Head Primordia Flashcards
What are pretrematic nerves?
Sensory branches of branchial arch nerves that are out of their arch territory
What is the function of the trochlear nerve (IV)?
Move the pupil downand out (superior oblique somatomotor innervation)
What is the structure of the optic placode?
An ectodermal thickening on the side of the head
What is E?
Stomodeum
Which nerve supplies branchial arch 2?
Facial nerve (VII)
What is the function of the facial nerve (VII)?
Branchiomotor to the muscles of facial expression, source of parasympathetics for lacrimal secretion (tears)/nasal and oral mucosa/salivary gland secretions, and taste to the anterior 2/3 of the tongue
What is the function of the hypoglossal nerve (XII)?
Somatomotor to intrinsic and extrinsic tongue muscles
What is the pathway of postsympathetic parasympathetic neurons of the head?
They synapse in one of four parasympathetic ganglia and then join branches of the trigeminal nerve to get to their target smooth muscle and glands
What structures do the linings of the pharyngeal (branchial) arches contribute to the formation of?
Skin of jaws and mucous membranes of the oral cavity, pharynx, larynx, and middle ear
What is an otocyst?
The primordium of the semicircular canals and cochlea of the inner ear
What type of neurons are associated with the vestibulocochlear nerve (VIII)?
Special sensory neurons
it is associated with the otic placode
What structures flank the embryonic foregut?
Pharyngeal (branchial) arches 2-6
What nerves supply the preotic somites (somitomeres)?
Oculomotor (III), trochlear (IV), and abducens (VI) nerves
Which branchial arch is supplied by the glossopharyngeal nerve (IX)?
Arch 3
What is the endoderm of the head?
Lining of the foregut that extends into the stomodeum - pharynx, larynx, auditory tube, and middle ear cavity
What type of neuron components does the olfactory nerve (I) contain?
Special sensory neurons (for smell and olfaction)
this nerve is associated with the olfactory placode
What nerve is associated with the optic placode?
The vestibulocochlear (auditory) nerve (cranial nerve VIII)
Which nerve contains special sensory neurons for hearing, balance, and equilibrium?
Cranial nerve VIII
Where do all sympathetic neurons in the head originate from?
Lateral horn of the spinal cord (T1-L2)
What is A?
Pharyngeal arches
Which cranial nerve is associated with post-otic somites?
a) facial
b) hypoglossal
c) oculomotor
d) spinal accessory
e) glossopharyngeal
b) hypoglossal
What nerves supply postotic somites?
Somatomotor neurons from the hypoglossal nerve (XII)
Which branchial arch is supplied by the vagus nerve (X)?
Arches 4-6
What nerve does the olfactory placode relate to?
Olfactory nerve (cranial nerve I)
What is the innervation source of the skin of the back of the head and most of the neck?
Cervical spinal nerves
What is the function of the olfactory nerve (I)?
Special sensory for olfaction (smell)
What nerve is the optic cup associated with?
Optic nerve (cranial nerve II)
What is unique about cranial nerve II (compared to other cranial nerves)?
It is a specialized brain fiber tract covered with meninges
What do preotic somites (somitomeres) develop into?
Extraocular eye muscles
What is the structure of the olfactory placode?
It is a thickened section of the surface ectoderm at the anterior end of the embryonic head
Which nerve supplies branchial arches 4-6?
Vagus nerve (X and the cranial part of nerve XI)
What is the function of vestibulocochlear nerve (VIII)?
Special sensory for hearing and balance
Which branchial arch is supplied by the trigeminal nerve (V)?
Arch 1
What structure are the non-retinal parts of the eyeball, dermis of facial skin, most bones of the neurocranium, and meninges derived from?
Head mesenchyme
What structures do the pharyngeal (branchial) arches contribute to the formation of?
Muscles, bones, and other tissues of the head and neck
What do the olfactory epithelium and special sensory neurons for smell differentiate from?
The olfactory placode
What does the optic placode develop into?
It invaginates and pinches off below the surface to form the otocyst (primordium of inner ear)
What is the pathway of post-synaptic sympathetic neurons in the head?
