brachial plexus Flashcards

Brachial plexus
Terms Definitions
ends at lateral antebrachial cutaneous nerve
Fibers of Radial Nerve?
C5,6,7,8, T1
Each trunk div into 2 divisions
Anterior: flexor
POsterior: Extensors
C7(extension), C8
myotome innervation of elbow extension
Deltoid Paralysis
Axillary nerve lesion (C5, C6)
loss of arm abduction at shoulder, flattened deltoid
Musculocutaneous n
Formed from lateral cordMotor innervation to muscles in anterior armSensory innervation from skin on lateral forearm
Nerve to sublavious
Upper Trunk C5, and 6
middle finger
where the C7 dermatome is tested(sensory)
Medial brachial cutaneous
From: medial cord
Roots: C8, T1
goes to medial and front skin of the arm
Fibers of Median Nerve?
Fibers of Ulnar Nerve?
muscle borders of axilla
short head of biceps
pec minor
3 branches from the roots, 1 branch from the upper trunk,3 branches from the lateral cord, 5 branches from medial cord, 5 from posterior cord
Upper Trunk
Comes from C5 and C6 roots
Gives rise to Lateral and Posterior Cords
Cords form Branches
\"LMM\" - Lateral cord forms Musculocuteanous and 1/2 of Median nn.\"MUM\" - Medial cord forms Ulnar and 1/2 Median nn.\"PAR\" - Posterior cord forms Axillary and Radial nn.
medial and posterior (same as T1)
cords innervated by C8
Thoracic Outlet Syndrome
A cervical rib can compress subclavian artery and inferior trunk, compression of the neurovascular bundle between the anterior and middle scalenes
Pain in arm and hand is almost always present
From what part of the plexus does Medial Pectoral Nerve originate?
Medial Cord
What part of the brachial plexus do the upper, lower, and middle subscapular nerves branch off of?
posterior cord
sleeve connective tissue starting in the neck (at the pre-vertebral fascia around deep muscles) and extends down around the vessels and nerves in the armpit (axilla)
what is the axillary sheath
Klumpke's Palsy (Total Claw Hand)
An embryologic or childbirth defect affecting the inferior trunk of the brachial plexus (C8, T1)
Atrophy of the thenar and hypothenar eminences
Atrophy of the interosseous muscles
Sensory deficits on the medial side of the forearm and hand
Disappearance of the radial pulse upon moving the head toward the opposite side
Clawing of all digits
What nerves originate from the roots?
long thoracic n.
dorsal scapular n.
lateral and posterior (same as C6 & 7)
cords innervated by C5
What cord does the median nerve branch off of?
Lateral and Medial cords
Erb's Palsy (Waiter's tip)
Traction or tear of the upper trunk of the brachial plexus (C5 and C6 roots); follows blow to shoulder or trauma during delivery
Limb hangs by side (paralysis of abductors)
posterior forearm medially rotated (paralysis of lateral rotators)
forearm is pronated (loss of biceps)
upper limb pulled superiorly suddenly (breaking a all from scaffolding), or stretching the upper limb superiorly (NOT DURING BIRTH)
2 ways lower brachial plexus injuries occur
C5 root (long thoracic nerve is distal on C5)
where the dorsal scapular nerve comes off the brachial plexus
medial cord terminal branches
lower subscapular
lower subscapular and
teres major
Origin of Axillary Nerve?
Posterior Cord
C6(extension), C7
myotome innervation of wrist extension
Horner's syndrome, upper or lower brachial plexus injury?
Lateral Cord
From Upper and Middle Trunks
Gives rise to Musculocutaenous and Median Nerves
3 Cords of Brachial Plexus
Lateral PosteriorMedial
Supra scapular nerve
Upper trunk
suprasinatus and infra spinatus
the ventral rami of which spinal nerves composes the brachial plexus
Median Claw
Distal Median nerve lesion (after branch containing C5-C7 branches off to feed forearm flexors), can be cause by Carpal tunnel syndrome
Lack of lateral finger flexion (2nd and 3rd digits) and wrist flexion
Dorsal and palmer aspects of lateral 3 1/2 fingers lose sensation
The ________ _____ supplies the shoulder joint, the surgical neck of the humerus, the deltoid, and the teres minor muscles before ending as the superior lateral brachial cutaneous nerve.
Axillary Nerve
what kind of fibers does the bplexus carry?
C5, C6
what roots are included in upper brachial injuries
Lower Trunk
Comes from Roots C8 and T1
Gives rise to Posterior and Medial Cords
Ulnar nerve contains which spinal cord segments?
