L7: forelimb muscles

what is the primary action of the supraspinatus muscle?

stabilize and extend shoulder

what nerve innervates the supraspinatus muscle?

suprascapular nerve

what is the primary action of the infraspinatus muscle?

stabilize, flex, and extend the shoulder

what nerve innervates the infraspinatus muscle?

suprascapular nerve

what is the primary action of the biceps brachii muscle?

1. flex elbow

2. extend shoulder

what nerve innervates the biceps brachii muscle?

musculocutaneous nerve

what is the primary action of the brachialis muscle?

flex elbow

what nerve innervates the brachialis muscle?

musculocutaneous nerve

what is the primary action of the triceps brachii muscle?

1. extend the elbow

2. flex shoulder

what nerve innervates the triceps?

radial nerve

extrinsic muscle of forelimb

muscles betweeen the forelimb and the trunk

intrinsic muscle of the forelimb

bridges one or more joints of the same limb

MCQ: what are extrinsic muscles?

muscles that have an attachment to the limb and attachment to the body

cutaneous muscles

completely located in the superficial fascia

onychectomy

surgical removal of the claws and third phalanx in cats

what allows cats to fully withdraw their claws?

unequal length of dorsal elastic ligaments

where is the dorsal elastic ligament in dogs?

extends from the proximal ends of the middle phalanges to the unguicular crests of the distal phalanges

what is the function of the dorsal elastic ligaments?

keep claws elevated

what happens when the deep digital flexor opposes the dorsal elastic ligaments?

protrudes the claws for scratching and digging

what is the origin of the interosseus muscle in horses?

palmar carpal ligament and proximal part of metacarpal bone 3

where does the interosseus muscle insert in horses?

abaxial surfaace of proximal sesamoid bones

what is the action of the interosseus muscle in horses?

to prevent overextenstion of metacarpal and metaphalangeal joints

what is another name of the interosseous muscle?

suspensory ligament

what is the function of the interosseus muscle?

1. part of stay apparatus

2. stabilizes fetlock

3. assist in locomotion

what is the origin of the deep digital flexor muscle in horses?

humerus, radius, and ulna

what enforces the deep digital flexor muscle at the metacarpus?

accessory or inferior check ligament

what is the inferior check ligament a continuation of?

palmar ligament

what does the deep digital flexor muscle do at the fetlock?

passes through the manica flexoria and over the palmar ligament

what does the deep digital flexor muscle do at the middle of the proximal phalynx?

emerges between two branches of the superficial digital flexor muscle and passes over the distal sesamoid bone

what is the insertion of the deep digital flexor muscle?

flexor surface of the distal phalanx

what is the action of the deep digital flexor muscle?

flexor of the coffin joint which flexes the whole foot

manica flexoria

thin tubelike ring around the deep digital flexor tendon

what is the origin of the superficial digital flexor in horses?

medial epicondyle of the humerus

what is the insertion of the superficial digital flexor in horses?

divides to insert on middle phalanx and proximal phalanx

what action does the superficial digital flexor muscle do?

1. flexes pastern joint

2. stabilizes the fetlock joint

accessory ligament of the superficial digital flexor

forms a direct attachment ot the caudodistal aspect of the radius

what are the flexor muscles of the antebrachium (forearm)?

1. deep digital flexor muscle

2. superficial digital flexor muscles

list the three heads of the deep digital flexor muscles

1. humeral

2. radial

3. ulnar

what innervates the flexor muscles of the antebrachial muscles?

median and ulnar nerves

what secures the caudomedial intrinsic muscles as they run over the carpus?

flexor retinaculum

what muscle will not be able to extend if there is high radial nerve injury?

the triceps will lose their function and elbow will not be able to extend

how will forearm appear with low radial nerve injury?

loss of extension of the distal limb resulting in toe drag

why is the radial nerve so important in the forearm?

most important for animal to bear weight and walk with a normal gait

what are the major extensor muscles of forearm?

