Lecture 2: Myology of thoracic limb Flashcards by kate terrill

what are the 4 extrinsic muscles attaches to the scapula

trapezius
rhomboideus
serratus ventralis
omotransversarius

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what are the parts of the trapezius

cervical
thoracic

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the omotransverarius and brachiocephalicus are very attached

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identify the muscle A

Identify the parts of the muscle associated with 5 and 6

A: Pectoralis muscles

superficial pectoral muscle
deep pectoral muscle

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identify the muscle

Serratus ventralis (2 parts)

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identify the muscle

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identify the ligament (1) and the bone (2)

Dorsal scapular ligament
Dorsal border of scapula

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what is the job of the Dorsal scapular ligament

starts at the supraspinatus ligament
Fibroelastic

Help keep scapula/limb in place

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how many parts does the rhomboideus have

2; cervical and thoracic

**under the trapezius muscle

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The Thoracic “Sling” is what kind of joint

Synsarcosis

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define Synsarcosis

joint that binds 2 bony structures by muscles

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identify the term:

The extrinsic muscles suspend the trunk between the forelimbs and fix the
scapula.

The Thoracic “Sling”

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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)

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whats wrong with this horse

Rupture of serratus ventralis muscle

the large protrusion is the scapula and cartilage out of place!

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list the Intrinsic Muscles of the Shoulder

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identify the 2 muscles

blue: Supraspinatus
green: Infraspinatus

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action of Supraspinatus

Extend & stabilize the humeral joint

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action of Infraspinatus m.

Fixator and abductor of the humeral joint

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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

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how many heads does the Deltoideus m. have in a horse

one!

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action of Deltoideus m.

Flexor and abductor of the shoulder

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origin of the Deltoideus m.

Caudal border of scapula,
aponeurosis which covers infraspinatus

aponeurosis is very big

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identify the muscles

blue: Deltoideus
green: *Subclavius

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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

1. Radial tuberosity 2. 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