Human Anatomy - Neck PDF

HUMAN ANATOMY PART I NECK BY Jerzy Gielecki M.D. Ph.D. & Anna Żurada M.D. OLSZTYN 2019 1 This guide of Head & Neck is created for the students to understand the basic fundamentals concerning the morphology of the bones, muscles, nerves & vessels of the head & neck. I would like to express great appr...

HUMAN ANATOMY PART I NECK BY Jerzy Gielecki M.D. Ph.D. & Anna Żurada M.D. OLSZTYN 2019 1 This guide of Head & Neck is created for the students to understand the basic fundamentals concerning the morphology of the bones, muscles, nerves & vessels of the head & neck. I would like to express great appreciation to my colleagues for their insight and dedication towards the completion of this manual. I am indebt to the students, members of the Anatomical Research Group for their advice. Jerzy Gielecki M.D., Ph.D J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 2 Lab. session 1 I. Regions of the neck II. Fascia of the neck 2.1. The superficial cervical fascia 2.2. The deep cervical fascia III. Muscles of the neck 3.1. The anterior group 3.2. The middle group 3.3. The posterior group IV. Fasciae and the tissue spaces of the neck 4.1. Anterior tissue space 4.2. Middle tissue space 43. Posterior tissue space V. The triangles of the neck 5.1. Anterior triangle of the neck 5.2. Posterior triangle of the neck 5.3. Fissures of the scalene muscles I. Regions of the neck J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 3 1. Anterior cervical region or anterior cervical triangle (regio cervicalis anterior)  Submandibular triangle (trigonum submandibulare)  Carotid triangle (trigonum caroticum)  Muscular triangle or omotracheal triangle (trigonum musculare)  Submental triangle (trigonum submentale) 2. Trigonum submentale (regio sternocleidomastoidea)  Lesser supraclavicular fossa (lateral cervical region) 3. Lateral cervical region; Posterior cervical triangle (regio cervicalis lateralis)  Omoclavicular triangle (trigonum omoclaviculare)  Greater supraclavicular fossa (fossa supraclavicularis maior) 4. Nuchal region or posterior cervical region (nucha) Fig. 1-1. Regions of the head & neck – lateral view. J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 4 II. Fascia of the neck The neck has two types of fascia: superficial and deep. These terms are used to distinguish the different types that can be incised and sutured. 1. The superficial cervical fascia The superficial cervical fascia (fascia colli superficialis) includes: Variable amounts of adipose tissue The platysma - voluntary muscle of facial expression. 2. The deep cervical fascia The deep cervical fascia (fascia colli profunda) gives off septa which can be subdivided into five parts: 1. The investing layer of deep cervical fascia. It splits to enclose: - sternocleidomastoid muscle - trapezius muscle - submandibular gland - parotid gland. 2. The pretracheal fascia forms a sheath around the thyroid gland. -It merges laterally with the investing layer of the deep cervical fascia and with the connective tissues comprising the carotid sheath. -Attachments of the pretracheal fascia are: - superiorly - body of the hyoid bone - laterally - omohyoid muscle - inferiorly - it extends into superior mediastinum of the thorax along the great vessels to merge with the fibrous pericardium. 3. The prevertebral fascia lies in front of 4 structures: 1. vertebral column 2. the prevertebral muscles 3. the cervical plexus 4. brachial plexuses. It extends from the base of the skull to the longitudinal ligament of the third vertebra. 4. The carotid sheath is a condensation of fascia of the neck. It encloses 1. The internal jugular vein laterally 2. The common and internal carotid artery medially 3. The vagus nerve posteriorly 5. Retropharyngeal Speace: Potential space that exists between the pretracheal fascia and the prevertebral fascia J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 5 III. Muscles of the neck The sixteen muscles of the neck are divided into anterior, middle, and posterior group. 1. The Anterior Group The anterior group consists of two muscles: 1. Platysma muscle (musculus platysma) ORIGIN: origin:: inferior border of the mandible, fascia, and skin of the face INSERTION: insertion:: fascia and skin over the great pectoral and deltoid muscles FUNCTION: tenses the skin of the neck, assists during the depression of the mandible INNERVATION : nerve supplying:: CN VII 2. Sternocleiodomastoid muscle (musculus sternocleiodomastoideus) Fig. 1-3. ORIGIN: mastoid process of the temporal bone (lateral surface) and nuchal line of the occipital bone INSERTION: manubrium of the sternum (anterior surface) FUNCTION: acting alone (one side) it turns the face superiorly towards the opposite side; acting together, turns the face superiorly upwards, flexing the neck. INNERVATION: cervical plexus and cervical part of CN XI Fig. 1-6. Muscles of the neck J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 6 1. The middle group The middle group consists of eight muscles subdivided into 2 groups: a. suprahyoid muscles (musculi suprahyoidei) contains four muscles: 1 Mylohyoid muscle (musculus mylohyoideus) ORIGIN: mylohyoid line on the internal aspect of the mandible INSERTION: the posterior fibres attach to the body of the hyoid bone, the anterior and middle fibres unite into a median fibrous raphe to form the muscular floor of the oral cavity FUNCTION: elevates the floor of the oral cavity, hyoid bone, and tongue INNERVATION: CN V3. 