Anatomy 1 - Lesson X:

Myologia- Part I

Objective: Students will examine the muscles of a canine in order to identify the

musculature of the body.

Practical Tasks 1-5:

1) M. latissimus dorsi, m. trapezius, m. rhomboideus, m. serratus ventralis, mm. pectorales

2) Extensors of the shoulder

3) Flexors of the shoulder

4) Extensors of the elbow

5) Flexors of the elbow

Practical Task 1:

Dissection

Deltoid scapular part is seen caudally on the spina scapulae, the trapezius thoracis above (much smaller

than cervicis) and trapezius cervisc on the cranial side of the spinae scapulae. The cutaneous trunci is

removed with the skin

(separate cleidocervicalis from trapezius cervicis)

Clean the border between trapezius and latissimus dorsi and you will see that latissimus running under

trapezius.

Move ventrally to the pectorals and dissect them to see the different musclefibres. Clean them very well.

Stretch the leg to easily see the fiber directions. Feel the humeral insertion of the deep pectoral.

(Transect them and you can later see more of the ventral and also the thoracis part of serratus vetralis-

not sure if it’s necessary)

Move back to the midline of the neck. Put your finger under the trapezius and transect both parts

horizontally.

You will find the rhomboidus under the trapezius. Separate it from latissimus dorsi. It’s not necessary to

separate the parts of rhomboideus but you can do it if you want.

Put a finger under the rhomboideus and transect all parts. You can now abduct scapula and show the

serratus vetralis, its dorsal side.

Practical Task 2: Extensors of the shoulder

Dissection

Clean and move trapezius (and omnotransversarius) caudally (or transect trapezius) to see supraspinatus

cranially to the spina scapulae.

Clean both the scapular and the acromial part of the deltoid.

Transect the both part of the deltoid and reflect them. Now you can see the infraspinatus ans below, you

can see the teres minor. The tendon of supraspinatus acts as the lateral collateral ligament of the

shoulder joint.

On the distal end of scapula, the small tendon of coracobrachialis is running on the one from

subscapularis. The tendon of subscapularis works as the medial collateral ligament of the shoulder joint.

Practical Task 3: Flexors of the Shoulder (M. supraspinatus and M. Infraspinatus described in task 2)

Dissection:

Clean latissimus dorsi from the remaning parts of the pectorals and then stretch it You can see that it has

two insertion points, one as fascia tensor antibrachii (Ulnar head of latissimus) and one in common with

to the one of the teres major on teres major tuberosity.

Go back to scapula and clean the medial muscles carefully because of the small coracobrachialis.

Clean and separate the teres major from the subscapularis.

(Biceps tendon works as a cranial collateral ligament)

Practical Task 4: Extensors of the Elbow

Dissection:

On lateral side

Clean and separate the long and lateral head of triceps. In between, the accessory head can be found, and

deep to them, also the medial head. Grab the three big heads and then search for the accessory, just to be

sure. (Between lateral and long heads is a big nerv running on brachialis)

Transect the lateral head and reflect it all the way down to the olecranon tuberosity, the anconeus is

vissible. Anconeus is small and triangular and filling up the space between humerus and Proc.

Anconeus.

Most caudally, you will find the tensor faciae antibrachi. Remember that it’s “a part of” latissimus dorsi.

Practical Task 5: Flexors of the Elbow

Dissection:

On lateral side

Clean and separate the long and lateral head of triceps. In between, the accessory head can be found, and

deep to them, also the medial head. Grab the three big heads and then search for the accessory, just to be

sure. (Between lateral and long heads is a big nerv running on brachialis)

On medial side

The biceps brachii can be best seen from medially. It’s the most cranially on this side. Clean it and

separate it from the medial head of triceps. The brachialis is also partly visible from this side,

caudolaterally to the distal part of the biceps. Clean biceps and you will find the transverse ligament

between the lesser and greater tubercle, this ligament fixes biceps. Do not transect it. If you trace the

tendon of biceps, you will find the joint cavity of the shoulder joint.