Muscle of the Shoulder and Upper Limbs. 1. The trapezius group 2. The deltoid group.

The Muscular SystemMuscle of the Shoulder and Upper Limbs

Two major muscle groups of the back and shoulder:

1. The trapezius group 2. The deltoid group

Trapezius muscle group

Large superficial muscleOrigin:

Occipital bone and spinous process of thoracic vertebrae

Insertion: Clavicle and scapula

Action: on scapula

Trapezius muscle group (in cats)

1. Clavotrapezius Elevates and

retracts scapula Extends forearm

in forward motion

Three separate trapezius muscles in cat compared to one in human:

Trapezius muscle group (in cats)

2. Acromiotrapezius

Adducts the scapula

Three separate trapezius muscles in cat compared to one in human:

Trapezius muscle group (in cats)

3. Spinotrapezius Adduct scapula

and pulls it posteriorly

Three separate trapezius muscles in cat compared to one in human:

Deltoid muscle (in humans)

Origin: Spine of scapula

Insertion: Deltoid tuberosity of

humerusAction:

Shoulder abduction, flexion, extension, rotation

Deltoid muscle (in cats)

1. Clavobrachialis (aka clavodeltoid)

Flexes the forearm abduction

Three separate deltoid muscles in cat compared to one in human:

Deltoid muscle (in cats)

2. Acromiodeltoid Flexes the

humerus and rotates it outward

Three separate trapezius muscles in cat compared to one in human:

Deltoid muscle (in cats)

3. Spinodeltoid Acts in synergy

with acromiodeltoid

Three separate trapezius muscles in cat compared to one in human:

Levator Scapulae VentralisAction:

Elevates scapula

Origin: Transverse process

of first 4 cervical vertebrae

Insertion: Vertebral border of

scapula

Latissimus dorsi

Action: pulls forelimb dorsocaudally

Origin: last 6 thoracic vertebrae, all lumbar

vertebrae and iliac crest

Insertion: intertubercular groove of humerus

Ventral View

clavotrapezius

clavobrachialisPectoralis

majorPectoantebrachialis