Cranial Nerves Flashcards
(27 cards)
By what week of embryonic development is the neural tube divided into distinct regions?
By weeks 6-8.
What regions of the brain arise from the forebrain (prosencephalon)?
The telencephalon (cerebrum and basal ganglia) and diencephalon (thalamus and hypothalamus).
Which cranial nerve arises from the telencephalon?
Olfactory nerve (CN I).
What cranial nerves arise from the mesencephalon?
Oculomotor (CN III) and trochlear (CN IV).
Which cranial nerves arise from the metencephalon?
Trigeminal (CN V), abducens (CN VI), facial (CN VII), and vestibulocochlear (CN VIII).
Where does CN IV emerge from the brainstem?
CN IV emerges from the dorsal aspect of the brainstem.
Which cranial nerve is an anomaly and emerges from the superior spinal cord?
The spinal accessory nerve (CN XI).
What is the function of the olfactory nerve (CN I)?
It is responsible for the sense of smell.
Where does the olfactory nerve pass to enter the nasal cavity?
Through the foramina in the cribriform plate.
What are the functions of the optic nerve (CN II)?
Vision and sensory input from the retina.
Where do the optic nerves join, and what happens to their fibers?
At the optic chiasm, medial fibers decussate, and lateral fibers remain on the same side.
What muscles does the oculomotor nerve (CN III) supply?
Superior, inferior, and medial rectus; inferior oblique; and levator palpebrae superioris.
What parasympathetic function does CN III perform?
Parasympathetic fibers from CN III supply the sphincter pupillae to constrict the pupil.
What muscle is supplied by the trochlear nerve (CN IV)?
Superior oblique muscle.
Why is CN IV susceptible to damage during head trauma?
Due to its long intracranial course, it is prone to damage in severe head trauma.
What muscle is supplied by the abducens nerve (CN VI)?
Lateral rectus muscle.
What are the sensory and motor functions of the trigeminal nerve (CN V)?
CN V has sensory functions (e.g., face, teeth) and motor functions (e.g., muscles of mastication).
What are the three divisions of the trigeminal nerve?
Ophthalmic (V1), maxillary (V2), and mandibular (V3).
What does the mandibular nerve (V3) supply?
The mandibular nerve supplies skin, teeth, mucosa, and muscles of mastication.
What are the main motor and sensory functions of the facial nerve (CN VII)?
CN VII provides motor innervation to facial expression muscles and taste sensation to the anterior two-thirds of the tongue.
How does the vestibulocochlear nerve (CN VIII) divide, and what are its functions?
It divides into vestibular (balance) and cochlear (hearing) nerves.
What are the sensory and motor functions of the glossopharyngeal nerve (CN IX)?
CN IX provides sensory input from the oropharynx and taste from the posterior one-third of the tongue, and motor innervation to the stylopharyngeus.
What are the sensory and motor functions of the vagus nerve (CN X)?
CN X provides sensory input from the pharynx, larynx, and viscera, and motor control of swallowing, speech, and autonomic functions.
What muscles are innervated by the spinal accessory nerve (CN XI)?
Sternocleidomastoid and trapezius muscles.
