Anatomy: Innervation of the Upper Limb Flashcards
How can you test the function of the musculocutaneous nerve?
Biceps deep tendon reflex - place the examiners thumb on the biceps tendon (within the cubital fossa) and the strike the examiners thumb briskly with a tendon hammer
Which nerve is responsible for the cutaneous supply of the medial part of palm, little finger, medial half of ring finger?
Ulnar nerve
Name the nerve roots which form the median nerve
C6-T1
Name the sensory functions of the axillary nerve
Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid - ‘badge patch’ (lateral aspect of arm)
Which nerve roots form the superior (upper) trunk of the brachial plexus?
C5 and C6
Name 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
Name the nerve roots which form the ulnar nerve
C8-T1
Name the motor functions of the radial nerve
Innervates the triceps brachii
Deep branch innervates the muscles in the posterior compartment of the forearm
Which cords of the brachial plexus contribute to the median nerve?
Lateral and medial
Name the two divisions of the radial nerve which arise just anterior to the lateral epicondyle
Superficial and deep
Name the sensory functions of the radial nerve
Innervates the posterior aspect of the arm and forearm
Superficial branch innervates the posterolateral aspect of the hand
Which nerve wraps around the posterior aspect of the surgical neck of the humerus, making it it vulnerable to injury in shoulder dislocation or fractured neck of humerus?
Axillary nerve
Which nerves are responsible for the cutaneous supply of medial posterior aspect of the arm?
Anterior rami of spinal nerves C8, T1 and T2
How do the branches of the brachial plexus reach the medial arm?
Pass through the axilla
What is the characteristic clinical sign of radial nerve injury?
Wrist drop - inability to extend the wrist and fingers due to paralysis of the posterior forearm muscles
What is the name given to the area of skin innervated by the axillary nerve?
Badge patch
Which is the most medial of the named nerves of the brachial plexus?
Ulnar nerve
Which structure forms the medial cord of the brachial plexus?
Anterior devision of the inferior trunk
Which cord of the brachial plexus forms the ulnar nerve?
Medial
Which nerve travels in the radial groove of the humerus?
Radial nerve
Which nerve forms the middle of the ‘M-shaped’ configuration of the named nerves within the axilla?
Median nerve
Which nerves are responsible for the cutaneous supply of lateral posterior aspect of the arm?
Anterior rami of spinal nerves C5 and C6 via the axillary nerve
Name the motor functions of the ulnar nerve
Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus
Which nerve is responsible for the cutaneous supply of the skin over anatomical snuffbox, lateral part of dorsum of hand, proximal thumb, index, middle and ring fingers?
Radial nerve
Where are the divisions of the brachial plexus located?
Immediately posterior to the subclavian vessels in the root of the neck
Which nerve is responsible for the cutaneous supply of the lateral aspect of the arm?
Radial nerve via lower lateral cutaneous nerve of arm
Which nerve is responsible for the cutaneous supply of the skin over distal phalanges/nail beds of thumb, index finger, middle and ring fingers?
Medial nerve
Which structures form the lateral cord of the brachial plexus?
Anterior division of the superior trunk and the anterior division of the middle trunk
Which nerve is responsible for the cutaneous supply of the anterolateral aspect of the forearm?
Musculocutanous nerve via the lateral cutaneous nerve of the forearm
How are the cords of the brachial plexus named?
According to their relationship with the axillary artery
Each trunk of the brachial plexus divides into a ________ and a ________ division
Each trunk divides into an anterior and posterior division
Where are the roots and trunks of the brachial plexus located?
Mainly between the anterior and middle scalene muscles in the root of the neck
Name the nerve roots which form the radial nerve
C5-T1
Name the sensory functions of the median nerve
Palmar cutaneous branch innervates the lateral part of the palm
Digital cutaneous branch innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand
Which structures form the posterior cord of the brachial plexus?
Posterior division of all 3 trunks
Name the nerve roots which give rise to the brachial plexus
Anterior rami of spinal nerves C5-T1
Which nerve is responsible for the cutaneous supply of a strip of skin down the middle of the posterior forearm?
Posterior cutaneous nerve of forearm
Name the nerve roots which form the musculocutaneous nerve
C5-C7
Name the sensory functions of the ulnar nerve
Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area
Why is the medial posterior arm a common site for cardiac referred pain?
Pain is referred via the intercostobrachial nerve and posterior cutaneous nerves of the arm (branch of radial nerve) and medial cutanous nerve of forearm
Which nerve root forms the middle trunk of the brachial plexus?
C7
In a mid-shaft fracture of the humerus, how could you test the function of the radial nerve?
Testing triceps function
Which cord of the brachial plexus forms the musculocutanous nerve?
Lateral
Why is the radial nerve vunerable to damage in a (spiral) mid-shaft fracture of the humerus?
Lies in the radial groove
Which cord of the brachial plexus forms the axillary nerve?
Posterior
What is the brachial plexus?
Collection of spinal nerves that form the peripheral nerves of the upper limb
Name the motor functions of the median nerve
Anterior interosseous nerve supplies all muscles of the anterior forearm except for the flexor carpi ulnaris and the medial part of flexor digitorum profundus
Recurrent branch innervates the thenar muscles
Palmar digital branch innervates the lateral 2 lumbricals
Name the nerve roots which form the axillary nerve
C5-C6
Which cord of the brachial plexus forms the radial nerve?
Posterior
Where are the cords of the brachial plexus located?
Around the axillary artery
Name the motor functions of the axillary nerve
Innervates the teres minor and deltoid muscles
Describe the structure of the brachial plexus
Roots → trunks → divisions → cords → branches
Which nerve is responsible for the cutaneous supply of the skin over the base of the thumb?
Radial nerve
Name the motor functions of the musculocutaneous nerve
Innervates the brachialis, biceps brachii and coracobrachialis muscles
Which nerve roots form the inferior (lower) trunk of the brachial plexus?
C8 and T1
