Myology

Front 1

Types and arrangements of skeletal muscle fibers

Back 1

Parallel: Fibers are parallel in arrangement.
Fusiform: Spindle shaped. One belly and two tapering ends.
Unipennate: one side parallel fibers
Bipennate: attached to the tendon
Multipennate: at right angle.
Triangular: Common tendon but fibers radiate in a triangular manner.

Front 2

skeletal muscle fibers diagram

Back 2

Front 3

Tendon

Back 3

Thick dense fibrous tissues, band like structure, originate from muscles and attached them to bones.

Front 4

Ligament

Back 4

Thick dense fibrous tissues, band like structure which binds the two bones and helps in the formation of joint.

Front 5

Aponeurosis

Back 5

Thick sheet of connective tissue originate from the muscles.

Front 6

Origin of muscle

Back 6

The attachment of the muscle which remains more stationary during during movement is termed the origin. In the limbs the proximal attachment is the origin.

Front 7

Insertion of muscle

Back 7

The movable part of the muscle during contraction is termed the insertion. In the limbs the distal attachment is the insertion.

Front 8

Muscles of the head

Back 8

1. Caninus
2. Levator nasolabialis
3. Levator labii maxillaris
4. Depressor labii maxillaris
5. Depressor labii mandibularis
6. Orbicularis oris
7. Buccinator
8. Zygomaticus
9. Malaris / Malar muscle
10. Masseter muscle

Front 9

Muscles of the head diagram

Back 9

Front 10

Caninus

Back 10

The caninus is located in between levator and depressor labii maxillaris of ox.
It originate from the facial tuber and insert to the lateral wall of the nostril. It pulls the lateral wall of the nostril caudally.

Front 11

Levator nasolabialis

Back 11

It is thin in the ox and in the horse divided into two thick part which originate from the rostral part of the frontal bone and insert in the maxillary lip and nostril. It raise the maxillary lip and lateral portion of the nostril.

Front 12

Levator labii maxillaris

Back 12

Thin muscle in the ruminant and dorsal to the caninus muscle causes elevation of maxillary lip and muzzle.

Front 13

Depressor labii maxillaris

Back 13

Thin muscle in the ruminant and ventral to the caninus muscle causes retraction of maxillary lip and muzzle.

Front 14

Depressor labii mandibularis

Back 14

It is a thin muscle layer originating beneath the masseter muscle at the caudal portion of the cheek. It causes depression of the mandibular lips and skin of the chin.

Front 15

Orbicularis oris

Back 15

It is located between the skin and mucous membrane and act as a sphincter muscle of the lip. Action: To close the lips.

Front 16

Buccinator

Back 16

It is more well developed in ruminants than in horses. It is broad, flat muscles which forms the major portion of cheek. Action: Retract (take back) the angle of the of the mouth.

Front 17

Zygomaticus

Back 17

is a strong muscle in ruminants. It extends from ventral surface of the eye to the maxillary lips. Action: Retract (take back) the angle of the of the mouth.

Front 18

Malaris

Back 18

located ventral and rostral to the eye. The muscle is well developed in ox than the horse. Action: Elevate the caudal portion of the cheek.

Front 19

Masseter muscle

Back 19

Strong, broad, flat muscle located on the lateral surface of the ramus of the mandible. Action: To close the jaw, movement of mandible and assisting in rumination.

Front 20

Muscles of the neck region

Back 20

1. Brachiocephalicus
2. Sternocephalicus
3. Cervical part of the trapezius
4. Splenius
5. Rhomboideus
6. Iliocostalis cervicis
7. Longissimus

Front 21

Brachiocephalicus

Back 21

is a thin muscle which extends along the side of the neck from the head to the arm. Action:It depresses the head and full the forelimb forward.

Front 22

Sternocephalicus

Back 22

It is the ventral muscle of the neck and extend from sternum to the angle of the mandible and mastoid process of the head. Action: Flex the neck and head.

Front 23

Cervical Part of the Trapezius

Back 23

is a wide, undivided, flat and triangular muscles of the neck and thorax. Action: The cervical part pulls the scapula dorsad and craniad.

The thoracic part pulls the scapula dorsad and caudad.

Front 24

Splenius

Back 24

It is a thin, large, flat, triangular muscle which lies on the lateral surface of the neck dorsal to the level of the cervical vertebra. Action: Elevate the head and neck.

Front 25

Rhomboideus

Back 25

The rhomboideus arises on the nuchal ligament from the second cervical to the fifth thoracic vertebrae. It is attached to the deep surface of the scapular cartilage. Action: Draws the scapula dorsally.

Front 26

Iliocostalis muscle

Back 26

is a strong, segmented muscle which extends across the series of ribs in contact with the lateral edges of the longissimus muscles. Action: Depress and retract the ribs and helps in expiration.

Front 27

Longissimus muscle

Back 27

This muscle lies medial to the intercostales muscle and extend from the atlas bone to the lumber region. It is the largest and longest muscles in the body. It is the most powerful extensor and flexor muscles of the vertebral column.
Action: Elevation of the neck, extending the head, extension and flexion of the vertebral column.

