12. anatomy of neck kk
TRANSCRIPT
General anatomy and Lymphatic drainage
of Neck
Dr. Krishna KoiralaMBBS, MS (ENT-HNS)
2016/12/262016/12/26
• Neck : Area between the lower border of mandible above and suprasternal notch and clavicle below
• Complex region :
– Passageway for communication between head and rest of the body
• Contains vital structures like larynx, trachea, esophagus, great vessels, cranial nerves, sympathetic trunk, spinal cord
Fascia and fascial spaces of Neck
• Importance of fascial planes
−Localization and spread of neck space infections is dependent upon the facial planes
− Dissection is easier, better controlled and more bloodless if it proceeds along the fascial planes
• Skin
– Contains constant natural lines of cleavage horizontally
– Incision along the cleavage line gives narrow scar
• Superficial fascia
− Thin layer that encloses platysma, cutaneous nerves, superficial veins, superficial lymph nodes
• Deep fascia
– Investing layer ,Visceral layer , Internal layer
• Investing layer • Superiorly attached to the nuchal line,
mastoid process and mandible
• Inferiorly attached to the spine of C7, clavicle and manubrium
• Splits to surround trapezius and sternomastoid
• Forms sheaths to parotid and submandibular gland , carotid sheath and cranial nerves
Superior nuchal line of occipital bone (a)Spinous processes of cervical vertebrae and nuchal ligament(b)Mastoid processes of temporal bones(c)Zygomatic arches(d)Inferior border of mandible(e)Hyoid bone(f)Manubrium(g)Clavicles(h)Acromion(i)
Folds to form the stylomandibular ligament(j)
• Middle layer ( Two subdivisions)
−Muscular division surrounds the
infrahyoid strap muscles
−Visceral division envelops the
pharynx, larynx, esophagus, trachea,
and thyroid gland
• Deep Layer (Prevertebral fascia)
• Surrounds deep muscles of neck
• Cervical sympathetic trunk lies superficial to fascia
• Cervical plexus, phrenic nerve and brachial plexus lie deep to fascia
Deep Neck Spaces• Described in relation to the hyoid bone• Those traverse the entire length of the neck
– Retropharyngeal space, Danger space, Prevertebral space, Visceral vascular space ( Carotid sheath)
• Suprahyoid
− Submandibular space, Parapharyngeal space, Peritonsillar , Masticator, Parotid, Temporal space
• Infrahyoid – Anterior visceral space
Parapharyngeal Space Boundaries
Base and superior limit - Skull Base
Apex – Lesser cornu of hyoid
Lateral – Ascending ramus of mandible, Medial Pterygoid, Parotid fascia and gland
Medial – Buccopharyngeal fascia
Anterior - Pterygomandibular raphe
Posterior -Prevertebral fascia
Inferior -Fascia lateral to angle of mandible
Parapharyngeal Space
• Subdivisions• Prestyloid• Poststyloid (neurovascular)
• Contents• Prestyloid compartment
• Retromandibular portion of the deep lobe of the parotid gland, adipose tissue, lymph nodes associated with the parotid gland
• Poststyloid compartment • Internal carotid artery, internal jugular vein, CNS IX- XII, sympathetic chain, lymph nodes
Retropharyngeal space• Immediately posterior to the nasopharynx,
oropharynx, hypopharynx, larynx, and trachea
• Boundaries • Buccopharyngeal fascia anteriorly • Alar fascia posteriorly • Carotid sheath and parapharyngeal space
laterally • Base of the skull superiorly• Inferiorly to the mediastinum at the level
of the tracheal bifurcation
• Divided into two lateral compartments (space of Gillette) by a fibrous raphe
• Each lateral space contains retropharyngeal nodes which usually disappear after 4-5 years of age
• Communicates with the parapharyngeal space and the posterior mediastinum so infection can spread to these areas
• Danger space
• Formed anteriorly by the alar fascia and posteriorly by the prevertebral fascia
• Extends down the mediastinum to the level of the diaphragm
• Prevertebral space
• Bounded anteriorly by the prevertebral fascia and posteriorly by the longus coli muscles of the spine
• Continues to the insertion of the psoas muscles
Submandibular space• Boundaries
– Inferior : superficial layer of the deep cervical fascia extending from hyoid to the mandible
– Lateral : body of the mandible
– Superior : mucosa of the floor of mouth
Subdivisions • Divided by the myelohyoid muscle into• Sublingual space ( Supramyelohyoid)– Contains sublingual gland,
hypoglossal nerve and Wharton’s duct – Continuous with the submaxillary
space via the posterior margin of the myelohyoid muscle
• Submaxillary space ( Inframyelohyoid)
Triangles of Neck
Anterior triangle Anteriorly - midline of neck
Posteriorly - anterior border of Sternocleidomastoid
Superiorly -lower border of mandible
Floor - myelohyoid, hyoglossus
Subdivided by bellies of digastric and omohyoid muscles into submental, submandibular, carotid, muscular triangles
Chief contents of anterior triangle Common carotid , external and
internal carotid arteries
Internal jugular vein
Vagus and recurrent laryngeal nerves
Submandibular gland
Lymphatic tissue
Posterior Triangle• Anteriorly by posterior border of SCM• Posteriorly by trapezius• Inferiorly - middle 3rd of clavicle• Floor - deep layer of deep cervical fascia• Roof - superficial layer of deep cervical
fascia• Subdivided to occipital and subclavian
by posterior belly of omohyoid muscle
Contents of posterior triangle Subclavian artery Brachial plexus Spinal accessory nerve Posterior cervical nodes
Lymph node Levels of Neck
( The Memorial Sloan Kettering Hospital –New
York Classification )
Level I ( Submental / Submandibular) Below myelohyoid muscle and above the lower
margin of the hyoid bone Anterior to the posterior border of the
submandibular glands Level I a : Submental ( between the anterior
bellies of the digastric muscle) Level I b : Submandibular (posterolateral to
the anterior belly of digastric)
Level II ( Upper jugular / upper deep cervical)
Base of skull to lower margin of hyoid bone Anterior to the posterior border of
sternomastoid and posterior to the posterior border of submandibular glands Level II a : Anterior, lateral or medial to the
internal jugular vein Level II b : Posterior to the internal jugular
vein with a fat plane separating the nodes and the vein
Level III (Middle jugular/ middle deep cervical nodes)
Lower margin of hyoid to lower margin of cricoid cartilage
Anterior to the posterior border of SCM and lateral to the medial margin of the CCA / ICA
Level IV ( Lower jugular / lower deep cervical nodes)
Lower margin of cricoid cartilage to level of the clavicle
Anterior and medial to an oblique line drawn through the posterior edge of the sternocleidomastoid muscle and the posterolateral edge of the anterior scalene muscle and lateral to the medial margin of the CCA
Level V (Posterior triangle nodes ) Level V a : superior half, posterior to levels II and
III Level V b : inferior half, posterior to level IV
Level VI (prelaryngeal /pretracheal /Delphian node)
From inferior margin of hyoid to manubrium In front of levels III and IV
Level VII (superior mediastinal ) Between CCAs, below top of manubrium