1. UNIT 4 part 4: THE MUSCLES!

2. MAJOR SKELETAL MUSCLES
*The names of muscles often describe them…a name may indicate a muscle’s relative size, shape, location, action, number of origins, location of attachments, or the direction of its fibers.*

3. MAJOR SKELETAL MUSCLES
Examples:
Triceps brachii: having 3 heads (triceps) or points of origin and located in the brachium (arm).
Pectoralis minor: of small size (minor) located in the pectoral region (chest).
Zygomaticus: located over the zygomatic bone in the face.
Internal (abdominal) obliques: Located near the inside with fibers that run obliquely (in a slanting direction).

4.  Muscles of Facial Expression:
● Lie beneath the skin of the face and scalp and are used to communicate emotion through facial expression

5.  Muscles of Facial Expression:
What do these do?
Orbicularis oculi: wink
Orbicularis oris: pucker the mouth
Zygomaticus: smile

6.  Muscles of Facial Expression:
What do these do?
Platysma: opens mouth as in fright
Buccinator: holds the cheek to your teeth
Risorius: “fake” smile
Procerus: frown

7.  Muscles of Mastication:
● These muscles attach to the mandible and are used in chewing
Masseter
Temporalis

8.  Muscles that move the head:
● Muscles in the neck and upper back used to move the head:
Sternocleidomastoid: if 1 contracts, lateral flexion of head; if both contract, flex the head to the chest

9.  Muscles of the Neck, Shoulder, & Torso:
Deltoid- abduction of arm
Pectoralis major- arm to chest flexion
Latissimus dorsi- arm away from chest extension
Trapezius- stabilizes, raises, retracts & rotates scapula
Latissimus dorsii

11.  Muscles of the Neck, Shoulder, & Torso:
External abdominal oblique- when pair contracts together, aids rectus abdominus; if just one  trunk rotation
Rectus abdominus- stabilize pelvis during walking (flexes vert. column)
Serratus anterior- pushing/punching “boxer’s muscle” 1:34)

12.  Muscles of the Neck, Shoulder, & Torso:
External intercostals- open up rib cage (increase volume)
Internal intercostals- contracts rib cage (decrease volume)
Breathing!

13.  Muscles of the Arm: Biceps brachii (flex lower arm)
Triceps brachii (extend lower arm)

14. Flexors of arm/hand
Extensors of arm/hand

15.  Muscles of the Hip & Leg:
Gluteus maximus- major thigh/leg extensor; complex & powerful!
Gluteus medius- steadies pelvis; important in walking, etc.; abducts & rotates thigh medially 1:45)

17.  Muscles of the Hip & Leg:
Sartorius- flexes & laterally rotates thigh/leg
Gracilis- adducts thigh/leg

18.  Muscles of the Hip & Leg:
QUADRICEP MUSCLES
Vastus lateralis- extends knee; leg flexion
Rectus femoris- extends knee; leg flexion
Vastus medialis- extends knee; leg flexion
(vastus intermedius underneath; don’t need to know)

19.  Muscles of the Hip & Leg:
Gastrocnemius- one of two major muscles of calf (plantar flexion);
Soleus- calf muscle underneath gastrocnemius (plantar flexion)
Tibialis anterior- dorsiflexion of foot

21.  Muscles of the Hip & Leg:
HAMSTRING MUSCLES
Biceps femoris- extends leg back & flexes knee
Semitendonosus- extends leg back & flexes knee
Semimembranosus- extends
leg back & flexes knee

23. *Calcaneal tendon (Achilles): tendon of gastrocnemius
Rectus femoris patellar tendon
*Patellar tendon (tendon); extends from rectus femoris to tibial tuberosity (Osgood-Schlatter)
*Calcaneal tendon (Achilles): tendon of gastrocnemius

24.  Miscellaneous:
Retinaculum- strong ligaments that secure a group of tendons in place

25. Diseases/Conditions that Affect the Muscular System:
Lou Gehrig’s (ALS): motor neurons break down so the impulse can’t travel to muscles
Botulism: toxin produced by a particular strain of bacteria; interferes with the release of acetylcholine  die of respiratory failure

26. Botox: inject the botulism toxin to paralyze muscles so don’t see wrinkles
Improper canning can lead to botulism poisoning

27. Muscle atrophy: degeneration & loss of muscle mass
Myasthenia gravis: body’s immune system produces antibodies that block muscle receptors for acetylcholine released from nerve at neuromuscular junction
Muscle atrophy: degeneration & loss of muscle mass
From bed-rest or loss of neural stimulation

29. Muscular Dystrophy: group of diseases that cause progressive weakness and loss of muscle mass.
abnormal genes (mutations) interfere with the production of proteins needed to form & maintain healthy muscle

31. Spasm: muscle cramp
often due to overuse, dehydration, electrolyte abnormalities, or poor circulation
Treatment: drink water/Gatorade; stop & gently stretch muscle; ice/heat muscle