2 Stylohyoid muscle (musculus stylohyoideus) ORIGIN: styloid process of the temporal bone. It descends medially and parallel to the posterior belly of the digastric muscle and divides into two muscular slips in its lower portion. Both slips pass on both sides of the digastric tendon INSERTION: via two muscular slips into the body of the hyoid FUNCTION: with the posterior belly of the digastric muscle, draws the hyoid bone in a posterosuperior direction INNERVATION: CN VII 3 Digastric muscle (musculus digastricus) ORIGIN: anterior belly - digastric fossa of the mandible posterior belly - mastoid notch of the temporal bone INSERTION: both bellies via intermediate tendon into body of hyoid bone FUNCTION: both muscles elevate the hyoid bone; the anterior belly draws the hyoid forward, while the posterior belly draws it backward INNERAVATION: anterior belly - V3, posterior belly - CN VII 4 Geniohyoid muscle (musculus geniohyoideus) is located superior to the mylohyoid muscle ORIGIN: mental spine of the mandible INSERTION: body of the hyoid bone FUNCTION: draws the hyoid bone and the tongue anteriorly INNERVATION: cervical ansa b. infrahyoid muscles (musculi infrahyoidei) contains four muscles: 5 Omohyoid muscle (musculus omohyoideus) ORIGIN: inferior border of the hyoid bone - superior belly is united with the inferior belly by the intermediate tendon INSERTION: superior border of the scapula - inferior belly FUNCTION: depresses hyoid bone 6 Sternohyoid muscle (musculus sternohyoideus) ORIGIN: body of the hyoid bone INSERTION: manubrium of the sternum, medial end of the clavicle FUNCTION: depresses hyoid bone 7 Sternothyroid muscle (musculus sternothyroideus) ORIGIN: oblique line of the thyroid cartilage J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 7 INSERTION: posterior surface of the manubrium of sternum FUNCTION: depresses hyoid bone and larynx 8 thyrohyoid muscle (musculus thyrohyoideus) ORIGIN: body and great horn of the hyoid bone INSERTION: oblique line of the thyroid cartilage FUNCTION: depresses hyoid bone and elevates larynx INNERVATION: branches of the cervicalis ansa supply all infrahyoid muscles 2. The Posterior group The posterior group is subdivided into two groups: a. medial or prevertebral group: 1. longus colli muscle (musculus longus colli) 2. longus capitis (musculus longus capitis) 3. rectus capitis anterior (musculus rectus capitis anterior) b. lateral group: 1. Scalenus anterior (musculus scalenus anterior) ORIGIN: transverse processes of the C3 and C6 vertebrae INSERTION: tubercle on the superior surface of the first rib FUNCTION: elevates the first rib, flexes the neck laterally, and plays a role in breathing. 2. Scalenus medius (musculus scalenus medius) ORIGIN: transverse processes of the C2 and C7 vertebrae INSERTION: superior surface of the first rib, posterior to the groove for the subclavian artery FUNCTION: elevates the first rib, flexes neck laterally 3. Scalenus posterior (musculus scalenus posterior) ORIGIN: transverse processes of the C2 and C7 vertebrae INSERTION: external surface of the second rib FUNCTION: elevates the second rib, flexes neck laterally INNERVATION: for both groups - ventral rami of the cervical nerves J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 8 IV. Fasciae and the tissue spaces of the neck Fasciae and the tissue spaces of the neck (Fig. 1-4) are divided into three compartments: 1. Anterior tissue space Anterior tissue space (spatium colli anterius) of the neck lies between the investing layer of the deep cervical fascia and the pretracheal fascia. a. suprasternal space contains the anterior jugular vein and venous jugular arch b. supraclavicular spaces may contain lymphoid tissue as well as nodes. 