Canine Muscles And Their Actions

Front 1

Sternocephalicus Muscle

Back 1

Located on both sides of body. Lies just below the ventral border of the brachiocephalicus.
Origin - occiput and the mastoid process (upper edge of the back end of the skull and the bottom of the skull behind the mastoid process)

Insertion - The manubrium of the sternum
Action and Function - Muscles together move head up and down in a nod. One at a time move head to one side.

Front 2

Omotransversarius Muscle

Back 2

Lies adjacent to the brachiocephalicus but is not as thick.
Origin - Wing of the Atlas C1
Insertion - Distal spine of the scapula
Action - Bilateral and unilateral flexion of the neck; draws the scapula forward

Front 3

Rhomboideus Muscle

Back 3

Thick muscle lies along the back of the neck to the back of the withers and is deep to the trapezius.Origin - Nuchal ligament and spinous processes of C2; supraspinous ligament and the spinous processes of T1-T7

Insertion - Medial aspect of the scapular cartilage
Action - Elevation of the scapula; bilateral extension of the head and neck; unilateral flexion of the head and neck (helps dog flex and look up and over the shoulder)

Front 4

Brachiocephalicus Muscle

Back 4

Has two origins and one insertion
Origin - Cleidocephalicus - occiput and nuchal ligament
Cleidomastoid - Mastoid process (Bottom of the skull behind the ear hole)
Instertion - Crest of the humerus
Action - Pulls head forward (unilateral flexion); pulls neck and head down and to one side (bilateral neck flexion); draws foreleg forward during limb extension

Front 5

Supraspinatus Muscle

Back 5

Lies deep to the trapezius and brachiocephalicus. Creates the form of the front aspect of the shoulder.
Origin - Supraspinous fossa of the scapula (top forward part of scapula).
Insertion - Greater and Lesser tubercles of the humerus
Action - Extension and internal rotation of the shoulder (the lesser tubercle assists with the internal rotation); helps to stabilize the shoulder joint

Front 6

Infraspinatus Muscle

Back 6

Lies deep to trapezius and deltoid. Contributes to the shoulders form and shape.
Origin - Infraspinous fossa of the scapula (top back part of the scapula).
Insertion - Lateral tuberosity of the humerus (outer side of the greater tubericle of the humerus).

Action - Flexion, abduction and external rotation of the shoulder. Helps stabilize the shoulder joint.

Front 7

Deltoid Muscle

Back 7

This muscle is a superficial muscle that has two portions. The dorsal portion is wider and is attached along the scapular spine and the acromial portion which is smaller and
tapers at both ends.
Origin - Posterior spine of the scapula and the acromion process (located at the bottom end of the spine of the scapula).
Insertion - Deltoid tuberosity of the humerus (located laterally along the humerus a third of the way down).

Action - Flexion, external rotation and abduction of the shoulder (Flexes shoulder joint flex and pulls the foreleg away from the body).

Front 8

Biceps Brachii Muscle

Back 8

Runs Distal from the shoulder joint and medial to the forearm to the proximal Radius

Origin - Supraglenoid tubercle of the scapula

Insertion - Radial tuberosity

Action - Extension of the shoulder and flexes the elbow

Front 9

Triceps Brachii Muscle

Back 9

This muscle is a fleshy superficial muscle that has three heads: two long heads and one lateral head.
Origin - Long head – Caudal distal boarder of the scapula to two thirds up the caudal boarder. Lateral Head – Posterior, proximal humerus .
Insetion - Olecranon process of the ulna(elbows point)
Action - Long Head – Flexes the shoulder joint and extends the elbow joint
Lateral Head – extends the elbow joint

Front 10

Latissimus Dorsi Muscle

Back 10

Superficial muscle where the distal attachment lies deep to the

triceps. It is a large thin muscle that is triangular in shape.
Origin - Teres major tuberosity

Insertion - Thoracolumbar fascia and the spinous processes of T7-L6.
Action - Retraction of the scapula, flexion and internal rotation of the shoulder, lateral flexion and extension of the opposing LD muscle. Draws the foreleg back under the body.

