Lecture 2: Myology of thoracic limb Flashcards
what are the 4 extrinsic muscles attaches to the scapula
trapezius
rhomboideus
serratus ventralis
omotransversarius
what are the parts of the trapezius
- cervical
- thoracic
the omotransverarius and brachiocephalicus are very attached
identify the muscle A
Identify the parts of the muscle associated with 5 and 6
A: Pectoralis muscles
- superficial pectoral muscle
- deep pectoral muscle
identify the muscle
Serratus ventralis (2 parts)
identify the muscle
identify the ligament (1) and the bone (2)
- Dorsal scapular ligament
- Dorsal border of scapula
what is the job of the Dorsal scapular ligament
starts at the supraspinatus ligament
Fibroelastic
Help keep scapula/limb in place
how many parts does the rhomboideus have
2; cervical and thoracic
**under the trapezius muscle
The Thoracic “Sling” is what kind of joint
Synsarcosis
define Synsarcosis
joint that binds 2 bony structures by muscles
identify the term:
The extrinsic muscles suspend the trunk between the forelimbs and fix the
scapula.
The Thoracic “Sling”
identify the muscles that make up the The Thoracic “Sling”
- trapezius
- rhomboideus m.
- Serratus ventralis m.
- Pectoralis m
(white line between trapezius and scapula is showing the dorsal scapular ligament)
whats wrong with this horse
Rupture of serratus ventralis muscle
the large protrusion is the scapula and cartilage out of place!
list the Intrinsic Muscles of the Shoulder
identify the 2 muscles
blue: Supraspinatus
green: Infraspinatus
action of Supraspinatus
Extend & stabilize the humeral joint
action of Infraspinatus m.
Fixator and abductor of the humeral joint
what are the 2 insertion points for the Infraspinatus muscle
– I: Superficial tendon – on the greater
tubercle of humerus
* Infraspinatus bursa (very large and important in horse)
– I: Deep tendon – on the caudal eminence
of greater tubercle
how many heads does the Deltoideus m. have in a horse
one!
action of Deltoideus m.
Flexor and abductor of the shoulder
origin of the Deltoideus m.
Caudal border of scapula,
aponeurosis which covers infraspinatus
aponeurosis is very big
identify the muscles
blue: Deltoideus
green: *Subclavius
what is significant about the *Subclavius muscle
- very close to the supraspinatus m.
- actually an extrinsic muscle NOT intrinsic
what is the origin of the *Subclavius
Cranial part of the sternum closely
associated to supraspinatus m.
what is the action of the *Subclavius
Complement the pectoral muscle
action of Subscapularis
Stabilize the shoulder and adduction
action of Teres Major
Mainly flexor of the shoulder
blue: Subscapularis
green: Teres Major
List the Intrinsic Muscles of the Brachium
what are the main ones we need to focus on
Dr. P stressed the Triceps Brachii and Biceps Brachii
origin of Biceps Brachii
Supraglenoid tubercle (very big, easy to find)
insertion of the Biceps Brachii
- Radial tuberosity
- extensor carpi radialis via lacertus fibrosus (tendon)
action of biceps brachii
Flexor of the elbow and extensor of the
shoulder
– Located between the tendon of origin of
biceps brachii and the intertubercular
grooves of the humerus
Intertubercular bursa
identify the muscle with the blue arrow
bicep brachii
– Tendinous insertion of biceps brachii on
the extensor carpi radialis m.
– Part of the stay apparatus
Lacertus fibrosus
T/F biceps brachii is very important for gait
true
lacterus fibrosis inserts in the extensor carpi radialis and goes to the metacarpus
**blocks 3 joints with animal is standing
origins of tricep brachii
– O: Long head – caudal border of the
scapula
– O: Lateral head – deltoid tuberosity
– O: Medial head –medial aspect of humerus
insertion of Triceps Brachii
– I: Olecranon tuber (ALL 3 insert here!)
action of Triceps Brachii
Extension of the elbow and flexion of
the shoulder
what muscle is being pointed to
heads of the tricep brachii
Between long head of triceps and olecranon
* Subcutaneous
Bursae- Subtendinous (2)
the tricep brachii is known as a _________ to the bicep brachii
antagonist
how many heads does the tricep of a horse have compared to a dog
3 in a horse; dog has 4
action of tricep brachii
Extension of the elbow and flexion of
the shoulder
(extension is MAIN action)
Intrinsic muscles of the antebrachium
and manus:
what muscles make up the Craniolateral
group and what are their actions
extend carpus and digit III
Intrinsic muscles of the antebrachium
and manus:extend carpus and digit III
what muscles make up the Caudomedial
group and what are their actions
Flex carpus and digit III
why don’t horses have a pronator/supinator
they cannot pronate/supinate because their radius and ulna are fused
origin of Extensor Carpi Radialis
Lateral supracondylar crest of the humerus (higher up than the rest of the extensors)
action of Extensor Carpi Radialis
Extend and fix the carpus and flex the elbow joint
extend is the main action
origin of Common Digital Extensor
- O: Lateral epicondyle of the humerus
insertion of Common Digital Extensor
I: Extensor process of distal phalanx and dorsal surface of proximal and middle phalanges
action of Common Digital Extensor
Extend the carpus and digit and flex the elbow joint
**main action is extend digit
blue: Extensor Carpi Radialis
green: Common Digital Extensor
blue: Lateral Digital Extensor
green: Extensor carpi ulnaris (Ulnaris
Lateralis)
origin of Lateral Digital Extensor
Lateral tuberosity of the radius, lateral
collateral ligament of the elbow
**tiny because we only have 1 digit, no lateral digits
insertions points for Extensor carpi ulnaris (Ulnaris Lateralis)
I: Short tendon –accessory carpal bone
I: Long tendon – metacarpal bone IV
action of Extensor carpi ulnaris (Ulnaris
Lateralis)
A: Flex and abduct the carpus
**innervated by radial nerve
blue: Flexor Carpi Ulnaris
green: Flexor Carpi Radialis
origins of Flexor Carpi Ulnaris
- O: Humeral head – Medial epicondyle of the
humerus - O: Ulnar head – olecranon
insertion of Flexor Carpi Ulnaris
I: Accessory carpal bone
action of Flexor Carpi Ulnaris
what nerve is involved
Flex the carpus and extend the elbow joint
ulnar n.
