Thoracic Limb Muscles OIA + Images

Superficial pectoral m.

• Red = descending pectoral m

• Green = transverse pectoral m

Origin: sternum

Insertion: crest of greater tubercle & cranial humeral border Action: adduct the thoracic limb

Deep (ascending) pectoral m.

Origin: sternum

Insertion: greater and lesser tubercles of humerus

Action: adduct thoracic limb and pull it caudally

Cutaneous Trunci m

Platysma M. (Cutaneous muscle of face and neck)

Brachiocephalicus m.

Origin: clavicular intersection

Insertion:

Green = cleidobrachialis: distal cranial humerus

Yellow/orange = cleidocephalicus:

• Pars mastoideus (Orange): mastoid process of temporal bone

• Pars cervicalis (Yellow): dorsal midline of neck

Action: pull thoracic limb cranially (and/or) depress and pull head and neck laterally

Clavicular Intersection

Highlighted Blue

Omotransversarius m.

Cranial-most attachment: wing of the atlas

Caudal-most attachment: distal spine of the scapula

Action: pull thoracic limb cranially (and/or) depress and pull head and neck laterally

Superficial Cervical Lymph Node (deep to omotransversarius m.)

Trapezius m.

Origin:

Red = cervical part: dorsal neck

Green = thoracic part: dorsal thorax

Insertion: spine of the scapula

Action: elevate the thoracic limb

Rhomboideus m.

Origin:

Green = rhomboideus thoracis: dorsal thorax

Yellow = rhomboideus cervicis: dorsal neck

Red = rhomboideus capitis: nuchal crest of occipital bone

Insertion: dorsal border of scapula and/or scapular cartilage

Action: elevate the thoracic limb

Serratus ventralis m.

Origin:

Red = serratus ventralis cervicis: cervical vertebrae

Green = serratus ventralis thoracis: thoracic wall (ribs)

Insertion: serrated face of scapula

Action: support and/or elevate the trunk

Latissimus dorsi m.

Origin: thoracolumbar fascia

Insertion: teres major tuberosity

Action: draw the thoracic limb caudally, flex or extend the humeral joint

Sternocephalicus m.

Origin: sternum

Insertion:

Green = mastoid part: mastoid process of temporal bone

Red = occipital part: occipital bone

Action: depress head and neck; draw head and neck laterally

Sternohyoideus m.

Origin: sternum

Insertion: basihyoid bone

Action: pull tongue and larynx caudally

Sternothyroideus m.

Origin: cranial aspect of sternum or ribcage

Insertion: thyroid cartilage

Action: pull tongue and larynx caudally

Deltoideus m.

Origin:

Green = Scapular Part: spine of scapula

Red = Acromial Part: acromion

Insertion: deltoid tuberosity of humerus

Action: flex the humeral joint

Supraspinatus m.

Origin: supraspinous fossa of the scapula

Insertion: greater tubercle of the humerus

Action: extend the humeral joint

Infraspinatus m.

Origin: infraspinous fossa of the scapula

Insertion: greater tubercle of the humerus

Action: flex humeral joint (varies); abduct limb at humeral joint

Teres minor m.

Origin: caudal border of scapula

Insertion: teres minor tuberosity of the humerus

Action: flex the humeral joint

Subscapularis m.

Origin: subscapular fossa of scapula

Insertion: lesser tubercle of humerus

Action: adduct limb at humeral joint, extend humeral joint

Teres major m. (parallels the caudal border of the scapula)

Origin: caudal border of scapula

Insertion: teres major tuberosity of humerus

Action: flex the humeral joint

Coracobrachialis m.

Origin: coracoid process of scapula

Insertion: crest of the lesser tubercle of the humerus

Action: adduct limb at shoulder, extend humeral joint

Biceps brachii m. (only one head in domestic mammals)

Origin: supraglenoid tubercle

Insertion: radial and ulnar tuberosities

Action: flex the cubital joint and extend the humeral joint

Brachialis m.

Origin: brachial groove of humerus

Insertion: ulnar and radial tuberosities

Action: flex the cubital joint

Triceps brachii m.

• long head = Green

• medial head = Red

• lateral head (not pictured)

• accessory head (not pictured)

Origin:

Long head: caudal border of scapula

Medial head: crest of the lesser tubercle

Lateral head: Tricipital line of humerus

Accessory head: neck of the humerus

Insertion: Olecranon tuber

Action:

extend the cubital joint (all heads);

flex the humeral joint (long head)

Triceps brachii m.

• long head = Green

• medial head (not pictured)

• lateral head = Yellow

• accessory head (not pictured)

Origin:

Long head: caudal border of scapula

Medial head: crest of the lesser tubercle

Lateral head: Tricipital line of humerus

Accessory head: neck of the humerus

Insertion: Olecranon tuber

Action:

extend the cubital joint (all heads);

flex the humeral joint (long head)

Triceps brachii m.