Front 11

Pectorales

Superficiales Muscles

Back 11

Anterior chest area, located in between the front legs.

Origin - Sternum
Insertion - Medial shaft of the humerus, inserts on the short vertical line.
Action - Forelimb adduction, movement towards the midline

Front 12

Longissimus Dorsi Muscle

Back 12

Longest Dorsal muscle. Longest muscle in the body. Runs deep to the scapula.
Origin - Transverse processes from C7-L6. The cervical portion can extend to the base of the skull. Extends 1-2 inches laterally from the spine
Insertion - Sacral ridge and the upper ilium. The caudal aspect of the fibers are broad and thinner as they intersperse into the gluteal fascia

Action - Extension and lateral flexion of the spine. Stabilizes the spine

Front 13

Serratus Ventralis Muscle

Back 13

Cervical potion is deep to the trapezius and brachiocephalicus. The thoracic portion is visible just behind the scapula
Origin - Cervical portion - Tansverse processes of C2-T8
Thoracic portion – On the lateral surface of the first seven ribs.
Insertion - Subscapular fossa (upper third of the costal surface of the scapula).
Action - Cervical - Draws the scapula forwards when neck is fixed, extends the neck when the scapula is fixed. Thoracic - Draws scapula backwards when the trunk is fixed and supports the trunk when the scapula is fixed. Aids in respiration.
Pulls shoulder blade back and down and rotates the blade (chest)

Front 14

Gluteus Medius Muscle

Back 14

Gives the dogs buttocks its form. Extends into the lumbar fascia.
Origin - Crest and gluteal surface of the ilium.

Insertion - Greater Trochanter

Action - Hip extension, hip internal rotation and hip abduction

Front 15

Gracilis Muscle

Back 15

Lies on the posterior, medial thigh
Origin - Pubic symphysis via the symphyseal tendon (middle bottom of the pelvis)
Insertion - Cranial boarder of the tibia.
Action - Adduction of the thigh, extension of the hip joint, extension of the hock.

Front 16

Sartorius Muscle

Back 16

Two long strap like muscles

Origin - Cranial part - runs from the iliac crest and the cranial ventral iliac spine, as well as from the lumbodorsal fascia.

The caudal part - runs on the

bony ridge between the two ventral spines of the ilium.

Insertion - Cranial part - Patella. Caudal part - cranial tibia.

Actions - Hip flexion and Cranial part extends the stifle where the Caudal part flexes the stifle.

Front 17

Quadriceps Muscles

Back 17

There are four muscle heads that make up this muscle Group. Vastus Lateralis, Vastus Medius, Deep Vastus Intermedius and the Rectus Femoris.
Origin - Rectus femoris - Cranial Ventral spine of the ilium (point of the haunch, Vastus muscles - lateral, medial and anterior surface of the femur.

Insertions - Group insets on the proximal cranial tibia crossing the stifle joint.

Actions - Stifle extension and the rectus femoris flexes the hip

Front 18

Tensor Fascae Latae Muscle

Back 18

Is a triangular shaped muscle located posterior to the flank

Origin - Proximal to the tuber coxae, cranial ventral iliac spine
Insertion - Lateral femoral fascia to the tibial tuberosity
Actions - Hip flexion and stifle extension

Front 19

Biceps Femoris -

Hamstring Muscle

Back 19

Large prominent superficial muscle located at the lateral thigh, posterior to the hip joint.
Origin - Sacrotuberous ligament and the Ischial tuberosities

Insertion - Tibial tuberosity, tibial crest, medial tuberosity of the tuber calcanei via the calcaneal tendon.

Actions - Extends the hip, stifle and hock. Also can flex stifle depending on the position of the leg.

