Head and Neck Development + Imaging w/ Headaches! Flashcards
Where are the 3 major growth areas of the head?
The skull base
Face
Cranial vault (calvarium)
What process enlarges the bones during development?
Endochondral ossification
Where are the fontanelles of the head located?
Anterior
Anterolateral/sphenoidal (each side)
Posterolateral/mastoid (each side)
Posterior
What are the flat paired bones of the skull formed from and by?
Formed from somatic mesoderm by intramembranous ossification.
What is unique about the TMJ/temporomandibular joint?
It is the only true synovial joint of the head. It has a fibrocartilage disc.
How many arches does a fetus have and what are the numbers?
1,2,3,4,6
Humans lack a 5th pharyngeal arch.
Name the CN that goes to each pharyngeal arch.
1 - V3
2 - VII
3 - IX
4 - X
6 - recurrent of X
Based on what you know regarding the arches, what muscles do they innervate?
1 is V3, so muscles of mastication.
2 is VII, so muscles of facial expression.
3 and 4 are IX and X, so muscles of the pharynx and palate.
6 is recurrent of X, so most of the phonation (laryngeal) muscles.
Describe the difference between a pharyngeal pouch and cleft.
A cleft is lateral, while pouches are medial.
What do the first pharyngeal pouches become?
Auditory tubes
What do the second pharyngeal pouches become?
Palatine tonsils
What do the third pharyngeal pouches become?
Inferior parathyroid and thymus.
What do the fourth pharyngeal pouches become?
Superior parathyroid and ultimobranchial body
What does the first pharyngeal cleft become?
External auditory meatus
What is unique about the third pharyngeal pouch?
During development, it sinks below the fourth pouch, which is why it contains the inferior parathyroid gland and the thymus.
What is malformation of the external ears commonly indicative of?
1st and 2nd arch development issues.
What is the significance of the cervical sinus in development and what do defects with it cause?
The cervical sinus needs to destroy itself during development. If not, it can form branchial cysts/fistulae.
You can have an external or internal branchial fistula/sinus, which appears as a hole in the neck or drains into the palatine tonsil.
Branchial cysts are self-isolated and fluid-filled. They do not open to skin or the pharynx.
Describe the path the thyroid gland descends down during development.
It leave the foramen cecum, going under the tongue and anteriorly, going under the hyoid anteriorly and descending in front of all the cartilages.
What is the abnormality we learned regarding thyroid development?
Thyroglossal duct cysts, where the thyroid tissue gets stuck as the gland moves down. Looks like a giant adam’s apple that is superior to where it should be.
At what week in development does a fetus look like a muppet?
3.5 weeks
At what week in development does a fetus look like an alien lizard?
5 weeks
Describe the underlying developmental issue in unilateral cleft lip and the two kinds.
Unilateral failure of the medial nasal prominence to fuse with the maxillary prominence.
Incomplete appears with an intact nose and a lip deformity unilaterally.
Complete appears with the unilateral lip fused to the nose.
What is the key developmental difference in unilateral cleft lip and oblique facial clefts?
Oblique facial clefts involve both the lateral and medial nasal prominences failing to fuse with the maxillary prominence, not just the medial.
Describe the underlying developmental issue in bilateral cleft lip and the two kinds.
Bilateral cleft lip is the same as unilateral but with both medial nasal prominences failing to fuse to the maxillary prominences. It has both incomplete and complete.
What part of the lip is responsible for the incisors?
Philtrum, which is the maxillary prominence fused.
What is the key difference between cleft lip and cleft palate?
Cleft lip involves failure of medial nasal prominence fusion.
Cleft palate involves failure of palatine shelf fusion.
What is holosprosencephaly and the two kinds?
Failure of cerebral hemispheres and lateral ventricles to separate. You can have semilobar or alobar.
What is a regular feature seen in extreme holosprosencephaly?
Proboscis in the forehead.
What kind of imaging would I use to check a TMJ?
CT and/or MRI.
What are the 4 types of headaches?
Sinus, cluster, tension, and migraine.
Define a sinus headache
A headache relating to the location and innveration of a paranasal sinus. Pain is usually found behind the browbone or cheekbones.
Define a cluster headache
A headache with recurring, intense, UNILATERAL pain around the eye and cheek, lasting ~30 mins.
Define a tension headache
A headache from muscle tension and fatigue, which causes BILATERAL scalp pain. Typically described as a band squeezing the head.
Define a migraine
A variable, UNILATERAL headache with/without sensory changes. Typically associated with pain, nausea, and visual changes.
What are the biggest red flags that would support CT head imaging?
Worst/first headache ever
Severe headaches with rapid onset
Post LP
What hematomas can cause headaches and what imaging would I use for each?
Epidural hematoma: would typically be associated with trauma, use CT or MRI.
Subdural hematoma: can use CT or MRI, semilunar shape.
Subarachnoid hemorrhage: use MRI preferably, since blood and CSF cannot be differentiated well on a CT. requires more slices and planes to diagnose since blood is going anywhere CSF can.
What can cause sensorineural hearing loss + vertigo and how would I image for it?
CNVIII dysfunctin most likely due to an acoustic neuroma or schwannoma. Can also affect CNVII since they both exit at the same area. (Stylomastoid foramen)
MRI recommended.
What are acute neurological signs usually caused by?
Vascular issues
What are progressive neurological signs usually caused by?
Tumors
What are the common causes of dysfunction of multiple CNs?
Growths, Ischemias, or MS.
What is dysfunction of CNVI often caused by?
Aneurysm of the internal carotid in the cavernous sinus or increased ICP.
What is dysfunction of CNIII often caused by?
space-filling lesion that pushes it against the opposite tentorial notch. Generally leads to increased ICP.
What is the main concern in neck masses for imaging?
If it is thyroid or non-thyroid.
How do I image a thyroid mass?
Biopsy, bloodwork, and sometimes ultrasound for the biopsy.
How do I image a non-thyroid mass?
CT scan, with and without contrast from the aortic arch to skull base.
