Human Anatomy - Neck PDF

PART III NECK OLSZTYN 2019 30 Lab. session 3 1. Larynx and Laryngopharynx 1. Cartilages of the larynx 2. Articulations of the laryngeal cartilages 3. Muscles of the larynx 4. Interior of the larynx 5. Vessels of the larynx 6. Nerve supply of the larynx 2. Oesophagus. Cervical portion 3. Trachea. Cer...

PART III NECK OLSZTYN 2019 30 Lab. session 3 1. Larynx and Laryngopharynx 1. Cartilages of the larynx 2. Articulations of the laryngeal cartilages 3. Muscles of the larynx 4. Interior of the larynx 5. Vessels of the larynx 6. Nerve supply of the larynx 2. Oesophagus. Cervical portion 3. Trachea. Cervical portion 4. Thyroid gland 5. Parathyroid glands 6. Vagal nerve 1. Pathways of the CN X 7. Accessory nerve ( CN XI ) NECK 31 1. The pharynx The pharynx is a common passage for the alimentary and the respiratory systems. It is a muscular tube extending from the base of the skull to the lower border of cricoid cartilage of the larynx (at the level of the 6th cervical vertebra, measuring about 12 cm in length, greatest width 5 cm). It becomes ( a width of 1.5 cm) the upper part of the oesophagus at the lower border of the cricoid cartilage (opposite C 6). The pharynx is subdivided into three regions: a. the nasopharynx b. the oropharynx c. the laryngopharynx. It communicates with: the nose the mouth the larynx the oesophagus the middle ear Relations of pharynx: - it is located in front of the vertebral column (prevertebral muscles & fascia) - it is a part of the visceral compartment of the neck - it is situated behind the nose, mouth, and larynx. The walls of the pharynx : a. the mucous coat is a continuous with that of the nose, middle ear, oral cavity, larynx, and oesophagus b. submucous coat is thickened superiorly, where the muscular coat is deficient, to form the median pharyngeal raphe c. pharyngobasilar fascia which is attached to the base of the skull d. muscular coat comprises: the superior constrictor muscle (musculus constrictor superior) O: Pterygoid hamulus, pterygomandibular raphe, mylohyoid line of the mandible and side of the tongue I: Median raphe of the pharynx. The inferior fibers of the superior constrictor muscle are overlapped by the middle constrictor muscle. NECK 32 middle constrictor muscle (musculus constrictor medius) O: Stylohyoid ligament and horns of the hyoid bone I: Median raphe of the pharynx inferior constrictor muscle (musculus constrictor inferior) O: Thyroid cartilage and side of the cricoid cartilage I: Median raphe of the pharynx F: All constrictor muscles constrict the wall of the pharynx during the act of swallowing. The constrictors are paired muscles which unite in a median raphe. The fibrous band of the raphe extends from the pharyngeal tubercle (above) to the inferior border of the inferior constrictor muscle. palatopharyngeus muscle (musculus palatopharyngeus) O: Hard palate I: Posterior border of the lamina of the thyroid cartilage salpingopharyngeus muscle (musculus salpingopharyngeus) O: Auditory tube (cartilaginous part) I: blends with palatopharyngeus F: With stylopharyngeus and palatopharyngeus elevates pharynx and larynx durig swallowing N: All muscles described above are supplied by the pharyngeal plexus (branches from the superior laryngeal nervus , from CN X). the stylopharyngeus muscle (musculus stylopharyngeus) enters the pharyngeal wall in the gap between the origins of the superior and middle constrictor muscles O: Styloid process (medial aspect, base of the styloid process) I: Descends medially from the superior and middle constrictor and inserts into the posterior and superior borders of the thyroid cartilage. CN IX follows the lateral margin of the stylopharyngeus. CN IX supplies the stylopharyngeus. NECK 33 Fig. 5-16. Muscles of the pharynx 1.1. The laryngopharynx The laryngopharynx extends from the upper border of the epiglottis and the posterior surfaces of the arytenoid and cricoid cartilages, where it is continuous with the oesophagus. It is delineated from oropharynx by lateral glosso-epiglottic folds (plica glossoepiglotica). In the anterior part of the laryngopharynx lies the inlet of the larynx. It is bounded: - above by: the upper border of the epiglottis - below b y: the arytenoid cartilages - laterall y: by aryepiglottic folds. The lateral wall of the laryngopharynx is bounded by the lamina of the thyroid cartilage. Between the inner surface of this lamina and the outer surface of the cricoid and arytenoid