Exam 3: Unit V Brachial Plexus Flashcards
What fibers form the Brachial plexus?
anterior primary rami of C5 through T1
may also receive some fibers from C4 and/or T2
In general, what does the brachial plexus supply?
upper extremities
How does the brachial plexus travel?
travels laterally over fib 1, into the axilla–> travels medial to lateral
Describe the “layout” of the brachial plexus
Roots combine into–> trunk, which divide into–> divisions, which combine to form –> cords, which divide into –> terminal nerves (branches)
“Rugby Team Drinks Cold Tequila/Beer”
What does each root of the brachial plexus receive from the sympathetic trunk?
gray ramus communicans
How do the roots of the brachial plexus pass?
b/w anterior and middle scalene muscles into the posterior triangle
posterior and superior to subclavian artery
What forms the scalene triangle?
anterior scalene, middle scalene, and first rib
In the brachial plexus, roots of what levels form the:
- superior trunk
- middle trunk
- inferior trunk
- C5, C6
- C7
- C8, T1
What do the trunks (superior, middle, and inferior) pass over and what do they enter?
pass over rib 1 into the axilla
What does each trunk of the brachial plexus split into?
anterior division and posterior division
What will the anterior divisions of the brachial plexus supply? what will the posterior divisions supply?
anterior–> ant. compartments or arm and forearm
posterior–> posterior compartments of arm and forearm
What are the cords of the brachial plexus named in relationship to? What are the names of the cords?
the axillary artery
Lateral, Medial, Posterior cords
What is the lateral cord formed by? What fibers does it contain?
anterior divisions of superior and middle trunks
- contains C5,C6,C7
(lies lateral to second part of axillary artery)
What forms the medial cord? What fibers does it contain?
formed by anterior division of the inferior trunk
- contains fibers C8 to T1
(lies medial to second part of axillary artery)
What is the posterior cord formed by? What fibers does it contain?
formed by union of posterior divisions of all three trunks (sup. middle, inf.)
- contains C5,C6,C7,C8,T1
(lies posterior to second part of axillary artery)
How many and what are the names of the nerves formed from roots of the brachial plexus?
two
- Dorsal Scapular Nerve (C5)
- Long Thoracic Nerve (C5,C6,C7)
What fibers does the Dorsal Scapular Nerve contain?
C5 ONLY
What muscles does the Dorsal Scapular Nerve supply?
- Levator scapula (also fibers from C3, C4)
- Rhomboid major
- Rhomboid minor
(C5 fibers)
What fibers does the Long Thoracic Nerve have? What muscles does it supply?
C5,C6,C7
Serratus anterior muscle
How many and what are the names of the nerve branching off of the trunks of the brachial plexus?
two
- Suprascapular Nerve ( C5,C6)
- Nerve to the subclavius (C5,C6)
What muscles does the Suprascapular Nerve supply?
(C5,C6)
- supraspinatus
- infraspinatus
(2 rotator cuff muscles)
What muscle does the Nerve to the Subclavius supply? What nerve fibers?
C5 and C6
- subclavius
How many and what are the names of the nerves branching off of the lateral cord of the brachial plexus?
two
- Lateral pectoral nerve (C5,C6,C7)
- Musculocutaneous Nerve (C5,C6,C7)
What does the Lateral Pectoral nerve supply?
Pectoralis Major (also gets innervation from Media Pectoral Nerve)
What are the two terminal branches of the lateral cord?
musculocutaneous nerve median nerve (partial contribution from medial cord too)
What muscles does the musculocutaneous nerve supply?
- coracobrachialis
- biceps brachii (long and short heads)
- brachialis
(muscles of anterior arm)
What muscles does the musculocutaneous nerve pierce?
pierces belly of coracobrachialis
After the musculocutaneous nerve supplies the muscles in the anterior arm, how does it continue? What does it become?
b/q the biceps brachii and brachialis into the forearm to become the Lateral Cutaneous Nerve of the Forearm
What does the Lateral Cutaneous Nerve of the Forearm supply?
skin over lateral aspect of the forearm, NOT the hand
How many and what are the names of the nerves branching off the medial cord of the brachial plexus?
(5)
- Medial Pectoral nerve
- Medial cutaneous nerve of the arm
- Medial cutaneous nerve of the forearm
- Ulnar nerve
- Median Nerve (gets partial contribution from medial cord)
What fibers does the Medial Pectoral Nerve contain? What muscles does it supply?
C8 and T1
- Pectoralis major (gets supplied by Lateral Pectoral Nerve too)
- Pectoralis minor
What nerves supply the Pectoralis major?
Lateral pectoral nerve and medial pectoral nerve
What fibers does the Medial Cutaneous nerve of the arm contain? What does it supply?
C8 and T1
- skin of medial arm b/w axilla and elbow
–> receives some fibers from T2 through a communication with intercostobrachial nerve
Besides receiving fibers from C8 and T1, what else does the Medial Cutaneous Nerve of the arm receive some fibers from?
from T2 through a communication with intercostobrachial nerve
What fibers does the Medial Cutaneous nerve of the forearm contain? What does it supply?
C8 and T1
- skin over biceps brachnii and skin over anterior and medial aspects of forearm proximal to the wrist
Describe how the Medial Cutaneous nerve oft he forearm leaves the medial cord?
leaves just distal to the medial cutaneous nerve of the arm
What are the two terminal branches of the medial cord?
Ulnar Nerve Median Nerve (also from lateral cord)
T/F. The Ulnar nerve gives off branches in the arm before entering into the forearm.
False– it does NOT give off branches in the arm
What fibers does the Ulnar nerve contain?
C8, T1, and sometimes C7
Describe how the Ulnar nerve travels.
travels medial to the brachial artery, in the medial bicipital sulcus (gives off NO branches in the arm)
–>
crosses over elbow on posterior side of medial epicondyle in sulcus for ulnar nerve
–> into forearm b/w 2 heads of flexor carpi ulnaris
(innervated 2 mucles in forearm and 2 sensory branches)
–> travels deep to flexor carpi ulnaris to the wrist
–> passes SUPERFICIAL to flexor retinaculum and divides into Superficial and Deep branches