Flashcards in Brachial Plexus_MSB Deck (119):
What is the function of the brachial plexus?
1) Functions in conducting signals from spine to shoulder, arm and hand
2) Supplies motor and sensory innervation to upper limb and pectoral girdle
What is the brachial plexus?
Major nerve network of the upper limb
Where does the brachial plexus begin and goes into?
Begins in the neck and extends into the axilla posterior to clavicle
What is the brachial plexus formed by?
Formed by lower cervical and upper thoracic spinal nerves
What system are the spinal nerves part of?
Part of the peripheral nervous system
How many pairs of spinal nerves are there? Name them.
31 pairs of spinal nerves
(8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal)
What do the brachial plexus consist of?
Anterior Rami C5, C6, C7, C8, T1
What does anterior rami mean?
anterior divisions of the spinal nerve
What is different about the C8 nerve in the brachial plexus?
All cervical spinal nerves except C8 emerge above their corresponding vertebrae, while the C8 nerve emerges below the C7 vertebrae.
Why are spinal nerves called mixed nerves?
Spinal nerves carry both sensory and motor information
What do spinal nerves forms from?
Posterior (sensory) and anterior (motor) roots
Each spinal nerve divides into two sections, what are they?
Why is it that within nerve plexus, fibres from the various anterior rami branch becomes redistributed?
Each nerve exiting the plexus has fibres from several different spinal nerves.
Why is it beneficial of the way the nerve plexus is distributed?
Since the fibres from the various anterior rami branch becomes redistributed, each nerve has fibres from several different spinal nerves. So, damage to a single spinal nerve will not completely paralyse the limb
What are the different categories under the brachial plexus?
What are the roots of the brachial plexus?
Anterior rami of C5 to T1
What are the trunks of the brachial plexus?
1) C5 and C6 roots joint to form the Superior Trunk of the plexus.
2) The middle trunk is a continuation of C7 root
3) The inferior trunk is formed by the union of C8 and T1 roots
What are the division of the brachail plexus?
1) Each turn divides into an anterior and posterior division.
2) As plexus passes through the cervicoaxillary canal posterior to the clavicle.
What are the cords of the brachial plexus?
1) The three posterior divisions join to form the Posterior Cord, which contains contributions from all roots C5 to T1.
2) The anterior divisions of the superior and middle trunks join to form the Lateral Cord, which contains contributions from roots C5 to C7.
3) The anterior division of the inferior trunk forms the Medial Cord, which contains contributions from roots C8 to T1.
How are the cords of the brachial plexus named?
Cords named according to their position in relation the axillary artery
What are the cords of the brachial plexus related to?
Cords are related to the second part of the axillary artery
What are the terminal branches of the brachial plexus?
The product of plexus formation are multisegment peripheral named nerves
Where is the musculocutaneous nerve derived from?
Derived from lateral cord
Where is the median nerve derived from?
Derived from both lateral and medial cords
Where is the ulnar nerve derived from?
Derived from medial cords
Where is the radial nerve derived from?
Derived from posterior cord
Where is the axillary nerve derived from
Derived from posterior cord
Name the terminal branches of the cords of the brachial plexus
1) Musculocutaneous Nerve
2) Median Nerve
3) Ulnar Nerve
4) Radial Nerve
5) Axillary Nerve
What are the roots of the musculocutaenous nerve?
C5 - C7
What muscles does the musculocutaneous nerve help to illicit movement (motor)?
Brachialis, Biceps Brachii and Corachobrachialis
Where does the musculocutaneous nerve send sensory information to?
1) Lateral cutaneous branch of forearm
2) Innervates lateral 1/2 of anterior forearm
3) Lateral portion of posterior forearm
What are the roots of the median nerve?
C6 - T1
What muscles does the median nerve help to illicit movement (motor)?
1) Forearm Flexors
2) Thenar muscles
Where does the median nerve send sensory information to?
1) Palmar cutaneous branch innervates lateral palm.
2) Digital citations branch innervates lateral 3 1/2 fingers of palmar hand
What are the roots of the ulnar nerve?
What muscles does the ulnar nerve help to illicit movement (motor)?
1) Muscles of the hand (except thinner muscles and 2 lateral lumbricals)
2) Flexor Capri Ulnaris
3) Medial 1/2 Flexor Digitorum Profundus
Where does the ulnar nerve send sensory information to?
Innervates anterior and posterior surface of medial 1 1/2 digits and palm
What are the roots of the radial nerve?
