The Brachial Plexus Flashcards
What are the 5 terminal branches that come out of the brachial plexus?
axillary nerve, musculocutaneous nerve, radial nerve, median nerve, ulnar nerve
What do the roots of the brachial plexus originate from?
ventral rami of the spinal nerves
[C4]C5-T1)
What makes up the lateral cord of the brachial plexus?
The anterior divisions of the upper and middle trunk
What makes up the posterior cord of the brachial plexus?
The posterior divisions of all 3 trunks (upper, middle, lower)
What makes up the medial cord of the brachial plexus?
The anterior division of the lower trunk
What muscles are innervated by the nerves arising from the anterior divisions of the brachial plexus?
anterior compartment of the upper limb
What muscles are innervated by the nerves arising from the posterior divisions of the brachial plexus?
posterior compartment of the upper limb
What nerves arise from the roots of the brachial plexus?
dorsal scapular, long thoracic
Spinal nerves of the dorsal scapular nerve
C4-C5
Function of dorsal scapular nerve
postganglionic sympathetic and motor information (NOT SENSORY) to levator scapulae and rhomboids
Spinal nerves of long thoracic nerve
C5-7
Function of long thoracic nerve
sensory, postganglionic, sympathetic, and motor to serratus anterior
What nerves do not provide sensory, postganglionic sympathetic, OR motor innervation to muscles, viscera/vessels, and skin?
DO NOT PROVIDE MOTOR INNERVATION- medial cutaneous of arm, medial cutaneous of the forearm, superficial branch of the radial nerve
DO NOT PROVIDE SENSORY INNERVATION- dorsal scapular nerve
What nerves arise from the upper trunk of the brachial plexus?
suprascapular nerve, subclavian nerve
spinal nerves of the suprascapular nerve
C4-6
Function of the suprascapular nerve
sensory, postganglionic sympathetic, and motor innervation to the supraspinatus and infraspinatus muscles
Spinal nerves of the subclavian nerve
C5-6
Function of the subclavian nerve
sensory, postganglionic sympathetic, and motor innervation of the subclavius muscle
What branches come off of the middle and lower trunk of the brachial plexus?
None
What spinal nerves does the upper trunk carry?
C[4]5-6
What spinal nerves does the middle trunk carry?
C7
What spinal nerves does the lower trunk carry?
C8-T1
How many anterior divisions are there and which trunks of the brachial plexus do they come from?
3
one from each trunk of the brachial plexus
How many posterior divisions are there and which trunks of the brachial plexus do they come from?
3
one from each trunk
Which nerves branch off of the divisions of the brachial plexus?
none
What branches off of/arises from the lateral cord of the brachial plexus?
lateral pectoral nerve, musculocutaneous nerve, lateral root of the median nerve
What branches off of/arises from the medial cord of the brachial plexus?
medial pectoral nerve, medial cutaneous nerve of arm, medial cutaneous nerve of forearm, medial root of the median nerve, ulnar nerve
What are the 3 sections of the trunks of the brachial plexus?
upper, middle, lower
What branches off of/arises from the posterior cord of the brachial plexus?
upper subscapular nerve, thoracodorsal nerve, lower subscapular nerve, axillary nerve, radial nerve
What arises from the anterior divisions of the upper and middle trunk?
The lateral cord
What arises from the posterior divisions of all 3 trunks?
posterior cord
What arises from the anterior division of the lower trunk?
medial cord
spinal nerves of the lateral pectoral nerve
C5-7
C7 innervation from ansa pectoralis
Function of lateral pectoral nerve
sensory, motor, and postganglionic sympathetic. innervation to the pectoralis major and pectoralis minor
Spinal nerves of the musculocutaneous nerve
C5-7
Function of the musculocutaneous nerve
sensory, postganglionic sympathetic and motor innervation of anterior compartment of the arm
(biceps brachii, coracobrachialis, brachialis)
What does the musculocutaneous nerve later become?
the lateral cutaneous nerve of the forearm
Function of the lateral cutaneous nerve of the forearm
(continuation of musculocutaneous)
sensory and postganglionic sympathetic innervation of skin over lateral aspect of the FOREARM
Spinal nerves of the lateral root of the median nerve
C5-7
Muscular branches of the median nerve (both lateral and medial roots)
sensory, postganglionic sympathetic, and motor innervation–>
SUPERFICIAL AND INTERMEDIATE ANTERIOR COMPARTMENT OF THE FOREARM:
(superficial) flexor carpi radialis, palmaris longus & pronator teres muscle
(intermediate) flexor digitorum superficialis
(**EXCEPT FCU–> ULNAR NERVE)
DEEP LAYER OF ANTERIOR COMPARTMENT OF FOREARM:
flexor pollicis longus, flexor digitorum profundus (lateral/radial portion)
pronator qudratus –> anterior interosseous nerve
THE HAND: lateral/radial two lumbricals
What nerves arise from the lateral root of the median nerve?
