5: Brachial Plexus+ Nerves in the upper limb Flashcards
Explain the origin of the Axilla nerve in the brachial plexus
It is a terminal branch of the posterior cord of the brachial pexus (C5-T1)
Which muscles does the Axilla nerve supply?
It supplies the Deltoid musle + teres minor
Which area of the skin gets its sensory innervation from the Axillary nerve?
Explain the route of the Axillary nerve
It emerges from the posterior chord of the brachial plexus at approx. level of the shulder joint and runs under the shoulder joint to innervate the deltoid
What is a common injury where the Axilla nerve gets damaged?
It gets damaged in shoulder dislocation
What are the consequences of damage to the Axillary nerve?
Loss of function of Deltoid
“Regimental batch” anesthesia
What is the origino of the radial nerve in the brachial plexus?
It is the terminal branch of the posterior chord
Which muscles are innervated by the radial nerve?
Almost all posterior muscles of the Arm and forearm
- Extensor comparment of the Arm
- Extensor compartment of forearm
- Brachioradialis –> supination
Explain the sensory innervation of the radial nerve
It supplies many areas of the lower posterior arm, the posterior forearm and hand
How does the radial nerve gets damged?
Why?
It runs closely related to the humerus (radial groove on humerus) –> mighe be damaged in #
What are the consequences of radial nerve damage?
- Motor function loss –> Dependant on site of lesion
- Loss of extensor function
- Elbow?
- Wrist?
- Finger?
- –> Wrist drop
- Loss of power grip –> initial extension needed
- Loss of extensor function
- Sensory:
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Anesthesia in lateral dorsal hand
3.
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Anesthesia in lateral dorsal hand
Explain the pathway of the radial nerve
- Terminal branch of posterior cord of Brachial Plexus
- Runs closely related to humerus in radial groove to the lateral epichondyle
- Devides at the level of the elbow into
- Deep branch
- descends posterior forearm –> externsor muscles innervation
- Superficial branch
- sensory branch suppliing the arm, forearm, thenar eminence and part of hand, runs close to the antomical snuffbox
- Deep branch
Explain the origin of the musculocutaneous nerve in the brachial plexus
It is a terminal branch of the lateral chord (C5-7)
Explain the route of the musculocuteneous nerve
It supplies and pinches the coracobrachialis muscle, runs deep protected by musces and emerges superficially to run down as the lateral cutaneous branch of the forearm
What is the motor function of the musculocuatneous nerve?
C5-7
–> innervates the flexor compartment of the arm
- biceps brachii
- brachialis
- coracobrachialis
What is the sensory function of the musculovutaneous nerve?
It supplies the anteriolateral part of the forerm
When might the musculocutaneous nerve be damged?
Normally well protected but might be damaged in lymph node removal in breast cancer
What is the origin of the ulnar nerve of the brachial plexus?
It is a terminal branch of the median chord (C8,T1)
Explain the route of the ulnar nerve
It runs posteriorly in the posterior medial epicondyle groove in the forearm (supercicially, can be palpated)
Runs down forearm medially and enters hand medially
What are common sites of damage to the ulnar nerve?
When might they occur?
- Injuries to medial epicondyle of humerus
- Injuries at the wrist –> self harm?
Which muscles does the ulnar nerve supply?
It supplies the
- flexor carpu ulnaris
- Medial half to flexor digitorium profundus
- Medial 2 lumbricals
- Inerosseus hand muscles
- Hypolthenar comparment
–> Most innervation to the hand (except thenar and lateral lumbricals)