cartilages is found a recess called the piriform fossa or the piriform recess (recessus piriformis). The piriform recess is bounded by: a. laterall y by the mucous membrane over the lamina of thyroid cartilage b. mediall y by the mucous membrane over the aryepiglottic folds, the arytenoid, and cricoid cartilages. NECK 34 2. Oesophagus. Cervical portion Oesophagus (oesophagus) is the alimentary tube connecting the laryngopharynx to the stomach. It begins at the lower border of the cricoid cartilage. Relations: Located in the visceral compartment of the neck between the vertebral column and the trachea (more about thoracic portion of the oesophagus see thorax labs). 3. Larynx Larynx A (larynx) mucous is the respiratory membrane with passage between pseudostratified the pharynx ciliated and epithelium the trachea. lines it. In adults, the larynx measures about 5 cm in length. Relations: It lies in the visceral compartment of the neck, at the level of the C3 and C6 vertebra below - hyoid bone behind - thyroid gland medially - carotid sheath. The skeleton of the larynx is formed by: cartilages joints ligaments membranes 3.1. Cartilages of the larynx a. Thyroid cartilage (cartilago thyroidea) - is shield-shaped and comprises of two quadrilateral laminae united anteriorly in the laryngeal prominence (Adam's apple). Thyroid cartilage has two surfaces: external surface includes: * oblique line or ridge (linea obliqua) with: - superior thyroid tubercle (tuberculum thyroideum superior) - inferior thyroid tubercle (tuberculum thyroideum inferior) internal surface includes: NECK 35 * attachments for the following ligaments and muscles: - vestibular ligament - vocal ligament - thyroepiglotticum ligament - thyroarytenoideus muscle - palatopharyngeus muscle. Thyroid cartilage has two borders: superior border contains the superior thyroid notch and the superior horns inferior border contains the inferior thyroid notch and the inferior horns. b. Cricoid cartilage (cartilago cricoidea) - is signet ring-shaped and is situated at the lower border of the larynx. The cricoid cartilage has two parts: the arch (arcus cartilaginis cricoideae) is located anteriorly. On the superior surface of the arch is the cricothyroid ligament and the conus elasticus On the inferior surface of the arch is the cricotracheal ligament. the lamina of cricoid cartilage (lamina cartilaginis cricoideae) is located posteriorly and contains facets for the arytenoid and thyroid cartilages.( arytenoids articular and thyroid articular surfaces ). c. Epiglottis (cartilago epiglottica, epiglottis) - is leaf-shaped. The epiglottic cartilage has two surfaces: anterior - lingual posterior - laryngeal. The stalk of epiglottis is formed by inferior part of cartilage and thyro-epiglottc ligament, which is attached to internal surface of thyroid cartilage. d. Arytenoid cartilage (cartilago arytenoidea) - has the shape of a three - sided pyramid. The arytenoid cartilage has three surfaces: posterior /concave/ medial anterolateral there are present following structures going from the superior part to inferior part of cartilage: colliculus, triangular fovea, arcuate crest and oblong fovea. * anterior process is referred to as the vocal process. It is the place of attachment of the vocal ligament NECK 36 * lateral process is referred to as the muscular process. It is the place of attachment of some of the muscles of the larynx. There are three minor cartilages of the larynx: e. Corniculate cartilages (cartilago corniculata) - small conical bodies that are situated at the tip of the arytenoid cartilage f. Cuneiforme cartilages (cartilago cuneiformis) lie within the aryepiglottic folds g. Triticeal cartilages (cartilago triticea) - lie within the thyrohyoid ligament. 3.2. Articulations of the laryngeal cartilages There are five articulations of the laryngeal cartilages: a. Cricothyroid joint (articulatio cricotyroidea) is a plane synovial joint located between the inferior horn of the thyroid cartilage and the lateral aspect of the cricoid cartilage. b. Crico-arytenoid joint (articulatio cricoarytenoidea) is a plane synovial joint between the base of arytenoid cartilage and the surface of the upper border of the cricoid lamina. c. The quadrangular membrane (membrana quadrangularis) aryepiglottic membrane that pass from the lateral margin of the epiglottis to the arytenoid cartilage. It has two free borders: the upper and posterior borders form the aryepiglottic fold