5: Brachial Plexus Flashcards
How is brachial plexus formed?
It is formed by ventral rami of lower four cervical and first thoracic nerves (C5, 6, 7, 8 and T1).
Pre-fixed condition of brachial plexus
Contribution from C4 nerve constitutes ‘pre-fixed condition’ of the brachial plexus with reduced T1 contribution. (Shift up)
So C4-C8
Post-fixed condition of brachial plexus
Contribution from T2 nerve constitutes post-fixed condition of the brachial plexus with reduced C5 contribution. (Shift down) so C6-T2
Parts of brachial plexus and their locations
Parts: roots, trunks, divisions, cords, branches
- Supraclavicular part (In the Posterior triangle of neck): roots, trunks, divisions
- Infraclavicular part (In the axilla): cords, branches
What part of brachial plexus is first affected in case of clavicle fracture?
Superior trunk
C5-T1 (all parts of brachial plexus) contribute to this.
Posterior cord + radial nerve
According to what are the cords in brachial plexus named?
Named in relation to axillary artery (posterior, medial, or lateral to it)
What nerves are branches from ROOTs?
- Nerve to serratus anterior (long thoracic nerve) (C5, C6, C7)
- Nerve to rhomboideus (dorsal scapular nerve) (C5)
What nerves are branches from UPPER TRUNK?
- Supra scapular nerve (C5, C6)
- Nerve to subclavius (C5, C6)
What’s Erb’s point?
Upper trunk of the brachial plexus where six nerves (C5 and C6 roots, nerve to subclavius and suprascapular nerve, anterior and posterior divisions of upper trunk) meet is called Erb’s point.
What nerves branches from the LATERAL CORD?
- Lateral pectoral nerve (C5, C6, C7)
- Musculocutaneous nerve (C5, C6, C7)
- Lateral root of the median nerve (C5, C6, C7)
Remember: Lilly loves me
What nerves branches from the MEDIAL CORD?
- Medial root of the median nerve (C8, T1)
- Medial pectoral nerve (C8, T1)
- Medial cutaneous nerve of the arm (C8, T1)
- Medial cutaneous nerve of the forearm (C8, T1)
- Ulnar nerve (C7, C8, T1)
Remember: Miss muneerah makes me unhappy
What nerves branches from the POSTERIOR CORD?
- Upper subscapular nerve (C5, C6)
- Lower subscapular nerve (C5, C6)
- Nerve to latissimus dorsi/Thoracodorsal nerve (C6, C7, C8)
- Axillary nerve (C5, C6)
- Radial nerve (C5, C6, C7, C8, T1)
Remember: ULTRA
What’s Erb’s paralysis (Erb-Duchenne’s palsy) ?
- It is an injury to the Erb’s point results in paralysis of muscles of the upper limb supplied by C5 and C6 fibres.
- All the muscles supplied by C5 and C6 fibres are affected.
Causes of Erb’s paralysis?
Causes of injury include:
1- birth injury (excessive stretching of upper trunk)
2- fall on the shoulder or during anesthesia (brachial plexus block)
Policeman’s tip or Waiter’s tip hand is seen in …?
Erb’s paralysis (Erb-Duchenne’s palsy)
What’s Klumpke’s paralysis ?
It occurs due to injury to the lower trunk of the brachial plexus (C8, T1).
C8 = medial forearm
T1 = medial arm
Causes of Klumpke’s paralysis ?
Causes of injury includes:
1- undue abduction of arm (as in clutching something with hands while falling from a height)
2- presence of cervical rib or birth injury/breech presentation.
What hand movements are lost in klumpke’s paralysis?
small intrinsic muscles are responsible for (flexion at the metacarpophalangeal joint and extension at the interphalangeal joints), these movements at the hand are lost.
The opposite movement is exaggerated (hyperextended at metacarpophalangeal joints and hyper flexed at inter phalangeal joints - CLAW HAND)
What’s the difference between between klumpke’s claw and ulnar claw
- Klumpke = total claw hand (C8, T1)
- Ulnar claw = partial claw hand (index & thumb are less affected)
Injury to long thoracic nerve leads to..?
paralysis of serratus anterior muscle, which is manifested by backward projection of scapula (winging of scapula).
Note: serratus protract (this action is lost), so the rhomboids take over they do the opposite (they retract) thus patient presents with winging
What causes long thoracic nerve injury?
Long thoracic nerve may be injured while removing the lymph nodes of the axilla.
What muscles lose their function in case of Erb’s paralysis?
Deltoid, Biceps brachii, Supraspinatus, Supinator, Teres minor, Infraspinatus. (No Abduction/ No lateral rotation/ No forearm flexion, No supination/ No wrist extension)
Remember: don’t be sorry treat it
Brachial plexus nerve block is done by injecting anesthetic into (1)? What’s the position of patient’s arm (2)? Doctor should be careful not to injure (3)?
1- axillary sheath
2- abducted and laterally rotated
3- axillary artery & branches of brachial plexus
