brachial plexus Flashcards
bachial plexus is formed by–
anterior rami (divisions) of cervical spinal nerves C5, C6, C7 and C8, and C8, and the first thoracic spinal nerve, T1
bachial plexus is structurally organized into______
roots→ trunks→ divisions→ cords→ branches
Cutaneous branches of the Brachial plexus include
i. Medial brachial cutaneous nerve (Medial cutaneous nerve of arm, branch of Ulnar nerve/ Medial cord)
ii. Medial antebrachial cutaneous nerve (Medial cutaneous nerve of forearm, branch of Ulnar nerve/ Medial cord)
iii. Posterior brachial cutaneous nerve (Posterior cutaneous nerve of arm, branch of Radial nerve)
iv. Posterior antebrachial cutaneous nerve (Posterior cutaneous nerve of forearm, branch of Radial nerve)
v. Inferolateral brachial cutaneous nerve (Inferior lateral cutaneous nerve of arm, branch of Radial nerve)
v. Superolateral brachial cutaneous nerve (Superior lateral cutaneous nerve of arm, branch of Axillary nerve)
vii. Lateral antebrachial nerve (Lateral cutaneous nerve of forearm, branch of Musculocutaneous nerve)
medial cord and ulnar nerve give rise to what cutaneous branches
i. Medial brachial cutaneous nerve (Medial cutaneous nerve of arm, branch of Ulnar nerve/ Medial cord)
ii. Medial antebrachial cutaneous nerve (Medial cutaneous nerve of forearm, branch of Ulnar nerve/ Medial cord)
the brach of the radial nerve give rise to which cutaneous branches
iii. Posterior brachial cutaneous nerve (Posterior cutaneous nerve of arm, branch of Radial nerve)
iv. Posterior antebrachial cutaneous nerve (Posterior cutaneous nerve of forearm, branch of Radial nerve)
v. Inferolateral brachial cutaneous nerve (Inferior lateral cutaneous nerve of arm, branch of Radial nerve)
axillary nerve gives rise to_____cutaneous branch
Superolateral brachial cutaneous nerve- arm
branch of Musculocutaneous nerve gives rise to _______ cutaneous branch
Lateral antebrachial nerve (Lateral cutaneous nerve of forearm, branch of Musculocutaneous nerve)
Suprascapular nerve (C____)
innervates
Suprascapular nerve (C4, C5, C6):
inervates – Supraspinatus muscle
– Infraspinatus muscle
Glenohumeral (shoulder) joint
Dorsal scapular nerve (C___):
Dorsal scapular nerve (C5):
innervate Rhomboids minor, and Rhomboid major muscles, and occasionally supplies
Levator scapulae muscle
supraclavicular nerves of Brachial Plexus and their roots
suprascapular C4-C6)
subclavian nerve (C4-C6)
dorsal scapular nerve (c5)
upper subscapular nerve (C5)
inferior subscapular nerve (C6)
long thoracic nerve ( C5-C7)
*thoracodorsal Nerve (C6-C8)
upper subscapular nerve (C5) vs inferior subscapular nerve (C6) innervations
Innervates– Subscapularis (superior portion) muscle– which controls the adduction and medial rotation of arm
Innervates:
I. Subscapularis (inferior portion) muscle– which controls adduction and medial rotation of arm
II. Teres major muscle– whose contraction results in the adduction and medial rotation of arm
Subclavian nerve (Nerve to subclavius, C4, C5 and C6):
Long Thoracic nerve (C___):
innervates
(C5 to C7)
Innervates– Serratus anterior muscle– whose contraction causes protraction of scapula, and it assists in upward rotation of scapula bone, stabilizes scapula
Lateral pectoral nerve (C___):
communites with_____
innervates____
what joints does it innervate
C5 to C7)
pierces costocoracoid membrane to reach the deep surface of Pectoral muscles, a communicating branch to Medial Pectoral nerve passes anterior to axillary vessels
Primarily Pectoralis major muscle– flexion, adduction, and medial rotation of humerus
III. Acromioclavicular and Glenohumeral (shoulder) joints
(sidenote : Suprascapular nerve (C4, C5, C6) innervates glenohumeral joint)
Medial pectoral nerve (C___):
is in between what___
what muscles does it innervate
axillary nerve (c __)
important and location
C5 and C6
innervation of axillary nerve
and what nerve is give off by the axillary nerve
vulnerable to injury when?
musculocutaneous nerve (C____)
what route does it follow?
gives rise to?
