Anatomy Unit 3- Upper Limb- Brachial Plexus of Nerves
divisions
Each of the 3 trunks branch distally into two _________, one anterior and one posterior.
3
How many total anterior divisions are made by each brachial plexus?
3
How many total posterior divisions are made by each brachial plexus?
roots, trunks, divisions, cords, and terminal branches
What are the 5 segments of the brachial plexus, in order from proximal to distal?
anterior ramus and posterior ramus
What are the names of the two structures that each spinal nerve branches into?
decreased ability to abduct at the shoulder, overall weakness in shoulder movement
What are the physical signs/symptoms if the axillary nerve is injured?
weakness in hand grip and opposition of thumb, abnormal sensation in lateral 3.5 digits
What are the physical signs/symptoms if the median nerve is injured?
decreased ability to perform flexion and supination at the elbow
What are the physical signs/symptoms if the musculocutaneous nerve is injured?
decreased ability to perform extension at: elbow, wrist, and digits; wrist "drop"
What are the physical signs/symptoms if the radial nerve is injured?
superior trunk, middle trunk, inferior trunk
What are the three trunks of the brachial plexus?
they create plexuses that innervate both the upper and lower limb
What do multiple anterior rami collectively create (similar to the way in which highways connect and create "interchanges")?
a big "m"
What do the branches of the lateral and medial cords form?
a slanted "y"
What do the branches of the posterior cord form?
communicate to the form the median nerve
What do the lateral and medial cords form as they branch distally?
they innervate the anterior musculature of the arm
What do the median, musculocutaneous, and ulnar nerves innervate collectively?
continues as musculocutaneous nerve
What does the lateral cord continue as?
continues as the ulnar nerve
What does the medial cord continue as?
axillary nerve and radial nerve
What does the posterior cord form as it branches distally?
anterior rami C5-T1
What is another name for a root of the brachial plexus?
carpal tunnel syndrom
What is it called if the impingement of the median nerve is at the flexor retinaculum (just before the hand)?
nerves connecting the spinal cord and upper limb; series of named highways carrying: efferent/motor nerve fibers, afferent/sensory nerve fibers
What is the brachial plexus of nerves?
receives anterior division of superior trunk and middle trunk
What is the contribution of the lateral cord?
receives anterior division of inferior trunk
What is the contribution of the medial cord?
receives posterior division of all 3 trunks
What is the contribution of the posterior cord?
lateral forearm
What is the cutaneous innervation of musculocutaneous nerve?
superolateral arm superficial to deltoid muscle
What is the cutaneous innervation of the axillary nerve?
lateral 3.5 digits and associated palm, posterior tips of same fingers
What is the cutaneous innervation of the median nerve?
areas of: posterior arm, posterior forearm, posterior hand and lateral 3.5 digits (except for distal tips)
What is the cutaneous innervation of the radial nerve?
medial 1.5 digits, associated palmar and dorsum surfaces of hand
What is the cutaneous innervation of the ulnar nerve?
origin: posterior cord; path: passes posterior of the surgical neck of the humerus
What is the key anatomy of the axillary nerve?
origin: lateral and medial cord; path: passes through cubital fossa, passes through carpal tunnel of wrist
What is the key anatomy of the median nerve?
origin: lateral cord; path: pierces the coracobrachialis muscle, courses deep to the biceps brachii muscle
What is the key anatomy of the musculocutaneous nerve?
origin: posterior cord; path: passes posterior to the humerus within the radial groove
What is the key anatomy of the radial nerve?
origin: medial cord; path: passes posterior to medial epicondyle, courses along the medial forearm into the hand (outside of carpal tunnel)
What is the key anatomy of the ulnar nerve?
all anterior arm mm.
What is the motor innervation of musculocutaneous nerve?
deltoid muscle and teres minor muscle
What is the motor innervation of the axillary nerve?
forearm mm., except: flexor carpi ulnaris muscle, lateral 1/2 of flexor digitorum profundus muscle; thenar muscles: move thumb
What is the motor innervation of the median nerve?
all posterior arm mm., all posterior forearm mm.
What is the motor innervation of the radial nerve?
1.5 forearm mm.: flexor carpi ulnaris muscle, medial 1/2 of flexor digitorum profundus muscle
What is the motor innervation of the ulnar nerve?
"build" nerves for anterior compartments of upper limb
What is the purpose of the anterior division of each trunk?
"build" nerves for posterior compartments of upper limb
What is the purpose of the posterior division of each trunk?
axillary nerve
What nerve might be damaged if a patient has a fracture at the surgical neck of the humerus?
radial nerve
What nerve might be damaged if a patient has a fracture in the middle of the shaft of the humerus?
communicates with C8 and T1 roots
What roots communicate with the inferior trunk of the brachial plexus?
continuation of the C7 root
What roots communicate with the middle trunk of the brachial plexus?
communicates with C5 and C6 roots
What roots communicate with the superior trunk of the brachial plexus?
both pass posterior to the humerus
Where do both the axillary and radial nerves pass?