1. extensor carpi radialis muscle

2. common digital extensor muscle

3. lateral digital extensor muscle

4. ulnaris lateralis muscle

what is the function of the common digital extensor muscle?

extend digits and carpus

what innervates the craniolateral extensor muscle of the forearms?

radial nerve

where do the craniolateral extensor muscles of the forearm arise?

near the lateral epicondyle of the distal humerus

what are the caudal brachium muscles?

1. triceps

2. tenser fascia antebrachia muscle

3. anconeus muscle

what muscle is the most important extensor of the elbow?

triceps

what is the location of the subtendinous bursa?

between the tendon and olecranon of the triceps muscle

what happens when the triceps muscle contracts?

pulls on olecranon so articular angle will open and elbow extends

where does the long head of the triceps originate from?

caudal border of scapula

where does the lateral, medial, and accessory heads originate from?

proximal aspect of humerus

lacertus fibrosis

fibrous strand in horses that extends from biceps muscle to extensor carpi radialis muscle

stay apparatus in horses

shoulder, elbow, and knee remain fixed in place to allow horse to stand for extended periods of time

what is the origin of the biceps brachii muscle in horses?

supraglenoid tubercle via fibrocartilagenous tendon

what does the biceps brachii muscles insert?

1. radial tuberosity (primary tendon)

2. lacertus fibrosus (additional in horses)

what are the cranial brachium muscles?

1. biceps brachii muscle

2. brachialis muscle

3. coracobrachialis muscle

what is the origin of the biceps brachii muscle?

supraglenoid tubercle

what is the insertion for the biceps brachii muscle?

proximal radius and ulna

what is the action of the biceps brachii muscle?

1. flexes elbow

2. extends elbow joint

what extrinsic muscle is the prime advancer of the forelimb during locomotion?

brachiocephalicus muscle

what condition is “sweeny”?

condition seen in horses due to injury of hte suprascapular nerve leading to shoulder popping in and out

what is the origin of the infraspinatus muscle?

infraspinous fossa of the scapula

what is the insertion point of the infraspinatus muscle?

greater tubercle

what is the action of the infraspinatus muscle?

1. stabilize shoulder joint

2. supports flexion or extension of joint

what are the lateral intrinsic muscles of the shoulder?

1. supraspinatus muscle

2. infraspinatus muscle

what is the origin of the supraspinatus muscle?

supraspinous fossa of the scapula

what is the insertion of the supraspinatus muscle in carnivores?

greater tubercle of the humerus

what is the insertion of the supraspinatus muscle in horses and ruminants?

two tendons on lesser and greater tubercles

what is the action of the supraspinatus muscle?

stabilize and extend the shoulder joint

where is the articular angle for the shoulder joint?

caudal

where is the articular angle for the elbow joint?

cranial

where are the origins and insertions of the intrinsic muscles of the forelimb?

on the appendicular skeleton

what does the omotransversarius muscle cover?

superficial cervical lymphnode

what forms the hump on the back of bos tarus indicus cattle?

widening of the rhomboideus muscle

what is the function of the omotransversarius muscle?

pulls neck laterally

what is the function of the trapezius muscle?

elevates the scapula

synsarcosis

connection of a limb to the body solely through muscles rather than a bony joint

what are the advantages to synsarcosis?

1. enhance mobility of animal

2. great shock absorber

3. helps redistribute weight of different regions of the body

central region of brachiocephalicus muscle

central region of brachiocephalicus muscle

what are the parts of the cleidobrachialis muscle?

1. cervical portion

2. mastoid portion

what are the muscles that branch off the clavicular tendon?

1. clydocephalicus muscle

2. clydobrachialus muscle

what is the function of the brachiocephalicus muscle?

1. moves forelimb proximally

2. displaces head and neck

what are the extrinsic muscles of the thoracic limb?

1. trapezius

2. rhomboideus

3. brachiocephalicus

4. omotransversarius

5. latissimus dorsi

6. superficial pectoral

7. deep pectoral

8. serratus ventralis

what is the function of the rhomboideus muscle?

1. draws limb forward

2. elevates limb and neck

3. fixes scapula against trunk