Mm. of Trunk

Question 0

Epaxial Muscles

Answer 0

lie dorsal to the transverse processes or axial skeleton

Question 1

hypaxial muscles

Answer 1

• lie ventral to the transverse processes of the vertebrae.

- include mm of neck, thorax, and abdomen & those directly ventral to the vertebrae

Question 2

divisions of neck & trunk muscles

Answer 2

1. Epaxial mm.

2. Hypaxial mm.

Question 3

Hypaxial mm.

Answer 3

Sternocephalicus m., sternohyoideus m., sternothyroideus m., Scalenus m., Intercostal mm., External Abdominal Oblique m., Internal Abdominal Oblique m., Transversus Abdominus m., Rectus Abdominus m.,

Question 4

Sternocephalicus mm.

Answer 4

O: cranial sternum
I: Mastoid process & occipital bone
A: draw head/neck sideways or ventrally if both contract simulateously

form ‘v-shaped’ m. when viewed cranially. lie immediately ventral to external jugular veins.

Question 5

Sternohyoideus m.

Answer 5

O: cranial sternum
I: Basihyoid bone (on the midline, cranial to larynx) [cranial to larynx]
A: pull tongue & larynx caudally (swallowing)

Question 6

Sternothyroideus m.

Answer 6

O: cranial sternum
I: Thyroid cartilage of larynx (lateral surface of larynx)
A: pull the tongue & larynx caudally (swallowing)

Question 7

Why are the sternohyoideus & sternothyroideus mm. grouped together?

Answer 7

They originate as a single common m. and separate into individual mm. a few cm from the 1st sternebra.

Question 8

Thyroid glands

Answer 8

dark red, elongated structures that lie lateral to cranial portion of trachea

Question 9

Scalenus m.

Answer 9

Triangular m. that lies ventral to serratus ventralis m.
O: Last 3 cervical vertebrae
I: 1st few ribs
A: “Anchors” cranial ribs during inspiration

Question 10

Intercostal mm. types

Answer 10

External intercostal m.

Internal intercostal m.

Question 11

External intercostal mm.

Answer 11

more superficial intercostal mm. & fibers run caudoventrally.

Question 12

Internal intercostal mm.

Answer 12

lie deep to external intercostal mm.

fibers run cranioventrally.

Question 13

Intercostal mm. OIA

Answer 13

O: Caudal border of 1 rib
I: Cranial border of the next
A: Pull ribs closer together

12 pairs exist on each side

Question 14

External Abdominal Oblique m.

Answer 14

Most superficial m. of lateral abdominal wall. Runs caudoventrally. BIGGEST abdominal gp m.

O: Caudal ribs & thoracolumbar fascia
I: Ventral midline
A:

Question 15

Internal Abdominal Oblique mm.

Answer 15

O: Thoracolumbar fascia, Tuber Coxae, Inguinal Ligament,
I: Aponeurosis (last rib/costal arch [outer rim] & linea alba

fibers run cranioventrally (to manus)

Question 16

Transversus Abdominus M.

Answer 16

O: Thoracolumbar fascia
I: Aponeurosis - dorsal to rectus femoris everywhere except very caudal, where its ventral too

fibers run ventral in a transverse plane. deepest m. of abdominal wall

Question 17

Rectus Abdominus M.

Answer 17

O: Sternum & 1st few ribs via an aponeurosis
I: Pectin of pubis

R/L mm. lie adjacent to each other on ventral midline (linea alba).
Tendinous bands give more control over contraction (give 6 pack look in ppl).

Question 18

Linea Alba

Answer 18

“White Line”
relatively avascular. holds sutures well.
therefore, its a common site for abdominal incisions.

Question 19

Epaxial mm.

Answer 19

Iliocostalis System., Longissimus System, Transversospinalis System, Splenius m.,

Question 20

Transversospinalis System

Answer 20

Sit medial & dorsal on vertebral column.
Caudal extent: sacrum & ilium
Cranial extent: skull

Question 21

Longissimus system

Answer 21

lateral and ventral to transversospinalis system.
Caudal Extent: Ilium
Cranial Extent: Skull

Question 22

Iliocostalis System

Answer 22

shortest system. lateral most & ventral most system.
Caudal Extent: Ilium
Cranial Extent: Ribs

Question 23

Epaxial Systems’ Functions

Answer 23

• extend vertebral column (both sides contract)

- pull side over (lateral flexion) [only one side contracts]

Question 24

Splenius m.

Answer 24

O: Spinous processes of cranial thoracic vertebrae, dorsal midline of the neck.
I: Caudodorsal border of the skull

Question 25

Nuchal Ligament

Answer 25

2 bands of elastic connective tissue

Run from cranial extent of the supraspinous ligament to the axis (yellow in color)

Question 26

Inguinal Lig.

Answer 26

Thickened caudal border of aponeurosis of external abdominal oblique m.
not technically a lig. it just protects the muscles.

Question 27

Muscles that form the Abdominal Wall

Answer 27

Rectus Abdominis m., Transverses Abdominis m., Internal Abdominal Oblique m., External Abdominal Oblique m.

Question 28

“Abdominal Press”

Answer 28

the smoother & more uniform the more effective the contraction of all the muscles is.

Question 29

Why is it important to know the muscle fiber’s directions?

Answer 29

• protection
• identification of muscles
• contraction direction

Question 30

Why do the fibers of the 4 muscles in the abdominal walls run different directions?

Answer 30

creates a meshwork which give strength to them. Meshwork makes abdominal m. group smoother and more uniform.

Question 31

Diaphragm

Answer 31

Attaches to caudal rib area.
Separates thoracic and abdominal cavities.
The relaxed m. is pushed cranially by organs of abdominal cavity.

Question 32

Order of Epaxial Muscles from Dorsal to Ventral

Answer 32

“Ten Little Indians”

1. Transversospinalis system
2. Longissimus system
3. Iliocostalis system

Question 34

Flexor angle of vertebral jts.

Answer 34

ventral side.

Question 35

Superficial Inguinal Ring

Answer 35

A slit in aponeurosis of insertion of external ab. oblique m.

Location: medial to vessels of femoral triangle.
Male dog: spermatic cord, external pudendal vessels leave/enter here.
Female dog: fat-filled sack (Vaginal Process) & external pudendal vessels leave/enter here.

Question 36

Vaginal Process

Answer 36

blind-ended, fat-filled sack that passes through superficial inguinal ring in females.

equivalent to vaginal tunic extension in males

Question 37

Vaginal Tunic

Answer 37

covers the spermatic cord and testes.