Extrinsic Muscles of the Canine Thoracic Limb

A. Cleidobrachialis m.

B. Pars cervicalis m.

C. Pars mastoideus m.

D. Clavicular tendon/intersection

Innervation:

- accessory n. (C11)

- ventral branches of cervical spinal nn.

Action:

- Advance the limb (extends shoulder joint)

- draws neck and head to side

A. Cutaneous truncii m.

Innervation: lateral thoracic n.

Action: Twitches the skin

A. Deep pectoral m.

Innervation: (caudal) pectoral n. (C8, T1)

Action:

- advancing the limb: pulls the trunk cranially (extend the shoulder joint)

- limb not supporting weight: draws the limb caudally (flex the shoulder joint)

- adducts the limb

A. Latissimus dorsi m.

Innervation: Thoracodorsal n. (C7,C8, T1)

Action:

- Draw the free limb caudally (as in digging)

- Flex the shoulder joint

A. Omotransversarius m.

Innervation: accessory n.

Action:

- Advance the limb

- Flex the neck laterally

* superficial cervical lymph node found deep and cranial to omotransversarius *

A. Rhomboideus capitis m.

B. Rhomboideus cervicis m.

C. Rhomboideus thoracis m.

Innervation: ventral branches of the cervical and thoracic spinal nn.

Action:

- Elevate the forelimb

- Draw the scapula against the trunk

A. Serratus ventralis m.

Innervation:

- ventral branches of the cervical spinal nn.

- long thoracic n.

Action:

- Support the trunk

- Depress the scapula

*very important bc it is so strong, acts like a sling to support the trunk *

A. Sternocephalicus m.

Innervation:

- accessory n.

- ventral branches of cervical spinal nn.

Action: draws head and neck to the side

A. Sternocephalicus m.

Innervation:

- accessory n.

- ventral branches of cervical spinal nn.

Action: draws head and neck to the side

A. Superficial pectoral m.

B. Descending pectoral m.

C. Transverse pectoral m.

Innervation: (cranial) pectoral n. (C7, C8)

Action: adduction (keep limb toward body)

A. Trapezius m.

*two parts: cervical and thoracic*

Innervation: accessory n.

Action:

- Elevate shoulder

- Abduct the forelimb

1. Brachiocephalicus m.

2. Omotransversarius m.

3. Sternocephalicus m.

4. Trapezius m.

**BOST**

What 4 muscles are innervated by the accessory n.?

1. Brachiocephalicus m.

2. Sternocephalicus m.

3. Rhomboideus m.

4. Serratus ventralis m.

**BSRS**

What 4 muscles are innervated by the ventral branches of the cervical spinal nn.?