Anatomy of the Neck Anterior triangle Midline of the neck Sternocleidomastoid muscle Lower border of the mandible Subunits of ant. triangle Submandibular triangle Submental triangle Carotid triangle Muscular triangle Submandibular triangle Anterior & posterior bellies of digastric muscle Lower border of the mandible Submental triangle Anterior bellies of the digastric muscle Hyoid bone Posterior triangle Anterior border of the trapezius m. SCM Middle third of the clavicle Subunits of post. Triangle Subclavian triangle Occipital triangle Fascial layer of the neck The cervical fascia represents a condensation of connective tissue that extends between anatomic structures Superficial Fascia Lies just below the dermis Deep portions of this layer encase the platysma muscle as well as the voluntary muscles of the face & scalp Deep cervical fascia Superficial layer Middle layer Deep layer Superficial layer of deep cervical fascia Begins from the vertebral spinous processes and splits to enclose the trapezious Again it splits to invest SCM as well as strap muscle Superior attachment : occipital protuberance , superior nuchal line & zigomatic arch Between parotid & submandibular glands the two layer rejoin to form the stylomandibular ligament Inferiorly the fascia split and attach to the anterior and posterior surface of the sternum : Suprasternal space of Burns Middel layer of the deep cervical fascia It encloses the thyroid gland , trachea , pharyngeal constrictor muscle & esophagus It extends from the hyoid bone down to the sternal attachments and is continuous with fibrous pericardium Deep layer of the deep cervical Fascia Anterior to the vertebral bodies Tips of transverse process Vertebral spines posteriorly From the skull base until the coccyx Prevertebral layer Alar layer ( until first thoracic vertebra ) Danger space A potential space is created between the alar and prevertebral fascias because it communicates directly with the mediastinum Prevertebral space Between the prevertebral fascia and vertebral body Retropharyngeal space Between alar and the visceral fascia Tissue space of the neck Between cervical fascia exist potential spaces Because superficial and deep layers of the deep cervical fascia fuse at the hyoid bone infection in the spaces above the hyoid does not spread directly to spaces below the hyoid Communication along the entire length of the neck occurs posteriorly along the retropharyngeal and prevertebral spaces . Submandibular space Between outer space of of mylohyoid muscle and superficialstructure within submandibular triangle Along the posterior free edge of the mylohyoid muscle it continuous with the sublingual space It also communicate with submental and contralateral submandibular space ` Intrapharyngeal space Inner surface of the superior constrictor muscle and the pharyngeal mucosa It also known as peritonsillar space Parapharyngeal space Medial : superior constrictor m. Lateral : pterygoid muscles and fascia of the parotid gland Inferior : Fascial attachment to the hyoid Posteromedially this space communicates with the retropharyngeal space providing a route to spread infection Retropharyngeal space Entire length of the neck Between visceral fascia and alar fascia From the skull base down to the T1 Danger space Between alar fascia and prevertebral fascia Retropharyngeal space→ danger space →mediastinum Prevertebral space Between prevertebral fascial and vertebral column From the skull base to the lower thoracic area Artery of the neck Common carotid artery Right side from brachiocephalic artery Left side from aortic arch It crosses by omohyoid muscle , , superior & middle thyroid vein Internal carotid artery it crosses by hypoglossal nerve , occipital artery & posterior belly of digastric muscle Near skull base it crosses by glossopharyngeal nerve ,stylohyoid , stylopharyngeous ,styloglossus muscle and styloid process External carotid artery It crosses superficially to styloglossus and stylopharyngeous muscle Terminal branches passing behind the condylar process Superior thyroid artery At the level of greater horn hyoid bone Superior part of thyroid gland , larynx and SCM Ascending pharyngeal artery At the level of sup. Thyroid artery posteriorly Supply pharynx , palate , tonsil , middle ear and meninges Lingual artery Above the superior thyroid artery Runs anterior and superior Passes beneath