Flashcards in Lecture 14 The Peripheral Nervous System Deck (22):
What is CN 1? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
Arise from the olfactory receptor cells of nasal cavity
Pass through the cribriform plate of the ethmoid bone
Fibres synapse in the olfactory bulb
Purely sensory (olfactory) function
What is CN 2? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
Arise from the retinas
Pass through the optic canals, converge and partially cross over the optic chiasma
Optic radiation fibres run to the occipital (visual) cortex
What is CN 3? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
Fibres extend from the midbrain through the superior orbital fissures to the extrinsic eye muscles
Motor function: raises the eyelid, directing the eyeball, constricts the iris (parasympathetic), and controls lens shape
What is CN 4? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
Fibres from the dorsal midbrain enter the orbits via the superior orbital fissures to innervate the superior oblique muscle
Motor nerve which directs the eyeball.
What is CN 5? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The trigeminal nerves
Largest cranial nerves which extend from the pons to the face.
It has 3 divisions
1. Ophthalmic (v1) passes through the superior orbital fissure
-conveys sensory info from anterior scalp, upper eyelid, nose, cornea and lacrimal gland
2. Maxillary (v2) passes through the Foramen rotundum
-conveys sensory info from nasal cavity, palate, upper teeth, skin of cheek, upper lip, lower eyelid
3. Mandibular (v3) passes through the Foramen ovale
-conveys sensory from anterior tongue, lower teeth, skin of chin, temporal region of scalp.
Supplies motor to muscles of mastication.
Convey sensory impulses from various areas of the face (v1), v2 and v3 and supplies motor fibres v3 for mastication
What is CN 6? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The abducens nerves
Fibres from inferior pons enter the orbits via the superior orbital fissures
Motor, innervating the lateral rectus muscle
Rem: you get a twitch in your eye (lateral rectus) when your doing AB work (abducens)
What is CN 7? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The facial nerves
Fibres from the pons travel and emerge through the stylomastoid foramina to the lateral aspect of the face
The biggest motor nerve of the face.
Motor functions include facial expressions, parasympathetic impulses to lacrimal and salivary glands
Sensory function (taste) from the anterior two thirds of the tongue
Rem: the funny looking guy who's face looks like a seven, has a funny facial expression (motor to face), drools (salivary glands). And meanwhile he is trying to eat a sandwich (sensory taste)
What is CN 8? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The vestibulocochlear nerves
-afferent fibres from hearing receptors (cochlear div) and equilibrium receptors (vestibular div) pass from inner ear through internal acoustic meatuses, and enters the brain stem st the pons, medulla boarder.
Rem: if your not receiving info from these receptors your stumble In a figure of 8 instead of a straight line.
What is CN 9? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The glossopharyngeal nerves
Fibres from the medulla leave the skull via the jugular Foramen and run to the throat
Motor function: innervates part of the tongue and pharynx for swallowing, and provide parasympathetic fibres to parotid salivary glands
Sensory functions: fibres conduct taste and general sensory impulses from the pharynx and posterior tongue
What is CN 10? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The Vagus nerve.
-it's the only cranial nerve that extends beyond the head neck region
It's the longest cranial nerve
Fibres from the medulla exit the skull via the jugular Foramen (think that one on the bottom of the head because it extends down neck (jugular)
Most motor fibres are parasympathetic fibres that help regulate activities of the heart, lungs, and abdominal viscera
Sensory fibres carry impulses from the thoracic and abdominal viscera and taste buds of posterior tongue and pharynx
What is CN 11? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The accessory nerve
-formed from the ventral rootlets from the c1-c5 region of spinal cord
-rootlets pass into the cranium via the Foramen magnum
-accessory nerves exit the skull via jugular foramina
-motor to the trapezius and sternocleidomastoid muscles
What is CN 12? What is its activity, and the Foramen it passes through? Is its sensory or motor or both?
The hypoglossal nerves
Fibres run from the medulla and exit the skull via the hypoglossal canal
Motor to extrinsic and intrinsic muscles of the tongue that contribute to swallowing and speech
How many spinal nerves do we have? Name them and their location
8 cervical nerves: C1-C8
12 thoracic: T1-T12
5 lumbar: L1-L5
5 sacral: S1-S5
1 coccygeal: Co
Each spinal nerve connects to the spinal cord via 2 roots. What are they?
Ventral root: contain motor (efferent) fibres from the ventral horn motor neurons
-fibres innervates skeletal muscles
Dorsal roots: contains sensory (afferent) fibres from sensory neurons in the dorsal root ganglia
Spinal nerves: rami
Each spinal nerve branches into mixed rami, what are they, and explain
All ventral Ramus except T2-T12 form plexuses (cervical, brachial, lumbar, and sacral
What is formed by the ventral rami of C1-C4 and what does it innervate?
Cervical plexus, which innervates skin and muscles of neck, ear, back of head, and shoulders
Phrenic nerve: major motor and sensory nerve of the diaphragm. Recieves fibres from C3-C5
What is formed by ventral rami of C5-C8 and T? What does it innervate?
It gives rise to the nerves that innervate the arm
The major branches of this plexus: like a tree
Roots: 5 ventral rami C5-T1
Trunks: upper, middle and lower
Divisions: anterior and posterior
Cords: lateral, medial and posterior
Branches: named nerves
Refer to slide 38 for image
Brachial plexus nerves: what are they and what do they innervate?
-axillary: innervates the deltoid, terres minor, and skin and joint capsule of the shoulder
-musculocutaneous: innervates bicep brachii and brachialis and skin of lateral forearm
-median: innervates the skin, most flexors and pronators in the forearm, and some intrinsic muscles of the hand
Ulnar: supplies the flexor carpi ulnaris, part of the flexor digitorum profundus, most intrinsic muscles of the hand, and skin and medial aspect of the hand.
Radius: innervates essentially all extensor muscles, supinators, and posterior skin of limb
Lumbar plexus: where does it arise from, what does it innervate, what are the nerves that branch from it?
Arises from L1-L4. Innovates the thigh, abdominal wall, psoas muscle
Femoral nerve: innervates quadriceps and skin of anterior thigh and medial surface of leg
Obturator nerve: passes through the Obturator Foramen to innervate adductor muscles.
Sacral plexus: where do they arise from, what muscles does it serve, what nerves are involved in the sacral plexus
Arises from L4-S4
Serves the butt, lower limb, pelvic structures, and perenium
The sciatic nerve is the longest nerve of the body, it innervates the hamstring muscles, adductor Magnus, and most muscles in the leg and foot
Composed of two nerves: tibial and common fibula
Name the 5 components of a reflex arc
2. Sensory neuron
3. Integration centre
4. Motor neuron