VET150 Muscular system- Extrinsic muscles of thoracic limb and related areas

cutaneous trunci muscle

tightly adhered to skin, twitches skin

Superficial pectoral muscle: descending and transverse

origin: cranial sternum

insertion: crest of the greater tubercle of the humerus

action: adduct the limb

Deep pectoral muscle

Origin: full length of the sternum

Insertion: greater tubercle of the humerus

Action: adducts and pulls limb caudally

Brachiocephalicus muscle: a "Y" shaped muscle with three parts.

Origin: clavicular intersection

Insertion: distal humerus (cleidobrachialis), cervical vertebrae/cranium (cleidocephalicus) mastoid process of temporal bone (cleidomastoideus)

Action: to advance the limb; to extend the shoulder and draw the neck and head to the side

trapezius muscle

Origin: Dorsal aspect of neck

Insertion: Spine of scapula

Action: Elevates and abducts limb; holds scapula to thorax

Rhomboideus muscle

origin: Occipital bone

insertion: dorsal border of scapula

Action: Elevates forelimb, holds scapula to thorax

Latissimus dorsi muscle

Origin: Last 7 thoracic vertebrae and spinous process of lumbar vertebrae

Insertion: proximal humerus

Action: Draws limb caudally Flexes shoulder joint

Serratus ventralis muscle

Origin: cervical vertebra and ribs

Insertion: Dorsomedial scapula

Action: Supports trunk, Holds scapula to thorax

Sternocephalicus muscle

Origin: sternum

Insertion: Occipital bone

Action: Draws head side to side

Platysma muscle

Origin: raphe on doral midline neck skin

Insertion: Attaches to muscles of lips

Action: draws commissures of lips caudally

Temporalis muscle

Origin: Parietal bone of skull

Insertion: Coronoid process of mandible

Action: closes mouth when chewing

Masseter muscle

Origin: Zygomatic arch

Insertion: Lateral side of the mandible

Action: Elevates the mandible to close the mouth when chewing

Digastricus muscle

Origin: Occipital and temporal bones

Insertions: Ventral mandible

Action: opens mouth

Mylohyoideus

Origin: Medial mandible

Insertion: Median raphe between mandibles

Action: Raises floor of mouth

Attachment

the junction of a skeletal muscle to bone. 3 types: tendon, aponeurosis and fleshy

Tendon

Attaches muscle to bone: an extension of the epimysium that consists of dense connective tissue

Aponeurosis

strong sheet of tissue that acts as a tendon to attach muscles to bone or muscle

Fleshy

an apparent direct attachment of muscle to the bone; in reality the muscle attaches to the periosteum of the bone by very short tendons

Origin

attachment of a muscle that remains relatively fixed during muscular contraction

Insertion

The attachment of a muscle tendon to a moveable bone or the end opposite the origin

Action

the body movement that a contraction of the muscle will produce

Umbilicus

depression on the abdomen marking site of entry of umbilical cord

Costal arch

caudal ventral border of the rib cage formed by the costal cartilages of the 10th, 11th and 12th ribs; the 13th rib does not attach to the costal arch.

Clavicular intersection

Divides the brachiocephalicus into two parts. Origin of both parts.

Jugular groove

Formed by the edges of the brachiocephalicus and sternocephalicus muscles. Jugular vein lives in the groove.