• long head = Green

• medial head (not pictured)

• lateral head = Yellow

• accessory head = Blue

Origin:

Long head: caudal border of scapula

Medial head: crest of the lesser tubercle

Lateral head: Tricipital line of humerus

Accessory head: neck of the humerus

Insertion: Olecranon tuber

Action:

extend the cubital joint (all heads);

flex the humeral joint (long head)

Tensor fasciae antebrachii m.

Origin: latissimus dorsi and associated fascia

Insertion: tuber olecrani

Action: extend the cubital joint (and tense the deep antebrachial fascia)

Anconeus m.

Origin: caudal aspect of distal humerus

Insertion: tuber olecrani

Action: extend the cubital joint

Extensor carpi radialis m.

Origin: lateral epicondyle of the humerus (and its crest)

Insertion: dorsal base of second and third metacarpal bones

Action: extend the carpal joints

Common digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: extensor processes of the distal phalanges

Action: extend the carpal and digital joints

Lateral digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: distal phalanges (also the proximal and/or middle phalanges) of lateral digit(s)

Action: extend the carpal and digital joints of the lateral-most digits

Ulnaris lateralis m.

Origin: lateral epicondyle of the humerus

Insertion: accessory carpal bone and lateral base of fifth metacarpal bone

Action: flex the carpal joints; abduct the manus

Supinator m.

Origin: lateral epicondyle of the humerus

Insertion: body of radius

Action: supination of the manus

Abductor digiti I longus m.

Origin: body of the ulna (in the carnivore)

Insertion: proximal end of metacarpal I

Action: abduct the first digit

Brachioradialis m.

Origin: lateral epicondyle of the humerus

Insertion: fascia near the carpus

Action: flexes the cubital joint and supinates the manus

Flexor carpi radialis m.

Origin: medial epicondyle of the humerus

Insertion: palmar base of metacarpal bones 2 and 3

Action: flex the carpal joints

Flexor carpi ulnaris m.

Origin:

• Green = humeral head: medial epicondyle

• Red = ulnar head: olecranon

Insertion: accessory carpal bone

Action: flex the carpal joints

Superficial digital flexor m.

Origin: medial epicondyle of the humerus

Insertion: middle phalanges of the digits (palmar aspects)

Action: flex the carpal joints, metacarpophalangeal and proximal interphalangeal joints

Deep digital flexor m.

Origin:

• Red = humeral head: medial epicondyle

• Yellow = radial head: radius

• Green = ulnar head: ulna

Insertion: flexor tubercles of distal phalanges

Action: flex the carpal and digital joints

Pronator teres m.

Origin: medial epicondyle of the humerus

Insertion: medial body of radius

Action: weak elbow flexion and weak pronation of the manus

Pronator quadratus m.

Attachments: apposed surfaces of the radius and the ulna

Action: pronation of the manus

Interossei muscles (associated with proximal sesamoid bones)

Origin: palmar base of respective metacarpal bone

Insertion: palmar base of respective proximal phalanx (& tendon of common digital extensor dorsally)

Action: flexes and supports metacarpophalangeal joint

Located under the tendons.

Carpal pads: Green

Metacarpal pads: Blue

Digital pads: Red

Dorsal ligament

Annular ligaments

Green = palmar annular ligament

Blue = Proximal digital annular ligament

Red = Distal digital annular ligament

Carpal Canal

Extensor retinaculum

Flexor retinaculum

Transverse humeral retinaculum

Lateral collateral ligament of cubital joint

Interosseous ligament

Medial Collateral Ligament of cubital joint

Palmar carpal ligament

Infraspinatus bursa

Intertubercular bursa

Lies under biceps brachii

Superficial pectoral m. (descending and transverse pectoral mm.)

Origin: sternum

Insertion: crest of greater tubercle & cranial humeral border

Action: adduct the thoracic limb

Deep (ascending) pectoral m.

Origin: sternum

Insertion: greater and lesser tubercles of humerus

Action: adduct thoracic limb and pull it caudally

Brachiocephalicus m.

Origin: clavicular intersection

Insertion:

cleidobrachialis: distal cranial humerus

cleidocephalicus: mastoid part: mastoid process of temporal bone cervical part: dorsal midline of neck

Action: pull thoracic limb cranially (and/or) depress and pull head and neck laterally

Omotransversarius m.

Cranial-most attachment: wing of the atlas

Caudal-most attachment: distal spine of the scapula

Action: pull thoracic limb cranially (and/or) depress and pull head and neck laterally

Trapezius m.

Origin: cervical part: dorsal neck

thoracic part: dorsal thorax

Insertion: spine of the scapula

Action: elevate the thoracic limb

Rhomboideus m.

Origin: rhomboideus thoracis: dorsal thorax

rhomboideus cervicis: dorsal neck

rhomboideus capitis: nuchal crest of occipital bone

Insertion: dorsal border of scapula and/or scapular cartilage

Action: elevate the thoracic limb

Serratus ventralis m.

Origin: serratus ventralis cervicis: cervical vertebrae

serratus ventralis thoracis: thoracic wall (ribs)

Insertion: serrated face of scapula

Action: support and/or elevate the trunk

Latissimus dorsi m.

