Class 11 Flashcards
What is the Brachial Plexus?
network of nerves that gives rise to all motor
& sensory nerves of upper extremity. Plexus arises from anterior rami of spinal nerves C5-T1 that undergo several mergers & splits into trunks & divisions, until they finally give rise to their terminal branches. Terminal branches are responsible for motor & sensory innervation of upper limb, include musculocutaneous, axillary, radial, median & ulnar nerves.
What is the Musculocutaneous Nerve?
Emerges as terminal branch of lateral cord of brachial plexus, from C5-C7 nerve roots. First muscle it enters is coracobrachialis. From here, it runs in flexor compartment superficial to brachialis but deep to biceps brachii muscle. As it descends, it pierces deep fascia & emerges lateral to biceps brachii.
The musculocutaneus nerve supplies motor innervation for?
- Biceps Brachii
- Brachialis
- Coracobrachialis
The musculocutaneus nerve supplies sensory innervation for?
The musculocutaneous nerve terminates & supplies anterolateral skin of forearm.
The musculocutaneus nerve supplies Articular Innervation for?
The musculocutaneous nerve provides articular innervation for elbow joint capsule.
What is the Axillary Nerve?
branches from posterior cord (C5 - T1) descends in
axilla anterior to subscapularis by traversing quadrangular space. Space in posterior scapular region, which is bounded by superior margin of teres major inferiorly, inferior margin of teres minor superiorly, lateral margin of long head of triceps brachii medially & surgical neck of humerus laterally.
Axillary Nerve (motor Innervation)
Motor fibres that innervate deltoid muscle, as well as teres minor muscle.
Axillary Nerve (Articular Innervation)
Supplies a branch to the glenohumeral joint
Axillary Nerve (Sensory Innervation)
Sensory innervation to skin of arm superficial to lower deltoid muscle & superficial to upper part of long head of the triceps.
What is the Radial Nerve?
largest terminal branch of brachial plexus. Originates from
posterior cord along with axillary nerve, carrying fibers from ventral roots of spinal nerves C5- C8 & T1.
Radial nerve arises in __________, between coracobrachialis & teres major muscles. Descends obliquely downwards through _______________________________, between bellies of medial & lateral head of triceps, through shallow depression on _______________________________.
• axilla
• posterior aspect of arm
• posterior surface of humerus (radial groove)
In distal part of arm, radial nerve wraps around ____________________ & courses anterior to _____________________. Upon crossing cubital fossa, radial nerve terminates by _______________________________.
• distal humerus
• lateral condyle of humerus
• dividing into two terminal branches: superficial (sensory) & deep (motor).
Deep motor nerve descends inferiorly through posterior aspect of forearm where it penetrates __________________.
• supinator muscle
Superficial branch continues course of radial nerve & enters hand from radial side. This branch is also known as _________________ because of its primary role to _________________ to thenar eminence & dorsal aspect of radial 3 and a half digits of hand.
• “sensory branch”
• provide sensation
What are Motor Branches?
Innervate triceps brachii, anconeus,
& brachioradialis muscles.
Deep motor branch of posterior
forearm provides motor innervation to posterior compartment of forearm muscles (wrist extensors & long muscles of thumb). These muscles include:
- Extensor carpi radialis longus
- Extensor carpi radialis brevis,
- Extensor carpi ulnaris
- Extensor digitorum
- Extensor indicis
- Extensor digiti minimi
- Extensor pollicis longus
- Extensor pollicis brevis
- Abductor pollicis longus.
What are Sensory Branches? (Radial Nerve)
It gives off two sensory branches that innervate skin of posterior aspect of arm, its inferior lateral aspect, & strip of skin down middle of posterior forearm.
Radial Nerve Muscles Supplied (*BEST)
• Brachioradialis
• Extensors
• Supinator
• Triceps
What is the Median Nerve?
Arises in axillary region. Formed by medial & lateral cords of brachial plexus. Contains fibres from roots of spinal nerves C6-T1, but in some individuals it can also contain fibers from C5.
After Median Nerve formation from brachial plexus, median nerve descends down _________________ in ________________.
centre of arm in superficial course
Just before it enters forearm, median nerve passes between tendons of biceps brachii & brachialis. It passes between deep & superficial heads of ___________________. Once it passes this point, it dives deeper & runs between flexor digitorum profundus & flexor digitorum superficialis.
• pronator teres muscle
The median nerve then passes through ____________________ beneath flexor retinaculum, & terminates by dividing into two ___________________.
• carpal tunnel
• terminal branches
The median nerve gives off numerous motor branches in forearm & hand regions & innervates the which muscles?
- Pronator teres
- palmaris longus
- flexor digitorum superficialis
- flexor carpi radialis
- flexor pollicis longus
- radial part of flexor digitorum profundus
- pronator quadratus
- muscles of the thenar eminence (flexor pollicis brevis, abductor pollicis
brevis, opponens pollicis, 1st and 2nd lumbricals)
There is a motor branch which supplies proximal aspect of palm. This branch _________ enter carpal tunnel & is hence spared in carpal tunnel syndrome. This is why carpal tunnel syndrome only has a _______________________ associated with it, all motor branches do not cross in carpal tunnel.
• does not
• sensory dysfunction
Median Nerve (Sensory Innervation)?
Skin of palmar & distal dorsal aspects of lateral three-and-the-half digits & adjacent palm. Skin of palmar & distal dorsal aspects of thumb & radial half of 2nd digit. Skin of palmar & distal dorsal aspects of adjacent sides of 2nd–4th digits. Skin of central palm.
