89 terms

Spinal Nerves

CT that covers peripheral nerve
CT that divides nerve into fascicles
CT that surrounds each axon
Spinal nerves pass through
Intervertebral foramina
Bundles of axons
Dorsal root carries ___ fibers.
Sensory fibers
Ventral root carries ___ fibers.
Motor fibers
Forms nerve plexuses
Ventral rami
Nerve plexuses (4):
Cervical plexus formed by
Ventral rami of first 4 cervical nerves
Innervates the infrahyoid muscles
Deep motor branches: Ansa cervicalis (C1-C3)
Nerves that innervate deep neck muscles: geniohyoid, thyrohyoid
+levator scapulae, scalene, sternocleidomastoid, and trapezius muscles
Segmental cervical nerves (C1-C5)
Nerve innervating diaphragm
Phrenic nerve (C3-C5)
Hiccups/ diaphragm spasms are caused by:
Irritation of phrenic nerves
What happens when phrenic nerve is severed?
Diaphragm is paralyzed--> artificial respirator
Plexus that innervates pectoral girdle & upper limb
Brachial plexus (C5-T1)
Brachial plexus palpated
Just superior to the clavicle at the lateral border of the sternocleidomastoid muscle
5 Main nerves of brachial plexus
Nerve that innervates deltoid & teres muscles
Axillary nerve
Nerve that supplies biceps brachii & brachialis muscles
Musculocutaneous nerve
Nerve that supplies the skin and most of the flexor muscles
Median nerve
Nerve innervates 5 intrinsic muscles of the lateral palm
Median nerve
Nerve activates muscles that pronate the forearm, flex the wrist and fingers and oppose the thumb
Median nerve
Nerve supplies sensation to the lateral palm, thumb, digits II-III and half of IV on the anterior surface, and the dorsum of digits II-IV
Median nerve
Nerve supplies the flexor carpi ulnaris and the medial part of the flexor digitorum profundus
Ulnar nerve
Nerve produces wrist and finger flexion, adduction and abduction of the medial fingers
Ulnar nerve
The largest branch of the brachial plexus and is a continuation of the posterior cord
Radial nerve
Nerve wraps around the humerus in the radial groove, then runs around the lateral epicondyle of the elbow
Radial nerve
Motor fibers innervate all the extensors of the upper limb, forearm supination, wrist and finger extension and thumb abduction
Radial nerve
Damage to radial nerve innervating forearm extensors causes
Wrist drop
Pressure on the radial nerve caused by pressing it into the radial groove on the humerus
Saturday night paralysis (crutches)
Bending or stretching of the neck in a direction away from side of injury- Radial disorder
Erb's palsy
When individuals have difficulty making a fist and gripping objects "claw hand", there is damage in the
Ulnar nerve
Problems adducting or abducting fingers due to damage in the
Ulnar nerve
Sensory deficit to half of III & all of IV due to damage in the
Ulnar nerve
Inability to pronate arm & difficulty flexing wrist due to damage in the
Median nerve
Carpal tunnel syndrome caused by repetitive flexion pressing nerve against the
Flexor retinaculum- median nerve
"Oh bleep nerve" due to hitting epicondyle
Ulnar nerve
Severed in suicide attempts
Median nerve
Rotates the scapula so that its inferior angle moves laterally and upward
Serratus anterior
When long thoracic nerve is chronically compressed as when doing military presses, or activities such as rock climbing
The scapula "wings" out away from the thorax
Plexus lies within the psoas major muscle
Lumbar plexus
Plexus innervate the anterolateral abdominal wall muscles, genitals, and psoas major
Lumbar plexus
Nerve provides sensation to skin of the genitals and proximal medial aspect of the thigh (inner thigh).
Ilioinguinal nerve (lumbar plexus) L1
Nerve sensory to the scrotum in males and labia majora in females
Genitofemoral nerve (lumbar plexus) L1-L2
Stimulation of this nerve causes the cremaster to contract which elevates the testes (cremasteric reflex).
