FUNCTIONAL COMPONENTS OF THE TWELVE PAIRS OF CRANIAL NERVES
Of the twelve pairs of Cranial Nerves:
3 may be considered “purely” sensory (aka afferent):
I – Olfactory for SVA (Smell, aka Olfaction)
II – Optic for SSA (Vision)
VIII – Vestibulocochlear for SSA (both Equilibrium and Hearing)
(Note: VIII1 is the Vestibular Branch for Equilibrium and
VIII2 is the Cochlear Branch for Hearing)
5 may be considered “purely” motor (aka efferent) (They are all, certainly, mostly motor):
III – Oculomotor for GSE to 4 of the 6 oculus muscles (SR, MR, IR, and IO)
* for GVE (Parasympathetic to Ciliary and Pupillary constrictors)
IV – Trochlear for GSE to 1 of the 6 oculus muscles (Superior Oblique)
VI – Abducens for GSE to 1 of the 6 oculus muscles (Lateral Rectus)
XI – Spinal Accessory for SVE to SCM and Trapezius muscles (derived from branchial arches)
XII - Hypoglossal for GSE to all intrinsic and extrinsic muscles of the tongue
(*Remember, for ANY muscle there will be some small component of sensory
input in order to monitor tension and length; but since this comes ONLY from
the muscle(s) being innervated, not generalized sensory input from an entire area,
it is considered small enough to be discounted.)
4 may be considered “both sensory and motor”:
V – Trigeminal for GSA from surface of head, neck, sinuses, meninges, teeth, gingival and
Anterior 2/3 of tongue
SVE for Muscles of Mastication (derived from branchial arches)
VII – Facial for GSA from a small area around the external ear and the tympanic membrane
for SVA (Taste) from Anterior 2/3 of the tongue
for SVE for Muscles of Facial Expression (derived from branchial arches)
for GVE (Parasympathetic to all glands of head except Parotid and skin glands)
IX – Glossopharyngeal for GSA from Posterior 1/3 of tongue and tympanic membrane
SVA (Taste) from Posterior 1/3 of tongue
GVA from the Carotid Body to monitor Blood O2 and CO2
SVE for stylopharyngeus muscle (derived from branchial arches)
and elevates the pharynx for speech and swallowing
GVE (Parasympathetic to the Parotid Gland)
X – Vagus for GSA from Epiglottic region of the tongue and small area around external ear
SVA (Taste) from Epiglottic region of the tongue
GVA from all of the pharynx, larynx and VISCERA of the ENTIRE BODY
SVE to the pharynx and larynx for swallowing, coughing, phonation
GVE (Parasympathetic to all thoracic and abdominal viscera as far caudal
as the splenic flexure of the colon. Controls smooth
muscle motility of the GI tract; secretion of digestive fluids, slowing of the
heart rate; constriction of the pupils; accommodation of the lens for near
vision; constriction of bronchioles (airway); relaxation of urinary bladder
sphincter, vasodilation of sex organs (erection) in both males and females;
vasodilation of skin (aka: superficial) blood vessels.
This is a Summary of Parts of Test #4 for Biology 240 (Lecture) on December 3, 2004
I.
Names and functions of the various Muscles of the Oculus
Consider both Extrinsic (4 Rectus Muscles and 2 Oblique Muscles) and
Intrinsic (the Ciliary Muscle controlling lens thickness and the
Radial and Circular Iris muscles controlling pupil size)
II.
Oculus Tunics, Landmarks, and other Significant Structures; Fluids of the Eye (Aqueous +
Vitreous Humors)
III.
Ganglia of the Autonomic Division of the Nervous System
A. Paravertebral Ganglia
B. Prevertebral Ganglia
C. Terminal Ganglia
(Which Branch of the ANS utilizes which of the above as the site of synapse between the
pre-ganglionic and post-ganglionic neuron of the TWO MOTOR NEURON Pathway before
arrival at the visceral effector?)
IV.
“Cranial Nerve Scramble”
Know the functional categories of nerve impulses carried by the Cranial Nerves; generalities
Such as: Which of the Cr. Nerves are SENSORY (and what sensation does each convey?)
Which of the Cr. Nerves are MOTOR (and to what muscles group(s)?
Which of the Cr. Nerves are BOTH (with what Sensory and what Motor?)
Plexuses
Know which Spinal Nerves form each of the four plexuses: Cervical, Brachial, Lumbar,
and Sacral. (Also, which Spinal Nerves DO NOT form plexuses?)
Features and Effects of Sympathetic and Parasympathetic N.S.
Be able to “compare / contrast” the effects of each; the features of each (ie: which neurotransmitter is utilized at which synapse?, are axons LONG or short; are effect long-acting
or short acting. Also, include in your comparison, the Somatic N.S.
Events occurring in the Accommodation of the Lens for Near Vision (and resultant degree
of Light Refraction.
A few general questions about the Brain (its 4 Principal Parts), the pre-central/post-central
Gyrus; sensation/perception (what does MODALITY refer to?) and the Eye.