Innervation of the Forelimb Flashcards
The movement of a muscle depends on:
Origin and insertion
Innervation
What is a course?
The pathway that a nerve travels
What is quadriplegia?
paralysis of all 4 limbs
plegia help me, I’m paralyzed
What is paraplegia?
paralysis of 2 limbs
(any 2 limbs)
para (pair of) limbs
What is monoplegia?
paralysis of 1 limb
What is hemiplegia?
paralysis of one side of the body
What 2 parts is the nervous system divided into?
central and peripheral nervous system
What is the peripheral nervous system further divided into?
cranial and spinal nerves
How many cervical vertebrae are there?
7
How many cervical nerves are there?
8
How many thoracic vertebrae are there?
13
How many lumbar vertebrae are there?
7
How many thoracic nerves are there?
13
How many lumbar nerves are there?
7
How many caudal vertebrae are there?
6
How many caudal nerves are there?
5
What is special about the atlas and axis compared to the rest of the spinal vertebrae
It is the only vertebrae that rotates the head from side to side
Where do the spinal nerves innervate from?
intervertebral foramen
Where is the terminal end of the spinal cord?
L6 or L7
The tapered end of the spinal cord is called the:
conus medullaris
What is the cauda equina and where does it innervate?
a bundle of nerve roots at the very end of the spinal cord, resembling a horse’s tail in appearance, which provides sensory and motor innervation to the lower (hind) limbs, bladder, and rectum
Sciatica (in humans) is similar to what condition in animals?
cauda equina syndrome
What is the first part of the central nervous system?
brain
what is the PNS comprised of?
ganglions and neurons
What are ganglions?
clusters of perkaryons
How many pairs of spinal nerves are in cats, horses, ruminants, and rabbits?
31-36 spinal nerves
What are the tracts of the peripheral nervous system?
nerves
How many pairs of spinal nerves are in pigs?
40
You probably shouldn’t put your hair in pigtails if you’re 40
How many cranial nerves are in all species?
12
How many pairs of spinal nerves are in dogs?
41
Pigtail lady and her dog
How many pairs of spinal nerves are in a chicken?
43
Pigtail lady: she owns a dog and 2 chickens
What is a spinal cord Intumescence? Where does it occur?
the enlargement of the spinal cord in certain areas ; cervical and lumbar where HL and FL attach
The cervical intumenscence is located from ___ to ___, and gives rise to the _________________.
-C7 -T1
-gives rise to the spinal nerves that form the brachial plexus that innervates the thoracic limb.
The lumbar intumenscence is located from ___ to ___, and controls the _________________.
- L4 - S3
- pelvic limbs (hindlimb) and pelvic organs.
Just below the lumbar enlargement, the spinal cord tapers into a medullary cone (conus medullaris), which is finally reduced to form the terminal filament.
What is the longitudinal CSF-filled space which runs the entire length of the spinal cord, and represents the most caudal portion of the ventricular system?
The central canal
Cauda equina syndrome usually affects what part of the body? Why?
Usually, the hindlimb is affected because the protruding disc compresses the nerve at L7/S1 disk space
last donut of lumbar conveyor belt, jelly is squished out
Equine steps on donut with hindlimb, so jelly protrudes out
What are some symptoms of cauda equina syndrome?
pain, paralysis, incontinence (involuntary urination), and lameness
What is a treatment for cauda equina syndrome?
laminectomy, removing part or all of the lamina, which is the bony arch that covers and protects the spinal cord. It is performed to relieve pressure on the spinal cord or nerve roots
A axial or transection of the spine looks like a butterfly, describe the various parts? The middle? the upper wing? lower wing?
middle - central canal
upper wing - dorsal horn (dorsal lateral groove)
lower wing - ventral horn
What is decussation?
Nerve fibers crossing over from one side of the nervous system to the other.
cussing and crossing 👀
What is the medial lemniscus?
A sensory pathway of the brainstem
What is the crucial role of decussation?
The organization of the nervous system and the coordination of sensory and motor functions.