Front 20

Semitendinosus -

Hamstring Muscle

Back 20

Superficial muscle just posterior to the bicep femoris. Form a portion of the posterior thigh.
Origin - Ischial tuberosities
Insertion - Posterior tibia, the crural fascia and the point of the hock.

Action - Hip extension, Hock extension, stifle flexion and extension (extends or flexes depending on the position of the leg)

Front 21

Semimembranosus - Hamstring Muscle

Back 21

Fleshy thick muscle that has two heads.
Origin - Ischial tuberosities
Insertion - Medial epicondyle of the femur and the medial head of the tibia

Action - Hip extension, stifle flexion and extension (extends or flexes depending on the position of the leg)

Front 22

Hind Adductor Muscle

Back 22

There are three adductor muscles. Adductor longus, adductor magnus and the brevis muscle. These muscles are found in the deep layer of the muscles.
Origin - They all originate on the pelvic joint via the symphyseal tendon. Also Near the ischiatic arch, the ventral surface of the pubis and ventral surface of the ischium.
Insertion - Inserts into the whole lateral lip of the caudal rough face of the femur.
Action - Adduct limb and extends the hip and stabilizes hind leg

Front 23

Masseter Muscles

Back 23

Forms the cheek

Origin - Zygomatic Arch of the maxilla

Insertion - Ramus of the mandible

Actions - Elevates the jaw bilaterally and moves the jaw unilaterally from side to side

Front 24

Frontalis (Frontal) Muscles

Back 24

Responsible for many facial expression. Is located over the frontal bones between the ears.

Origin - Surface and boarder of the frontal bone

Insertion - Surface and boarder of the frontal bone

Actions - Movement of the ears and scalp

Front 25

Trapezius Muscles

Back 25

Most superficial muscle. Lies over the shoulders.

Origin - Nuchal ligament (C2-C7) and the spinous processes of T1-T8

Insertion - Anterior and posterior spine of the scapula

Actions - Elevates the scapula, protracts and retracts the scapula; Cervical portion draws the scapula forward while thoracic portion draws the scapula backwards

Front 26

Rectus Abdominus Muscles

Back 26

Wide band of flat muscle to the left and righ of the midline.

Origin - Sternum and costal cartilage

Insertion - Cranial, ventral rim of the pupic bone

Actions - Initiates flexion of the back, provides support for the trunk and protects the internal organs

Front 27

External Oblique Muscles

Back 27

Superficial muscle that runs from the lower half of the rib cage to the ventral midline.

Origin - Lateral aspect of ribs 6-13

Insertion - Fascia of the midline and the groin (tuber-coxae to the pelvis symphisis).

Actions - Trunk support, lateral flexion of the trunk and protraction of the hindlimb (helps limb move under the body)

Front 28

Intercostals Muscles

Back 28

Muscle tissues that run between the ribs

Origin - Posterior surface of the proceeding rib

Insertion - Anterior surface of the preceding rib

Actions - The perform in the act of respiration

Front 29

Iliopsoas Muscles

Back 29

Deep Hip flexor muscle

Origin - Ventral surface of the transverse processes of T13-L6 and the ventral surface of the ilium

Insertion - Lesser trochanter of the femur

Actions - Hip flexion

Front 30

Gluteus Superficialis Muscles

Back 30

Forms a triangle around ventral anterior base of the tail.

Origin - Sacrum, iliac spine and the gluteal fascia

Insertion - Greater trochanter of the femur

Actions - Hip abduction and extension

Front 31

Gasrocnemius Muscles

Back 31

Large bulge on the back of the leg between the stifle and the hock.

Origin - Medial and lateral condyles of the femur

Insertion- Calcaneal tuber (point of the hock)

Actions - Hock extension and stifle flexion

Front 32

Pectineus Muscles

Back 32

The most anterior adductor of the hip

Origin: iliopubic eminence (prepubic tendon and cranial border of pubis)

Insertion - distal body of femur

Actions - Adduct and medially rotate the thigh, primary function is hip flexion.