2. Middle tissue space Middle tissue space (spatium colli medium) of the neck is a visceral compartment between the pretracheal and prevertebral fascia. It is subdivided into two compartments:  previsceral space lies in front of the trachea and thyroid gland  retrovisceral space is located behind the oesophagus. Middle tissue space contains: 1. thyroid gland 2. larynx 3. trachea 4. pharynx 5. oesophagus Fig. 1-7. Transverse cross-section of the neck. S.C.M. - sternocleidomastoid muscle, ICA internal carotid artery, IJV- internal jugular vein, CN X - vagal nerve. J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 9 3. Posterior tissue space Posterior tissue space (spatium colli posterius) or prevertebral space lies between the anterior surface of the vertebral column and the prevertebral fascia. It contains: a. prevertebral muscles b. cervical and brachial plexus. J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 10 The triangles of the neck The regions of the neck are subdivided into two main cervical triangles: 1. Anterior triangle of the neck Anterior triangle of the neck (trigonum colli anterius) consists of: left triangle (a+b+c on the Fig. 1-5) right triangle Fig. 1-8. Triangeles of the neck. mp - mastoid process, md - mandible, scm - sternoclediomastiod muscle, trm - trapizues muscle, acr - acromion, st - manubrium of the sternum, shm - sternohyoid muscle, 1- anterior belly of digastric muscle, 2- posterior belly of digastric muscle, 3- superior belly of omohyoid muscle, 4inferior belly of omohyoid muscle. a. Submandibular triangle (trigonum submandibulare) - Fig. 1-5-a. It is bounded by: 1. Laterally by the posterior belly of the digastric muscle 2. Medially by the anterior belly of the digastric 3. Inferiorly by the mandible The floor is formed by:  mylohyoid muscle  hyoglossus muscle. The submandibular triangle contains: 1. submandibular gland 2. lymph nodes 3. facial artery 4. submental artery 5. CN XII /the end/ 6. mylohyoid nerve /CN V3/ 7. glossopharyngeal nerve J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 11 b. Carotid triangle (trigonum caroticum) - Fig. 1-5-b. It is bounded by: sternocleidomastoid muscle – lateral border omohyoid muscle - superior belly - medial border digastric muscle - posterior belly – superior border The carotid triangle contains: 1. common carotid artery and its bifurcation 2. internal jugular vein 3. vagal nerve 4. cervical ansa 5. superior laryngeal nerve c. Muscular or omotracheal triangle (trigonum musculare seu omotracheale) - Fig. 1-5-c. It is bounded by:  sternocleidomastoid muscle  omohyoid muscle / superior belly - lateral border  sternohyoid muscle. The omotracheal triangle contains:  thyroid gland 2. Posterior triangle of the neck Posterior triangle of the neck (triangles d + e) d. Occipital triangle (trigonum occipitale) - Fig. 1-5-d. It is bounded by:  sternocleidomastoid muscle  omohyoid muscle /inferior belly /  trapezius muscle. The floor is formed by:  scalene muscles  splenius capitis muscle  levator scapulae muscle. The occipital triangle contains : 1. CN XI /external branch/ 2. cutaneous branches from the cervical plexus i. the lesser occipital nerve 3. the great auricular nerve 4. the transverse cervical nerve 5. the supraclavicular nerve e. Supraclavicular or subclavian triangle (trigonum supraclaviculare) Fig. 1-5-e It is bounded by:  sternocleidomastoid  omohyoid /inferior belly/  clavicle. The floor is formed by: scalene muscles + anterior and posterior scalene fissure. J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 12 The supraclavicular triangle contains: 1. subclavian vein 2. subclavian artery 3. brachial plexus Fissures of the scalene muscles There are two fissures (Fig. 1-6) that are confined by the scalene muscles: a. Anterior fissure of the scalene muscles It is bounded by: anteriorly - sternocleiodomastoid muscle posteriorly - anterior scalene muscle inferiorly - first rib. The anterior fissure of the scalene muscles contains: subclavian vein (on the first rib is located a groove for the subclavian vein, anterior to the scalene tubercle). Fig. 1-9. Localisation of the fissures of the scalene muscle b. Posterior fissure of the scalene muscles It is bounded by:  anteriorly - anterior scalene muscle  posteriorly - middle scalene muscle  inferiorly - first rib The posterior fissure of the scalene muscles contains: J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 13  below - subclavian artery (on the first rib is situated a groove for the subclavian artery posterior to the scalene tubercle - see Bones Joints and Ligaments page. 59 or www.anatomy3a.com) above - brachial plexus The subclavian artery and the brachial plexus are sometimes separate by the minor scalene muscle, which is not always present. J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 14 Fig. 1-10. Cranial Nerves (CN) & their fibres 1. Oh Once One Tries Taking Anatomy Finding Very Good Vacations Appear History 2. Some Say Marry Money But My Brother Says Big Brains Matters More J. St. Gielecki & A. Żurada –NECK Copyright MedRadEd © 2019 HUMAN ANATOMY PART II NECK BY Jerzy Gielecki M.D. Ph.D. & Anna Żurada M.D. OLSZTYN 