Unit 4 Part 2 -- Muscles
Anatomy and Physiology of Muscles
- Location and Action of muscles in the human body
- Location, origin, insertion and function of major muscles in the cat
- Smiling Vs. Frowning
When you smile, you use around 17 muscles.
When you frown, you use around 40 muscles.
I. Skeletal Muscle Groups
- Frontalis – Raises eyebrows and skin of forehead.
- Orbicularis oris – Puckers lips. "Kissing muscle"
- Orbicularis oculi – Closes eye. "Winking muscle"
- Zygomaticus – Elevates corners of mouth. "Smiling muscle"
- Depressor anguli oris – Lowers corner of lips (muscle for frowning)
- Levator Labii – raises lips
- Depressor Labii – Lowers lip
Muscles of Mastication (Chewing)
- Temporalis – Elevates mandible.
- Masseter – Closes jaw.
- Mentalis – Raises Chin
Sternocleidomastoid – Behind ears to neck.
Together they flex head on chest
Separately it tilts the head to the side.
- Located on chest.
- Flexor of upper arm.
- Small triangular muscle located deep (beneath) the Pectoralis Major
- Downward rotation and stabilization of the scapula.
- Pectoralis major
- Back Muscles
Trapezius – Back of head to neck.
Elevates shoulders and extends head
"Shrugging and Gargling muscle"
- Latissimus dorsi
- Located on lower back.
- Extensor of upper arm.
Deltoid – Located on shoulder.
- Abductor of upper arm.
- Deltoid – Located on shoulder.
- Flexor of lower arm.
- Extensor of lower arm.
- Biceps brachii
- Flex wrist
- Extend wrist
- Wrist Flexors
- External oblique – Outermost layer of abdominal wall.
- Internal oblique – Middle layer.
Transversus abdominus – Innermost layer.
- Together the three abdominal wall muscles are antagonists to the diaphragm and assist in defecation, urination, vomiting, and childbirth.
- Rectus abdominus – Middle of abdomen and flexes the trunk.
- Intercostals – Between the ribs (Internal for exhaling/expiration and external for inhaling/inspiration)
- Diaphragm – Between thorax and abdomen
Iliopsoas – Flexor of thigh and trunk (if thigh is still)
- Postural muscle of trunk (Keeps trunk from falling backwards).
Gluteus maximus – Buttocks
- Extensor of thighs.
Adductor muscles / Groin muscles(magnus, brevis, and longus)
- Adduct thighs.
Magnus Brevis Longus All 3 Together
Hamstrings – Semimembranosus, Semitendinosus, and Biceps femoris.
- Flexes lower leg (calf to thigh)
Quadriceps femoris – Rectus femoris and Vastus muscles (lateralis, medialis, and intermedialis)
- Extend lower leg.
Sartorius – Longest muscle in body.
- Flexes calf on thigh and thigh on pelvis and rotates leg.
- Lower Leg
Tibialis anterior – Shin muscle
- Dorsiflexes foot
- Responsible for shinsplints
Gastrocnemius – Calf
- Plantar flexes and inverts the foot
Peroneus (fibula) Group – longus, tertius,brevis
- Plantar flexion and eversion of foot.