Equine Anatomy Oifs

Front 1

Deltoideus

Back 1

origin: Caudal border and spine of scapula.
insertion: Deltoid tuberosity.
action: Flex shoulder.
innervation: Axillary nerve.

Front 2

Infraspinatus

Back 2

origin: Arises from and occupies the infraspinous fossa of the scapula.
insertion: Has two tendons of insertion: deep and superficial.

deep: Caudal part of greater tubercle.
superficial: Greater tubercle.
innervation: Suprascapular nerve.

Front 3

Supraspinatus

Back 3

origin: Arises from and occupies the supraspinous fossa of the scapula. Its epimysium provides an insertion site for the subclavius.
insertion: Cranial parts of the lesser and greater tubercles of the humerus.
action: Stabilize the shoulder joint and also to extend the shoulder.
innervation: Suprascapular nerve.

Front 4

Subscapularis

Back 4

origin: Arises from and occupies the subscapular fossa of the scapula.
insertion: Lesser tubercle of the humerus.
action: Primarily a shoulder joint stabilizer and secondarily an adductor of that joint.
innervation: Subscapular nerve.

Front 5

Teres major

Back 5

origin: Caudal angle of scapula.
insertion: Teres major tuberosity of the humerus with the latissimus dorsi.
action: Flex the shoulder joint.
innervation: Axillary nerve.

Front 6

Coracobrachialis

Back 6

origin: Coracoid process on the medial aspect of the supraglenoid tubercle of the scapula.
insertion: Proximal aspect of shaft of humerus.
action: Adduct the arm.
innervation: Musculocutaneous nerve.

Front 7

Triceps brachii

Back 7

origin: (long head) Caudal border of the scapula.
origin: (lateral head) The deltoid tuberosity and the curved rough line that extends from it to the neck of the humerus (see Fig. 15-33/2 in Sisson).
origin: (medial head) The medial aspect of the body of the humerus on the roughened area caudal and distal to the teres major tuberosity.
insertion: All three heads insert on the olecranon of the ulna.
action: The triceps is the most important elbow extensor. Because of its origin on the scapula the long head has a minor role in flexing the shoulder.
innervation: Radial nerve (the radial nerve supplies all of the extensors of the forearm).

Front 8

Biceps brachii

Back 8

origin: Supraglenoid tubercle of the scapula.
insertion: Radial tuberosity.
action: Primarily a fixator of the shoulder and flexor of the elbow.
innervation: Musculocutaneous nerve.

Front 9

Brachialis

Back 9

origin: Proximal one-third and caudal surface of the humerus. It occupies the spiral groove (see Fig. 23-12/3 in Dyce). Also note its topographical relationship with the radial nerve.
insertion: Craniomedial part of the proximal radius under the medial collateral ligament.
action: Flex elbow.
innervation: Musculocutaneous nerve and partially by the radial nerve.

Front 10

Extensor carpi radialis

Back 10

origin: Lateral epicondyloid crest of the humerus and adjacent rough area proximal to the capitulum
insertion: The metacarpal tuberosity along with the lacertus fibrosus.
action: Prevent flexion of the carpal joint and to extend the carpus and flex the elbow.
innervation: Radial nerve.

Front 11

Common digital extensor

Back 11

origin: (humeral head) Constitutes the bulk of the muscle and arises from the cranial aspect of the lateral epicondyle of the humerus in common with the extensor carpi radialis
origin: (radial head) The small radial head (not incorporated into the main muscle) arises from the lateral tuberosity on the proximal extremity of the radius.
*insertion: Primarily on the extensor process of PIII but with smaller attachments on the dorsoproximal aspects of PI and PII.
*action: Extend carpus and joints of the digits and flex elbow.
*innervation: Radial nerve.

Front 12

Lateral digital extensor (forelimb)

Back 12

origin: The lateral tuberosity of radius, the lateral border of the radius, and the lateral aspect of the body of the ulna
insertion: The eminence on the dorsal aspect of the proximal end of the proximal phalanges
action: Extend the digit and carpus.
innervation: Radial nerve.