musculocutaneous nerve (C____)
innervates _____
gives off____ artery
and damage to ____ will lead to
median nerve innervates muscle of the______ and _____
forearm and hand
median nerve path
what it gives off and it innervates
Anterior interosseous branch in the upper part of the forearm, and ends with its innervation of Pronator quadratus
Median nerve innervates the following: (4)
I. Pronator teres– pronation of radioulnar joint
II. Flexor carpi radialis– flexion, and adduction of wrist
III. Palmaris longus– flexion of wrist, and tensing of palmar aponeurosis
IV. Flexor digitorum superficialis– flexion of proximal interphalangeal joints of 2nd, 3rd, 4th, and 5th fingers
in mid year, I will pronate and flex in capri where there is long palms and flex my digit! super!
as well as FLexor, Abductor, Opponens pollis of the thumb and 1st and second lumbricals
Flexor muscles of anterior compartment of forearm, including:
a. Pronator quadratus– pronation of forearm
b. Flexor digitorum profundus– flexion of wrist at metacarpophalangeal and interphalangeal joints
c. Flexor pollicis longus–flexion of phalanges of the thumb
innervated by median nerve
thenar (palm) group of muscles
flexor pillicis breves, abductor pollicis breves, opponens pollicis
FOA pollis breves
innervated by median nerve
1st and 2nd Lumbricals
associated with the index and middle fingers
innervated by the median nerve
muscles innervated by median nerve in anterior compartment
+ 1st and 2nd lumbricals
wrist and distal radioulnar joints gives off what nerves
Palmar cutaneous nerve
II. Palmar digital cutaneous nerve-
carpal tunnel
symptoms
compress the median nerve, resulting in a compression neuropathy (Carpal tunnel syndrome)
Carpal tunnel syndrome is characterized by tingling, burning and pain (needle, pin) through the course of median nerve particularly over the outer fingers and radiating up the arm, with weakness in thumb and the first two fingers
Supracondylar fracture damages ______ nerve
Supracondylar fracture
draw out brachial plexus
hand of benediction
what mainly innervates the posterior part of the upper limb?
radial nerve
Radial nerve (C5 to C8, and T1):
path and gives of what braches
what muscles are innervated by the radial nerve
I. Brachioradialis– weak flexor of forearm
II. Triceps brachii– extension of forearm, resist dislocation of shoulder
III. Anconeus– extension of the forearm at elbow joint, stabilizes elbow joint during pronation and supination
IV. Extensor carpi radialis longus– extension and abduction of wrist
V. Elbow, wrist, and radial metacarpophalangeal joints
unco brachi has extensive long tricps and his wrist, elbow and radial metacapophalangeal joints are affected by it
anconeous, brachioradiallis, extesor carpi radialis longus, tricep bracchi
radial nerve Gives off Posterior Interosseous nerve and innervates what muscles
I. Extensor carpi radialis brevis– extension and abduction of wrist
II. Supinator– supination of forearm
III. Extensor digitorum– extension of proximal interphalangeal and metacarpophalangeal joints of 2nd, 3rd, 4th, and 5th fingers
IV. Extensor digiti minimi– extension of little finger at interphalangeal and metacarpophalangeal joints
V. Extensor carpi ulnaris– extension and adduction of wrist
VI. Extensor pollicis longus- extension of thumb at carpometacarpal, metacarpophalangeal, and interphalangeal joints
VII. Extensor pollicis brevis– extension of thumb at carpometacarpal, and metacarpophalangeal joints
VIII. Extensor indicis– extension of little finger
IX. Abductor pollicis longus– abduction of thumb at carpometacarpal, and metacarpophalangeal joints
radial nerve gives off
I. Posterior brachial cutaneous nerve (Posterior cutaneous nerve of arm)
II. Posterior antebrachial cutaneous nerve (Posterior cutaneous nerve of forearm)
IV. Inferiolateral brachial cutaneous nerve (Inferior lateral cutaneous nerve of arm)
f) Radial nerve also gives off Dorsal (digital) cutaneous nerves
posterior interosseous cutaneous nerve
damage to radial nerve will lead to
wrist drop because wont be able to extend
name some radial nerve injuries
g) Fracture of mid-shaft or radial groove or lateral epicondyle of Humerus bone,
Improper use of crutches (prolonged compression in axillary region),
person gets drunk on Saturday night and ends up falling asleep on a chair with arm hanging over the back of chair (Saturday night palsy) can cause– Radial nerve injury,
which can lead to:
i. wrist drop (loss of wrist extension due to inability to extend the hand and fingers)
ii. loss of sensory, and motor functions in posterior arm, forearm, and hand
In the upper arm, the Median nerve is _______ to Brachial artery and the Ulnar nerve is _______to the brachial artery
______ is a site of compression fro the ulna nerve
lateral
medial
canal of guyon
ulnar nerve (C8 and T1)
descends medial to Brachial artery
passes through back of elbow (medial epicondyle )