Genitofemoral nerve
Reflex for regulating temperature for sperm production
Cremasteric reflex
Nerve motor to the adductor magnus, gracilis and obturator externus muscles
Obturator nerve (lumbar plexus)
Nerve is biggest of the lumbar plexus
Femoral nerve (L2-L4)
Nerve motor to the quadriceps and sartorius muscles of the thigh and to the pectineus and iliacus
Femoral nerve
Damage to this nerve results in an inability to extend the leg at the knee
Femoral nerve
If the spinal roots of the lumbar plexus are compressed
Will have abnormal gait/walk
2 Plexuses overlap & share fibers
Lumbar & Sacral= lumbosaral plexus
Plexus supplies the gluteal region, floor of the pelvis and the lower extremities
Sacral plexus
What is the largest nerve of the sacral plexus/body?
Sciatic nerve
2 nerves of sciatic nerve
Tibial & fibular nerve
Nerve innervates short head biceps femoris,fibularis muscles, tibialis anterior, toe extensors.
Fibular nerve (Sciatic)
Nerve innervates long head biceps femoris, knee flexors, plantar flexors.
Tibial nerve (Sciatic)
Nerve innervates muscles of perineum, urogenital diaphragm, anal & urethral sphincters.
Pudendal nerve (Sacral plexus)
Nerve innervates the knee joint, the fibularis longus and brevis muscles, tibialis anterior, extensor hallucis longus and extensors digitorum longus and brevis
Common fibular nerve
Nerve supplies the posterior compartment of the lower leg
Tibial nerve
Nerve motor to the gluteus medius and minimus and to the tensor fascia latae
The superior gluteal nerve
Nerve innervates the gluteus maximus.
The inferior gluteal nerves
Damage/pinching of sciatic nerve results in pain from _ to _
butt to back of leg
Condition characterized by intense stabbing pain radiating over the course of the sciatic nerve from gluteal region to toes
Condition below the knee, injury to common fibular (peroneal) nerve innervating the tibialis anterior
Foot drop
Unable to dorsiflex the foot while walking which can cause the individual to stumble and fall
Foot drop
Calf muscles cannot plantar flex the foot resulting in a shuffling gait due to
Damage to tibial nerve
The area of the skin innervated by a single pair of spinal nerves
What spinal nerve does NOT innervate dermatomes?
Knowledge of dermatomes help determine
damaged nerves & level of spinal cord injury
Loss of sensation corresponding to the region of skin supplied by the affected nerve due to
Damage/infection of spinal nerve or dorsal root ganglion
Asphyxiation may result if the ______ nerve is damaged. This nerve is derived from the _______plexus.
Phrenic; cervical
Damage to the femoral nerve results in an inability to ___________ the leg.
Carries fibers to posterior trunk where it innervates skeletal muscle & skin of somite
Dorsal ramus
Infrahyoid muscles innervated by
Ansa cervicalis
Innervates biceps brachii muscle
Musculocutaneous nerve
Wrist drop results from damage to the ___ nerve
Radial nerve
Difficulty making a fist & grabbing objects results from damage to ___ nerve
Median nerve
A hypoactive patellar reflex may indicate damage to the ___ nerve
Femoral nerve
Foot drop results from damage to the ___ nerve
Common fibular/peroneal nerve
Shuffling gait due to damage to the ___ nerve
Tibial nerve
Type of receptor causes muscles to relax & lengthens in response to excessive tension
Golgi tendon organ
Type of receptor that works to maintain tension in the muscle
Muscle spindle
Damage to corticospinal tract is detected by abnormal reflex known as the
Babinski sign
An absent corneal reflex may indicate damage to the
Reflexes that are observed on one side of body when other side is stimulated are ___.
Pupils constrict when bright light strikes eye; sympathetic or parasympathetic?
Parasympathetic division
Ciliospinal reflex is mediated through sympathetic or parasympathetic?
Sympathetic division