Front 13

Ulnaris lateralis

Back 13

origin: Lateral epicondyle of the humerus.
insertion: Accessory carpal bone and Metacarpal IV (see Fig. 6-26 in Hackett and Sack).
action: Flex carpal joint.
innervation: Radial nerve.

Front 14

Flexor carpi radialis

Back 14

origin: Medial epicondyle of humerus.
insertion: Proximal end of Metacarpal II.
action: Flex carpus and extend elbow.
innervation: Median nerve.

Front 15

Flexor carpi ulnaris

Back 15

origin: Medial epicondyle of the humerus.
insertion: Accessory carpal bone.
action: Flex carpus and extend elbow.
innervation: Ulnar nerve

Front 16

Superficial digital flexor (forelimb)

Back 16

origin: Medial epicondyle of humerus.
insertion: Bifurcates to the lateral and medial aspects of the distal end of PI and the lateral and medial aspects of the proximal end of PII.
action: Flex digits and carpus and extend elbow.
innervation: Ulnar nerve.

Front 17

Deep digital flexor (forelimb)

Back 17

origin: (humeral head) Medial epicondyle of humerus.
origin: (ulnar head) Medial surface of olecranon.
origin: (radial head) Medial and caudal surface of radius.
insertion: The plantar surface of the distal phalanx (semilunar line, see Fig 23 – 25 in Dyce).
innervation: Median and ulnar nerves.

Front 18

Interosseus (forelimb)

Back 18

origin: Palmar carpal ligament and adjacent parts of Metacarpal III.
insertion: Abaxial surfaces of proximal sesamoid bones and common digital extensor tendon via its extensor branches.
action: Prevent over extension of fetlock joint.
innervation: No contractile function.

Front 19

Tensor fascia latae

Back 19

origin: Coxal tuber.
insertion: Lateral patellar ligament, cranial border of tibia, patella via fascia lata.
action: Flex hip.
innervation: Cranial gluteal nerve.

Front 20

Superficial gluteal

Back 20

origin: Coxal tuber, gluteal fascia.
insertion: Third trochanter.
action: Flex hip, abduct thigh.
innervation: Cranial and caudal gluteal nerves.

Front 21

Middle gluteal

Back 21

origin: Longissimus dorsi muscle, coxal tuber, iliac wing, sacrum, sacrosciatic ligament.
insertion: Greater trochanter (caudal part).
action: Extend hip, abduct thigh.
innervation: Cranial and caudal gluteal nerves.

Front 22

Deep gluteal

Back 22

origin: Ischiatic spine.
insertion: Greater trochanter (cranial part).
action: Abduct thigh.
innervation: Cranial gluteal nerve.

Front 23

Biceps femoris

Back 23

origin: Sacrum, sacrosciatic ligament, ischiatic tuberosity.
insertion: Inserts at three locations: 1) fascia lata and patella, 2) lateral patellar ligament and tibial crest, 3) calcanean tuber.
action: Primary function is to extend hip.
innervation: Caudal gluteal and sciatic nerves.

Front 24

Semitendinosus

Back 24

origin: Transverse processes of caudal vertebrae, ventral surface of ischiatic tuberosity, septum between this muscle and biceps femoris.
insertion: Medial aspect of distal end of crest of tibia (on a conspicuous prominence, see Fig. 15-86/13 in Sisson) and on the calcanean tuber.
action: Extend hip and hock, flex the stifle..
innervation: Caudal gluteal and sciatic nerves.

Front 25

Semimembranosus

Back 25

origin: Sarcotuberous ligament, ventral surface of ischiatic tuberosity.
insertion: Medial epicondyle of femur.
action: Extend hip.
innervation: Sciatic nerve.

Front 26

Gracilis

Back 26

origin: Pelvic symphysis.
insertion: Medial patellar ligament, medial surface of tibia.
action: Adduct limb.
innervation: Obturator nerve.

Front 27

Sartorius

Back 27

origin: Iliac fascia, tendon of psoas minor.
insertion: Medial patellar ligament, tibial tuberosity.
action: Flex hip, adduct limb.
innervation: Saphenous nerve.

