The Muscular System, pt. 2
Jan 01, 2016
A muscle depends on other muscles to assist in movement.
For this reason muscles are called prime movers, antagonists or
synergysts.
Names for muscles are based on six points of identification:•Action•Origin/insertion point•Location•Shape or use•Direction of their fibers•The number of their sections
Muscles of the neck, back and thorax.
These muscles assist in:•Rotation of the head•Flexion and extension of the head on the neck•Breathing•Attachment of the forelimbs to the body
The important muscles of the dorsum include the epaxial
group:iliocostalislongissimus
transversosspinalis
During respiration:•External intercostals lift the ribs•Internal intercostals lower the ribs•Diaphragm contracts and flattens out causing thorax to enlarge and the lungs to expand
Muscles of the Forelimbs
With help from the back and upper thorax, the muscles of the upper
forelimbs contribute to movement of the distal extremities.
Muscles include the triceps brachii and biceps brachii
Abdominal Muscles:
These muscles keep the organs in place, support and compress the
abdomen, contract during parturition, defecation, urination and coughing.
They also assist in rotating the vertebral column.
Linea Alba
A fibrous band running the length of the abdomen, which is a central
attachment of the abdominal muscles.
A very important landmark for abdominal surgery
Muscles of the Hindlimb
These muscles have several functions in movement.
The most important muscle groups include
*Gluteal group*Quadricep group
*Semi group
Semi group descends the posterior hind leg and
form the “hamstrings”. These muscles flex the distal extremity.
Gastrocnemius: flexes the leg and foot, the tendon at the insertion is commonly called the Achilles tendon
Miscellaneous muscles
Arrector pili: Smooth muscles attached to hair on the dorsum. When stimulated these muscles
raise the hair on the back.
Cutaneous trunci: a muscle that attaches to the dermis and controls the insect twich in large animals
Cremaster
Another large animal muscle that is part of the spermatic cord and attaches to the scrotum. This muscle contracts and relaxes, raising and lowering the testicles, helping to regulate testicular temperature