They synapse in the cervical sympathetic ganglia and then leave the sympathetic trunk to enter the head as a plexus on the large arteries. They then follow arteries all the way to the targets (or leave vessels to join branches of the trigeminal nerve)
Which branchial arch is supplied by the facial nerve (VII)?
Arch 2
If a newborn has small jaws from a smaller than normal branchial arch 1, migration of what cell type was likely diminished?
a) somite mesoderm
b) primitive streak
c) neural crest
d) surface ectoderm
e) foregut mesoderm
c) neural crest
What is the structure of the pharyngeal (branchial) arches?
Bars of the mesoderm that flank the primitive oral cavity and pharynx
What cell/tissue type do head somites develop into?
Skeletal muscle
What is the function of the optic nerve (II)?
Special sensory for vision
What is the stomodeum?
An invagination of the ectoderm at the site of the oral membrane that leads to development of oral and nasal cavities
What is formed from the surface ectoderm?
The epidermal part of the skin of the head and neck and the mucous membranes of the oral and nasal cavities
What is the most cranial derivative of the foregut?
a) esophagus
b) oralcavity
c) nasal cavity
d) pharynx
e) larynx
d) pharynx
What develops into the intrinsic muscles of the tongue?
Postotic somites
What structures does the head mesenchyme contribute to?
Non-retinal parts of the eyeball, dermis of facial skin, most bones of neurocranium, and meninges
What nerve supplies the jaw and oral cavity?
Mandibular division of the trigeminal nerve (V3)
What cranial nerves do head somites hook up to?
Cranial nerves III, IV, VI, and XII
What is the nerve supply for the midface (cheeks, nasal cavity, and upper jaw)?
Maxillary divison of the trigeminal nerve (V2)
What is the source of general sensory neurons for the forehead, external nose, and orbit?
Ophthalmic division of the trigeminal nerve (V1)
What type of neuron components does the hypoglossal nerve (XII) contain?
Somatomotor neurons
It is associated with somites, which develop exclusively into skeletal muscle
What are branchiomotor fibers?
Motor fibers to muscle derived from branchial arches
Which of the following is an extension of the neural tube/brain?
a) olfactory placode
b) stomodeum
c) thyroid diverticulum
d) optic cup
e) otic placode
d) optic cup
What is B?
Otic Placode
What type of neuron components does the abducens nerve (VI) contain?
Somatomotor neurons
it is associated with somites, which only develops into skeletal muscle
What is the function of the spinal accessory nerve (XI)?
Motor to the sternocleidomastoid and trapezius muscles
Which nerve supplies branchial arch 3?
Glossopharyngeal nerve (IX)
What nerves supply extraocular eye muscles?
Oculomotor (III), trochlear (IV), and abducens (VI)
extraocular eye muscles formed by preotic somites
What cranial nerves are the “special sensory neurons” and what primordia are they associated with?
Cranial nerves I, II, and VIII Associated with the ectoderm
Which nerve supplies branchial arch 1?
Trigeminal nerve (V)
arch 1 has two divisions (maxillary and mandibular) that are supplied by V2 and V3 respectively
What regions of the head/neck are supplied by the maxillary divison of the trigeminal nerve (V2)?
The midface (nasal cavity, cheeks, and upper jaw)
What are the components of the mesoderm for the head/neck region?
Somitomeres (somites), head mesenchyme, and pharyngeal (branchial) arches
What nerve supplies taste to the anterior 2/3 of the tongue?
Chorda tympani branch of the facial nerve
All glands and tissues in the head that require parasympathetic innervations are in the territory of what cranial nerve?
a) vagus
b) glossopharyngeal
c) trigeminal
d) facial
e) spinal accessory
c) trigeminal
What is C?
Lens Placode
What do the visual retina and special sensory neurons for vision develop from?
The optic cup (from the inner layer and the optic stalk respectively)
What nerves supply the intrinsic muscles of the tongue?
Hypoglossal nerve (XII)
the intrinsic muscles of the tongue are formed from postotic somites
What is the pathway of pre-synaptic sympathetic neurons in the head?
Originate in the lateral horn of the psinal cord, travel in the sympathetic trunk to the cervical sympathetic ganglia where they synapse
Which nerve supplies general sensory neurons for the orbit contents and upper face?
