Nerve supply of upper arm: Brachial plexus Flashcards
Does the brachial plexus supply the upper limbs or lower limbs?
Upper limbs
Does the brachial plexus innervate the skin or muscles of upper limbs?
Innervates muscles and skin
Which 5 spinal segmental levels form the brachial plexus, and do the nerves originate from the anterior or posterior rami roots?
C5
C6
C7
C8
T1
Nerves originate from anterior rami of each segmental level
What are the 5 parts of the brachial plexus, and what are the functional differences between these divisions?
Roots, trunks, divisions, cords, branches
No functional differences, just easier to explain routes of brachial plexus
What are the 5 anterior roots that form the brachial plexus?
C5
C6
C7
C8
T1
What are the names of the 3 trunks of the brachial plexus, and how do they relate to the 5 roots?
Superior trunk: Formed by combination of C5 and C6
Middle trunk: Formed by C7
Inferior trunk: Formed by combination of C8 and T1
Which brachial plexus trunk is not formed by a combination of multiple anterior roots?
Middle trunk: Only formed by C7
How are the divisions of the brachial plexus formed from trunks?
Each trunk splits into anterior (move towards front of body) and posterior division (moves towards back of body)
How many divisions are in the brachial plexus in total, and which ones supply the front/back of body?
6 divisions in total, as each trunk splits into anterior and posterior divisions
3 anterior divisions to supply front
3 posterior divisions to supply back
Where in the body do the cords of the brachial plexus form from divisions, and how are they named?
In axilla, divisions combine to form lateral, posterior, medial cord
Named in relative position to axillary artery
Which 2 brachial plexus divisions combine to form the lateral cord, and where is this positioned relative to the axillary artery?
Anterior division of superior trunk
Anterior division of middle trunk
Furthest and behind axillary artery (closest to back of body)
Which 3 brachial plexus divisions combine to form the posterior cord, and where is this positioned relative to the axillary artery?
Posterior divisions of superior, middle, inferior trunks
Directly behind axillary artery, in front of lateral cord
Which brachial plexus divisions combine to form the medial cord, and where is this positioned relative to the axillary artery?
Only anterior division of inferior trunk
In front of axillary artery
Which 5 major nerves are formed from the cords of the brachial plexus, to innervate the upper arm?
Musculocutaneous
Axillary
Ulnar
Radial
Median
Which brachial plexus cord forms the musculocutaneous nerve, and what roots innervate it?
Formed from terminal branch of lateral cord, only carries nerves from C5,C6,C7
Which compartment of the upper arm is innervated by musculocutaneous nerve, and what 3 muscles are these?
Anterior (flexor) compartment muscles:
Coracobrachialis
Biceps brachii
Brachialis
Does the musculocutaneous nerve only supply the upper arm?
No
Emerges lateral to biceps brachii and brachialis to enter forearm, becomes lateral cutaneous nerve
In which part of the forearm does the musculocutaneous nerve become the lateral cutaneous nerve and provide sensory innervation?
Lateral half of anterior forearm
Small part of posterior forearm
Which brachial plexus cords form the axillary nerve, and what roots innervate it?
Direct continuation of posterior cord, only carries nerves from C5,C6
How many branches does the axillary nerve have?
Anterior branch
Posterior branch
Articular branch
Which 2 muscles does the posterior branch of axillary nerve supply motor innervation to?
Posterior aspect of deltoid
Teres minor
Where in the arm does the posterior branch of axillary nerve provide sensory/cutaneous innervation, and what is the name of this nerve now?
Skin over inferior region of deltoid: Regimental badge area
Upper lateral cutaneous nerve
Which muscle does the anterior branch of the axillary nerve provide motor innervation to?
Anterior aspect of deltoid
Which part of the arm does the anterior branch of the axillary nerve provide sensory/cutaneous innervation to?
anterior, anterolateral shoulder
What is supplied by the articular branch of the axillary nerve?
Upper part of triceps brachii
Glenohumeral joint
In the brachial plexus, the median nerve carries nerves from which roots?
C5,C6,C7,C8,T1
Does the median nerve provide motor innervation in the upper arm?
No,
It provides motor innervation to all muscles in the anterior forearm except flexor carpi ulnaris and flexor digitorum profundus
And thenar muscles and 2 lateral lumbrical muscles in hand
Which muscles in the anterior forearm receive motor innervation from the median nerve?
All except flexor carpi ulnaris and flexor digitorum profundus
Which 3 muscles in the hand receive motor innervation from the median nerve?
2 lateral lumbricals
Thenar (thumb) muscle
Which 2 branches does the median nerve give off to supply cutaneous innervation in hand?
Palmar cutaneous nerve: Lateral aspect of palm
Digital cutaneous nerve: Lateral 3.5 fingers on palmar/anterior surface
Which branch of the median nerve in the hand provides motor innervation to the 2 lateral lumbricals?
Motor branch
Which branch of the median nerve in the hand provides motor innervation to the thenar muscle?
Thenar/recurrent branch
The radial nerve of the brachial plexus carries nerves from with roots?
C5,C6,C7,C8,T1
Which muscle in the posterior upper arm receives motor innervation from the radial nerve?
Triceps brachii
How many muscles in the posterior forearm are supplied by radial nerve?
All of them
Before the radial nerve becomes the deep branch, which 2 posterior forearm muscles does it supply motor innervation to?
Radial nerve supplies brachioradialis and extensor carpi radialis
Before terminating as deep branch and supplying rest of posterior forearm muscles
How many muscles in the posterior upper arm are supplied motor innervation by the radial nerve?
Triceps brachii
This is the only muscle in the posterior upper arm compartment
Which 2 cutaneous branches does the radial nerve give off to provide sensory innervation to the upper arm in 2 areas?
Lower lateral cutaneous nerve: Lateral aspect of upper arm, inferior to deltoid
Posterior cutaneous nerve: Posterior surface of upper arm
Which cutaneous branch does the radial nerve give off to provide sensory innervation to the forearm?
Posterior cutaneous nerve of forearm: Strip of skin down middle of posterior forearm
Which cutaneous branch does the radial nerve give off to provide sensory innervation to the hand?
Superficial/dorsal radial sensory nerve: Dorsal (posterior) surface of lateral 3.5 digits
The ulnar nerve of the brachial plexus carries nerves from which roots?
C8 and T1
Which 2 muscles in the anterior forearm receive motor innervation from the ulnar nerve?
Flexor carpi ulnaris
Medial half of flexor digitorum profundus
Which branch of the ulnar nerve in the hand supplies motor innervation to the hypothenar muscles?
Deep branch
Which branch of the ulnar nerve in the hand supplies motor innervation to the 2 medial lumbricals?
Deep branch
Which branch of the ulnar nerve in the hand supplies motor innervation to the palmar and dorsal interosseous?
Deep branch
Which branch of the ulnar nerve in the hand supplies motor innervation to adductor pollicis?
Deep branch
What are the 3 cutaneous branches that arise from the ulnar nerve in the hand?
Superficial branch: Palmar surface of medial 1.5 fingers
Palmar cutaneous branch: Medial half of palm
Dorsal cutaneous branch: Dorsal surface of medial 1.5 fingers and associated area
