Mr. GroveCat Dissection

Anatomy Physiology

Muscle Group 1

Muscle Group 1 are the muscles of the thorax, ventral view; abdomen, ventral view; head and neck, ventral view and lateral view.

These muscles include: (make a check list for these muscles)

Under Skin:

  1. Cutaneous Maximus – Covers most of the sides of the body in the thoracic and abdominal areas. It twitches the skin – it is not found in man. Look for: light brown fibers adhering tightly to the underside of the skin (it will not be on the test.)
  2. Platysma – Found around the neck and face. It will stick close to the skin too (not on test.)

Superficial Muscles – Thorax, Ventral View:

  1. Pectoantebrachialis – The most anterior of the four chest muscles – it is not found in man.
  2. Pectoralis Major – Small in the cat but large in man.
  3. Pectoralis Minor – The largest of the pectoral muscles of the cat. In man it is small.
  4. Xiphibumeralis – The most posterior of the pectoral muscles. Look for a v shape – not found in man.

Superficial Muscles – Abdomen, Ventral View:

  1. External Oblique - Covers mostly the lateral part of the abdomen.
  2. Internal Oblique - Lies just under the External Oblique.
  3. Transversus Abdominis – Lies under the Internal Oblique.
  4. Rectus Abdominis – Two parallel muscles running down the middle of the ventral surface – in man this is the “6 – pack”.
  5. Latissimus Dorsi – Mostly seen on the dorsal side but is very prominent on the lateral ventral surface as well. In humans when well developed gives the back a “v shape” or “bat wing” look.

Superficial Muscles – Head and Neck, Ventral View:

  1. Clavobrachialis – The most anterior of the shoulder and arm muscles.
  2. Sternomastoid – A large “V” shaped band of muscle on the ventral/lateral surface of the neck.
  3. Cleidomastoid – It lies lateral to the Sternomastoid. In man, the two muscles are combined and called the sternocleidomastoideus.
  4. Sternohyoid – Two bands of muscle that run along the mid-ventral line in the neck.
  5. Sternothyroid – Look deep to the sternohyoid and to the outside (lateral).
  6. Digastric – Below the inner edge of the mandible.
  7. Mylohyoid – Look for muscle fibers running transversely between the digastric muscles.

Watch out and do not damage the following structures:

  • External Jugular Vein, anterior Facial Vein, Posterior Facial Vein, Transverse Jugular Vein.
  • Parotid and submaxillary salivary glands, Lymph glands.

Superficial Musles – Head and Neck, Lateral View:

  1. Masseter – The most prominent muscle on the lateral surface of the face. To feel yours, touch your cheek and gnash your teeth – the muscle will contract.
  2. Temporalis – Located dorsal to the masseter.

You would be wise to make a check list of these muscles. Even when we move on to another muscle group or even something completely different in the cat you should refer back to your check list and quiz yourself and lab partners. Constant review is the key to doing well on the cat practical. You will find that the cat practical is one of the most difficult tests in all of the life sciences, if not all sciences. This form of test is highly used at the university level – many a possible doctor has been eliminated from a pre-med program for not being able to master this kind of an exam. Whenever you get ahead in the dissection, stop and quiz your lab team on what you have learned – do not waste time.