canal guyon
what muscles are innervated by the ulnar nerve
I. Flexor carpi ulnaris– flexion, and adduction at wrist joint
II. Flexor digitorum profundus (medial/ ulnar half)– flexion of distal interphalangeal joints of 2nd, 3rd, 4th, and 5th fingers
IV. Palmaris brevis– tenses skin of palm on the ulnar side during a grip action
. Most of the Intrinsic muscles of hand (except those in the Thenar group of muscles, and first two lumbricals), and these include:
A. Dorsal Interossei– abduction of 2nd, 3rd, and 4th fingers away from the axial line
B. Palmar Interossei– adduction of 2nd, 3rd, and 4th fingers towards the axial line
C. Adductor pollicis– adduction of thumb
D. 3rd and 4th Lumbricals–
E. Hypothenar group of muscles, including:
i. Flexor digiti minimi brevis– flexion of little finger at metacarpophalangeal joint
ii. Abductor digiti minimi– abduction of little finger at metacarpophalangeal joint
iii. Opponens digiti minimi– opposition of little finger
Medial cord gives off the following cutaneous branches that innervates the front and medial side of arm, and forearm:
Medial cord gives off the following cutaneous branches that innervates the front and medial side of arm, and forearm:
I. Medial brachial cutaneous nerve (Medial cutaneous nerve of arm)
II. Medial antebrachial cutaneous nerve (Medial cutaneous nerve of forearm)
Ulnar nerve gives off the following cutaneous branches in hand and palm:
i. Palmar digital cutaneous nerve– innervates the medial part of palm
ii. Dorsal (posterior) cutaneous nerve– innervates the medial third of dorsum of hand
iii. Dorsal (digital) cutaneous nerves– innervates medial side of ring finger, and sides of little finger
ways the ulnar nerve can be damaged
when brachial plexus forms from branches it passes through ______
and supply of where in the body
After their formation, these nerves passes between the Scalenus anterior and Scalenus medius muscles to enter the base of neck
c) Supply motor, sensory (cutaneous/skin), and articular (joint) nerve fibers to chest, shoulder, arm, forearm, and hand regions
Roots, Trunks, and Divisions reside ‘________r’, while cords are ‘_______r’
supraclavicular
infraclavicular
anterior vs posterior divisions innervate what?
________fibers innervates the muscles that act at shoulder or flex the elbow
C5 and C6 fibers innervates the muscles that act at shoulder or flex the elbow
_________fibers innervates the muscles that are part of forearm or extend the elbow
C7 and C8 fibers innervates the muscles that are part of forearm or extend the elbow
_____ fibers innervates the intrinsic muscles of hand
T1 fibers innervates the intrinsic muscles of hand
brachial plexus gives rise to suprascapular nerve
Clinical significance of Suprascapular nerve:
Clinical significance of Dorsal scapular nerve C5:
Upper subscapular nerve
vs Lower subscapular nerves
Clinical significance of Subscapular nerves
Upper subscapular nerve (C5):
Subscapularis (superior portion) muscle– adduction and medial rotation of arm
I. Subscapularis (inferior portion) muscle–adduction and medial rotation of arm
II. Teres major muscle– adduction and medial rotation of arm
Clinical significance of Subscapular nerves– Injury to subscapular nerve can cause a reduced ability to medially rotate, and adduct the arm
Subclavian nerve (Nerve to subclavius, C5 and C6):
innervates
I. Subclavius muscle– anchoring, depressing and stabilization of clavicle bone, assists in lifting the ribs during respiration
II. Sternoclavicular joint
Long Thoracic nerve
innervation
(C5 to C7),
Innervates Serratus anterior muscle–
Clinical significance of Long thoracic nerve:
- Winging of scapula
(C5 to C7),
Innervates Serratus anterior muscle whose contraction results in protraction of scapula, and assists in upward rotation of scapula bone, stabilizes scapula
draw out brachial plexus
nerves that innervate the arm
________fibers innervates the muscles that act at shoulder or flex the elbow
_________fibers innervates the muscles that are part of forearm or extend the elbow
__________ fibers innervates the intrinsic muscles of hand
C5 and C6 fibers innervates the muscles that act at shoulder or flex the elbow
– C7 and C8 fibers innervates the muscles that are part of forearm or extend the elbow
T1 fibers innervates the intrinsic muscles of hand
subclavian nerve
inneravtes what joint
innervates
clinical significance of thoraco dorsal
lateral pectoral nerve
clinical significance to lateral pectoral nerve
Medial pectoral nerve
Axillary nerve innervates
ix) Axillary nerve (C5 and C6):
a) Terminal branch of Posterior cord of Brachial plexus, receiving fibers from C5 and C6
b) Innervates the following:
I. Deltoid– which causes shoulder abduction, and flexion, abduction, and rotation of arm
II. Teres minor– which causes lateral rotation of upper arm III. Acromioclavicular and Glenohumeral (shoulder) joints
