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