Brachial plexus

Sensory for radial nerve?

-lateral aspect of upper arm -posterior surface of upper arm -dorsal surface of lateral 3.5 digits.

sensory?

-lateral forearm

action?

-shoulder abduction

Nerve roots of axillary nerve?

C5-C6

Nerve roots of the musculocutaneous nerve?

C5-C6

what passes through quadrangular space of axilla? what are the other spaces?

-Quadrangular space=axillary nerve and posterior circumflex humeral artery. -provides a passage for structures to access posterior arm and shoulder -clavipectoral triangle-bounded by clavicle, pec major and deltoid (cephalic vein, medial and lateral pectoral nerves) -exit inferiorly and laterally (most structures)

what are the different sections of the brachial plexus?

-Roots-between anterior and medial scalene muscles to base of neck -Trunks-at base of neck roots become trunks Sup. Mid. Inf. -Divisions-form in posterior triangle of the neck -cords-form in the axilla -nerves

Course?

-arises from lateral cord of brachial plexus -leaves axilla and pierces coracobrachialis muscle -passes down arm anterior to brachialis and deep to biceps brachii -emerges laterally to biceps tendon -continues into forearm as lateral cutaneous nerve to provide sensory innervation.

course?

-arises from posterior cord of brachial plexus -exiting axilla posteriorly to the brachial artery. Here it supplies branches to the long and medial heads of the triceps brachii. -The radial nerve then descends down the arm, travelling in a shallow depression on the surface of the humerus-radial groove -As it moves inferiorly, the radial nerve wraps around the humerus in a lateral direction, and gives a branch to the lateral head of the triceps brachii. During its course in the arm, the nerve is accompanied by the deep branch of the brachial artery.

Where do the trunks of the brachial plexus travel to in the neck?

-begins to move laterally crossing the posterior triangle of the neck

what happens in the posterior triangle to the brachial plexus?

-splits into divisions -Within the posterior triangle of the neck, each trunk divides into two branches. -One division travels anteriorly (toward the front of the body) and the other posteriorly (towards the back of the body). Thus, they are known as the anterior and posterior divisions. -We now have three anterior and three posterior nerve fibres. These divisions leave the posterior triangle and pass into the axilla region. They recombine in the next part of the brachial plexus.

damage?

-stab wound to axilla -compresion between two heads of biceps brachii

what are they named in relation to?

-the axillary artery.

motor for radial nerve?

-three heads of triceps brachii (extension of the elbow) -majority of extensors in forearm-extension of the wrist and fingers -supination of the forearm

nerve roots of the ulnar nerve?

C8-T1

snesory?

Innervates the anterior and posterior surfaces of the medial one and half fingers, and the associated palm area.

how do these nerves enter the neck?

-After their formation, these nerves pass between the anterior and medial scalene muscles to enter the base of the neck.

motor?

-All forearm fleecers except flexor carpi radials and flexor carpi ulnaris Thenar muscles, two lateral lumbricals

Anatomical course?

-Arises form medial and lateral cords -After originating from the brachial plexus in the axilla, the median nerve descends down the arm, initially lateral to the brachial artery. - Halfway down the arm, the nerve crosses over the brachial artery, and becomes situated medially. The median nerve enters the anterior compartment of the forearm via the cubital fossa.

where do the roots become trunks?

-At the base of the neck, the roots of the brachial plexus converge, forming three trunks. These structures are named by their anatomical position.

Motor function?

-Innervates muscles in anterior part of upper arm-coracobrachialis, biceps brachii, brachialis

what are the names of the brachial cords?

-Lateral -Posterior -Medial

roots of the median nerve?

C6-T1

what happens to ulnar nerve at wrist?

-At the wrist, the ulnar nerve travels superficially to the flexor retinaculum. It enters the hand via the ulnar canal (or Guyon's canal). In the hand the nerve terminates by giving rise to superficial and deep branches.

Course?

-Continuation of the medial cord -contains roots from C8-T1 -the ulnar nerve descends down the medial side of the upper arm. At the elbow, it passes posterior to the medial epicondyle, entering the forearm. -At the medial epicodyle, the nerve is easily palpable and vulnerable to injury.

What happens to the median nerve in the forearm? What 2 nerves form in the forearm from median nerve?