Ophthalmic division of the trigeminal nerve (V1)
What does the chorda tympani branch of the facial nerve supply?
From arch 2 to the stomodeum/oral cavity - supplies taste to the anterior 2/3 of the tongue
A flushed face (dilationofarteries) and lack of sweating on the face may be produced by compression of which of the following?
a) facial nerve
b) spinal accessory nerve
c) trigeminal nerve at its origin
d) ganglia associated with the trigeminal nerve
e) sympathetic trunk
e) sympathetic trunk
What does the olfactory placode differentiate into?
It invaginates to form a pit and differentiates into olfactory epithelium and special sensory neurons for smell
What nerve provides the general sensory fibers for the head mesenchyme?
Trigeminal nerve
What is the function of the glossopharyngeal nerve (IX)?
Visceral sensory for pharynx/middle ear cavity, taste for back of tongue, parasympathetic for parotid salivary gland secretion, brnachiomotor for stylopharyngeus, special sensory for chemo- and baroreception
What regions of the head/neck are supplied by the mandibular division of the trigeminal nerve?
Jaw and oral cavity
If the otic placode fails to develop in an embryo, which of the following deficits will be exhibited in that individual?
a) loss of balance
b) diminished sense of taste
c) loss of general sensation onthe side of the head
d) blindness
e) loss of smell
a) loss of balance
also deafness
Which of the following has an ectodermal lining?
a) primitive oral cavity
b) larynx/vocal cords
c) middle ear cavity deep to the ear drum
d) nasopharynx
e) esophagus
a) primitive oral cavity
b is endoderm from foregut diverticulum, c is endoderm from first pharyngeal pouch, d/e are endoderm of the foregut
What is the function of the vagus nerve (X)?
Branchiomotor to the pharynx/larynx/esophagus, visceral sensory to the larynx/foregut/midgut minus pharynx, parasympathetic to laryx/foregut and midgut mucosa, special sensory for chemo- and baroreception of the aorta
Which nerves do presynaptic parasympathetic neurons of the head leave from?
Cranial nerves III, VII, IX, and X - oculomotor, facial, glossopharyngeal, and vagus respectively
What is the pathway of presynaptic parasympathetic nerves of the head?
They leave the brain with cranial nerves III, VII, IX (and X) aka the oculomotor, facial, glossopharyngeal, and vagus respectively. They leave these nerves (except for nerve X/vagus) to synapse in one of four parasympathetic ganglia.
What is the function of the trigeminal nerve (V)?
General sensory innervation to the face, forehead, orbit contents, and nasal/oral cavities as well as branchiomotor to the muscles of mastication
What do postotic somites develop into?
Intrinsic muscles of the tongue
Which primordia will develop into the organs of special senses (smell, sight, hearing, balance)?
Ectoderm
What is the function of the oculomotor nerve (III)?
Extraocular eye muscle somatomotor innervation, raising upper eyelids, and pupil constriction (via parasympathetics)
What develops into extraocular eye muscles?
Preotic somites (somitomeres)
What is head mesenchyme?
Loose, mesodermal, connective tissue surrounding the brain
What nerve is the endoderm of the head supplied by?
Visceral sensory neurons
What is D?
Olfactory Placode
What does the tympanic branch of the glossopharyngeal nerve supply?
From arch 3 to the middle ear (visceral sensory neurons)
What does the optic cup differentiate into?
The inner layer of the cup becomes the visual retina and the optic stalk of the cup is where special sensory neurons for vision develop
What is the structure of the optic cup?
An evagination of the neural tube (developing brain)
What is the head mesenchyme derived from?
Ectodermal neural crest
it is not derived from the primitive streak like postcranial mesenchyme
What is the function of the abducens nerve (VI)?
Somatomotor for abduction of the pupil (motor to the lateral rectus muscle)
What does the ophthalmic division of the trigeminal nerve (V1) supply?
From arch 1 to the area around the optic cup - general sensory neurons for the orbit contents and upper face
What regions of the head/neck are supplied with general sensory neurons from the ophthalmic divison of the trigeminal nerve (V1)?
Forehead, external nose, and orbit