the lower border forms the ventricular fold ( false vocal cord ). d. Conus elasticus, cricovocal membrane (conus elasticus) is triangular in shape, having an upper free border that is deep to the thyroid lamina, a lower border which is attached to the cricoid cartilage, and an anterior border which is continuous with the ligament of the opposite side. The free border extends from the back of the laryngeal prominence to the vocal process of the arytenoid cartilage and forms the vocal fold (true vocal cord). e. Thyrohyoid membrane (membrana thyrohyoidea) is a fibrous membrane uniting the upper border of the thyroid cartilage to the posterior surface of the body and the greater horns of the hyoid bone. NECK 37 3.3. Muscles of the larynx The muscles of the larynx can be divided into two catagories. a. The extrinsic muscles of the larynx have attachment outside the larynx: the infrahyoid muscles stylopharyngeus muscle inferior constrictor muscle b. The intrinsic muscles of the larynx are confined to the larynx: cricothyroid muscle (musculus cricothyroideus) extends from the inferior horn and lower border of the thyroid cartilage to the outer anterolateral surface of the cricoid cartilage. There is straight and oblique parts of this muscle. posterior crico-arytenoid muscle (musculus cricoarytenoideus posterior) passes from the posterior surface of the lamina of the cricoid to the muscular process of the arytenoid cartilage lateral crico-arytenoid muscle (musculus cricoarytenoideus lateralis) passes from the lateral surface of the cricoid arch to the muscular process of the arytenoid cartilage transverse and oblique arytenoid muscles (musculus arytenoideus transversus et obliqus) are attached to the posterior surface of both arytenoid cartilages thyroarytenoid muscle (musculus thyroarytenoideus) passes from the back of the laryngeal prominence along the outer surface of the conus elasticus to the anterolateral surface of the arytenoid cartilage. Some fibres are attached to the free border of the conus elasticus and form the vocalis muscle, other fibers pass upwards towards the side of the epiglottis forming the thyro-epiglottic muscle. aryepiglotticus is located in ary-epiglottic fold. All intrinsic muscles except the cricothyroid muscle (supplied by superior laryngeal nerve) are supplied by the inferior laryngeal nerve - a branch from the reccurent laryngeal nerve. Muscles of larynx serve as sphincters of rima glottides except posterior crico-arytenoid muscle which works as dilator of rima glottides and cricothyroid muscle which makes tense of vocal folds. NECK 38 3.4. Fig. Ryc. 5-17. Larynx, thyroid gland and trachea. 3.5. 1.4. Interior of the larynx It is subdivided into three portions: upper, middle, and lower part. a. The upper portion, supraglottic portion (pars supraglottica) of the larynx extends from the laryngeal inlet to the vestibular folds. Inlet to the larynx (aditus ad laryngem) includes: The free upper border of the epiglottis forms the base of the triangle (the inlet is triangular in shape) Apex of the triangle is located between the two aryepiglottic folds (plicae aryepiglotticae) at the interarytenoid notch (incisura interarytenoidea) The inlet of the larynx has four walls: * anterior wall: the epiglottis and the thyroid cartilages * lateral walls: the aryepiglottic folds * posterior wall: the interarytenoid notch NECK 39 Piriform recess (recessus piriformis) is located laterally to the inlet of the larynx. b. The middle portion - glottis (pars glottica) is the smallest part of larynx and is bounded by the vestibular and vocal folds. The gap between the vestibular folds is known as the rima vestibuli (rima vestibuli). The gap between the vocal folds and vocal process of the arytenoid cartilages (posteriorly) is known as the rima glottidis (rima glottis) or glottis. That part between the vocal ligaments is called the intermembranous part or phonation part. That part between the arytenoid cartilages is called the inter-cartilaginous or respiratory part. The mucous membrane between the vestibular and vocal folds has slit like pace is known as ventricle or sinus of the larynx. A small pouch of mucous called the saccule extends upwards from the anterior and of each ventricle between the vestibular fold and the inner surface of the thyroid cartilage. The intermittent release of expired air between the adducted vocal folds results in their vibration and in the production of sound. The frequency