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felice.d’[email protected]@FeliceDArcoLectures are on Youtube!https://www.slideshare.net/bluetango84
LEARNING OBJECTIVES
Basic embryology of the neck: only what you
need to understand pathology
Basic Neck Anatomy
Radiological anatomy to come in next lessons!
Rad-Path correlations in the workshop!
Part I: Embryology
Thyroglossal Duct
Tongue
Thyroid Gland
Osmosis.org
During development, a small depression (FORAMEN CAECUM) forms between the anterior 2/3 and the posterior 1/3 of the tongue
Osmosis.org
Osmosis.org
Thyroid Gland Migrates Downwards as it Grows!
But it remains connected by a tiny canal called Thyroglossal Duct
Osmosis.org
T. Gland passes caudally to the Hyoid Bone (going slightly off midline)
Osmosis.org
T. Gland finally settles down in front of the Trachea
Osmosis.org
The walls of the TGD are lined by lymphoid cells + epithelial cells
which can secrete mucus into the
cavity
The walls of the duct normally stick to each other involution begins!!
By the third trimester the duct is usually gone !Osmosis.org
Osmosis.org
Harnsberger 2004
In some people Thyroid tissue remains in the residual duct: ectopic thyroid !
Radiology Case Reports 11(3) 2016
Pharyngeal arches, pouches, and clefts
Endoderm
Ectoderm
Mesoderm
Osmosis.org
4 GW embryo
Arch
PouchCleft
the Famous Pharyngeal Apparatus
Osmosis.org
Arches : 1 to 6 Craniocaudal direction
1
2
3
4
65?
4 Clefts: ectoderm (lying the external part of the arches)
1
2
3
4
4 Pouches: endoderm (lying the internal part of the arches)
1
2
3
4
Important!!! From each Pharyngeal arch - a different region of the head and neck !
https://depositphotos.com/
Important!!! In each Pharyngeal arch - artery + nerve + cartilage for different regions of the head and neck !
https://teachmeanatomy.info/
Osmosis.org
1st Pharyngeal Arch: Everything you need to Chew
How structures from this Arch are innervated? CN5 , V3
Osmosis.org
1st Pharyngeal Arch: Everything you need to Chew
What about the bones? Mandible, Maxilla, Incus , Malleus
Zygomatic bone
Temporal bone
Osmosis.org
1st Pharyngeal Arch: Everything you need to Chew
What about the Muscles? Swallowing, Chewing + tensor tympani
1st Arch
2nd arch
2nd Pharyngeal Arch: facial expression!
2nd Pharyngeal Arch: facial expression!
Osmosis.org
What about the nerves and bones? Facial N, Hyoid Bone, styloid process , stapes
All about the Ossicles
Otic capsule (together with the inner ear)
1st Arch
2nd Arch
Osmosis.org
What about the Muscles? Swallowing (post belly digastric), stapedial muscle
1st Arch
2nd arch
2nd Arch
1st Arch
2nd Pharyngeal Arch: sound and swallowing !
Osmosis.org
3rd Pharyngeal Arch: IX nerve !
Osmosis.org
4th and 6th Pharyngeal Arches: X nerve
Laryngeal Cartilage
Muscles of the larynx, pharynx and mouth!
1st BCC
That's why often malfof middle and external
ear are together!
What if doesn’t fade away….
Part II: Anatomy
Anatomy of the Neck
Superficial Cervical Fascia: thin layer of subcutaneous connective tissue that lies between the dermis of the skin and the deep cervical fascia
Contents: platysma, nerves, blood / lymphatic vessels, fat.
Pathology (related to the content!!): Teratoma, Vasc. Malformations/neoplasm, Cellulitis, PlexiformNeurofibromas (NF1), Subcutaneous Fat Fibrosis(neonates)
NB: It is considered by some to be a part of the Panniculus adiposus, and not true fascia.Bailey, B.J. Ed: Head and Neck Surgery-Otolaryngology 2006.