2019 16 Lab. session 2 1. Arteries of the neck 1.1. Common carotid artery 1.2. External carotid artery 1.3. Internal carotid artery 1.4. Subclavian artery 6. Veins of the neck 2.1. Internal jugular vein 2.2. External jugular vein 2.3. Anterior jugular vein 7. Lymphatic drainage of the neck 3.1. Groups of the superficial nodes 3.2. Groups of the deep nodes 8. Nerves of the neck 4.1. Ventral branches of upper cervical spinal nerves 4.2. Dorsal branches of upper cervical spinal nerves 4.3. Cranial nerves 4.4. The autonomic nervous system of the neck J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 17 1. Arteries of the neck Arteries of the neck consists of the four following arteries (Fig. 2-1): 1.1. Common carotid artery Common Carotid Artery - CCA (arteria carotis communis) is a main artery of the neck. Origin of the vessel: The left side - arises from the aortic arch The right side - arises from the brachiocephalic trunk (the first branch of the aortic arch) End of the vessel: It ends at the bifurcation of the common carotid artery, where the carotid sinus or carotid bulb (sinus caroticus) is located. It is sensitive to the pressure changes in the blood (baroreceptor). The carotid body (glomus caroticum) is a neurovascular structure located on the posterior wall of the bifurcation of the common carotid artery. It is sensitive to chemical changes in the blood (chemoreceptor). Both structures above are innervated by the CN IX nerve. Relations:  anterolaterally: infrahyoid and sternocleidomastoid muscles  posteriorly: prevertebral fascia and muscles  medially: trachea, oesophagus, larynx, and pharynx. Branches: The common carotid artery has no branches. In the carotid triangle, the CCA is divided into two branches: external carotid artery ( ECA ) and internal carotid artery ( ICA ). ECA and ICA are separated by:  styloglossus  stylopharyngeus  CN IX  pharyngeal branches of CN X. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 18 1.2. External carotid artery External Carotid Artery - ECA (arteria carotis externa) is a anteromedial branch of the common carotid artery. Origin of the vessel: Bifurcation of the common carotid artery. End of the vessel: It divides into two terminal branches. Relations: At the level of the upper border of thyroid cartilage, the ECA passes through the parotid gland and terminates behind the neck of the mandible by dividing into the maxillary and superficial temporal arteries. In the carotid triangle :  Under the investing layer of the deep cervical fascia  Medially to ICA, hypoglossal nerve, cervical ansa (ansa cervicalis) and internal jugular vein  laterally to the pharynx  deep to the posterior belly of the digastric muscle. Within parotid gland :  Lateral to ICA  Medial to the CN VII and retromandibular vein. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 19 Fig.6-5. Localisation of the arteries, veins, and main nerves of the neck Branches: The external carotid artery gives off eight branches that can be categorised into two groups: a. From the anterior aspect  Superior thyroid artery (arteria thyroidea superior) descends with the external laryngeal nerve, under the superior belly of the omohyoid muscle, from the carotid triangle to the muscular triangle to the upper pole of the thyroid gland. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 20 Branches:  Superior laryngeal artery with the superior laryngeal nerve (branch of CN X ) pierces the thyrohyoid membrane to supply the larynx and proceeds to give off small branches that supply the pharynx.  cricothyroid artery - supplies the middle part of the larynx.  branches for the thyroid gland  branches for the infrahyoid muscles.  Lingual artery Relations: * above the superior thyroid artery at the level of the hyoid bone * it forms a distinct loop which is related to the hypoglossal nerve (its crossed superficially) * passes beneath the hypoglossal muscle to enter the tongue. Branches:  dorsal branches for the tongue and the tonsil of the soft palate  sublingual artery for sublingual gland and floor of the mouth  deep lingual artery for the body and the tip of the tongue  suprahyoid artery  Facial artery Relations on the neck: * It arises just above the lingual artery and arches over the submandibular gland. * It turns around the inferior border of the mandible and takes a course across the face to the medial angle of the eye. * It is located deep to the stylohyoid and posterior belly of the digastric muscles. * It comes into contact with the submandibular gland and weaves in and out beneath the inferior border of the mandible before crossing on to the face 4 cm in the front of the mandibular angle. Branches on the neck:  ascending palatine artery  tonsillar artery  submental artery to the suprahyoid muscles J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 21 b. From the posterior aspect  Ascending pharyngeal artery It is the smallest branch of the ECA. Relations: * Emerges between the ECA and the ICA and then ascends on the lateral wall of the pharynx to the base of the skull. Branches:  pharyngeal to the pharynx and the palate  meningeal to the dura mater  inferior tympanic to the middle ear  Occipital artery Relations: * It arises at the same level as the facial artery. * It runs backwards across carotid sheath where the CN XII hooks around it. Branches:  branches for muscles (neck and suboccipital)  mastoid branch  auricular branch  occipital branch.  