of the voice is determined by changes in the length and the tension of the vocal ligaments. The quality of voice production is controlled by the muscles of the soft palate, tongue, floor of the mouth, cheeks, and lips. Vowel sounds are usually purely oral with the soft palate raised where the air is channeled through the mouth rather than the nose. The physician tests the mobility of the soft release of expired air between the adducted vocal folds. Singing a note requires a more prolonged release of the expired air between the adducted vocal folds. c. The lower portion - infraglottic portion (pars infraglottica) which extends from the rima glottis to the first tracheal ring. It has following walls: anterior wall is formed by the arch of cricoid cartilage lateral walls is formed by conus elasticus posterior wall is formed by lamina of the cricoid cartilage. There are two sphincters in the larynx: (1) at the inlet and (2) at the rima glottidis. The sphincter at the inlet is used only during swallowing. As food is passed backward between the tongue and the hard palate, the larynx is pulled up beneath the back of the tongue. The epiglottis is pushed backward by the tongue and serves as a cap over the laryngeal inlet. The food or fluids now enters the oesophagus by passing over the epiglottis or moving down the grooves on either side of the laryngeal inlet, the piriform fossae. In coughing or sneezing, the rima glottidis serves as a sphincter. After inspiration, the vocal folds are adducted. The intrathoracic pressure rises when the vocal folds are suddenly abducted. The sudden release of the compressed air often dislodges foreign particles or mucus from the respiratory tract and NECK 40 carries the material up into the pharynx. After deep inspiration, the rima glottidis is closed and the muscles of the anterior abdominal wall now contract. The upward movement of the diaphragm is prevented by the presence of compressed air within the respiratory tract. 3.6. Vessels of the larynx a. arteries of the larynx: the superior laryngeal artery (arteria laryngea superior) branch of superior thyroid artery runs together with internal branch of the superior laryngeal nerve and supplies internal surface of the larynx the inferior laryngeal artery (arteria laryngea inferior) branch of inferior thyroid artery passes with the inferior laryngeal nerve and supplies inferior part of the larynx. b. veins of the larynx accompany appropriate arteries. c. lymphatic drainage of the larynx the superior deep cervical lymph nodes drain from the supraglottic part the inferior deep cervical lymph nodes drains from the infraglottic part 3.7. Nerve supply of the larynx a. Superior laryngeal nerve (nervus laryngeus superior) branch of vagal nerve is divided into two branches: External branch - smaller (motor and sensory) - to the cricothyroid muscle Internal branch - larger (sensory) - to the mucous of supraglottic portion of the larynx. It passes through the piriform recess where forms the laryngeal nerve fold (plica nervi laryngei). C.C.. Injuries of this nerve can cause dangerous effects during the passage of solids and liquids. Food can be aspired causing laryneal obstruction (choking). If some object enters the larynx, the patient is in danger of asphyxiation. Emergency therapy must be offered to supply air to the trachea and lungs. A large needle should be inserted into the median cricothyroid ligament. This procedure is called a cricothyrotomy. b. Inferior laryngeal nerve (nervus laryngeus inferior) - is a branch from the reccurent laryngeal nerve ( branch of vagal nerve ) that supplies mucous of infraglottic portion of the larynx and all the intristic muscles (except the cricothyroid muscle). NECK 41 4. Trachea. Cervical portion Trachea (trachea) is a part of the respiratory system. It is a tube composed of cartilages and membranes. The trachea is maintained by a series of C-shaped rings of hyaline cartilage, which are incomplete posteriorly. Posteriorly, across the gap of each cartilage, is a thin coat of unstriated muscle (trachealis). This wall is called membranous wall. The cartilages are united by fibro-elastic membranes, named anular ligaments. Relations: It begins at the level of the 6th cervical vertebra (at the lower border of the cricoid cartilage). Anteriorly is situated the thyroid gland and posteriorly the trachea lies on the oesophagus (more about thoracic portion of the trachea see next lab. sessions). Tracheostomy is surgical procedure in which opening in trachea is made to allow patients in bad condition ventilation by respirator. 