Spinal nerves Flashcards
Nerve (2)
1) Found in PNS
2) Hundreds of thousands of axons wrapped together in connective tissue
Dorsal ramus (3)
1) Serves dorsal trunk
2) Carries visceral motor, somatic motor, sensory information
3) Skin, muscles of back
Ventral ramus (4)
1) Ventral trunk
2) Upper/lower limbs
3) Visceral motor, somatic motor
4) Body surface, body wall, limbs
Plexus (2)
(1) Network of interconnecting nerves
2) Cervical, brachial, lumbar and sacral
Dermatome (2)
(1) Region of skin that carries sensory information through a specific pair of spinal nerves
2) Include cervical, thoracic, lumbar, sacral
Cervical plexus
Combination of the ventral rami of spinal nerves C1-C5
Phrenic nerve (4)
1) Most important nerve of cervical plexus
2) Supplies motor and sensory fibers to diaphragm
3) Irritation of this nerve causes hiccups
4) Severing nerve would paralyze diaphragm, which would require a ventilator (mechanical respirator)
“Three four five keeps the diaphragm alive”
Phrenic nerve in C3-C5 keeps diaphragm alive
Ganglia (2)
1) Found in PNS
2) Clusters of nerve cell bodies in the PNS
Spinal nerves (pairs, regions) (6)
1) 31 pairs total
2) Cervical - 8 pairs (C01-C08)
3) Thoracic - 12 pairs (T01-T12)
4) Lumbar - 5 pairs (L01-L05)
5) Sacral - 5 pairs (S01-S05)
6) Coccygeal - 1 pair
Spinal nerve roots - names and operation
1) Dorsal root - axons of AFFERENT sensory neurons
2) Ventral root - Axons of EFFERENT motor neurons
3) Join together - ALL spinal nerves are mixed sensory and motor
Afferent Signals
1) Received by spinal nerves
2) Signal passes through dorsal roots
3) Into spinal cord
4) Up to brain for processing
Efferent signals (5)
1) Decision in the brain is made to move
2) Signal passes down the spinal cord
3) Out to the appropriate spinal level
4) Out the ventral root to destination
5) For voluntary motor contraction
Brachial plexus components (4)
1) Ventral Rami of Spinal Nerves C5-T1
2) Roots combine to form three trunks:
a) superior
b) middle
c) inferior
Trunks form two divisions:
a) anterior
b) posterior
Divisions branch into three cords:
a) lateral
b) posterior
c) medial
Axillary nerve (Brachial Plexus) (2)
1) Motor to three muscles:
a) Deltoid
b) Teres minor
c) Long head of the triceps brachii
2) Sensory information
a) from shoulder joint
Radial nerve (Brachial Plexus) (2)
1) Motor to muscles:
a) Triceps brachii
b) 12 muscles of forearm for wrist and finger extension
2) Sensory information
a) Associated joints and overlying skin
Median nerve (Brachial Plexus) (2)
1) Muscles:
a) Flexor muscles of the forearm
b) Thenar muscles (thumb)
2) Sensory information
a) Skin on digits 1-3 and 1/2 of digit 4
Ulnar nerve (Brachial plexus) (2)
1) Muscles:
a) Flexor muscles of the forearm, wrist and hand
2) Sensory information
a) Skin on 1/2 of digit 4 and 5
Musculocutaneous nerve (Brachial plexus) (2)
1) Muscles
a) Flexor muscles of elbow
b) Biceps brachii
c) Brachialis
2) Sensory
a) Skin on radial side of forearm
Lumbar plexus (3)
1) Ventral rami of L1-L4
2) Anterior division
3) Posterior division
Femoral nerve (Lumbar plexus) (2)
Muscles:
a) Hip flexors
b) Knee extensors
Sensation:
a) Skin on the anterior thigh
Lateral femoral cutaneous nerve (Lumbar Plexus)
Sensation
a) Skin on anterior, lateral, posterior surfaces of thigh
Saphenous nerve (Lumbar Plexus)
Sensation:
a) Skin from the medial surface of the leg
Sacral Plexus (2)
1) Ventral rami of L4-S4
2) Sciatic nerve
a) Largest nerve in body
b) Inferior trunk, posterior surface of thigh
Sciatic nerve branches
1) Common fibular (peroneal) nerve
a) Travels laterally
2) Tibial nerve
a) Travels along posterior surface of tibia