-In the forearm, the nerve travels between the flexor digitorum profundus and flexor digitorum superficialis muscles. The median nerve gives rise to two major branches in the forearm: Anterior interosseous nerve - Supplies the deep muscles in the anterior forearm. Palmar cutaneous nerve - Innervates the skin of the lateral palm.

What happens to the ulnar nerve in the forearm?

-In the forearm, the ulnar nerve pierces the two heads of the flexor carpi ulnaris, and travels alongside the ulna. Three branches arise in the forearm: -Muscular branch: innervates some muscles in the anterior compartment of the forearm. -Palmar cutaneous branch: innervates the skin of the medial half of the palm. -Dorsal cutaneous branch: innervates the skin of the medial 1 and 1/2 fingers, and the associated palm area. (The functions of these nerves are explored in more detail later in the article).

motor function?

-Provides innervation to deltoid muscle and teres minor -The axillary nerve innervates the teres minor and the deltoid muscles. -The teres minor is part of the rotator cuff muscles of the shoulder. This set of muscles acts to stablise the glenohumeral joint. Acting individually, the teres minor externally rotates the upper limb. The muscle is innervated the posterior terminal branch of the axillary nerve. -The deltoid is situated at the superior aspect of the shoulder. It performs abduction of the upper limb at the glenohumeral joint. The muscle is innervated by the anterior terminal branch of the axillary nerve.

how does the median nerve enter the hand? What two branches are formed in the hand?

-The median nerve enters the hand via the carpal tunnel, where it terminates by dividing into two branches: -Recurrent branch - Innervates the thenar muscles. -Palmar digital branch - Innervates the palmar surface and fingertips of the lateral three and half digits. Also innervates the lateral two lumbrical muscles.

how does the radial nerve enter the forearm? what branches does it form in the forearm?

-To enter the forearm, the radial nerve moves anteriorly over the lateral epicondyle of the humerus, through the cubital fossa. Within the forearm, the nerve terminates by dividing into two branches: -Deep branch - A motor branch. It innervates the muscles in the posterior compartment of the forearm. -Superficial branch - A sensory branch. It contributes to the cutaneous innervation of the hand and fingers.

course?

-formed within axilla region -directly off posterior cord -immediately after formation lies posterior to axillary artery -anteriorly to the subscapularis muscle -exits axilla via quadrangular space (gap in posterior wall exits with posterior circumflex humeral artery) -around surgical neck of humerus -divides into two branches in the posterior scapular regions -posterior terminal branch- motor innervation to teres minor and skin over inferior region of deltoid -Anterior terminal branch-motor innervation to deltoid

sensory

-lateral palmar surface -lateral 3.5 fingers (palmar surface)

Nerve roots for radial nerve?

C5-T1

where do the divisions converge?

Once the anterior and posterior divisions have entered the axilla, they combine together to form three nerves. (cords)

what are the trunks of the brachial plexus called?

Superior middle inferior

Action?

The Anterior Forearm In the anterior forearm, the muscular branch of the ulnar nerve supplies two muscles: -Flexor carpi ulnaris - Flexes and adducts the hand at the wrist. -Flexor digitorum profundus (medial half ) - Flexes the fingers. The remaining muscles in the anterior forearm are innervated by the median nerve. The Hand The majority of the intrinsic hand muscles are innervated by the deep branch of the ulnar nerve. The hypothenar muscles (a group of muscles associated with the little finger) are innervated by the ulnar nerve. It also innervates some other muscles of the hand: -Medial two lumbricals -Adductor pollicis -Interossei of the hand The other muscles in the hand (such as the thenar eminence) are innervated by the median nerve.

What are the roots of the brachial plexus?

The roots of the brachial plexus are formed by the anterior divisions of spinal nerves C5-T1 (the posterior divisions go on to innervate the skin and musculature of the trunk).

sensory

shoulder joint and skin beneath deltoid muscles-regimental badge sign

action?

extension at the elbow, extension of wrist and fingers

function?

flexion of the wrist

Action?

-Flexion of the elbow -biceps brachii is also an forearm supinator!

motor functions?

-Muscles of the hand (apart from thenar muscles and two lateral lumbricals) -Flexor carpi radialis flexor digitorum profundus