrows: it is the phonatory part of the larynx.
The lower part is the subglottic space that communicates with the trachea. In the end, the glottis is limited by two narrowing: upper, the ventricular bands, and lower, the vocal cords.
Between the two, the laryngeal cavity presents a dilation: the ventricles of Morgagni, dilation which is extended by an upward diverticulum: the ventricular appendage. The strictures correspond to muscles, in the vocal cords, and ligaments: for example, the lower thyro-arytenoid ligament is the vocal ligament. The vocal muscle is the lower thyro-arytenoid muscle.
On the cricoid plate, the arytenoid cartilages are cut. These cartilages are roughly triangular, and they present an anterior process: the vocal process. The vocal ligament is inserted there up to the angle of the thyroid cartilage. On the thyroid cartilage, the inferior constrictor muscle of the pharynx inserts and surrounds the pharynx back. The lining of the pharynx penetrates each side of the larynx to form the laryngo-pharyngeal aligners.
The ice space therefore has two parts:
– anterior, membranous, which is the phonatory part;
– posterior, cartilaginous, between the arytenoid cartilages.
The vocal muscle is the tensor of the vocal cords. The cricoarytenoid muscle is the only dilator.
All of these muscles are innervated by the lower laryngeal nerve.