origin of Flexor Carpi Radialis
- O: Medial epicondyle of the humerus
insertion of Flexor Carpi Radialis
- I: Metacarpal bone II
action of Flexor Carpi Radialis
what nerve is involved
Flex the carpus and extend the elbow joint
Median n.
(it is a small muscle)
what muscle is this
SDF
what muscle is this
DDF
origin of Superficial Digital Flexor
O: Medial epicondyle of the humerus and radius (proximal accessory ligament)
action of SDF
Flex the digit (proximal interphalangeal joint) and carpus and extend the elbow joint
how many heads does the DDF have
- O: Humeral head – Medial epicondyle of the
humerus (distal accessory ligament) - O: Ulnar head –olecranon
- O: Radial head –radius
action of DDF
- A: Flex the digit and carpus and extend the elbow joint
what is being pointed to
proximal= green, distal= red
proximal and distal accessory “check” ligament (connective tissue)
what is the the suspensory apparatus
Suspensory ligament
* Aka interosseous muscle
why is the Suspensory ligament referred to as a ligament
what is the definition of a ligament
binds 2 structures–> connects bone to bone
T/F The suspensory apparatus is Passive: DOES NOT FLEX JOINTS
true; it fixes the joint
T/F The suspensory apparatus has very little muscle fiber in large animals
true
what are the 4 parts of the suspensory apparatus
Broken down into 4 anatomical areas
* Proximal
* Mid-body (divides in 2 to make branches)
* Branches
* Extensor branches
where do the branches of the suspensory apparatus insert at
proximal sesamoid bone
where does the extensor branches of the suspensory apparatus go
dorsal; fuse with common digital extensor tendon
what are Distal Sesamoidean Ligaments
Continuation of suspensory ligament distal to sesamoids
T/F Stay Apparatus prevents joints from collapsing
true; allows them to stand all day!
what is the term for:
Group of muscles, tendons, ligaments, fascia and joints.
Allows horses to maintain their standing posture for hours, without energy loss
Equine stay apparatus
Can horses sleep standing?
no, they “rest” standing
sleep on ground like a dog for about 4 hours or less
origin of Supraspinatus
– O: Supraspinous fossa.
insertion of Supraspinatus
Greater and lesser tubercles of humerus
insertion of Deltoideus
Deltoid tuberosity
insertion of *Subclavius
supraspinatus muscle epimysium
origin of Subscapularis
Subscapular fossa
insertion of Subscapularis
Lesser tubercle of humerus
origin of Teres Major
Caudal angle of the scapula and
adjacent caudal border of scapula
insertion of Teres Major
Teres major tuberosity of humerus
insertion of Triceps Brachii
Olecranon tuber
insertion of Extensor Carpi Radialis
Metacarpal tuberosity
Extensor Carpi Radialis
Common Digital Extensor
Lateral Digital Extensor
Extensor carpi ulnaris (Ulnaris
Lateralis)
what nerve is involved with these muscles
radial n.
insertion of Lateral Digital Extensor
Dorsal aspect of proximal phalanx
action of Lateral Digital Extensor
what nerve is involved
Extend the carpus and digit; Radial n.
origin of Extensor carpi ulnaris (Ulnaris lateralis)
what nerve is involved
Lateral epicondyle of the humerus; radial n.
insertion of Superficial Digital Flexor
Flexor surfaces of proximal and middle
phalanges
action of Superficial Digital Flexor and nerve involved
Flex the digit (proximal interphalangeal joint) and carpus and extend the elbow joint
Ulnar n.
origin of Deep Digital Flexor
O: Humeral head – Medial epicondyle of the
humerus (distal accessory ligament)
* O: Ulnar head –olecranon
* O: Radial head –radius
insertion of Deep Digital Flexor
- I: Flexor surface of the distal phalanx
action of Deep Digital Flexor and nerve involved
N: Median and ulnar nn.
A: Flex the digit and carpus and extend the elbow joint