What part of the brainstem does not decussate? (remains on the same side)
temporal halves
Why should you study decussation?
It is critical in clinical neuroscience for interpreting neurological signs and symptoms and diagnosing conditions affecting the nervous system.
What are the layers of the spinal cord? Where are they located?
dura mater (outer layer)
arachnoid mater (middle layer)
pia mater (inner layer).
What is ependyma?
Epithelial cell layer that line the central canal and produces the cerebrospinal fluid (CSF)
- cuboidal and cilliated
What is the lumbar cisterna?
a subarachnoid space in the lumbar region that contains CSF fluid
Where you would do a lumbar tap
What nerves are in the brachial plexus of a dog at the level of the axillary space ?
1) musculocutaneous (MU)
2) axillary (AX)
3) suprascapular (SP)
4) subscapular (SB)
5) radial (RA)
6) ulnar (UL)
7) median (ME)
MASSRUM. Took a massive bottle of rum and stuck it under armpit
What is a lumbar puncture, and where is it performed?
Also known as a spinal tap, it is a procedure that collects CSF from the lumbar cistern.
Collected from the lumbosacral space, either between L4 -L5 or L5- L6
What is the covering of the brain and spinal cord called?
meninges
What is inflammation of the spinal cord called? What is it caused by?
meningitis; caused by bacteria, viruses, fungi, and parasites
What are 9 symptoms of meningitis in dogs?
-Fever
-Lethargy
-Stiff neck
-Headache
-Seizures
-Vomiting
-Loss of appetite
-Sensitivity to light
-Confusion, or disorientation
What is the coccygeal ligament?
a ligament that connects the sacrum to the coccyx for the tail
What is the location in the cervical region for a CSF tap?
Cerebellomedullary cistern
What 2 nerves make up the cervical loop and what do they innervate?
ventral branch of C1 and the hypoglossal nerve (cranial 12). They innervate the hyoid apparatus
rope around neck, tongue sticks out. Hypoglosssal also inn. tongue
What innervates the caudal part of the external ear?
ventral branch of cervical 2 (C2) and cranial 7. They join the caudal auricular branch of the facial nerves.
Which nerves innervate the diaphragm? What is the difference in cats?
Ventral roots of C5-C7 from the phrenic nerve that runs caudally within the mediastinum
(cats: ventral roots of C4-C7)
How many cranial nerves are there?
12
12 disciples got on Jesus’ nerves
Which nerve is the 12th cranial nerve?
hypoglossal nerve
you get to the end and stick your tongue out :p
Which nerves are part of the vagus group?
Glossopharyngeal vagus and accessory nerves
The brachial plexus is usually formed by the ventral branches of the __, __, & __ cervical and __ & __ thoracic spinal nerves. Sometimes, C__ and/or T__ are present.
6th, 7th, & 8th cervical n.
1st and 2nd thoracic n.
Sometimes C5 and/or T2 are present.
Which 4 muscles & skin area are in the same region but are NOT supplied by the brachail plexus? Instead, they are supplied by the dorsal and ventral branches of the cervical and thoracic spinal nerves.
brachiocephalicus, omotransversarius, rhomboidius, & trapezius muscles & the skin over the upper shoulder region
aBORT mission
The brachial plexus gives origin to the nerves that innervate ________.
charlie brown teacher
Innervate the muscles and skin of the thoracic limb, parts of the shoulder girdle musculature, and the lateral wall of the thorax and abdomen.
What are the mixed nerves?
Musculocutaneous n.
Ulnar n.
Median n.
Radial n.
Axillary n.
Thoracodorsal n.
mum rat
What are the motor nerves?
Suprascapular
Subscapular
Cranial pectoral
Caudal pectoral
Long thoracic
Lateral thoracic
SSCCLL
What makes a nerve mixed?
It has sensory and motor function
What makes a nerve motor?
It has no sensory function
What is the origin of the musculocutaneuous nerve?
C6-C7 (sometimes C8)
What is the origin of the ulnar nerve?
C8-T2
The ulnar, older nerve. So has the “older” numbers
What is the origin of the radial nerve?