5. Thyroid gland Thyroid gland (glandula thyroidea) is an endocrine gland which extends from C5 to Th1. The thyroid gland is butterfly- shaped, lies on the trachea just above the thoracic inlet and is closely related to the thyroid cartilage. Hormons which are secreted by thyroid gland regulate metabolism. It consists of: a. right lobe base is located at the level of fourth tracheal ring apex lies beneath the right oblique line of the thyroid cartilage b. left lobe base is located at the level of fourth tracheal ring apex lies beneath the left oblique line of the thyroid cartilage c. the isthmus is situated between the right and left lobes. The thyroid gland is invested by a capsule of connective tissue. NECK 42 Arteries of thyroid gland: superior thyroid artery ( branch of external carotid artery ), inferior thyroid artery ( branch of subclavian artery ). Veins of thyroid gland : superior thyroid vein ( tributary of internal jugular vein ), inferior thyroid vein ( tributary of internal jugular vein or brachiocephalic vein ). Fig. 5-18. Thyroid gland, parathyroid glands and larynx. Goitre is enlargement of thyroid gland. There are a lot of reasons for this condition. Treatment of goitre depends on causes and includes pharmacology and surgical procedures. 6. Parathyroid glands Parathyroid glands (glandulae parathyroidae) are small, spherical, endocrine glands which are situated at the back of the thyroid gland. There are usually two pairs: the superior and the inferior NECK 43 parathyroids. The superior parathyroid glands lies near the middle of the lobe of the thyroid gland. The inferior parathyroid glands are usually described as lying near the base of the thyroid lobe. NECK 44 7. Vagal nerve Vagal nerve (nervus vagus) includes four nuclei: Nuclei of vagal nerve: a. The dorsal nucleus of the vagal nerve (parasympathetic) lies in the medulla b. The medial part of the nucleus ambiguous (special visceral motor) c. The nucleus of the tractus solitarius (visceral sensory) d. The nucleus of the spinal tractus of the trigeminal nerve (somatic sensory) NECK 45 Fig. 5-19. Structure and branches of the vagal nerve Vagal nerve consists of five types of fibers: a. The general visceral motor fibres (parasympathetic) supply the heart, lungs, and the alimentary canal near to the splenic flexure b. The special visceral motor fibres - innervate the striated muscles of the larynx, pharynx, and palate c. The general visceral sensory fibres come from the mucous membrane of the palate, pharynx, larynx, heart, lungs, and the alimentary canal d. The special visceral sensory (taste) fibres come from the valleculae and the epiglottis NECK 46 e. The somatic sensory fibres supply the posterior part of the external auditory meatus and the tympanic membrane. Course of the CN X The nerve emerges from the medulla lateral to the olive as rootless and leaves the skull through the jugular foramen with the inferior petrosal sinus and the glossopharyngeal nerve medially and the accessory nerve and the internal jugular vein laterally. It descends through the neck and thorax to the oesophageal plexus, where it joins with its fellow of the opposite side to form the anterior and posterior gastric nerves. Near the base of the skull the vagus has superior and inferior ganglia. NECK 47 Fig. 5-20. Distribution of the vagal nerve. Relations (on the neck) The nerve lies deeply in the carotid sheath, between the internal jugular vein laterally and the internal and common carotid arteries medially. It lies on the pre-vertebral fascia and muscles. In the root of the neck, the right nerve passes forwards in front of the subclavian artery to enter the thorax. Branches (on the neck) a. Meningeal branch (ramus meningeus) arises from the superior vagal ganglion NECK 48 b. Auricular nerve (nervus auricularis) supplies the skin of the posterior part of the external auditory meatus and the tympanic membrane c. Pharyngeal branch (ramus pharyngeus) passes between the internal and external carotid arteries to reach the pharyngeal plexus and supply the muscles and mucous membrane of the pharynx and the soft palate d. Superior laryngeal nerve (nervus laryngeus superior) descends between the pharynx medially and the internal and external carotid arteries and divides below the hyoid bone into internal and external branches. The internal