_______ gives off the Superolateral brachial cutaneous nerve (Superior upper lateral cutaneous nerve of arm)– skin over the superolateral arm
– fall from a tree
– dislocations of shoulder joint
– compression of axilla with a crutch – fracture of surgical neck of Humerus
Axillary nerve may be injured
Injury to Axillary nerve can result in:
- paralysis of the teres minor muscle and deltoid muscle, resulting in loss of abduction of arm, weak flexion, extension, and rotation of shoulder
- loss of sensation in the skin over the over the superior part of lateral aspect of arm
know where musculocutaneous is located
musculocutaneous Gives off______
Gives off the Lateral antebrachial cutaneous nerve (Lateral cutaneous nerve of forearm)
clinical significance of musculocutaneous
median nerve gives off
both ulna and median nerve give rise to palmar cutaneous and palmar digital
Carpel tunnel (canal):
_______ Gives off Posterior Interosseous nerve, which provide motor supply to following muscles:
Radial nerve (C5 to T1)
I. Extensor carpi radialis brevis– cause extension and abduction of wrist
II. Supinator– whose primary action is supination of forearm
III. Extensor digitorum– cause extension of proximal interphalangeal and
metacarpophalangeal joints of 2nd, 3rd, 4th, and 5th fingers
IV. Extensor digiti minimi– whose primary action is extension of little finger at interphalangeal and metacarpophalangeal joints
V. Extensor carpi ulnaris– whose primary action is extension and adduction of wrist
VI. Extensor pollicis longus- whose primary action is extension of thumb at carpometacarpal, metacarpophalangeal, and interphalangeal joints
VII. Extensor pollicis brevis– whose primary action is extension of thumb at carpometacarpal, and metacarpophalangeal joints
VIII. Extensor indicis– whose primary action is extension of little finger
IX. Abductor pollicis longus– whose primary action is abduction of thumb at carpometacarpal, and metacarpophalangeal joints
extensors and supinators
Fracture of distal end of Humerus bone (Supracondylar fracture)– can lead to
Median nerve injury, which can result in weakness of middle and index fingers to contract, with weakness of wrist flexion (Hand of benediction)
radial nerves gives off
posterior aspect of arm, and the posterolateral aspect of the wrist, and hand:
I. Posterior brachial cutaneous nerve (Posterior cutaneous nerve of arm)
II. Posterior antebrachial cutaneous nerve (Posterior cutaneous nerve of forearm)
IV. Inferiolateral brachial cutaneous nerve (Inferior lateral cutaneous nerve of arm)
Gives off the Dorsal digital cutaneous nerves that innervates the– skin at the lateral 2/3rd of dorsum of hand, and posterior surfaces over the proximal phalanges of lateral three and a half fingers (Remainder of each fingers is innervated by Palmar digital branches of Median and Ulnar nerves)
radial nerve injury can lead to
how can the radial nerve be injured
Fracture of mid-shaft or radial groove or lateral epicondyle of Humerus bone, Improper use of crutches (prolonged compression in axillary region), person gets drunk on Saturday night and ends up falling asleep on a chair with arm hanging over the back of chair (Saturday night palsy) can cause– Radial nerve injury, which can lead to:
i. wrist drop (loss of wrist extension due to inability to extend the hand and fingers) ii. loss of sensory, and motor functions in posterior arm, forearm, and hand
Erb-Duchenne palsy– Injuries to the upper (superior) parts of
Brachial plexus (C5 and C6) can occur due to
4 examples given
excessive stretching of neck of a neonate during the delivery process, shouler distocia
fall from a motorcycle or a horse, and landing on the shoulder
chronic microtrauma to superior trunk of Brachial plexus from carrying heavy backpack for longer time (e.g, hickers) can cause sensory and motor deficits in the distribution of– Musculocutaneous and Radial nerves
acute brachial plexus neuritis (neuropathy) -inflammation of nerves
prolonged hyperduction of arm when someone is trying performing some manual tasks over the head (e.g, painting a ceiling)
Hyperabduction syndrome- compresssion of axillary vessels
compression of nerves (e.g, Carpel tunnel syndrome, Guyon tunnel syndrome
Signs and symptoms of Erb-Duchenne palsy– Injuries to the upper (superior) parts of
Brachial plexus (C5 and C6)
affected limb hangs limply, adducted and medially rotated
excessive extension at elbow joint
forearm is pronated
wrist is weakly flexed due to the normal tone of wrist flexors relative to the weakened wrist extensors– Waiter’s tip position
loss of sensation in the lateral aspect of forearm
Erb’s palsy (injury to _____
presents as damage to superior (upper) part of Brachial plexus
Klumpke’s paralysis-
Injuries to the lower (inferior) parts/ inferior trunk of Brachial plexus (C8 and T1) can occur when:
i. upper limb is suddenly pulled superiorly
klaw fingers
Signs and symptoms Klumpke’s paralysis-
