Lecture 9: Upper Limb Nerves, Dermatomes & Myotomes (Upper limb vascular & transitional areas) Flashcards
Supraclavicular branches of the brachial plexus:
-Branches exit the brachial plexus “superior” to the clavicle
-Largely located in the cervical region
Important branches:
-Long thoracic nerve
-Suprascapular nerve
-Dorsal nerve
Infraclavicular branches (terminal branches) of the brachial plexus:
-Branches exit plexus inferior to clavicle
-Primarily located in axilla/armpit
-Musculocutaneous nerve (C5,6,7)
-Axillary (C5/6)
-Radial (C5-T1)
-Median (C5-T1)
-Ulnar (C8/T1)
Musculocutaneous nerve-
Origin=>
Function=>
O: terminal branch of lateral chord
F: Motor to anterior arm;
-Coracobrachialis
-Biceps
-Brachialis
Sensory:
-Anterolateral forearm
Which nerve innervates the highlighted area?
Musculocutaneous nerve
The musculocutaneous nerve travels through what muscle?
coracobrachialis muscle belly
The musculocutaneous nerve innervates what compartment?
anterior compartment of the forearm
What does the musculocutaneous nerve turn into after passing the cubital fossa?
Lateral cutaneous nerve of forearm
Axillary nerve:
Origin=>
Function=>
O: terminal branch of the posterior cord
F: Motor to lateral shoulder
-Deltoid
-Teres minor
Sensory to:
-Skin of lateral shoulder
What is the axillary nerve pathway?
-heads posteriorly in axilla
-Travels through the quadrangular axillary space
-Wraps around posterior aspect of humoral neck
-Relationship with the surgical neck of the humerus
What is the most likely site of injury for the axillary nerve?
Surgical neck of the humerus
Picture: fracture of the surgical neck of the humerus (complete deltoid atrophy of the left shoulder
What is the most likely site of injury for the musculocutaneous nerve?
Coracobrachialis muscle
Radial nerve (C5,6,7,8, T1):
Origin=>
Function=>
O: terminal branch of posterior cord
F: Motor to;
-Extensor muscles of the posterior arm
-Extensor muscles of posterior forearm
-Brachioradialis
-Supinator Muscle
Sensory to:
-Skin of posterior arm, forearm and hand
-Dorsal surface of digits 1,2,3 and lateral 1/2 of 4th digit
Radial nerve pathway:
-Heads posteriorly in axilla
-Travels posteriorly, inferior to the quadrangular axillary space
-Wraps around posterior aspect of humeral shaft
-Relationship w/ the radial groove of humerus
Axilla innervates which muscles?
Deltoid and teres minor
Radial nerve innervates what?
extensors of arm and forearm and supinator digits 1,2,3 & lateral 1/2 of 4th digit
What is the most likely site of injury for the radial nerve?
radial groove of humerus
Radial nerve:
Sensory branches in posterior arm=>
-Post cutaneous nerve of forearm
-Lower lateral cutaneous nerve of arm
Terminal branches of the radial nerve are:
Deep branch (motor)
Superficial branch (sensory)
Deep(motor) branch of the radial nerve innervates what?
posterior compartment of the forearm
Superficial (sensory) branch of the radial nerve innervates what?
contributes to the cutaneous innervation of the dorsal hand and fingers.
Fracture of the radial groove of the humerus injures which nerve and causes what?
Radial nerve; wrist drop
Median nerve(C5,6,7,8,and T1):
Origin=>
Function=>
O: Terminal branch of lateral and medial cords
F: Motor to muscles of the anterior forearm and hand:
-Flexors of wrist
-Pronators of forearm
-Flexors of digits 1,2,3
-lumbricals 1 and 2
-Thenar muscles
Sensory to:
-Palmar surface of digits 1,2,3 and lateral 1/2 of digit 4
Median nerve pathway:
Heads inferiorly from axilla, traveling down anteromedial arm (within layers of muscle)
-Crosses anterior elbow within cubital fossa
-travels down forearm
-enters hand via carpal tunnel
What are the likely sites of injury for the median nerve?
