formation and injuries of brachial plexus Flashcards
What is brachial plexus
• A major nerve network supplying the upper limb.
• Formed by the union of anterior rami of C.5, C.6, C.7, C.8 and T.1 spinal nerves.
Anterior rami form nerve plexuses:
Cervical plexus anterior branches C1-C4
Brachial plexus anterior branches C5-T1
Lumbar plexus anterior branches L1-L4
Sacral plexus anterior branches L4-S4
Posterior rami do not form plexuses
what is typical spinal nerve
Formed by the union of an anterior (ventral) root and a posterior (dorsal) root which are attached to the sides of the spinal cord by small rootlets.
The dorsal nerve root contains a spinal sensory dorsal root ganglion.
The spinal nerve then divides into
an anterior ramus and a posterior ramus.
how and what parts of brachial plexus
- roots
2.trunks
3.division
3.cords - branches
what location of parts of the brachial plexus
• Roots lie between scalenus anterior and scalenus medius muscles in the lower part of posterior triangle of the neck.
• Trunks lie in the lower part of posterior triangle of the neck.
• Divisions lie behind the middle part of clavicle.
• Cords and terminal Branches lie in the axilla.
what formation of the brachial plexus
Brachial plexus is formed by the anterior or ventral rami of C5, C6, C7, C8 and T1 spinal nerves
what anterior rami for the formation of the roots
Roots consist of the ventral rami of C5, C6, C7, C8 and T1 spinal nerve
what formation of the trunks
Roots united to form 3 trunks: Superior, middle and inferior trunks.
C5 and C6 roots united to form the superior trunk. C7 root continues as the middle trunk.
C8 and T1 roots united to form the inferior trunk.
what formation of the division
Each trunk divides into an anterior division and a posterior division.
how formation of the cords
Divisions rearrange to form 3 cords: medial, lateral and posterior cords.
-Anterior divisions of superior and middle trunks united to form the lateral cord.
-Anterior division of inferior trunk continues as the medial cord.
-Posterior divisions of all three trunks united to form the posterior cord.
what formation of terminal branches
The 3 cords finally gives off 5 terminal branches
• Posterior cord divides to form the radial and axillary nerves.
• Lateral cord divides to form - musculocutaneous nerve and
- lateral root of median nerve.
Brachial plexus:
• starts as 5 ventral rami (roots)
• ends as 5 terminal branches
Musculocutaneous n. (C5,6,7)
Axillary nerve (C5,6)
Radial nerve (C5,6,7,8 - T1)
Median nerve (C5,6,7,8 - T1)
Ulnar nerve (C7,8 - T1)
what branches from the roots
Branches from the roots:
i. Dorsal scapular (DS) nerve (nerve to rhomboids) from C5 root.
ii. Long thoracic (LT) nerve from C5,6,7 roots.
what branches from the trunks
2 branches are given off from the upper trunk.
Branches from the upper trunk:
i. Suprascapular nerve (SS) nerve (C5 C6).
ii. Nerve to Subclavius (Sc) nerve (C5,C6).
what is erb’s point and 6 nerves:
Erb’s point is the region of upper trunk of brachial plexus where 6 nerves meet:
1. Root of C5
2. Root of C6
3. Suprascapular nerve
4. Nerve to Subclavius
5. Anterior division
of superior trunk
6. Posterior division
of superior trunk
what branches from the divisions
divisions have no branches
what structure supplies by the division
• Anterior divisions supply structures in anterior (flexor) compartment of the upper limb.
• Posteriordivisionssupplystructuresinposterior (extensor) compartment of the upper limb.
what branches from lateral cord
3 branches are given off from the lateral cord.
Lateral cord branches:
i. Lateral pectoral (LP) nerve.
ii. Musculocutaneous (Mc) nerve.
iii. Lateral root of median (LRMN) nerve.
what branches from medial cord
Medial cord branches:
i. Medial pectoral (MP). U
ii. Medial cutaneous nerve of arm (MCNA).
iii. Medial cutaneous nerve of forearm (MCNFA).
iv. Medial root of median nerve (MRMN).
v. Ulnar nerve (U).
what branches from posterior cords
Posterior cord branches:
i. Up. Subscapular (US).
ii. Thoracodorsal nerve (TD).
iii. Lower Subscapular nerve (LS).
iv. Radial nerve (R).
v. Axillary nerve (A).
what is dermatomes of upper limb
Dermatome is the area of skin innervated by somatic sensory fibres from a single spinal nerve (single spinal cord segment).
Clinically, dermatome maps can be used to determine the sensory function of a particular spinal nerve or spinal cord segment.
what causes and results from brachial plexus injuries
Causes:
• Trauma
e.g. forceps delivery, gunshot or stab injuries, fall from height, automobile accidents etc.
• Compression
e.g. aneurysm of axillary artery,
malignancy of breast and lung
Results:
• Motor deficit: Paralysis
• Sensory deficit: Anaesthesia
what actually the upper trunk injury : Erb’s Palsy
Injuries to the upper trunk involve C.5 and C.6 roots of the brachial plexus.
Causes: Excessive increase in the angle between neck and shoulder.
e.g. excessive stretching of baby’s neck during difficult delivery.
e.g. following a fall on shoulder, in adults.
Results
Paralysis of muscles of shoulder and arm that are innervated by C5,6 roots.
e.g. suprascapular nerve [sup/inf-spinatus] nerve to subclavius [subclavius] axillary n. [deltoid, teres minor] musculocutaneous n. [BB,BR,CB]
Loss of sensation down the lateral side of arm
Deformity: Waiter’s tip position
• Arm is : adducted
: medially rotated at shoulder jt.
• Duetoparalysisof:
Abductors : supraspinatus, deltoid Lateral rotators : infraspinatus, teres minor
• Forearm is : extended at elbow joint
: pronated at radio-ulnar jt.
• Due to paralysisof:
Flexors : biceps brachii, brachialis Supinators : biceps brachii
what is lower trunk injuris: Klumpke’s Play
Injuries to the lower trunk involve C.8 and T.1 roots of the brachial plexus.
Cause: Excessive abduction of the arm. e.g. excessive pulling of baby’s upper
limb during delivery.
e.g. clutching at an object while falling from height.
Deformity: True Claw Hand
• Hyperextension of metacarpophalangeal jts.
• Flexion of interphalangeal joints
• Due to paralysisof:
• Lumbricals and interossei
• All small / intrinsic muscles of hand
innervated by C8 and T1 nerve roots.
Sensory deficit:
• Loss of sensation along medial side of arm
[may extend to medial side of forearm, hand, and medial two fingers].