C7-T1 (sometimes T2)
What is the origin of the axillary nerve?
C7-C8
What is the origin of the thoracodorsal nerve?
C7-T1
The brachial plexus is located cranial to the _____ between the long muscle of the ____ and the _____ muscles.
1st rib, neck, scaleni
Innervation for the musculocutaneous n.?
Biceps brachii
Brachialis
Coracobrachialis
Musclular reporter on the BBC network
Innervation for the Ulnar n.?
3
SDF
DDF (ulnar + humoral head)
Flexor carpi ulnaris
Innervation for the median n.?
5
Pronator teres
Pronator quadratis
SDF
DDF (all heads)
Flexor carpi radialis
Innervation for the radial n.?
there are 8
Triceps brachii
Tensor fascia antibrachii
Extensor carpi radialis
Extensor carpi ulnaris
Anconeus m.
Supinatior
LDE (lateral digital extensor)
CDE (common digital extensor)
ET’s CLEATS are RAD
Exten
Tri
Cde
Lde
Extens
Anc
Tes
Sup
Innervation for the axillary n?
Deltoideus
Teres major
Teres minor
Innervation for the thoracodorsal n?
Latissimus dorsi
What nerve innervates all of the extensor muscles?
Radial n.
What is the origin of the suprascapular nerve?
C6-C7
What is the origin for the subscapular nerves?
C6-C7
What is the origin of the cranial pectoral n.?
(Sometimes C6), C7-T1
What is the origin of the caudal pectoral n.?
C8-T1 (sometimes T2)
What is the origin of the long thoracic n.?
C7 (sometimes C8)
What is the origin of the lateral thoracic n.?
C8-T1 (sometimes T2)
Innervation of the suprascapular n.?
Supraspinatus
Infraspinatus
Innervation of the subscapular n.?
Subscapularis
technically also supraspin. but it has no affect on it, so doesn’t count
Innervation of the cranial pectoral n.?
Superficial pectoral
- ascending + transverse part
Innervation of long thoracic n.?
Serratis ventralis
Innervation of lateral thoracic n.?
Cutaneous trunci
What are the 3 reflex tests?
Withdrawal reflex
Biceps reflex
Triceps reflex
What nerves are being evaluated during the withdrawal reflex test?
Radial
Ulnar
Median
What is evaluated during the biceps reflex test?
(nerve, origin, and muscle)
Musculocutaneous n.
Spinal cord C6-C8
Biceps brachii m.
What is evaluated during the triceps reflex test?
(nerve, origin, muscle)
Radial n.
Triceps brachii m.
Spinal cord C7-T2 (origin)
What is the reaction of a grade 0 response, and what is it called?
- no response
- Areflexia
What is the reaction of a grade 1 response, and what is it called?
- reduced reflex
- Hyporeflexia
What is the reaction of a grade 2 response, and what is it called?
- brief flexion
- Normoreflexia
What is the reaction of a grade 3 response, and what is it called?
- exaggerated response
- Hypereflexia
What is the reaction of a grade 4 response, and what is it called?
- exaggerated response with clonus (repetitive movement)
- Hypereflexia
Is a grade 0 reflex response UMN or LMN damage?
(upper/lower motor neuron damage)
LMN
Is a grade 1 reflex response UMN or LMN damage?
LMN
Is a grade 2 reflex response UMN or LMN damage?
trick question, there is no damage!
Is a grade 3 reflex response UMN or LMN damage?
UMN
Is a grade 4 reflex response UMN or LMN damage?
UMN
What part of the spinal cord is affected during Areflexia?
C6-C8
What part of the spinal cord is affected during Hyporeflexia?
C6-C8
What part of the spinal cord is affected during Hypereflexia?
C6 cranial/spinal
What is a reflex?
An involuntary response to stimuli
What is nociception?
The response/detection of danger
NOOO there is danger
What is a monosynaptic reflex + examples?
A reflex with no interneurons involved. There is 1 communication.
(ex: bicep + tricep reflex)
What is a polysynaptic reflex + examples?