anterior interosseous nerve
palmar cutaneous branch
recurrent branch of median nerve
common and proper palmar digital nerves
and muscular branches to hand and forearm
What muscles are innervated by the recurrent branch of the median nerve?
flexor pollicis brevis, abductor pollicis brevis and opponens pollicis muscles
What two nerves arise from the medial and lateral root of the median nerve and provide sensory and postganglionic innervation to the skin of the hand?
palmar cutaneous branch- skin of radial aspect of the palm of the hand
common and proper palmar digital nerves- skin of digits 1-4
spinal nerves of the medial pectoral nerve
C8-T1
Function of the medial pectoral nerve
sensory, postganglionic sympathetic and motor inn. to pec major and minor
Function of the medial cutaneous nerves of the arm and forearm
ONLY SENSORY AND POSTGANGLIONIC SYMPATHETIC INN–> medial aspect of arm and forearm
**NO MOTOR
What nerves/branches arise from the medial root of the median nerve?
(same as lateral root)
muscular branches in forearm and hand
anterior interosseous nerve
palmar cutaneous branch
recurrent branch of the median nerve
common and proper palmar digital nerves
spinal nerves of the medial root of the median nerve
C8-T1
Spinal nerves of the ulnar nerve
C7-T1
What nerves/branches come off of the ulnar nerve?
muscular branches in forearm,
palmar cutaneous branch,
- common palmar digital nerves
- proper palmar (digits 4-5) digital nerves
dorsal cutaneous branch,
deep (terminal) branch
Muscular branches of the ulnar nerve provide innervation to which muscles?
MUSCULAR BRANCH
flexor carpi ulnaris
flexor digitorum profundus (ulnar portion)
DEEP MUSCULAR BRANCH (C8-T1) (terminal branch)
Abductor digiti minimi Flexor digiti minimi Flexor pollicis brevis Opponens digiti minimi Palmar interossei Dorsal interossei Medial/ulnar two lumbricals Adductor pollicis muscles
What two nerves arise from the ulnar nerve and provide sensory and postganglionic sympathetic innervation to skin on the ulnar side of the palm (digit 4 and 5) and the skin on the dorsal surfaces of digit 4 and 5 (ulnar side)?
palmar cutaneous branch
dorsal cutaneous branch
Spinal nerves of upper subscapular nerve
C5-6
Function of upper subscapular nerve
sensory, postganglionic sympathetic and motor inn. to subscapularis muscle
spinal nerves of the thoracodorsal nerve
C6-8
Function of thoracodorsal nerve
sensory, postganglionic sympathetic and motor inn. of latissimus dorsi
spinal nerves of the lower subscapular nerve
C5-6
Function of the lower subscapular nerve
sensory, postganglionic sympathetic and motor inn. to subscapularis and teres major muscles
Spinal nerves of the axillary nerve
C5-6
“2 assassins”
Function of the axillary nerve
sensory, postganglionic sympathetic and motor inn. to the deltoid and teres minor muscles
What nerve comes off the of the axillary nerve and provides sensory and postganglionic sympathetic innervation to the skin over the superior, lateral aspect of the arm?
The superior lateral cutaneous nerve of the arm
Spinal nerves of the radial nerve
C5-T1
“5 rats”
Muscular branches of the radial nerve (arm and forearm)
sensory, postganglionic sympathetic and motor inn.
POSTERIOR COMPARTMENT OF ARM/FOREARM- triceps brachii, anconeus
ANTERIOR COMPARTMENT OF ARM- brachialis
POSTERIOR COMPARTMENT OF FOREARM-
(Superficial)-bachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum, extensor digiti minimi
(deep) - supinator, extensor indicis, abductor pollics longus, extensor pollicis brevis, extensor pollicis longus
- -> INCLUDES THUMB MUSCLES
What nerve arises from the radial nerve and supplies sensory and postganglionic sympathetic innervation to the skin on the posterior aspect of the forearm?
posterior cutaneous nerve of forearm
What does the superficial (terminal) branch of the radial nerve provide innervation to?
sensory and postganglionic sympathetic innervation to skin of radial side of dorsum of hand (back of hand on lateral side)
What muscle is innervated by both the musculocutaneous nerve and a small branch of the radial nerve?
The brachialis muscle