Anterior Primary Rami of Spinal nerves C5 C6 C7
Brachial Plexus consists of:
Formed by ant, primary rami of C5 C6 C7 C8 T1
i. Upper trunk formed by union of C5&C6
ii. Middle Trunk formed by C7
iii. Lower Trunk formed by union of C8&T1
Each trunk divides into
- Posterior(Dorsal) Division.
i.Lateral Cod: Union of anterior division of Upper & Middle trunk
ii. Medial cord: Anterior division of lower trunk
iii. Posterior Cord: Union of posterior division of all three trunks.
BRANCHES OF BRACHIAL PLEXUS:
Branches of the Root:
- Long Thoracic nerve (nerve to serratus anterior) C5 C6 C7
2, Dorsal Scapular nerve (to rhomboids ) C5
Branches of Upper Trunk:
- Suprascapular nerve (to supra & infra spinatus) C5 C6
- Nerve to Subclavius C5 C6 (gives accessory phrenic nerve)
Branches of Lateral Cord: (2LM)
1.Lateral pectoral nerve (C5 C6 C7)
2.Musculocutaneous nerve (C5 C6 C7)
3.Lateral root of median nerve (C5 C6 C7)
Branches of Medial Cord: (4MU)
1.Medial Pectoral nerve (C8 T1)
2. Medial Cutaneous nerve of arm (C8 T1)
(joined by Intercostobrachial nerve)
- Medial Cutaneous nerve of forearm (C8 T1).
- Ulnar nerve (C7 C8 T1)
- Medial root of median nerve (C8 T1)
Branches of Posterior Cord: (UTLAR)
- Upper subscapular(C5 C6)
- Thoracodorsal nerve (nerve to latissimus dorsi) C6 C7 C8
- Lower subscapular nerve (C5 C6)
- Axillary nerve (C5 C6)
- Radial nerve (C5 C6 C7 C8 T1)
VARIATIONS OF BRACHIAL PLEXUS
Pre-fixed brachial plexus:
* When superior most (ant, Ramus is C4) & intetior most is C8,
Post-fixed brachial plexus:
* When superior most (ant. Ramus is C6) & interior most is T2.
BRACHIAL PLEXUS INJURIES
Injuries to the brachial plexus affects movement (cause paralysis) & cutaneous sensations (cause anaesthesia)
* Disease, stretching & wounds in the lateral cervical region (posterior triangle of neck) or in the axilla.
* Also in newborn due to excessive stretching of neck during delivery
* Usually results from an excessive increase in the angle between neck & shoulder for e.g. when a person thrown from motorcycle or a horse.
INJURIES TO SUPERIOR PART OF PLEXUS
- C5, C6 involved
- Also known as Erb’s Duchene paralysis
- Muscles supplied by C5 & C6 are usually involved like deltoid, biceps, brachialis, brachio-radialis,
- Loss of sensation on the lateral aspect of upper limb
- WAITER’s TIP (POLICEMAN’s TIP) position
- Superior plexus injury in hikers-muscle Spasms & severe disability.