C8, T1
mixed to epaxial dermatomes
what is in the dorsal rami
Positive "bottle sign"
with a proximal median nerve lesion, the thumb cannot be fully abducted
nerve to subclaviussuprascapular n.
Origin of Medial Brachial Cutaneous & Medial Antebrachial Cutaneous Nerves?
medial aspect of cuboidal fossa
where the T1 dermatome is tested(sensory)
Wrist drop
Saturday Night Palsy
Lesion of the radial nerve which innervates the Brachioradialis, Extensors of the wrist and fingers, Supinator, and Triceps
Radial nerve innervates BEST
anterior and medial scalenes (NOT POSTERIOR), and the first rib
which scalene muscles border the scalene triangle, and what forms the base of the triangle
Lateral root of the median nerve
From: lateral cord
Roots: C5, C6, C7
Muscles: fibers to the median nerve
lateral C5-C7, posterior C5-T1, medial (C8-T1)
what spinal nerves are the lateral, posterior and medial cords innervated by?
post fixed brachial plexus
Instead of C5 to Th 1, a post fixed plexus includes fibers from as low as Th 2 to Th 3 These fibers can be stretched over the second or third ribs and such pressure can initially cause sensory loss and if sufficent, motor disturbances, up to and including paralysis of affected muscles
the neck is stretched where the velocity of the shoulder is reduced relative to the head and neck (the shoulder catches on something and the neck is pulled)
how does an upper brachial plexus injury occur
not in the triangle! the veins is anterior to the anterior scalene muscle, while the artery is posterior to the anterior scalene
where is the subclavian vein in relation to the scalene triangle?
Organization of Brachial Plexus
medial, posterior
cords innervated by T1
Bone borders of Axilla
upper scapula
rib 1
where the C4 dermatome is tested(sensory)
Suprascapular Nerve
From: Superior trunk
Roots: C5, C6
Muscles: supraspinatus and infraspinatus
Axillary n.
Formed from posterior cordMotor innervation to deltoidSensory inneration from skin over deltoid (lateral shoulder)
Median nerve contains which spinal cord segments?
C6, C7, C8
myotome innervation of wrist flexion
Long Thoracic Nerve
From: roots
Roots: C5, C6, C7
Muscles: serratus anterior
Medial Cord
Comes from Lower Trunk
Gives rise to Ulnar and Median nerves
What cord does the Musculocutaneus nerve branch off of?
Lateral cord
erb Duchenne palsy
increased displacement of head to opposite shouler
newborn in difficult delivery
injury to superior part of brachial plexus
paralysis to muscles of shoulder and upper arm supplied by c5 and c6
Deloid, biceps, brachialis and brachioradialis
presented as upperlimp with adducted shoulder, medially rotated arm and extended elbow
waiter's tip
Medial Antebrachial Cutaneous nerve
From: Medial cord
Roots: C8, T1
Goes to medial skin of the forearm
Claw Hand
due to ulnar nerve lesion-hollow on back of the hand because of the atrophy of instrinsic muscles
Medial Antebrachial Cutaneous
skin of forearm as far as wrist
medial aspect of hand
where the C8 dermatome is tested(sensory)
Divisions form Cords
Anterior division forms the medial and lateral cordsSupplies the anterior ULPosterior divisions form the posterior cordSupplies the posterior UL
What nerves originate from the posterior cord?
thoracodorsal n.
upper subscapular n.
lower subscapular n.
acute brachial plexus neuritis
sudden onset of pain around shoulder. inflamation around brachial plexus
result of upper resp infection, vaccination. superior trunk of brachial plexus
suprascapular nerve (C5 & 6)supraspinatus and infraspinatus-rotator cuff)
1 branch from the upper trunk
loss of some wrist flexors and all instrinsic hand muscles (lose C8, T1)
adduction, internal rotation of the shoulder, extended elbow, pronated forearm (arm kind hangs there tucked in due to muscle tone)
the clinical presentation of Erb's palsy (describing arm postition)
What nerves originate from the medial cord?
medial pectoral n.
medial brachial cutaneous n.
medial antebrachial cutaneous n.
lateral aspect of the cubital fossa (inside elbow)
where the C5 dermatome is tested(sensory)
1.the first part of the axillary artery2. the axillary vein3. the brachial plexus (starts around the trunks region)
what is contained in the axillary sheath specifically (3)
it holds vessels open, such as veins to allow blood to flow back to the heart more easily(kind of like the lungs are stuck to the pleural cavity)
how does the axillary sheath help blood flow
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