the hyoglossus muscle to enter the tongue Facial artery On the anterior surface of carotid , deep to the digastric muscle Passes through the submandibular gland , crosses the inferior border of the mandible Branches in the neck : ascending palatine artery , tonsillar artery , branches of the submandibular gland , submental artery Occipital artery From posterior surface of the external carotid artery the hypoglossal nerve hooks around it Supply suboccipital region of the scalp , SCM , digastric and stylohyoid muscle Posterior auricular artery Posteriorly at the level of the upper border of digastric muscle Passes between the mastoid and ear Branches to the parotid gland , auricle and scalp Terminal branches Superficial temporal : toward the scalp Maxillary artery : infratemporal fossa → pterygopalatine fissure → pterygopalatine fossa Thyrocervical thrunk Arises from the first part of the subclavian artery just anterior to the scalenus anrerior muscle Transverse cervical branch → SCM , trapezius Inferior thyroid artery : deep to the carotid sheath Supply inferior portion of the thyroid , sup. & inf. Parathyroid gland and a portion of larynx and trachea Inter the thyroid at the level of cricoid Vein of the neck Internal jugular vein Sigmoid sinus → intrenal jugular vein → subclavian vein Major tributaries :inferior petrosal sinus Common facial vein lingual vein superior thyroid vein middle thyroid vein External jugular vein Posterior auricular vein + posterior branch retromandibular vein Deep to the platysma but superficial to the SCM Terminate in the subclavian vein At its midportion it joined by posterior external jugular vein Anterior jugular vein Confluence of the vein in the submandibular region Drain to the external jugular or subcalavian vein Nerve of the neck Glossopharyngeal nerve Sensory , motor , parasympathic component It has superior and inferior ganglion Anterior to the internal and deep to the external carotid artery Pass between superior and middle constrictor muscle Innervate tonsil , pharynx and tongue Tympanic nerve Arises from inferior ganglion Tympanic canaliculus → middle ear (jacobson nerve ) Sensory fiber to the middle ear , eustachian tube and mastoid cavity Lesser petrosal nerve Preganglionic parasympathetic fibers Tympanic plexus → floor of middle cranial fossa → foramen oval → infratemporal fossa → otic ganglion In the otic ganglion it synapsis with postganglionic fiber of parasympathic that supply the parotid gland Carotid branch Arises from IX nerve just below the skull base Unit with carotid branch of vagus nerve and carries sensory information back from the carotid body and carotid sinus Pharyngeal branch Reach to the pharyngeal plexus on the middle constrictor muscle Sensory innervation Stylopharyngeus branch Only motor branch of the IX nerve Supply stylopharyngeal muscle Tonsilar branch Form a plexus with the lesser palatine nerve Supply tonsil and soft palate Lingual branch Taste and general sensation to the posterior 1/3 tongue Vagus nerve Superior and inferior ganglion at the jugular foramen Sensory , motor and parasympathetic fibers Superior ganglion branches Meningeal branch( posterior cranial fossa ) Auricular branch (pinna, EAC, TM ) Superior ganglion branch Pharyngeal branch ( pharynx and palate ) Superior laryngeal nerve Right RLN : in front the subvlavian a. Left RLN : in front the aortic arch Accessory Nerve Cranial component : sensory Join the vagus nerve pharyngeal plexus Spinal component : motor ( C2 – C4 ) lateral to IJV emerge 1 cm above Erb point Hypoglossal nerve Occipital bone → under posterior belly digastric → looping around occipital a.→ across carotid arteries → deep to the submandibular gland → on the surface of hyoglossus muscle Innervation : interinsic muscle of tongue , styloglossus , hyoglossus , genioglossus Ansa cervicalis Motor innervation to the strap muscle Upper branch : hypoglossus nerve Lower branch : C2 , C3 from the cervical plexus Cervical sympathetic trunk Thoracic spinal cord → sympathetic cervical ganglia → Superior cervical ganglia ( at the level of the C2 & C3 behind the carotid sheath internal carotid nerve passes into carotid canal → internal carotid plexus Cervical sympathic (cont ) Middle cervical ganglia : At the level of C6 Inferior cervical ganglia : in the root of the neck Cervical plexus From C1 – C6 Motor & sensory nerve Phrenic