Myology

Brachioradialis m.

Most cranially located muscle in forelimb

1. origin

distolateral humerus

2. insertion

distal radius

3. action

supination of forearm

4. More developed in the cat vs dog, so it can make cephalic veinpuncture more challenging

commonly mistaken for the cephalic vein

Extensor Carpi radialis m.

Largest muscle in the craniolateral muscle group of forearm

lies deep to the brachioradialis muscle

1. origin

lateral epicondyle of the humerus

2. insertion

proximal metacarpals II and III

3 action

extends carpal joint

Common digital extensor m.

The distal aspect of the tendon divides and separates into four parts to insert on the digits

1. origin

lateral epicondyle of humerus

2. insertion

distal phalanges of digits II, III, IV, V

3. actions

extends carpus

extends digits

Supinator m.

Forms the lateral side of a “V’ with the pronator teres muscle

1. origin

lateral epicondyle of humerus

2. insertion

cranial aspect of proximal radius

3. action

supination of antebrachium

flexes elbow

Omotransversarius m.

1. Origin

wing of atlas

2. Insertion

spine and acromion of scapula

3. Action

advances leg

Rhombodius m.

Long muscle that fans out over neck and scapular region of back

1. origin

occipital bone of head

2. Insertion

dorsal border of scapula

3. action

elevates forelimb

Trapezius m.

Triangular shaped muscle that lies over the dorsal part of the scapula

1. origin

dorsal aspect of neck

2. insertion

spine of scapula

3. action

elevates the limb

abducts the limb

Serratus ventralis m.

Very strong, fan shaped muscle that covers lateral surface of neck and cranial half of lateral thoracic wall

1. origin

cervical vertebrae and ribs

2. insertion

dorsomedial scapula

3. action

supports trunk

HUMERUS MUSCLE ATTACHMENT

Brachiocephalicus m.

1. origin

clavicle

2. Insertion

humerus, mastoid, and dorsal neck

3. action

pulls limb forward, extends shoulder

Superficial Pectoral m.

1. origin

cranial sternum

2. insertion

greater tubercle of humerus

3. action

adducts thoracic limb

Deep Pectoral m.

1. origin

sternum

2. insertion

greater and lesser tubercles of humerus

3. action

adducts the throacic limb

pulls the thoracic limb caudally

Latissimus Dorsi m.

Large triangular shaped muscle that covers most of throacic wall

1. origin

thoracolumbar spinous process

2. insertion

humerus

3. Action

draws limb caudally

flexes shoulder joint

Deltoideus m.

1. origins

spine & acromion

2. insertion

deltoid tuberosity

3. action

flex shoulder joint

Infraspinatus m.

1. origin

infraspinous fossa

2. insertion

lateral aspect of the greater tubercle

3. action

flexes shoulder joint

abducts forelimb

primary stabilizer of the lateral shoulder

Supraspinatus m.

1. origin

supraspinous fossa

2. insertion

greater tubercle

3. action

extends shoulder joint

primary stabilizer of the lateral shoulder

Subscapularis m.

1. origin

subscapular fossa

2. insertion

lesser tubercle

3. action

adducts limb

rotates arm medially

Teres major m.

1. origin

caudal border of scapula

2. insertion

teres major tuberosity

3. action

flexes the shoulder joint

Biceps Brachii m.

1. origin

distal scapular spine

2. insertion

proximal and medical aspects of radius and ulna

3. action

flexes elbow joint

extends shoulder joint

Triceps Brachii m.

Large muscle mass on the caudal aspect of the humerus, muscle has 4 individual heads

1. origin

scapula and humerus

2. insertion

olecranon process

3. action

extends the elbow joint

flexes the shoulder

Tensor Fasciae antebrachii m.

Thin strap-like muscle located on the medial aspect of the brachium

1. origin

Fascia of the latissimus Dorsi muscle

2. insertion

olecranon process

3. action

extends the elbow joint