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:
-
Anesthesia in lateral dorsal hand
3.
-
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)
Explain the cutaneous innervation of the hand
Medial part of hand (up to medial part of ring finger)
What are the consequences of ulnar nerve damage?
“Claw hand”
due to–> loss of lumbrical contraction –> no flexionin MCP joints and no extension in the IP joints
- limited adduction of thumb
- Numbness in medial side of hand
What is the ulnar paradox?
A more distal lesion of the ulnar nerve causes a less sever claw hand than a more proximal lesion
- because ulnar also innervates FDP
- in more distal lesion FDP is paralised and Flexion at IP joints is less
What is the origin of the median nerve in the brachial plexus?
It is the terminal recombinant of the medial and lateral cord
Explain the route of the median nerve
- Originates from the lateral and median cords of the brachial plexus
- runs down anteriorly following the brachial artery to the cubital fossa
- Enters the hand via the carpal tunnel
Which muscles does the median nerve supply?
- Most flexors of forearm and hand
- thenar compartment of hand
- lateral lumbrical muscles
Explain the sensory innervation of the median nerve
It supplies most of the lateral palmar surface and finger tips of fingers 1-3
What is the commonest cause for damage of the median nerve?
Carpal tunnel syndrome
What are the consequences of median nerve injury?
- Loss of sensation
- Loss of fine movements –> most movements of thumb + 1-2 fingers
- –> Benediction Sign (Schwurhand) when trying to flex hand
What does damage to the long thoracic nerve cause?
Innervation loss of Serratur Anterior –>
Pressing against a wall will lead to “winging” of the scapula resulting from the loss of activity of serratus anterior
What is an Erb-Dunchenne Palsy?
Injury to the upper rours of the brachial Plexus –> C5+6
Which situations might lead to an Erb’s-palsy?
Overstretch the neck relative to the shoulder
(might also happen during childbirth)
What are the consequences of an Erb’s palsy?
“Waiters Tip” position due to:
- suprascapular nerve, musculocutaneous nerve, axillary nerve palsy
- paralysis and atrophy of the deltoid, biceps, and brachialis muscles
What is a Klupke’s palsy?
Damage to the lower roots of the brachial plexus (C8+T1)
What is the common cause of a Klupke’s palsy?
Over abdcution of the shoulder e.g.
- due to gripping overhead to break a fall.
- during childbirth
How would someone with Klupke’s palsy present?
- Claw hand
- due to
- median and ulnar function loss –> muscles of the hand
- Ulnar: Fingers slightly seperated from one another (no adduction+abduction possible), lumbricals
- lumbricals+ thenars
Which spinal segments do spproximately allow movement in the
- Shoulder girdle
- Shoulder joint
- Elbow joint
- Wrist joint
- Fingers and thumb
Explain the formation and organisation of the brachial Plexus
- C5-T1 roots
- C5+6, T7, C8+T1 combine to form the upper, middle and lower trunks
- Each roots devides into a Posterior and Anterior devision
- The Anterior devisions of the upper and middle trunk joint to give rise to the lateral cord,
- Terminal branches: devides into the musculocutaneous nerve and half of the median nerve
-
all posterior devisions join to give rise to the posterior cord
- devides into axillary and radial nerve
-
and the anterior devision of the lower trunk continues as the medial cord
- devides into ulnar nerve and half of the median nerve
What is the thoracodorsal nerve?
Which muscle does it supply and where does it originate?
It originates in the brachial plexus from the posterior chord and supplies latissimus dorsi
Where do the upper and lower subscapular nerves originate?
What do they supply
The originate from the posterior chord of the brachial plexus –>
supply: subscapularis and teres major,
Where does the lateral pectoral nerve originate?
What does it supply?
It originates from the lateral cords of the brachial plexus and supplies the Pec major+ parts of pec minor
Where does the median pectoral nerve originate?
What does it innervate?
Is mainly supplies pec minor and arises from the medial cord of the brachial plexus
What is the Name of the different sections in the brachial Plexus?
Read That Damn Cadaver Book
- Roots
- Trunks
- Devisions
- Chords
- Branches
What is a somatic nerve?
Somatic= controlls voluntary movement in body
What is a branch of the C5 Nerve route of the Brachial Plexus?
What does it innervate?
The Dorsal Scapula nerve
- supplies Rhomboids
What is the anatomical relationship of the roots of the brachial plexus to adjacent structures?
It i in the posterior triangle of neck
- between anterior and middle scalene muscle
What is the Origin of the Long Thoracic Nerve?
Branch from C5-C7 Roots in the Brachial Plexus
What does the Suprascapular Nerve Supply?
Where does it originate?
Supplied the Suprespinatus and infraspinatus
- branch of superior trunk of brachial plexus
What does the Nerve to Subscapularis supply?
Where does it originate?
It is a branch of the Superior Trunk of the brachial Plexus
- supplies the subscapularis
What are the branches of the Lateral chord of the brachial Plexus?
- Lateral pectoral nerve –> Pec major
- 2 Terminal Branches
- Musculocutaneous Nerve
- Part of Median Nerve
- 2 Terminal Branches
What are the branches of the Posterior chord of the brachial Plexus?
4 Branches + end in radial nerve
- Superior Subscapular Nerve
- subscapularis
- Thoracodorsal Nerve
- latissimus dorsi
- Inferior Subscapular Nerve
- Subscapularis and teres major
- Axillary Nerve
- deltoid and teres major
What are the branches of the Medial chord of the brachial Plexus?
Gives Rise to Ulnar and part of Median Nerve +
- Medial Pectoral Nerve (pec minor)
- Medial Cutaneous Nerve of Arm
- Medial Cutaneous Nerve of Forearm
What are the symptoms of carpal tunnel syndrome?
- nocturnal loss of sensation (paresthesia) and pain in lateral volar part of hand
- radiation of pain into arm
- loss of power grip
- Later
- atrohpy of thenar compartment
- paresis of abductor pollicis brevis and opponens pollicis