A reflex with 1 or more interneurons involved. There are multiple communications.
(ex: withdrawal reflex)
Which reflex is being tested? How can you tell?
Biceps reflex
- The narrow end of the reflex hammer is placed on top of the dorsum of the index finger and tapped.
What 6 nerves of the branches of the brachial plexus are of less clinical concern?
- Cranial pectoral n.
- Caudal pectoral n.
- Lateral thoracic n
- Long thoracic n.
- Thoracodorsal n.
- Subscapular nn.
What is the origin of the phrenic nerve in dogs?
C5, C6, C7
-Sometimes C4
What is the origin of the phrenic nerve in cats?
C4-C7
Why do horses suffer from muscle sweeny?
They do not have a scapular acromion to add protection to the inner scapular notch.
What causes muscle sweeny?
Damage to the suprascapular n.
What does damage to the musculocutaneous n. cause?
- Difficulty flexing the elbow
- Loss of skin sensation on the medial aspect of the affected muscles
- Muscle atrophy
What is the largest nerve of the brachial plexus?
The radial n.
The radial nerve gives innervation to all extensors EXCEPT:
The shoulder joint
Damage to the radial nerve leads to ________.
Paralysis
paw dragging
inability to extend the CARPALS
What is the effect of paralysis of the ulnar n.?
- Inability to flex (hypereflexia)
- loss of skin sensation
What is a trunk?
2 or more nerve tracks fusing together
(ex: median-ulnar trunk)
What is the effect of damage to the subscapular n.?
Difficulty of:
-Adduction
- Extension of joint
What is affected by damage to the axillary nerve?
Flexion
What is affected by damage to the thoracodorsal nerve?
Flexion of the shoulder joint
What is an autonomous zone?
An area of skin that is served by a single nerve
Which 3 nerves have limitd distribution but considerable functionable importance?
-Suprascapular n.
-Axillary n.
-Musculocutaneous n.
SAM
What are 4 things done to conduct a lameness diagnosis?
-gait analysis
-reflex testing
-nerve block
-pinch
What is a brachial plexis avulsion? Causes?
Complete or partial tear in the brachial. It is caused by falling, overextension, or trauma.
What reflex is this?
Insert photo
When diagnosing lameness of the shoulder joint, anesthesia of what nerves plays a role?
-axillary n.
-suprascapular n.
When diagnosing lameness of the elbow and carpal joint, anesthesia of what nerves plays a role?
-median n.
-ulnar n.
When diagnosing lameness of the fetlock joint and further digital joints, anesthesia of what nerves plays a role?
-palmar n.
-digital n.
When blocking nerves, why are they blocked sequentially from distal to proximal?
To determine the location of the lesion
Which nerve block would most specifically relieve lameness resulting from fracture of the navicular bone?
palmar digital
A stray dog is presented after being hit by a car. He has hypotonic forelimbs, spastic paresis of the hindlimbs. All four limbs have proprioceptive deficits and the sensation loss is worse in the forelimbs. Where is the lesion?
Cervicothoracic C6-T2
What nerve branch is from the cranial part of the brachial plexus? It passes between the suprascapular and subscapular muscles
suprascapular n.
What is this nerve?
musculocutaneous n.
Which nerve innervates all of the flexors of the brachium?
musculocutaneous n.
Which 2 nerves innervate the subscapular muscle?
subscapular n. and axillary n.
Which nerve innervates the interossei muscle?
ulnar n.
You’re preforming a withdrawal reflex test on a patient. You apply a pinch between the patient’s toes. What nerves extend all the way from the brachial plexus to the apex of the distal limb, to provide sensory innervation for this reflex?
Radial nerve, median nerve, and ulnar nerve
What is this vein of the forelimb?
Omobrachial vein
What vein is this?
axillobrachial vein
What vein is this?
cephailic vein
Which vein of the forelimb is being catheterized in this image?
cephalic vein
What injury is suspected with the limb hanging limply, non-weight bearing with no pain reflex below the elbow following trauma?
brachial plexus avulsion
