Nerve Supply to the Thoracic Limb Flashcards
1
Q
What is the brachial plexus formed by?
A
the ventral branches of spinal nerves C6-T1
2
Q
What are the nerves emerging from the brachial plexus arranged around?
A
the axillary artery
3
Q
What do the most cranial nerves in the brachial plexus receive contribution from?
A
the most cranial spinal cord segments and the corresponding dorsal root ganglion
4
Q
What do the most caudal nerves in the brachial plexus receive contribution from?
A
caudal segments of the spinal cord and dorsal root ganglion
5
Q
What type of fibers are in the nerves of the brachial plexus?
A
motor (GSE) and sensory (GSA)
6
Q
What do the sensory fibers of the nerves in the brachial plexus supply?
A
convey sensory information form the muscle spindles within the skeletal muscles, other mechanoreceptors in the tendons, ligaments, and joint capsule, and the skin
7
Q
What do the motor fibers of the nerves in the brachial plexus supply?
A
the skeletal muscle, and facilitate their contraction which causes movement at the joint and the limb as a whole
8
Q
What are the roots of the cleidobrachial nerve?
A
C6 and C7
9
Q
What does the cleidobrachial nerve supply?
A
the cleidobrachialis muscle
10
Q
What are the roots of the deep pectoral nerves?
A
C6-C8
11
Q
What do the deep pectoral nerves supply?
A
the pectoralis ascendens
12
Q
What are the roots of the thoracodorsal nerve?
A
C6-T1
13
Q
What does the thoracodorsal nerve innervate?
A
the latissimus dorsi
14
Q
What are the roots of the long thoracic nerve?
A
C8-T1
15
Q
What does the long thoracic nerve supply?
A
serratus ventralis thoracis
16
Q
What are the roots of the lateral thoracic nerve?
A
C8-T1
17
Q
What does the lateral thoracic nerve supply?
A
GSE fibers to the muscular axillary arch, the cutaneous trunci and the cranial preputial muscles
18
Q
True or False: the lateral thoracic nerve has cutaneous sensory fibers
A
false; the fibers come from T3-L3 spinal nerves
19
Q
What are the possibilities that the extrinsic muscles of the thoracic limb are innervated by?
A
nerves from the brachial plexus, accessory nerve, or segmental cervical and or thoracic spinal nerves
20
Q
What extrinsic muscles of the thoracic limb are innervated by nerves from the brachial plexus?
A
pectorals, latissimus dorsi, and serratus ventralis thoracis
21
Q
What extrinsic muscles of the thoracic limb are innervated by the segmental spinal nerves?
A
the rhomboideus and serratus cervicis
22
Q
What extrinsic muscles of the thoracic limb are innervated by the accessory nerve?
A
the trapezius and omotransversarius
23
Q
What supplies the cleidocervicalis and the distal part of the brachiocephalicus?
A
the accessory nerve along with the segmental cervical nerves
24
Q
What are the intrinsic muscles supplied by?
A
the branches of the brachial plexus
25
What are the roots of the axillary nerve?
C6-C8
26
What does the axillary nerve supply?
the primary flexors of the shoulder joint and the skin of the cranial and lateral aspect of the shoulder and brachium
27
What are the primary flexors of the shoulder joint?
the teres major, teres minor, and the deltoideus
28
Where does the axillary nerve course?
in between the teres major and the subscapularis
29
What does injury to the axillary nerve cause?
lack of cutaneous sensation on the lateral aspect of the shoulder region and the craniolateral aspect of the upper brachial region and atrophy of the teres major, teres minor, and deltoideus
30
Why does injury to the axillary nerve have no impact on the shoulder joint flexion?
the latissimus dorsi and the long head of triceps compensate for the motor function
31
What reflex test can be used to test for axillary nerve damage?
a pinprick test in the autonomous zone
32
How do the latissimus dorsi and the long head of triceps flex the shoulder?
the latissimus dorsi pulls the humerus caudally and the long head of triceps pulls the scapula ventrally
33
What does the subscapular nerve supply?
the subscapularis
34
Where does the cranial lateral cutaneous brachial nerve course?
it emerges caudal to the shoulder joint on the lateral side of the limb at the distal edge of the deltoideus muscle
35
What does the cranial lateral cutaneous brachial nerve innervate?
the skin on the lateral brachial region and caudal scapular area
36
What does the descending branch of the cranial lateral cutaneous brachial nerve join?
the medial branch of the superficial radial nerve to form the cranial cutaneous antebrachial nerve
37
What are the roots of the suprascapular nerve?