Origin: thoracolumbar fascia

Insertion: teres major tuberosity

Action: draw the thoracic limb caudally, flex or extend the humeral joint

Sternocephalicus m.

Origin: sternum

Insertion: mastoid part: mastoid process of temporal bone

occipital part: occipital bone

Action: depress head and neck; draw head and neck laterally

Sternohyoideus m.

Origin: sternum

Insertion: basihyoid bone

Action: pull tongue and larynx caudally

Sternothyroideus m.

Origin: cranial aspect of sternum or ribcage

Insertion: thyroid cartilage

Action: pull tongue and larynx caudally

Deltoideus m.

Origin: spine of scapula and acromion

Insertion: deltoid tuberosity of humerus

Action: flex the humeral joint

Supraspinatus m.

Origin: supraspinous fossa of the scapula

Insertion: greater tubercle of the humerus

Action: extend the humeral joint

Infraspinatus m.

Origin: infraspinous fossa of the scapula

Insertion: greater tubercle of the humerus

Action: flex humeral joint (varies); abduct limb at humeral joint

Teres minor m.

Origin: caudal border of scapula

Insertion: teres minor tuberosity of the humerus

Action: flex the humeral joint

Subscapularis m.

Origin: subscapular fossa of scapula

Insertion: lesser tubercle of humerus

Action: adduct limb at humeral joint

Teres major m. (parallels the caudal border of the scapula)

Origin: caudal border of scapula

Insertion: teres major tuberosity of humerus

Action: flex the humeral joint

Coracobrachialis m

Origin: coracoid process of scapula

Insertion: crest of the lesser tubercle of the humerus

Action: adduct limb at shoulder

Biceps brachii m. (only one head in domestic mammals)

Origin: supraglenoid tubercle

Insertion: radial and ulnar tuberosities

Action: flex the cubital joint and extend the humeral joint

Brachialis m.

Origin: brachial groove of humerus

Insertion: proximal radius and/or ulna

Action: flex the cubital joint

Triceps brachii m. (long, medial, and lateral heads in all species carnivores also have an accessory head)

Origin: caudal border of scapula (long head); proximal humerus (other heads)

Insertion: tuber olecrani

Action: extend the cubital joint (all heads); flex the humeral joint (long head)

Tensor fasciae antebrachii m.

Origin: latissimus dorsi and associated fascia

Insertion: tuber olecrani

Action: extend the cubital joint (and tense the deep antebrachial fascia)

Anconeus m.

Origin: caudal aspect of distal humerus

Insertion: tuber olecrani

Action: extend the cubital joint

Extensor carpi radialis m.

Origin: lateral epicondyle of the humerus (and its crest)

Insertion: dorsal base of second and third metacarpal bones

Action: extend the carpal joints

Common digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: extensor processes of the distal phalanges

Action: extend the carpal and digital joints

Lateral digital extensor m.

Origin: lateral epicondyle of the humerus

Insertion: distal phalanges (also the proximal and/or middle phalanges) of lateral digit(s)

Action: extend the carpal and digital joints of the lateral-most digits

Ulnaris lateralis m

Origin: lateral epicondyle of the humerus

Insertion: accessory carpal bone and lateral base of fifth metacarpal bone

Action: flex the carpal joints; abduct the manus

Supinator m

Origin: lateral epicondyle of the humerus

Insertion: body of radius

Action: supination of the manus

Abductor pollicis longus m

Origin: body of the ulna (in the carnivore)

Insertion: medial metacarpus

Action: abduct the first digit

Brachioradialis m

Origin: lateral epicondyle of the humerus

Insertion: fascia near the carpus

Action: flexes the cubital joint and supinates the manus

Flexor carpi radialis m

Origin: medial epicondyle of the humerus

Insertion: palmar base of metacarpal bones 2 and 3

Action: flex the carpal joints

Flexor carpi ulnaris m. (2 heads: humeral and ulnar)

Origin: medial epicondyle and olecranon

Insertion: accessory carpal bone

Action: flex the carpal joints

Superficial digital flexor m.

Origin: medial epicondyle of the humerus

Insertion: middle phalanges of the digits (palmar aspects)

Action: flex the carpal joints, metacarpophalangeal and proximal interphalangeal joints

Deep digital flexor m. (3 heads: humeral, radial, ulnar)

Origin: humerus (medial epicondyle), radius, ulna

Insertion: flexor tubercles of distal phalanges

Action: flex the carpal and digital joints

Pronator teres m

Origin: medial epicondyle of the humerus

Insertion: medial body of radius

Action: weak elbow flexion and weak pronation of the manus

Pronator quadratus m

Attachments: apposed surfaces of the radius and the ulna

Action: pronation of the manus

Interossei muscles (associated with proximal sesamoid bones)

Origin: palmar base of respective metacarpal bone

Insertion: palmar base of respective proximal phalanx (& tendon of common digital extensor dorsally)

Action: flexes and supports metacarpophalangeal joint