UNIT 4 part 5: THE MUSCLES!

1. UNIT 4 part 5: 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 Orbicularis oris Zygomaticus Platysma Buccinator

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

7.  Muscles that move the head: ● Muscles in the neck and upper back used to move the head: Sternocleidomastoid

8.  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

10.  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 • Serratus anterior- pushing/punching “boxer’s muscle”

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

12.  Muscles of the Arm: • Biceps brachii (flex) • Triceps brachii (extend)

13. Flexors of arm/hand • Extensors of arm/hand

14.  Muscles of the Hip & Leg: • Gluteus maximus- major thigh/leg extensor; complex & powerful! • Gluteus medius- steadies pelvis; important in walking, etc.

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

17.  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)

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

20.  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 • *Patellar ligament (tendon) • *Calcaneal tendon (Achilles)

21. Rectus femoris- patellar tendon

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

23. 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

24. Myasthenia gravis: blocks acetylcholine from nerve (body’s immune system produces antibodies that block muscle receptors) • Curare: drug that blocks acetylcholine released from a nerve

25. As a Result of Diseases/Conditions, Muscles can have: • Muscle atrophy: degeneration & loss of muscle mass • From bed-rest or loss of neural stimulation