C6-C7
38
Where does the suprascapular nerve course?
between the subscapularis and the supraspinatus muscle, and passes cranial to the edge of the scapular notch
39
What does the suprascapular nerve supply?
the primary extensors of the shoulder joint
40
What are the primary extensors of the shoulder joint
the supraspinatus and the infraspinatus
41
What can cause injury to the suprascapular nerve?
a fracture at the neck of the scapula
42
What does injury to the suprascapular nerve cause?
prominent scapular spine, outward deviated shoulder joint, paralysis of the primary extensors of the shoulder joint
43
How does loss of function of the suprascapular nerve affect support of the shoulder joint?
it affects lateral support since the tendinous support is compromised
44
Why is shoulder extension unaffected when the suprascapular nerve is injured?
the brachiocephalicus compensates for it
45
How does the brachiocephalicus extend the shoulder?
it pulls the humerus cranially
46
True or False: There are no cutaneous/sensory branches from the suprascapular nerve
True
47
What are the roots of the musculocutaneous nerve?
C6-C8
48
What does the musculocutaneous nerve supply?
the primary flexors of the elbow joint
49
What are the primary flexors of the elbow joint?
the biceps brachii, the brachialis, coracobrachialis, and the medial aspect of the antebrachium
50
Where does the musculocutaneous nerve run?
cranial to the brachial artery on the caudal border of the biceps brachii
51
Where does the motor innervation of the musculocutaneous nerve end?
in the biceps brachii
52
What does the sensory branch continue as and where?
it continues in the medial forearm as the medial cutaneous antebrachial nerve
53
What does damage to musculocutaneous nerve cause?
loss of function to the biceps brachii and brachialis, and loss of sensation to the medial aspect of the antebrachium
54
What might a dog not do if the musclulocutaneous nerve is injured?
difficulty flexing the elbow joint while going up the stairs, or offer their paw
55
What compensates for elbow flexion when the musculocutaneous nerve is injured?
the latissimus dorsi compensates and the relaxation of the triceps brachii flexes it
56
What reflex tests can be used to determine if the musculotaneous nerve is damaged?
the pinprick test and the biceps tendon test
57
What would cause a false positive biceps tendon reflex result?
too much pressure on the biceps tendon causing it to flex
58
What would cause a false negative biceps tendon reflex result?
too much pressure on the triceps tendon does not allow the dog to flex the elbow
59
What are the roots of the radial nerve?
C6-T1
60
What does the radial nerve supply?
the extensors of the elbow joint, and the extensors of the carpus and digits, the tensor fascia antevrachii, the anconeus, brachioradiallis, supinator muscles
61
What is the course of the radial nerve?
it lies lateral to the axillary artery in the axilla and enters the limb close to the insertions of the teres major and latissimus dorsi, then between the medial and long head of triceps, then along the caudal border of the brachialis muscle to spiral around the caudal aspect of the humerus
62
What does the radial nerve do during its course of the brachial region?
it supplies all four parts of the triceps brachii
63
At the distal part of the humerus, what does the radial nerve do?
divides into a deep branch and a superficial branch
64
What is the course of the deep branch of the radial nerve and what does it supply?
it runs under the extensor carpi radialis and the rest of the carpal and digital extensors to supply them
65
What is the course of the superficial branch of the radial nerve and what does it supply?
it has medial and lateral branches that run distally on either side of the cephalic vein and supplies the skin on the craniolateral aspect of the antebrachium and craniomedial aspect of the manus
66
What can cause injury to the radial nerve?
trauma on the lateral side of the humerus, avulsion of the brachial plexus, fracture of the first or second rib, erratic venipuncture procedure
67
What does injury to the proximal branches of the radial nerve cause?
loss of extension of the elbow, carpus and digits, non weight-bearing limb, knuckling of the paw, loss of sensation in the craniolateral antebrachium and craniomedial manus
68
What does injury to the distal branches of the radial nerve cause?
loss of digital and carpal extension, knuckling of the paw but the patient is still weight bearing
69
Why is the patient still weight bearing when there is damage to the distal branches of the radial nerve?
because the triceps brachii is unaffected
70
What would nerve damage of the radial nerve at the level of the cephalic vein cause?
sensory loss to the point of damage
71
What reflex tests can be used to test if the radial nerve is injured?
