Nerves of the Upper Limb Flashcards
In basic terms what does the brachial plexus do?
- Nervous Supply to the Upper Limb – Including all but 1 Extrinsic Back Muscle
- Sensory and Motor
What nerves form the brachial plexus?
• Anterior Rami of
– C5-8 and T1
What structural pattern/hierarchy defines the brachial plexus?
– Roots-Trunks-Divisions-Cords-Nerves/Branches
- mnemonic; real teenagers drink cold beer
What game launchers does Fraser Chisholm have on his desktop?
Epic, Steam and Origin
Describe dermatomes
- Area of skin innervated by a spinal segment
- Segmental pattern from embryology
- Variation and overlap
Where does the nervous supply of the skin come from?
- Named nerves supplying skin
- Named nerves contain afferent neurones from more than 1 spinal level
- Don’t confuse with dermatomes
What are myotomes?
• A group of muscles
innervated by a single
spinal segment
• Usually with a
common actionWhat spinal segment innervates lateral rotation of the glenohumeral joint?
C5
What spinal segment innervates medial rotation of the glenohumeral joint?
C6 C7 C8
What spinal segment innervates abduction of the glenohumeral joint?
C5
What spinal segment innervates adduction of the glenohumeral joint?
C6 C7 C8
What spinal segment innervates flexion of the glenohumeral joint?
C5
What spinal segment innervates extension of the glenohumeral joint?
C6 C7 C8
What spinal segment innervates flexion of the elbow joint?
C5 C6
What spinal segment innervates extension of the elbow joint?
C6 C7
What spinal segment innervates flexion of the wrist?
(C6) C7
What spinal segment innervates extension of the wrist?
C6 (C7)
What spinal segment innervates pronation of the radio-ulnar joints?
C7 C8
What spinal segment innervates supination of the radio-ulnar joints?
C6
What spinal segment innervates digital flexion of the metcarpo-phalangeal and interphalangeal joints?
(C7) C8
What spinal segment innervates digital extension of the metcarpo-phalangeal and interphalangeal joints?
C7 (C8)
What spinal segment innervates lateral and medial abduction of the third digit of the metcarpo-phalangeal joints?
T1
What spinal segment innervates lateral and medial adduction of the third digit of the metcarpo-phalangeal joints?
Doesn’t happen, the third digit is the centre line so it cannot move towards itself
What spinal segment innervates abduction and adduction of digits 2,4 and 5 of the metcarpo-phalangeal joints?
T1
What feature of named nerves makes them useful for testing nerve roots?
• Named nerves will contain efferent neurones from multiple spinal levels
What musculoskeletal nomenclature makes naming nerve supply a bit easier?
• Muscles in each compartment have the same (named) nerve supply (usually)
What was the mantra of the brachial plexus again?
– Roots-Trunks-Divisions -Cords-Nerves/Branches
– Real Teenagers Drink Cold Beer
Where do the roots of the brachial plexus travel from to reach the plexus in the axilla?
from the neck, under the clavicle where they join up with the axillary artery
What are the roots of the brachial plexus? (anterior rami)
C5 C6 C7 C8 T1
What are the trunks of the brachial plexus and from what roots do they form?
Superior - from C5 and C6
Middle - from C7
Inferior - from C8 and T1
How does one recognise the terminal nerves?
They form an M, the middle of which is the median nerve
Where do the roots of the brachial plexus lie?
In between the scalenus medius and scalenous anterior muscles in the scalene groove
Where does Scalenous anterior lie?
between the two subclavian vessels (artery and vein)
What does the scalene groove sound like?
A lizard croc jazz villain from an 80s Spiderman cartoon
Whats the best way to learn the brachial plexus?
Draw it out lots
By what landmark are divisions of the brachial plexus often found?
Under the clavicle
Discuss cords of the brachial plexus
Lateral Medial and Posterior cords made from divisions of trunk
• Named for relation to Axillary artery
- Ant div of Upper and Middle Trunk form
- -> Lateral cord
- All posterior divisions form
- -> Posterior cord
- Ant div of inferior Trunk forms
- -> Medial cord
Why can you not see the posterior cord on many diagrams/prosections?
Because it is posterior to the axillary artery
What are the terminal branches of the brachial plexus?
Musculocutaneous Nerve
Median Nerve
Radial (and Axillary) Nerve
Ulnar Nerve
What does the musculocutaneous terminal branch of the brachial plexus supply?
Motor
– Arm, Anterior Compartment muscles
Sensory
– Lateral Cutaneous nerve of the forearm
What does the median terminal branch of the brachial plexus supply?
Motor
– Forearm, Anterior compartment
muscles
– Hand, thenar muscles +
Sensory
– 1⁄2 skin of palm
What does the ulnar terminal branch of the brachial plexus supply?
Motor
– Forearm, 1 1⁄2 muscles
– Hand, small muscles
Sensory
– 1⁄2 skin of hand
What does the radial terminal branch of the brachial plexus supply?
Motor
– Arm, Posterior
Compartment muscles
Sensory
– Forearm, posterolateral skin
– Hand, dorsal skin
What does the axillary terminal branch of the brachial plexus supply?
Motor
– Deltiod and Teres Minor Muscles
Sensory
– Skin of supra-lateral arm
On the lateral cord of the brachial plexus, how many minor branches are there?
3
On the posterior cord of the brachial plexus, how many minor branches are there?
3
On the medial cord of the brachial plexus, how many minor branches are there?
4
check location of this
Discuss the minor branches of the brachial plexus
• Meet them again regionally • May also encounter . – Intercostal brachial nerve (T2) . • Cutaneous in axilla • Nerve to subcalvius . • Small muscle that anchors and stabilises clavicle • Suprascapular nerve . – Suprascapular foramen . • Artery above, nerve below
What are the two most common causes of brachial plexus injuries?
Obstetric and traumatic
Discuss upper brachial plexus injuries
(Erb’s palsy)
– Roots C5, 6
– “Waiters Tip” appearance
- as limb will be adducted, internally rotated and pronated
Discuss lower brachial plexus injuries
(Klumpkey’s palsy)
– Roots C8, T1
– Ulnar Claw
– as there is a weakness in intrinsic hand muscles and so abduction and adduction
Other than muscle weakness, what is caused as a result of a brachial plexus injury?
Sensory deficits in relevant dermatomes
What extrinsic back muscle is not innervated by the brachial plexus
The trapezius muscle which receives its supply from the accessory nerve (CN XI)
