What is a plexus?
WHAT IS A PLEXUS???AN AREA WHERE FIBERS OF ONE SPINAL NERVE ARE INTERCHANGED WITH FIBERS OF OTHER SPINAL NERVES TO FORM NEW PERIPHERAL NERVES CONTAINING FIBERS OF MANY SPINAL NERVES. SIMILAR TO THE LA FREEWAY SYSTEM.
What is the BRACHIAL PLEXUS?
A. 5 SPINAL NERVE ANTERIOR PRIMARY RAMI, BEGINNING WITH C5, ENDING IN 5 Major TERMINAL NERVES. - C5, C6, C7, C8, T1. (a plexus will always be plus or minus 1 segment - i.e. it could start on C4)
What does the brachial plexus supply?
- nerve supply to the upper extremity. Muscles form from many different segments of the embryo. Shows nerves by segments in case of paralysis or injury. A plexus is like a freeway interchange. A nerve is like a phone trunk line with thousands of wires in it. Some break off of one wire and join another. Start out with several spinal nerves (plexus only forms from anterior primary rami) Each containing 2 or more nerves from each of the rami.
What are the 2 branches off the roots of the brachial plexus, and what do they supply?
1. DORSAL SCAPULAR NERVE
a) RHOMBOID MAJOR
b) RHOMBOID MINOR
2. BRANCHES OF C5-C7 UNITE TO FORM THE LONG THORACIC NERVE
a) SERRATUS ANTERIOR
What are the roots of and branches off the superior trunk of the brachial plexus?
Roots = C5 & C6
(1) NERVE TO SUBCLAVIUS
(2) SUPRASCAPULAR NERVE
What are the DIVISIONS of the brachial plexus?
1. EACH TRUNK DIVIDES INTO ANTERIOR AND POSTERIOR DIVISIONS
a) ANTERIOR DIVISION WILL SERVE ANTERIOR COMPARTMENT - don't have small nerves coming off of them, they will unite to form chords.
b) POSTERIOR DIVISION WILL SERVE POSTERIOR COMPARTMENT
What are the branches off the medial cord?
MEDIAL PECTORAL NERVE
(1) PECTORALIS MINOR
(2) PECTORALIS MAJOR
c) MEDIAL BRACHIAL CUTANEOUS NERVE
d) MEDIAL ANTEBRACHIAL CUTANEOUS NERVE
What is the POSTERIOR CORD?
a) POSTERIOR DIVISIONS OF SUPERIOR, MIDDLE, AND INFERIOR TRUNKS
What are the branches off the posterior cord?
1. THORACODORSAL NERVE
a. latissimus dorsi
2. UPPER SUBSCAPULARIS
3. LOWER SUBSCAPULARIS
a. TERES MAJOR
What are the TERMINALS of the brachial plexus?
1. POSTERIOR CORD
a) AXILLARY NERVE
b) RADIAL NERVE
2. LATERAL CORD
a) MUSCULOCUTANEOUS NERVE
b) LATERAL HEAD OF THE MEDIAN NERVE
3. MEDIAL CORD
a) MEDIAL HEAD OF THE MEDIAN NERVE
b) ULNAR NERVE
What 3 things does the axillary nerve supply?
(2) TERES MINOR
(3) UPPER LATERAL BRACHIAL CUTANEOUS NERVE
What 4 things does the Radial Nerve supply?
(1) MUSCLES OF THE POSTERIOR COMPARTMENT OF THE ARM AND FOREARM
(2) LOWER LATERAL BRACHIAL CUTANEOUS NERVE
(3) POSTERIOR ANTEBRACHIAL CUTANEOUS NERVE
(4) SUPERFICIAL BRANCH--CUTANEOUS TO HAND
What 2 things does the musculocutaneous nerve supply?
(1) MUSCLES IN THE ANTERIOR COMPARTMENT OF THE ARM
(2) LATERAL ANTEBRACHIAL CUTANEOUS N.
What 2 things does the median nerve supply?
(1) MEDIAN NERVE SERVES THE MUSCLES IN THE ANTERIOR COMPARTMENT OF THE FOREARM, EXCEPT 1 & 1/2 MUSCLES, WHICH ARE INNERVATED BY THE ULNAR NERVE. EXCEPTIONS ARE:
(a) FLEXOR CARPI ULNARIS
(b) MEDIAL 1/2 OF FLEXOR DIGITORUM PROFUNDUS
(2) PALMAR CUTANEOUS BRANCH
What 3 things does the ulnar nerve supply?
(1) MUSCLES OF THE HAND WITH THE EXCEPTION OF 1 & 1/2 MUSCLES, WHICH ARE INNERVATED BY THE MEDIAN NERVE. THE EXCEPTIONS ARE:
(a) ONE: MUSCLES OF THE THENAR EMINENCE
(b) ONE-HALF: THE LATERAL TWO LUMBRICALS
(2) PALMAR CUTANEOUS BRANCH
(3) DORSAL CUTANEOUS BRANCH
What are the SUPRACLAVICULAR NERVES?
SUPRACLAVICULAR NERVES - anterior branches of rami of cervical nerves - cutaneous branches.
1. C3 & C4
What are the INTERCOSTAL NERVES?
INTERCOSTAL NERVES -high in axilla they may provide some of the skin of the axilla on the medial side.
What are DERMATOMES?
DERMATOMES - see ppt slides. Dermatomes - cutaneous nerves. C7 is in the middle of the hand. In clinical practice you will test to see if someone has lost sensation, what kind (hot, cold, touch, etc).
What is phantom limb pain?
Phantom Limb Pain - found in amputees that still feel pain in the limb that's been cut off b/c brain doesn't know that limb has been cut off. The end of the nerve had to be cut off, but it heals over and has lots of stimuli. Lots of little fibers that used to go down to the limb - can be hot, cold, pressure, pain, etc. and brain thinks it is from limb that isn't there.