The triceps reflex test, ECR relflex test, painprick test, and proprioceptive test
72
When determining if the radial nerve is injured, what is the triceps reflex test good for?
testing for proximal radial nerve injury, it is not needed for distal radial nerve injury because the patient is still weight bearing
73
What is the target of the triceps reflex test?
the golgi tendon receptors in the triceps tendon
74
What is the target of the ECR reflex test?
muscle spindle receptors within the extensor carpi radialis
75
What does the triceps reflex test test for?
extension of the elbow joint
76
What does the ECR reflex test test for?
extension of the carpus
77
Where would you try the pinprick test in order to determine if the radial nerve is injured?
on the dorsomedial aspect of the carpus and antebrachium
78
What are the roots of the median nerve?
C7-T1
79
What is the course of the median nerve?
it courses along the median axis of the limb along the brachial and median artery in the brachial, antebrachial and the manus
80
At the brachium where is the median nerve located?
between the brachial artery cranially and the ulnar nerve caudally
81
At the elbow, what is the course of the median nerve?
it courses under the pronator teres
82
What does the median nerve innervate?
the flexors of the carpus and digits, and has a sensory branch to the caudomedial aspect of the manus
83
What are the flexors of the carpus and the digits?
flexor carpi radialis, deep digital flexor, the superficial digital flexor, the pronator teres, and the pronator quadratus
84
Which heads of the deep digital flexor are supplied by the median nerve?
all three
85
What do the sensory fibers of the median nerve supply?
the skin on the palmar aspect of the manus
86
What structure does the median nerve pass through?
the carpal canal
87
What digits does the median nerve supply and as what?
it becomes the digital nerves and supplies digits I-II and the axial border of digit IV
88
What does injury to the median nerve cause?
overextended carpus and digits with claws raised off of the ground and loss of cutaneous sensation in the caudomedial aspect of the manus
89
What muscles are affected if the median nerve is injured?
damage to the pronator teres and the flexor carpi radialis
90
What are the roots of the ulnar nerve?
C8-T1/2
91
What does the ulnar nerve supply?
the flexors of the carpus and digits, and sensory to the caudal aspect of the antebrachium, palmar aspect of the manus and lateral digits
92
Which flexors of the carpus and the digits does the ulnar nerve supply?
the flexor carpi ulnaris, superficial digital flexor, and the ulnar head of the the DDF and the lateral part of the humeral head
93
What is the course of the ulnar nerve?
it leaves the brachial plexus and runs distally caudal to the median nerve close to the brachial vein in the medial aspect of the brachium
94
The caudal cutaneous antebrachial nerve, a branch of the ulnar nerve, supplies what and what is its course?
it runs caudally in the distal third of the brachium over the olecranon/ medial epicondyle of the humerus to supply the caudal aspect of the antebrachium
95
After giving off the caudal cutaneous antebrachial nerve, what is the course of the ulnar nerve?
it passes over the medial epicondyle and deep to the flexor carpi ulnaris and then runs distally between the DDF and flexor carpi ulnaris to the carpal canal
96
The dorsal cutaneous branch of the ulnar nerve supplies what and what is its course?
it crosses the lateral aspect of the accessory carpal bone to supply the lateral aspect of the manus
97
What does damage to the ulnar nerve cause?
loss of sensation to the V digit and the abaxial border of the IV digit
98
What muscle is affected by ulnar nerve damage?
flexor carpi ulnaris
99
What reflex test can be used to determine if the ulnar nerve is damaged?
the pinprick test on the caudal antebrachial region + 5th digit
100
What supplies the dorsomedial aspect of the manus?
the radial nerve
101
What are the superficial set of nerves called that supply the palmar aspect of the manus?
palmar common digital nerves
102
What are the deep sets of nerves called that supply the palmar aspect of the manus?
the palmar metacarpal nerves
103
What provides motor innervation to the interossei muscles?
the deep branch of the ulnar nerve from the palmar branch
104
In the cat, what does the median nerve pass through and with what?
the supracondylar foramen with the brachial artery