-anterior elbow within cubital fossa
-Carpal tunnel
Carpal tunnel syndrome:
Compression of the median nerve as it passes through the carpal tunnel:
-Typing
-Mechanics
-Pregnancy
-Obesity
Will first impact function of median nerve in the hand (motor and sensory)
-Patient will complain about numbness and tingling in the first 3.5 digits and weakness of thumb movements.
As the condition progresses, sensory changes can radiate into the forearm, and even the axilla
To relieve symptoms, partial or complete surgical division of the flexor retinaculum may be necessary (carpal tunnel release)
Damage to what type of nerve causes this deformity and what is the deformity called?
Median nerve lesion; Ape hand deformity
Ulnar nerve(C8 & T1):
Origin=>
Function=>
O: terminal branch of medial cord
F: Motor to medial forearm and hand:
-Medial 1/2 of flexor digitorum profundus
-Hand intrinsics
-Lumbricals 3&4
-Hypothenar group
-Palmar and Dorsal interossei
Sensory to:
-Palmar and dorsal surface of medial 1/2 of digit 4 and all of digit 5
Ulnar nerve pathway:
-Inferiorly from axilla, traveling down anteromedial arm (protected by muscle)
-Passes posterior to medial epicondyle
-Travels down medial forearm
-Enters hand external to carpal tunnel
What is the most likely injury site for the ulnar nerve?
medial epicondyle
Fracture of medial epicondyle of humerus can cause injury to what nerve and cause what?
Ulnar nerve; Claw hand
Identify the cutaneous supplies to the colored portions of the photo:
Answers:
Identify the cutaneous supplies to the colored portions of the photo:
Median:
-Palmar surface of lateral 3.5 digits
Ulnar:
-Palmar and dorsal surface of medial 1.5 digits
Radial:
-Dorsal surface of lateral 3.5 digits
How many pairs of spinal nerves are there?
31
Nerves are ________ matter pathways that provide a route for motor and sensory signals to travel between PNS and CNS.
white
Spinal nerves are _____________ and will carry signals to and from targets/receptors on the same side of the body.
Ipsilateral
_________________ carries ____________ information into CNS so it can ascend in the cord to reach the cortex.
Posterior/Dorsal root; sensory/afferent
________________ carries __________ information out of CNS that has descended from the cortex to the cord.
Ventral/Anterior root; motor/efferent
True or false: Testing both dermatomes and myotomes can provide important clinical feedback about function of spinal nerves.
True
Dermatomes of the upper limb (anterior)
(Posterior)
C5:
Myotome=>
Function=>
M: Deltoid Muscle
F: Abduction of arm at shoulder
C6:
Myotome=>
Function=>
M: Biceps
F: Flexion of the arm at the elbow
C7:
Myotome=>
Function=>
M: Triceps
F: Extension of the arm at the elbow
C8:
Myotome=>
Function=>
M: Small muscles of the hand
F: Finger flexion
T1:
Myotome=>
Function=>
M: Small muscles of the hand
F: Finger abduction
Clinical test C5:
Dermatome=>
Myotome=>
D: sensation of skin of anterior/lateral arm (skin over deltoid)
M: muscle strength of deltoid (arm abduction)
Clinical test C6:
Dermatome=>
Myotome=>
D: sensation of anterior skin of thumb
M: Muscle strength of biceps (elbow flexion)
Clinical test C7:
Dermatome=>
Myotome=>
D: sensation of anterior skin of digits 2 & 3
M: Muscle strength of triceps (elbow extension)
Clinical test C8:
Dermatome=>
Myotome=>
D: Sensation of skin of digits 4 & 5
M: muscle strength of finger flexors
Clinical test T1:
Dermatome=>
Myotome=>
D: sensation of skin of anteromedial elbow
M: muscle strength of finger abductors
The reflex arc:
-simplest of all neuronal responses
-Autonomic
-Predictable
-Acquired
Tendon reflexes of the upper limb:
Practice these on a friend or family member:
Identify the arteries:
1) Brachiocephalic trunk
2) Radial
3) ulnar
4) Axillary
Name the artery:
Subclavian artery
Name the structures and arteries:
1) Subclavian
2) Axillary
3) Pectoralis minor
4) Brachial artery
Where does the axillary artery lie?