Posterior auricular artery Relations: * It passes along the upper border of the posterior belly of the digastric. * It passes through the apical part of the parotid gland to the lateral aspect of the scalp. Branches:  auricular branch  posterior tympanic artery - to the middle ear  branches to the muscles  stylomastoid artery  occipital branch c. The terminal branches of the ECA:  superficial temporal artery J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 22  maxillary artery are described in relation to the face (see lab. 5) 1.3. Internal carotid artery Internal Carotid Artery (arteria carotis interna) - ICA is the posterolateral branch of the common carotid artery. Relations on the neck: * In the carotid triangle - lateral to the ECA. * Laterally, the artery is crossed by the stylohyoid, posterior belly of the digastric and the XII nerve. * It leaves the neck passing through the carotid canal. Within the neck, the ICA has no branches. PATHWAY: Common Carotid ------> Internal Carotid ------> Into the Foramen Lacerum ------> medially to Carotid canal ------> then Anteriorly through Cavernous Sinus ------> Then superiorly again 1.4. Internal carotid artery Internal Carotid Artery (arteria carotis interna) ICA supplies the greater part of the brain and the contents of the orbit. Origin It arises from the bifurcation of the common carotid artery (CCA) at the level of the upper border of the thyroid cartilage (CV 6). End It terminates intracranially in the middle cranial fossa, medially to the anterior clinoid process of the sphenoid bone. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 23 Course of the ICA The vessel ascends to the base of the skull being first located posterolaterally to the external carotid artery then medially to that artery. ICA leaves the neck by passing through the carotid canal of the petrosus part of the temporal bone. It passes upward and then forward by the cavernous sinus piercing the roof of the sinus and then turning backwards onto itself before dividing into the anterior and middle cerebral arteries. Relations within the neck It lies within the carotid sheath with:  internal jugular vein - laterally  vagus nerve - behind. In the carotid triangle ICA lies:  laterally and posteriorly to the ECA  posteriorly and medially to the sternocleidomastoid muscle  anteriorly to the prevertebral fascia and the sympathetic trunk. ICA is crossed laterally by:  the stylohyoid muscle  the posterior belly of the digastric muscle  hypoglossal nerve. In the parapharyngeal space, the ICA lies posteriorly and medially to the ECA and separated from it by:  the stylopharyngeus muscle  the styloglossus muscle  glossopharyngeal nerve  pharyngeal branches of the vagus nerve. 1.5. Subclavian artery Subclavian artery (arteria subclavia) is unique in that it has different relations on both sides of the body. Origin: The right side arises from the brachiocephalic artery The left side arises from the arch of the aorta J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 24 Relations: The right artery: * Medially to the scalenus anterior * It lies behind the jugular vein * Laterally to the oesophagus and trachea * The right recurrent laryngeal nerve and the ansa subclavia hook around it. the left artery: * behind the left common carotid artery, the left vagus, and left phrenic nerves * laterally to the oesophagus, trachea, and left recurrent laryngeal nerve * the thoracic duct and phrenic nerve cross anterior to it, the left recurrent laryngeal nerve does not hook around it. Branches:  vertebral artery (arteria vertebralis) supplies the brain and spinal cord  internal thoracic artery (arteria thoracica interna) supplies the thorax  thyrocervical trunk (truncus thyrocervicalis) Branches:  inferior thyroid artery (arteria thyroidea inferior)  branch for thyroid gland (ramus thyroideus)  ascending cervical artery (arteria cervicalis ascendens)  inferior laryngeal artery (arteria laryngea inferior)  transverse cervical artery (arteria transversa colli)   suprascapular artery (arteria suprascapularis)  costocervical trunk (truncus costocervicalis) Branches:  deep cervical artery (arteria cervicalis profunda)  highest intercostal artery (arteria intercostalis suprema) J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 25 2. Veins of the neck The neck encloses three main veins. 