Front 28

Muscles of the neck region diagram

Back 28

Front 29

Muscles of the neck region diagram

Back 29

Front 30

Muscles of the neck region diagram

Back 30

Front 31

Muscles of the neck region diagram

Back 31

Front 32

Muscles of the Thoracic Region

Back 32

1. Levatores costarum
2. Intercostales externi
3. Intercostales interni
4. Rectus thoracis
5. Transversus thoracis
6. Retractor costae
7. Serratus dorsalis caudalis
8. Diaphragm

Front 33

Levatores costarum

Back 33

They constitute a series of small muscles which overlie the vertebral ends of the intercostal space.
Origin: The transverse process of the thoracic vertebrae.
Insertion: The cranial border of the succeeding rib.
Action: Draw the rib cranially and assist in inspiration.

Front 34

Intercostales externi

Back 34

This muscle occupied the external part of the intercostal space, extending from the levatores costarum to the sternal extremity of the rib.
Origin: The caudal border of the ribs.
Insertion: The cranial border of the succeeding ribs.
Action: Draw the ribs cranially and assists in inspiration.

Front 35

Intercostales interni

Back 35

They located underneath of the intercostales externi.
Origin: Cranial border of the ribs.
Insertion: Caudal border of the preceding ribs.
Action: Helps in expiration.

Front 36

Rectus thoracis

Back 36

This and straight muscle lies on the cranioventral aspect of the thorax.
Action: Inspiration.

Front 37

Transversus thoracis

Back 37

Flat muscles and situated on the thoracic surface of the sternum.
Action: Assist in expiration.

Front 38

Retractor costae

Back 38

It is a thin muscle located in the angle formed by the last rib and the ends of the lumbar transverse processes.
Origin: Transverse processes of the first two or three lumbar vertebrae.
Insertion: Caudal border of the last rib.
Action: Retract the last rib and aid in forced expiration.

Front 39

Serratus dorsalis caudalis

Back 39

In ox it is very poorly developed and present 3-4 digitations.
Origin: Thoraco-lumbar fascia.
Insertion: Caudal border of the last three ribs.
Action: Assist in expiration by drawing the ribs caudally.

Front 40

Muscles of the Thoracic Region diagram

Back 40

Front 41

Muscles of the Thoracic Region diagram

Back 41

Front 42

Diaphragm

Back 42

It is a broad, unpaired muscles which forms a partition between the thoracic and abdominal cavities. In outline it has some resemblance palm-leaf fan. The thoracic surface it is strongly convex while the abdominal surface is concave. Its outer part is muscular while central part is tendinous.

Front 43

Diaphragm Attachments

Back 43

Costal Part: Cartilages of the 8th-10th ribs in horse.
Sternal part: The dorsal surface of the xiphoid cartilage.
Lumbar part: The right crus by means of ventral longitudinal ligament is attached to the first four or five lumbar vertebrae. The left crus attached in a similar fashion the the first and second vertebrae.

Front 44

Openings and content of the diaphragm

Back 44

The aortic hiatus: is an interval between the two crura and ventral to the last thoracic vertebra. It contains descending aorta, right vena azygos, and cisterna chyli.
The esophageal hiatus: Perforates the right crus and transmit the esophagus.
Foramen venae cavae: It pierce the tendinous center about 2-3 cm to the right of the median plane and caudal vena cava pass through it.

Front 45

Diaphragm diagram

Back 45

Front 46

Abdominal muscles General functions

Back 46

In general abdominal press which causes compression of abdominal viscera leading to:

Defecation

micturition (urination)

parturition (giving birth)

and expiration (exhale)

Front 47

Abdominal muscles

Back 47

1. Obliquus externus abdominis
2. Obliquus internus abdominis
3. Transversus abdominis
4. Rectus abdominis
5. Cremaster muscle.

Front 48

Obliquus externus abdominis

Back 48

It is the most extensive of the abdominal muscles. It is a broad sheath, irregularly triangual in shape, whose fibers directed caudad and ventrad, but which in the area of the paralumbar fossa are seen to pass in a horizontal direction.
Origin: The caudal border and lateral surface of the last eight ribs and fascia over the intercostal muscles.
Insertion: By means of aponeurotic tissue to the coxal tuber, prepubic tendon and linea alba.
Action: Abdominal press.
Blood Supply: Lumbar and dorsal intercostal arteries.

Front 49

Abdominal muscles diagram

Back 49

Front 50

Obliquus internus abdominis

Back 50

is situated beneath the obliquus externus abdominis muscle. Its fiber directed ventrad, craniad and mediad. It occupies the entire flank region from the coxal tuber to the last rib.
Origin: The coxal tuber.
Insertion: The caudal border of the last rib, the prepubic tendon, and the linea alba.
Action: Compression and support of the abdominal viscera.
Blood supply: Lumbar arteries and dorsal intercostal arteries.

Front 51

Transversus abdominis

Back 51

As a muscular sheet it is located deep to the Obliquus internus abdominis and rectus abdominis.
Origin: Deep lumbar fascia.
Insertion: Linea alba.
Action: Compress abdominal viscera.
Blood supply: Branches from the iliac artery.