Front 28

Pectineus

Back 28

origin: Cranial border of pubis.
insertion: Medial border of femur.
action: Flex hip, adduct thigh.
innervation: Obturator nerve

Front 29

Adductor

Back 29

origin: Ventral surface of pubis and ischium.
insertion: Caudal surface and medial epicondyle of femur.
action: Adduct thigh.
innervation: Obturator nerve

Front 30

Vastus medialis

Back 30

vastus medialis

origin: Medial surface of femur.
insertion: Patella.
action: Extend stifle.
innervation: Femoral nerve.

Front 31

Vastus intermedius

Back 31

origin: Cranial surface of femur.
insertion: Patella.
action: Extend stifle.
innervation: Femoral nerve.

Front 32

Vastus lateralis

Back 32

origin: Lateral border of femur.
insertion: Patella.
action: Extend stifle.
innervation: Femoral nerve.

Front 33

Rectus femoris

Back 33

origin: Body of ilium.
insertion: Patella.
action: Extend stifle, flex hip.
innervation: Femoral nerve.

Front 34

Tibialis cranialis

Back 34

origin: Lateral condyle of tibia and tibial tuberosity.
insertion: Splits into three attachment sites: (1) medial or cunean branch on T1+2 (2) dorsal branch on T3 and Mt3 (3) lateral branch on T4.
action: Flex tarsus.
innervation: Peroneal nerve.

Front 35

Peroneus tertius

Back 35

origin: Extensor fossa of femur in common with the long digital extensor.
insertion: Splits into two attachment sites: (1) dorsal branch on T3 and Mt3 (2) lateral branch on calcaneus and T4.
action: Links the actions of stifle and tarsal joints.
innervation: No contractile function.

Front 36

Long digital extensor

Back 36

origin: Extensor fossa of femur in common with peroneus tertius.
insertion: Extensor process of PIII with smaller attachments on the dorsoproximal aspects of PI
and PII.
action: Flex tarsus, extend stifle and digits.
innervation: Deep peroneal nerve.

Front 37

Lateral digital extensor (hindlimb)

Back 37

origin: Lateral collateral ligament of stifle and lateral condyle of tibia.
insertion: Joins the tendon of the long digital extensor in the proximal third of metatarsus.
action: Assists the long digital extensor in flexing the tarsus.
innervation: Superficial peroneal nerve.

Front 38

Popliteus

Back 38

origin: Lateral epicondyle of femur.
insertion: Caudomedial border of tibia.
action: Flex stifle.
innervation: Tibial nerve.

Front 39

Gastrocnemius

Back 39

origin: Lateral head: lateral supracondylar tuberosity of femur; medial head: medial supracondylar tuberosity of femur.
insertion: Calcanean tuberosity.
action: Extend tarsus, flex stifle.
innervation: Tibial nerve.

Front 40

Superficial digital flexor (hindlimb)

Back 40

origin: Supracondylar fossa of femur (under the gastrocnemius).
insertion: Bifurcates to the lateral and medial aspects of the distal end of P1 and the lateral and medial aspects of the proximal end of PII. (Also calcaneous) (see Fig. 23-28/3 in Dyce).
action: Flex digits and extend tarsus and also functions in the reciprocal mechanism.
innervation: Tibial nerve.

Front 41

Deep digital flexor (hind limb)

Back 41

origin: Medial digital flexor on the lateral condyle of the tibia, lateral digital flexor and the tibialis caudalis have extensive origins on the caudal aspect of the tibia.
insertion: Plantar surface of distal phalanx (semilunar line, see Fig. 23-25 in Dyce).
action: Flex digits, extend tarsus.
innervation: Tibial nerve.

Front 42

Interosseus (suspensory ligament) hindlimb

Back 42

origin: Plantar surface of distal row of tarsal bones and the proximal plantar surface of Metacarpal III.
insertion: Proximal sesamoid bones and long extensor tendon via its extensor branches.
action: Prevent overextension of fetlock joint.
innervation: No contractile function.

Front 43

Masseter

Back 43

origin: Fascial crest and zygomatic arch.
insertion: Ramus of mandible.
action: Close the mouth.
innervation: Mandibular nerve