Between the first rib and the lower border of teres major or pectoralis muscle.
The axillary is divided into three parts:
Describe the 1st part=>
-Lies before the muscle
-One branch
-Supplies upper part of the thoracic cavity
-Superior Thoracic Artery
The axillary is divided into three parts:
Describe the 2nd part=>
-Covered anteriorly by muscle
-Two branches:
1st branch: supplies some parts of the pectoral and deltoid regions (thoracoacromial)
2nd branch: supplies lateral thoracic wall including serratus anterior muscle (Thoracic artery)
The axillary is divided into three parts:
Describe the 3rd part=>
–Located after the pectoralis minor
-Three branches:
1st branch: Subscapular artery; supplies the muscle of the scapular region
2nd &. 3rd branches: Anterior & Posterior circumflex humeral arteries; turn around the surgical neck of the humerus anteriorly and posteriorly respectively. Supply muscles attached to the proximal head of the humerus.
After passing the inferior border of teres major or pectoralis, the name of the axillary artery will change to _____________.
Brachial Artery
This artery starts at the lower border of teres major or pectoralis major. Then it runs down in the arm.
Brachial Artery
Where does the brachial artery end?
distal part of the cubital fossa, dividing into the radial and ulnar arteries.
The larger of the two terminal branches of the brachial artery:
Ulnar artery
Where does the ulnar artery lie and pass?
Lies: Under the flexi carpi ulnaris
-Accompanied by the ulnar nerve on it’s way
Passes: distally over the anterior aspect of the wrist to the palm
What does the ulnar artery supply blood to?
-The elbow
-Muscles of the anterior compartment on the medial side
-Deep muscles of anterior compartment of forearm
-Majority of the muscles of the posterior compartment and the wrist joint
What artery does the ulnar artery take part in forming?
Palmar arterial arches
Where does the radial artery supply blood to?
Lateral side of the forearm
The radial artery descends from where, passes through where, and end where?
Descends: Lateral side of the forearm under the brachioradialis toward the distal part of the forearm through the snuff box.
Passes through: The first interosseous space in the hand
Enters: Palm of hand
The radial artery takes part in forming what artery?
Deep palmar arch
What artery is the major source of blood supply for the dorsal surface of the hand?
Radial Artery
Branches from the radial artery form what?
Dorsal arterial arch at the level of the carpal bones.
Aside from the branches that make the dorsal arterial arch from the radial artery, what do the other branches do?
Join with terminal branches of the ulnar artery to form the superficial and deep palmar arterial arches.
Identify the numbered structures:
1) Radial Artery
2) Ulnar artery
3) Deep palmar (arterial) arch
4) Pisiform
5) Distal limit of superficial palmar arch
Identify the numbered structures:
1) Ulnar artery
2) radial artery
3) Deep palmar arch
4) Superficial palmar arch
Identify the structures:
1) Brachial artery
2) Median Nerve
3) Ulnar nerve
Identify the structures:
1) Cubital fossa
2) Brachioradialis muscles
3) Pronator teres muscles
4) Biceps brachii tendon
5) Brachial artery
6) Median nerve
7) Cephalic vein
8) Radial nerve
9) Median cubital vein
10) Ulnar nerve
Locations of the arterial pulses of the upper limbs:
Identify the structures:
1) Anatomical snuff box
2) Cephalic vein
3) Dorsal venous network
4) Basilic vein
Identify the structures:
1) Brachiocephalic vein
2) Subclavian vein
3) Axillary vein
4) Brachial vein
5) Cephalic vein
6) Basilic vein
7) Median cubital vein
8) Median antebrachial vein
9) Radial vein
10) Ulnar vein
Identify the structures:
1) Axillary vein
2) Cephalic vein
3) Basilic vein
Identify the structures:
1) Flexor retinaculum
2) Median nerve
3) Flexor pollicis longus tendon
4) Flexor digitorum superficialis tendons
5) Flexor digitorum profundus tendons