Front 52

Rectus Abdominis

Back 52

It is confined to the ventral abdominal wall. It extend from the sternum to the pubis. It is a straight muscle.
Origin: The ventral and lateral surface of the sternum
Insertion: The prepubic tendon.
Action: Abdominal press.
Blood supply: Cranial and caudal epigastric arteries.

Front 53

Cremaster muscle

Back 53

of male may be regarded as detached portion of the obliquus abdominis externus muscle which separates as slip of fleshy tissue to enter the inguinal canal.

Front 54

Abdominal tunic

Back 54

This is a sheet of elastic tissue which assists the muscles in supporting the great weight of the abdominal viscera. It is practically coextensive with the obliquus externus abdominis which it covers. Ventrally it is thick and is intimately adherent to the aponeurosis (flat tendon) of the muscles. Laterally it become thinner and is more easily separated

Front 55

Inguinal canal

Back 55

Inguinal canal or space is a term applied to an oblique passage through the caudal part of the abdominal wall. It begins at the deep inguinal ring and ends at the superficial inguinal ring. Canal in between the deep and superficial inguinal ring formed the inguinal canal. This canal is formed by the obliquus internus abdominis muscles.

Front 56

Inguinal canal contents

Back 56

In the male: Contains (i)Spermatic cord, (ii)the vaginal tunic, (iii) the cremaster muscles, (iv) the external pudendal artery, (v) the inguinal lymph vessels, and (vi) branches of ilioinguinal and genitofemoral nerve.
In the female: it contains (i) the external pudendal artery, , and (ii) branches of ilioinguinal and genitofemoral nerve.

Front 57

Inguinal canal diagram

Back 57

Front 58

Flank

Back 58

The soft lateral abdominal wall formed by the obliquus abdominis externus and internus, and transversus abdominis muscle is known as flank.

Front 59

Flank diagram

Back 59

Front 60

Paralumbar fossa

Back 60

The triangular depression of the upper lateral abdominal wall is called paralumbar fossa. The cranial border is marked by the last rib, caudal border extend up to the tuber coxae, dorsal border is at the label of the transverse processes of the lumbar vertebrae. The ventral border is marked by the upper part of the abdominal muscles.

Front 61

Clinical importance of Flank and Paralumbar fossa

Back 61

Flank: For the gastrointestinal, reproductive and urinary tract operation.

Paralumbar fossa: Operation related to the stomach and intestines.

Front 62

Prepubic tendon

Back 62

Prepubic tendon is the tendon of insertion of two recti abdominis muscles but also furnishes the attachment of obliquus abdominis muscle, gracilis and pectinous muscles. It is attached to the cranial part of the pubic bones

Front 63

Prepubic diagram

Back 63

Front 64

Linea alba

Back 64

It is a median fibrous raphe (line) extends from the xiphoid cartilage to the prepubic tendon. It is formed chiefly by the junction of the aponeuroses of the obliquus abdominis externus, internus and transversus abdominis. Slightly caudal to its middle is the umbilicus.

Front 65

Muscles of the forelimb

Back 65

Front 66

Muscles of the arm

Back 66

1. Biceps brachii- Flexor
2. Bracialis- Flexor
3. Triceps brachii-Extensor
4. Coracobrachialis-Flexor

Front 67

Shoulder muscles lateral view

Back 67

Front 68

Shoulder muscles medial view

Back 68

Front 69

Muscles of the forearm (extensor)

Back 69

Extensor group:

1. Extensor carpi radialis
2. Extensor digitorum communis
3. Extensor digitorum lateralis
4. Extensor carpi ulnaris

Front 70

Muscles of the forearm (flexor)

Back 70

Flexor muscles:

1. Flexor carpi radialis
2. Flexor carpi ulnaris
3. Flexor digitorum superficialis
4. Flexor digitorum profundus.

Front 71

Muscles of the forearm lateral view

Back 71

Front 72

Muscles of the forearm medial view

Back 72

Front 73

Muscles of the hip and thigh

Back 73

1. Gluteus superficialis
2. Gluteus medius
3. Gluteus profundus
4. Quadratus femoris
5. Tensor fascae lata
6. Semitendinosus
7. Semimembranosus
8. Gracilis
9. Adductor
10. Pectineus
11. Biceps femoris
12. Quadriceps femoris

Front 74

Muscles of the pelvic limb

Back 74

Front 75

Muscles of the pelvic limb

Back 75

Front 76

Muscles of the leg (extensor)

Back 76

Extensor muscles:

Tibialis cranialis
Extensor digitorum longus
Fibularis longus (peroneal muscle)
Extensor digitorum lateralis.
Extensor digiti I longus

Front 77

Muscles of the leg (flexor)

Back 77

Flexor muscles:

Gastrocnemius
Flexor digitorum superficialis
Flexor digitorum profundus
Tibialis caudalis
Popliteus.

Front 78

5 Muscles of Hindlimb

Back 78

Front 79

5 Muscles of Hindlimb

Back 79