Superficial Cervical Fascia (yellow)
From internet
Subcutaneous fat tissue between the skin and the superficial layer of the deep cervical fascia (green)
Superficial layer DCF
Skin
Anatomy of the Neck
Deep Cervical Fascia (DCF): 3 layers superficial (SL), middle (ML) and deep (DL)
The layers divide neck in compartments (on the axial plane).
Neck is also divided in Suprahyoid neck (SHN) Infrahyoid neck (IHN) (on the coronal and sagittal plane)
Hyoid Bone
Superficial Layer DCFSHN: Around Masticatory Sp. & Parotid Sp; part of
carotid space
www.statdx.com
Superficial layer DCF
Superficial Layer DCFIHN: surrounds strap, sternocleidomastoid &
trapezius muscles
www.statdx.com
Superficial layer DCF
Middle Layer DCFSHN: defines Pharyngeal Mucosal Spacedeep margin; contributes to carotid space
www.statdx.com
ML - DCF
Middle Layer DCFIHN: Surrounds Visceral Sp.; contributes of
carotid space
www.statdx.com
ML - DCF
Deep Layer DCF
www.statdx.com
SHN & IHN: Surrounds perivertebral space (paraspinal and pre-vertebral components), Contributes to carotid space.
DL - DCF
Deep Layer DCF: Alar FasciaPart of the DL-DCF which forms the lateral and posterior walls of the
Retropharyngeal space and separates this space from the Danger Space (virtual space)
www.statdx.com
DS: from the skull base to the mediastinum; Boundaries ANT: Retropharyngeal Sp. POST: pre-
vertebral component of periveterbal space
Masticator space: VM ++
Subcutanous : hemangioma ++
Masticator space : RMS++
Strap muscles/midline : TGD
Retropharyngeal space: abscess
Space or Anatomic region Differential DiagnosisSuperficial Fascia Teratoma, Vascular Malformations, lipoma, plexiform
Neurofibroma, fibromatosis colli of SCM (in neonates), Infantile Hemangioma
Danger Sp. Cellulitis/Abscess, Infantile Hemangioma
Masticator Sp. Venous/lymphatic Malf., rhabdomyosarcoma, cellulitis/abscess, Infantile Hemangioma
Parotid Sp. Infection, Lymphatic malf., RMV thrombosis, Infantile Hemangioma
Carotid Sp. IJV thrombosis, lymphadenopathy, abscess, neuroblastoma, Infantile Hemangioma
Retropharyngeal Sp. Cellulitis/Abscess, extension of tumours or goiter, Infantile Hemangioma
Perivertebral Sp. Neuroenteric cyst, Cellulitis/Abscess, Spondylodiskitis, Infantile Hemangioma
Posterior Cervical Sp. Lymphatic malf., lymphadenopathy, lymphoma, Infantile Hemangioma
Submandibular/Sublingual Sp.
Thyroglossal cyst, venous/lymphatic Malf, dermoid cyst, ranula, sublingual gland disease, Infantile Hemangioma
Pharyngeal and Parapharyngeal Sp.
Lymphangioma, paraganglioma, rhabdomyosarcoma, abscess, Lymphoma , Infantile Hemangioma
CECT appearance Do not forget the levels of the Neck !
Drawing by F. Gaillard
Tonsils
Lev
el I
I A
Level II A
Level V a
Summary
basic embryology helps you understand neck
malformations and congenital abnormalities
Division of thee neck in spaces (remember deep
cervical fascia)
Use supra vs infrahyoid neck as first step
Space location useful for DDX
felice.d’[email protected]@FeliceDArcoLectures are on Youtube!https://www.slideshare.net/bluetango84
Great Ormond Street Hospital for Children Neuroradiology Team + Camilla
Dr. O. CarneyDr. U. LobelDr. K MankadDr S. SudhakarDr. Asthik Biswas