C5 - T1
What muscles does the radial nerve help to illicit movement (motor)?
1) Triceps brachii
2) Forearm extensors
Where does the radial nerve send sensory information to?
1) Innervates posterior aspect of arm and forearm
2) Posterior and lateral aspects of hand
What are the roots of the axillary nerve?
What muscles does the axillary nerve help to illicit movement (motor)?
1) Teres Minor
Where does the axillary nerve send sensory information to?
Superior lateral cutaneous nerve oe arm innervates inferior region of the deltoid (Regimental badge area)
Where does the roots of the plexuses usually pass through?
The posterior triangle of the neck
In the roots of the plexus, where are the gaps between located?
The roots of the brachial plexus give rise to which two nerves?
Long Thoracic Nerve
Dorsal Scapular Nerve
Where is the long thoracic nerve located?
Originates from anterior rami C5 to C7
Where does the long thoracic nerve pass through?
Passes vertically down neck and medial wall axilla
What muscle does the long thoracic nerve innervate?
Where does the Dorsal Scapular Nerve originate?
Originates from C5 roots
Where does the Dorsal Scapular Nerve pass through?
Passes posteriorly piercing middle scalene to travel along medial border of scapula
What muscle does the Dorsal Scapular Nerve innervate?
2) Levator Scapulae
Where does the Long Thoracic Nerve lie?
Lies on superficial aspect of serratus anterior
How would the Long Thoracic Nerve be injured?
It is susceptible to injury through direct trauma or stretch, for example:
1) Blow to the ribs underneath an outstretched arm
2) Damaged during surgery for breast cancer
3) Stab injuries
4) Carrying heavy bags over the shoulder for a prolonged time
What are the symptoms of an injured long thoracic nerve?
A posterior shoulder or scapular burning type of pain may be reported
What would paralyse the serrates anterior (Winged scapula)?
A lesion of the long thoracic nerve
- injury of the long thoracic nerve
How would a doctor diagnose somebody that has a paralysed serrates anterior?
Patient pushes an outstretched arm agains a wall.
"C5,C6,C7, raise your wing up to heaven"
Which part of the trunk does the branches arise from?
Superior (upper) trunk of the brachial plexus
Name the branches arising from the trunks originating from the supper trunk of the brachial plexus.
1) Nerve to Subclavius
Where does the nerve to subclavius pass through?
Passes anteroinferiorly over subclavian artery and vein
Where does the nerve to subclavius insert into
Where does the Suprascapular nerve pass through?
Passes laterally through posterior triangle of neck, deep to trapezius to enter supraspinous fossa through spurascapular notch
Where does the Suprascapular nerve insert into
What causes a suprascapular nerve injury?
Trauma to shoulder or scapula
What happens during a suprascapular nerve injury?
Entrapment neuropathy in suprascapular notch
What is a symptom of the suprascapular nerve injury?
1) Shoulder pain
2) Weakness/Wasting of Supraspinatus and Infraspinatus
What does the Supraspinatus (SITS) muscle do?
Assists Deltoid in abduction of arm
What does the Infraspinatus (SITS) muscle do?
lateral rotation of humerus
What is the lateral pectoral of the brachial plexus?
Most promixal branch from lateral cord
Which artery does the lateral pectoral pass with to penetrate where?
Passes anteriorly together with thoracoacromial artery to penetrate clavipectoral fascia
Where is the clavipectoral fascia located?
What is the Musculocutaneous Nerve?
Large terminal branch
Where does the musculocutaneous nerve pass through and penetrate?
Passes laterally to penetrate coracobrachialis and pass between Biceps Brachii and Brachialis in arm
Where does the musculocutaenous nerve terminate?
Terminates at the lateral cutaneous nerve of forearm
Where does the musculocutaneous nerve innervate?
Innervates all 3 flexor muscle sin anterior arm Coracobrachialis, Bieps Bracii, Brachialis
What is the lateral root of median nerve?
Largest terminal branch of lateral cord
Where does the lateral root of median nerve pass through to form?
Passes medially to join similar branch form medial cord to form median nerve
Name a musculocutaneous nerve injury
Where would the musculocutaneous lesion occur?
May occur in injuries to upper arm/ shoulder (e.g. fracture of humerus)
Isolated lesions are rare
What are the symptoms of a musculocutaenous nerve injury?