2.1. Internal jugular vein Internal jugular vein (vena jugularis externa) is the main vein of the neck. Arises as the continuation of the sigmoid venous sinus, ascends through the neck and behind the medial end of clavicle, where it is joined by the subclavian vein to form the brachiocephalic vein. Tributaries:  sigmoid sinus (sinus sigmoideus)  occipital sinus (sinus occipitalis)  inferior petrosal sinus (sinus petrosus inferior)  occipital vein (vena occipitalis)  facial vein (vena facialis)  pharyngeal plexus (plexus pharyngeus)  lingual vein (vena lingualis)  superior and inferior thyroid veins (vena thyroidea superior et inferior)  thoracic duct (ductus thoracicus) on the left side  right lymphatic duct (ductus lymphaticus dexter) on the right side. 2.2. External jugular vein External jugular vein (vena jugularis externa ) is a superficial vein formed behind the angle of the mandible by the union of the posterior branch of the retromandibular vein and the posterior auricular vein. It may enter either the internal jugular, brachiocephalic, or subclavian veins. Tributaries:  posterior auricular vein (vena auricularis posterior)  occipital vein (vena occipitalis)  suprascapular vein (vena suprascapular)  transverse cervical vein (vena transversa colli) J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 26 2.3. Anterior jugular vein Anterior jugular vein (vena jugularis anterior) begins below the hyoid bone to enter the external jugular or subclavian veins. The jugular arch unites the two anterior jugular veins. There are two veins which are branches of brachiocephalic veins: the vertebral vein and the deep cervical vein. Internal jugular and subclavian veins catheterisations are procedures which allow to use central venous line for clinical needs like checking central venous pressure or parenteral nutrition 3. Lymphatic drainage of the neck Lymphatic drainage of the neck comprises the two following groups: 3.1. Groups of the superficial nodes a. Superficial cervical lymph nodes (nodi lymphatici cervicales superficiales) receive vessels from around the lower part of the ear, the floor of the external acoustic meatus, and the region of the angle of mandible. They are located in the lateral cervical triangle and along CN XI. Superficial cervical nodes get lymph from occipital nodes. Efferent lymphatic vessels go to the deep cervical nodes and mainly to supraclavicular nodes. b. submandibular lymph nodes (nodi lymphatici submandibulares) receive vessels from the oral cavity - efferent vessels go to the deep cervical nodes. c. submental lymph nodes (nodi lymphatici submentales) receive lymph from the anterior part of mandible, the lower lip, and the tip of tongue. Efferent lymphatic vessels pass to the deep cervical nodes or to the submandibular nodes. d. infrahyoid lymph nodes (nodi lymphatici infrahyoid) e. pretracheal lymph nodes (nodi lymphatici pretracheales) f. paratracheal lymph nodes (nodi lymphatici paratracheales) g. retropharyngeal lymph nodes (nodi lymphatici retropharyngei) J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 27 All efferent vessels from (d) to (g) drain into the deep cervical nodes (nodi lymphatici cervicales profundi). 3.2. Groups of the deep nodes The deep cervical chain lies along the carotid sheath, deep to the sternocleidomastoid muscle. From the deep cervical nodes, lymph is collected into the jugular trunk. The left jugular trunk drains into the thoracic duct and the right jugular trunk drains into the right lymphatic duct. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 HUMAN ANATOMY PART III NECK BY Jerzy Gielecki M.D. Ph. D. & Anna Żurada M.D. 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 ) J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 31 The pharynx 1. 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 by: 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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: J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 palate by asking the patient to say ‘ah’ with the mouth open. Speech involves the intermittent 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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). J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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) J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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 J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019 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.. J. St. Gielecki and A. Żurada –NECK MedRadEd © 2019