nerve pierces the thyrohyoid membrane to supply the mucous membrane of the larynx above the vocal folds. The external nerve descends on the larynx to supply cricothyroid muscle. It divides into: external branch (ramus externus) descends on the lateral surface of the inferior constrictor of the pharynx to the cricothyroid muscle and supplies these muscles and the mucous membrane of the anterior wall of the larynx internal branch (ramus internus) is sensitive only. It supplies the mucous membrane of the larynx above the vocal folds. The internal branch produces at the piriform recess an elevation called the laryngeal fold (plica nervi pharyngei) e. Superior cervical cardiac branches (rami cardiaci cervicales superiores) descend to the cardiac plexuses f. Right recurrent laryngeal nerve (nervus laryngeus recurrent dexter) hooks around the right subclavian artery. Left recurrent laryngeal nerve ( nervus laryngeus recurrent sinister ) hooks around the arch of aorta. It ascends in the groove between the oesophagus and trachea. It enters the larynx and supplies the intrinsic muscles except the cricothyroid and the mucous membrane below the vocal folds. It gives off: inferior cervical cardiac branches (rami cardiaci cervicales inferiores) for the cardiac plexus inferior laryngeal nerve (nervus laryngeus inferior) * anterior branch (ramus anterior) * posterior branch (ramus posterior) (for more information about CN X see labs in the thorax). 6.1. A. Pathways of the CN X 1. Motor fibres originate: Nucleus ambiguous situated in medulla oblongata NECK 49 Vagus nerve exits the medulla oblongata in the posterolateral sulcus Superior ganglion of CN X - situated in the jugular foramen Inferior ganglion of CN X Motor fibres split into a. b. and c. a. b. c. Pharyngeal branch External branch Main trunk of the vagal nerve pharyngeal between ICA of superior and ECA: laryngeal nerve supplies cricothyroid Pharyngeal plexus supplies Levator veli Recurrent laryngeal nerves muscle palatini muscle, Salpingopharyngeous, Right recurrent Left recurrent palatoglossus and laryngeal nerve laryngeal nerve palatopharyngeous hooks around muscles subclavian right hooks around arch of aorta Both ascend in the groove between the oesophagus and trachea to enter the larynx through the inferior pharyngeal constrictor muscle and supplies the intrisic muscles of the larynx except the cricothyroid muscle 2. Sensory fibres begin from two areas a. and b. a. Mucous membrane of the pharynx, larynx, and soft palate b. Posterior part of the external auditory meatus and the tympanic membrane Pharyngeal plexus Pharyngeal branch of CN X and the superior laryngeal nerve Auricular branch of CN X both merge in the inferior ganglion of CN X Superior ganglion of CN X CN X Dorsal vagal nucleus, nucleus of solitary tract, nucleus of spinal tract, and the spinal nucleus of the trigeminal nerve NECK 50 3. Parasympathetic fibres originate: Dorsal vagal nucleus /intracranial part of CN X/ Superior and inferior ganglion of CN X / extracranial part of CN X/ Parasympathetic fibres split to a. and b. a. b. Superior cervical cardiac branches Inferior cervical cardiac branches Deep parts of cardiac plexus Right superficial Left deep part of part of Cardiac plexus NECK 51 7. Accessory nerve ( CN XI) Accessory nerve (nervus accesorius) supplies muscles sternocleidomastoid and trapezius. Nucleus of accessory nerve extends from medulla oblongata to cervical part of spinal cord.( it is extension of ambiguous nucleus ) Accessory nerve consists of motor fibers for muscles: trapezius and sternocleidomastoid. Course of the CN XI The nerve consist of two roots cranial root and spinal root. The cranial root emerges between olive and inferior cerebellar peduncule of medulla and connects with spinal root. The spinal root emerges spinal cord between anterior and posterior roots of spinal nerves and passes through foramen magnum inside skull and meets with cranial root. They form trunk of accessory nerve. This nerve leaves the skull through the jugular foramen. It divides into internal and external branches. Internal branch connects with vagal nerve. It carries fibres for pharyngeal and cardiac branches of vagal nerve. External branch descends through sternocleidomastoid, pierces this muscle and passes to anterior border of trapezius. Branches a. Internal branch connects with pharyngeal and cardiac branches of vagal nerve b. External branch for trapezus and sternocleidomastoid.. NECK