What is a nerve plexus
a complex, web-like network of intersecting nerves in the peripheral nervous system, functioning like a “junction box” to organize and distribute nerve signals
How many spinal nerves are there
31 pairs from the spinal cord through the intervertebral foramina
Cervical plexus range
C1-C4 runs through spinal cord to in vertebral foramina
Brachial plexus range and function
C5-T1 provides nearly all motor and sensory function to the upper limb, including the shoulder, arm, forearm, and hand
Axillary nerve origin/range
C5-C6 anterior posterior articular
Radial nerve origin
C5-T1 controlling movement and sensation in the arm, specifically responsible for extending the elbow, wrist, and fingers
Musculocutaneous nerve origin
C5-C7 anterior arm muscles brachii
Median nerve origin
C5-T1 flexor muscles in forearm
Ulnar nerve origin
C8-T1 providing power and dexterity to the hand
Lumbosacral plexus origin
T12-S4 Supplies muscles and skin of lower limb and pelvis
Femoral nerve origin
L2-L4 providing crucial motor and sensory function to the anterior thigh and medial leg
Sciatic nerve origin
L4-S3 controls muscles in the posterior thigh, lower leg, and foot (motor) while providing sensation to the skin of the leg and foot, enabling movement like walking and feeling touch
Dermatome definition
An area of skin innervated by the sensory
neurons of a single spinal segment/nerve
Myotome definition
A muscle group innervated by the motor neurons of a single spinal segment/nerve
Phrenic nerve range and function
C3-C5 Provides motor control for diaphragm contraction
Tibial nerve
L4-S3 provides essential motor and sensory functions to the lower leg and foot
Name the cranial nerves in the brain
Olfactory 1
Optic 2
Oculomotor 3
Facial 7
Vestibulocochlear 8
Glossopharyngeal 9
Vagus 10
Autonomic nervous system definition
detects and responds to changes in homeostatic functions that are not under conscious control
What does the ANS divide into
Sympathetic division (“fight or flight”)
Parasympathetic division (balance)
Which of the following is a characteristic of the parasympathetic nervous system?
Long pre-ganglionic neurons and short post-ganglionic neurons
Where are the cell bodies of sympathetic pre-ganglionic neurons located?
Lateral horn of grey matter (thoracic spinal cord)