1) Marked weakness of elbow flexion
[Flexor muscles: Biceps Brachii, Brachialis, Coracobrachialis affected]
2) Pain aggravated by elbow flexion
Where is the medial pectoral nerve located?
Pectoralis Major and Minor
Where does the medial cutaneous nerve of arm pass through?
Passes through axilla supplies skin on medial side of distal 1/3 of arm
Where does the medial cutaneous of forearm innervate?
Innervates skin over biceps brachii and skin over medial forearm down to wrist
What is the ulnar nerve?
Large terminal branch of medial cord
Where does the ulnar nerve pass through?
Passes through arm and forearm into hand
Where does the ulnar nerve innervate?
Intrinsic muscles of hand
Name the branches from medial cord of brachial plexus.
1) Medial Pectoral Nerve
2) Medial Cutaneous nerve of arm
3) Medial Cutaneous of the forearm
4) Ulnar Nerve
5) Medial root of Median Nerve
Name the branches from lateral cord of brachial plexus.
1) Lateral Pectoral
2) Musculocutaenous Nerve
3) Lateral root of Median Nerve
Name the branches from posterior cord of brachial plexus
1) Superior (Upper) and Inferior (Lower) Subscapular Nerve
2) Thoracodorsal Nerve
3) Axillary Nerve
4) Radial Nerve
Where does the Superior and Inferior Subscapular Nerve innervate?
2) Teres Major
Where does the Thoracordorsal Nerve pass through?
Passes vertically along the posterior axillary wall
Where does the Thoracordorsal nerve innervate?
Where does the Axillary nerve originate?
Originates from posterior cord
Where does the axillary nerve pass through?
Passes inferiorly and laterally along posterior wall axilla
Passes posteriorly around surgical neck of humerus
Where does the Axillary Nerve innervate?
Deltoid and Teres Minor
Where does the radial nerve pass into?
Passes into posterior compartment of arm
Where is the Axillary Sheath?
Extension of the deep cervical fascia
Where is the axillary sheath found/
Encloses the 1st portion of axillary artery, axillary vein and the brachial plexus
Where is local anaesthetic injected?
Local anaesthetic can injected into the space where the axillary sheath encloses. The anaesthetic will be retained there and the upper limb with anaesthetised.
Where are fractures of the radius and operations on the hand done?
Can be done under this axillary block
Name the brachial plexus injury.
1) Stretch/Neuropraxia/Praxis Injury
What happens during a Praxis injury
1) Nerves damaged but not torn
3) Most common type of injury
4) 90 - 100% return of function
What happens during a neuroma?
1) Scar tissue around injury prevents communication iwht muscle, thus impairing movement
2) Requires surgery for removal of scar tissue
What happens during rupture of the brachial plexus?
1) Nerves torn in 1 or more places, but not detached form spinal column
2) Surgery may repair, damage usually permanent
What happens during avulsion of the brachial plexus?
1) Most serious brachial plexus injury
2) Nerve torn from spinal cord
3) Permanently damaging consequences
Name the obstetrical brachial plexus injuries
Most brachial plexus injuries occur at birth
1) Shoulder dystocia
What happens during shoulder dystocia?
Feotal head is delivered, but shoulder are trapped behind mother's pelvic bone
Do babies improve from shoulder dystocia?
- In many cases child will recover full function in 1st week of life
- If no improvement in 1st or 2nd week, recovery is not likely
- Permanent impairment occurs in up to 25% of cases
Name the two brachial plexus palsies
1) Upper Plexus Palsies
2) Lower Plexus Palsies
What happens during a upper plexus palsies?
Tearing of roots C5 and C6
What muscles are affected during the upper plexus palsies?
1) Deltoid: Supinator of superior radio-ulnar joint
2) Biceps, Brachialis: Elbow Flexors
What is the condition called of the upper plexus palsies
Erb - Duchenne Palsy (Waiters tip)
What is the symptom of the Erb-Duchenne Palsy?
Arm hangs by side with forearm pronated and palm facing backwards
What are possible causes for the upper plexus palsies?
1) Downward traction of an infants arm during birth
2) Adults severe falls forcing side of head and shoulder apart (e.g. Motorcycle injuries)
What happens during a lower plexus palsies?
Tearing of T1 root
What muscle is affected during the lower plexus palsies?
Paralysis of Intrinsic muscles of hand
What is the condition of the lower plexus palsies called?
What is the symptom of the Klumpke Paralysis?
Hand assumes claw like appearance