o
Striated in appearance but is involuntary
Muscle Innervation
- is the stimulation of a muscle by an impulse
transmitted by a motor nerve
o
Motor nerves enable the brain to stimulate a muscle to
contract. When the stimulation stops, the muscle relaxes.
Antagonistic Muscle Pairs
Contraction
- the tightening of a muscle. As is contracts, it
becomes shorter and thicker causing the belly to enlarge
Relaxation
- occurs when a muscle returns to its original form. As
the muscle relaxes it becomes longer and thinner, belly is no
longer enlarged.
Flexion
- decreasing the angle
Extension
- increasing the angle
Muscles named for their location
Pectoalis major
– anterior chest wall
Lateralis
- means toward the side
Medialis
- towards the midline
Muscles named for their direction
Oblique
- slanted or at an angle
Rectus
- means in a straight alignment with the vertical axis of
the body
Sphincter –
ring like
Transverse
Muscles named for number of divisions
Biceps brachii
Triceps brachii
Muscles names for their size or shape
Gluteus Maximus-
largest muscle of the butt
Deltoid Muscle
- shaped like an inverted triangle
Muscles named for strange reasons
Hamstring group-
consist of 3 separate groups biceps femoris,
semitendinosus, and semimembranosus muscles. Function- knee
flexion and hip extension
Head
Frontalis
- in the forehead and raises and lowers the eyebrows
Temporalis
- moves the lower jaw up and back to close the mouth
Masseter
- which is one of the strongest in the body, moves the
lower jaw up to close the mouth when chewing
Trunk
External and Internal Oblique-
o
External
- flex and rotate the vertebral column; flex the
torso and compress the abdomen.
o
Internal
- flex the spine, support the abdominal contents,
help breathe, and rotate the spine.
Rectus Abdominis
- helps flex the trunk, assists in breathing, and
supports the spine
Transverse Abdominis
- located on the side of the abdomen.
Engaged when a person laughs or coughs.
Shoulders and Arms
Deltiod
- forms the muscular cap of the shoulder
Trapezius
- muscle moves the head and shoulder blade
Biceps Brachii
- located in the anterior upper arm, flexes the
elbow
Triceps Brachii
- located in the posterior upper arm, extends the
elbow
Muscles of the legs
Rectus Femoris
- extends the leg at the knee
Quadriceps femoris
- made up of 4 muscles including vastus
lateralis and vastus medialis, which flex and extend the leg at
the knee
Hamstring group
- involved in knee flexion and hip extension
Gastrocnemius
- the calf muscle that flexes the knee and bends
the foot downward.
Muscle Disorders
Myalgia
- tenderness or pain in the muscles
Myorrhexis
- the rupture or tearing of a muscle
Rhabdomyolysis
- can result from a direct or indirect muscle
injury. Death of muscle fibers releases their contents into the
bloodstream, where they can lead to complications such as renal
failure.
