MSK - Brachial Plexus Flashcards
Images reproduced, with permission, from teachmeanatomy.info
What is the Brachial Plexus?
Where does it originate from?
Where does it lead?
What is it made of?
It is a network of nerve fibres
Originates from anterior rami (divisions) of cervical vertebral nerves C5, C6, C7 and C8, and of the first thoracic vertebral nerve, T1
Runs from neck, through axilla and into the arm
The Brachial Plexus can be divided into how many parts?
Name each of these parts
5
Roots
Trunks
Divisions
Cords
Branches
Which rami of which spinal nerves form the root part of the Brachial Plexus?
Anterior Rami of spinal nerves C5, C6, C7, C8 and T1
How many nerve fibres make up the trunks?
3
What nerve fibres combine to give this number of trunks?
Name the three trunks and explain how they get their names
Superior Trunk - C5 and C6 roots combine
Middle Trunk - Just a continuation of C7
Inferior Trunk - Combination of C8 and T1
When are the trunks formed?
Just before they enter the axilla through the apex
How many divisions does each trunk make as it enters the Axilla?
2
What happens to each division?
One travels anteriorly and one travels posteriorly
How are the cords formed?
Recombination of the six Divisions into three nerve fibres
How are the Cords named?
By their position relative to the Brachial Artery
Name the three cords and what divisions they are formed by
Lateral Cord - Formed by:
- Anterior division of superior trunk
- Posterior division of middle trunk
Posterior Cord - Formed by:
- Posterior division of superior trunk
- Posterior division of middle trunk
- Posterior division of inferior trunk
Medial Cord - Formed by:
- Anterior division of inferior trunk
Name the five branches that go on to supply the upper limb
Musculocutaneous
Axillary
Median
Radial
Ulnar
What roots does the Musculocutaneous nerve contain nerve fibres from?
C5, C6, C7
What does the Musculocutaneous nerve innervate?
Brachialis, Biceps brachii and Corocobrachialis muscles
What are the sensory functions of the Musculocutaneous nerve?
Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm
What roots does the Axillary nerve contain nerve fibres from?
C5 and C6
What does the Axillary nerve innervate?
Deltoid, Teres minor and the Long head of the Triceps brachii
What are the sensory functions of the Axillary nerve?
Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”)
What roots does the Median nerve contain nerve fibres from?
C6 – C8 and T1
What does the Median nerve innervate?
Most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbrical muscles that move the index and middle fingers
What are the Sensory functions of the Median Nerve?
Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand.
What roots does the Radial nerve contain nerve fibres from?
C5-C8 and T1
What does the Radial nerve innervate?
Triceps brachii, and the Extensor muscles in the posterior compartment of the forearm.
What are the Sensory functions of the Radial Nerve?
Posterior aspect of the arm and forearm, and the posterior, lateral aspect of the hand
What roots does the Ulnar nerve contain nerve fibres from?
C8 and T1
What does the Ulnar nerve innervate?
Muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus
What are the Sensory functions of the Ulnar Nerve?
Anterior and posterior surfaces of the medial one and half fingers, and associated palm area