nerve (motor br : C3,C4,C5 ) Sensory br : lesser occipital nerve greater auricular nerve Anterior cutaneous nerve supraclavicular nerve Lymphatics of the neck Superficial group : submental submandibular superficial cervical anterior cervical Deep group : pretracheal , paratracheal perithyroid retropharyngeal The node of Rouviere refers to the highest retropharyngeal lymph node which is adjacent to the jugular foramen Compartment of the neck Level I Posterior belly of the digastric muscle Body of the mandible Hyoid bone Submandibular nodes Preglandular Postglandular Prevascular Postvascular Intracapsular Drainage Upper & lower lip , Cheek skin , nasal skin & mucosa , medial canthus , anterior alveolus , anterior tonsillar pillar soft palate , 2/3 anterior of the tongue , submandibular salivary gland Drain into upper internal jugular nodes Submental nodes 2-8 nodes Between anterior belly of digastric muscle Mylohyoid platysma Drain mentum , midportion of the lower lip , anterior alveous , anterior 1/3 of the tongue Second drainage to ipsilat. & contralat. preglandular or prevascular submandibular nodes or IJV Level II Base of the skull → carotid bifurcation or hyoid bone Posterior border of SCM → lateral border of sternohyoid muscle Level III Carotid bifurcation to the omohyoid muscle or cricothyroid notch Level IV Along the inferior 1/3 of the IVJ from the omohyoid to the clavicle Level V From the anterior border of the trapezius m. to the posterior border of SCM and the clavicle inferiorly Level VI Surrounded midline visceral structure From the hyoid bone to the sternal notch The lateral border is the carotid sheath Consists of paratracheal node , perithyroid nodes , precricoid ( Delphian ) nodes and nodes along the RLN Level VII The upper mediastinal lymph node and inferior to the suprasternal notch Anterior nodal group Anterior jugular chain Juxtavisceral chain : prelaryngeal prethyroid pretracheal paratracheal Prelaryngeal : supraglottis Prethyriod : infraglottic , thyroid isthmus , anteromedial thyroid lobe Pretracheal node : from thyroid isthmus to the innominate vein ,2-12 node ,thyroid gland and trachea Paratracheal : lateral aspect of thyroid & parathyroid gland , postcricoid , trachea, esophagus Lateral group Superficial chain : related to EJV drain to transverse cervical Deep group Spinal accessory chain Transverse cervical chain Internal jugular chain Spinal accessory chain : up to 20 nodes Transverse cervical chain : 12 nodes Internal jugular chain : 30 nodes on left side : thoracic duct on right side : right lymphatic duct Sublingual nodes Along collecting trunk of the tongue & sublingual gland Drain anterior floor of the mouth & ventral surface of the tongue Connect to the submandibular group or upper IJ chain Parotid Nodes Extraglandular group : preauricular & infraauricular nodes Drain lateral and frontal aspects of the scalp, anterior auricle , external auditory canal , skin of the lateral face , buccal mucosa Intraglandular nodes : drain the same side Retropharyngeal node Between pharyngeal wall and prevertebral fascia Lateral group : 1-3 nodes at the level of C1 Medial group : to the level of the cricoid Drain nasal cavity,sphenoid sinus, ethmoid sinus,hard & soft palate, nasopharynx & posterior pharyngeal wall The retropharyngeal space can be accessed by rotating the pharynx medially and opening the infected tissue between the pharynx and cervical spine Occipital nodes Superficial group : 2-5 nodes Between SCM & trapezius m. at apex of posterior triangle , superficial to the splenius m. & deep to investing fascia Drain occipital scalp , posterior cervical skin → deep group → upper spinal accessory Postauricular nodes 1-4 nodes over fibrous insertion of SCM on the mastoid tip Drain posterior parietal scalp , skin of mastoid and postauricular area → infraauricular parotid LN Cont. Deep group : 1-3 nodes deep to the splenius m. along the course of the occipital artery Drain the deep musculature of the neck in occipital region→ INJ & spinal accessory nodes Thoracic duct Passes up through mediastinum → left root of the neck → posterior to the carotid sheath & medial to the anterior scalene m. It empties through multiple branches into the lowest portion of the IJV , the subclavian vein or both Main duct may extend as high as 5 cm above the clavicle
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