1. © 2017 Pearson Education, Inc.

2. Divisions of Skeletal Muscles (7-9)
Axial muscles
Arise on the axial skeleton
About 60 percent of skeletal muscles in this category
Position head and spinal cord and move rib cage
Appendicular muscles
Stabilize or move the appendicular skeleton

3. Figure 7-12a An Overview of the Major Skeletal Muscles.

4. Figure 7-12b An Overview of the Major Skeletal Muscles.

5. Origin, Insertion, and Action (7-9)
The end of the muscle that stays stationary
Insertion
The end of the muscle that moves when the muscle contracts
Action
What happens when the muscle contracts
Examples: flexion, extension, adduction, abduction

6. Description of Actions (7-9)
Described as relative to the bone that is moved
Example, “flexion of the forearm”
Described as the joint that is involved
Example, “flexion at the elbow”

7. Primary Actions of Muscles (7-9)
Prime mover, or agonist
The muscle that is chiefly responsible for producing a movement
Antagonist
Muscle that opposes a movement by another muscle
A functional opposite to the agonist
Synergist
Muscle that helps the prime mover work efficiently
Fixators are synergists that stabilize the origin of a prime mover

8. Example of Primary Actions of Muscles (7-9)
Flexion of the elbow
The biceps brachii is prime mover in flexion of the elbow
The triceps brachii is an antagonist to the biceps brachii
The brachialis is a synergist in flexion of the elbow assisting the biceps brachii
The rhomboid muscles are fixators during flexion of the elbow in that they stabilize one of the origins of the biceps brachii

9. Basis for Names of Skeletal Muscles (7-9)
Names of muscles often give clues to identification
Orientation of muscle fibers
Structural features
Origin and insertion
Primary function

10. Axial Muscles (7-10) Muscles of the head and neck Muscles of the spine
Muscles of the trunk
Muscles of the pelvic floor

11. Muscles of the Head and Neck (7-10)
Muscles of the face
Originate on surface of skull
Insert into dermis of the skin
Contraction causes movement of the skin
Muscles associated with the mouth
Orbicularis oris – constricts the opening of the mouth
Buccinator – compresses cheeks when blowing forcefully
Temporalis and pterygoid – assist the masseter in chewing

12. Muscles of the Head and Neck cont. (7-10)
Scalp contains a two-part muscle, the occipitofrontalis
Anterior is the frontalis muscle
Posterior is the occipitalis muscle
Two are connected by the epicranial aponeurosis
Platysma
Covers ventral neck
Extends from the base of the neck to the mandible

13. Figure 7-13 Muscles of the Head and Neck.

14. Figure 7-13 Muscles of the Head and Neck.

15. Muscles of the Neck (7-10) Muscles of the neck Includes:
Control position of the larynx
Depress the mandible
Tense the floor of the mouth
Provide stable foundation for muscles of the tongue and pharynx
Includes:
Digastric
Mylohyoid
Stylohyoid
Sternocleidomastoid
Omohyoid

16. Figure 7-14 Muscles of the Anterior Neck.

17. Muscles of the Spine (7-10)
Splenius capitis and semispinalis capitis
Work together to either extend the head or tilt the head
Erector spinae, or spinal extensors
Maintain an erect spinal column and head
Subdivided into: spinalis, longissimus, and iliocostalis divisions
Quadratus lumborum
Flex the spinal column and depress the ribs

18. Figure 7-15 Muscles of the Spine.
Semispinalis capitis
Splenius capitis
Erector spinae
muscles
Iliocostalis
Longissimus
Spinalis
Quadratus
lumborum
Figure 7-15 Muscles of the Spine.

19. Axial Muscles of the Trunk (7-10)
External and internal intercostals
Externals elevate ribs and internals depress ribs
Diaphragm
Separates the thoracic and abdominopelvic cavities
External and internal obliques, and the transversus abdominis
Compress abdomen, can flex spine
Rectus abdominis
Depresses ribs, flexes spine

20. Figure 7-16 Oblique and Rectus Muscles and the Diaphragm.

21. Figure 7-16 Oblique and Rectus Muscles and the Diaphragm.

22. Muscles of the Pelvic Floor (7-10)
Pelvic cavity floor called the perineum
Formed by broad sheet of muscles that:
Support the organs of the pelvic cavity
Flex the coccyx
Control movement of material through the anus and urethra

23. Figure 7-17 Muscles of the Pelvic Floor.

24. Figure 7-17 Muscles of the Pelvic Floor.

25. Appendicular Muscles (7-11)
Muscles of the shoulder and upper limbs
Muscles that position the pectoral girdle
Muscles that move the arm, forearm, and wrist
Muscles that move the hand and fingers
Muscles of the pelvic girdle and lower limbs
Muscles that move the thigh and leg
Muscles that move the foot and toes

26. Muscles That Position the Pectoral Girdle (7-11)
Trapezius
Diamond-shaped muscle, has many actions depending on the region
Rhomboid
Adducts and rotates scapula laterally
Levator scapulae
Elevates scapula (as in shrugging your shoulders)
Serratus anterior
Abducts and rotates scapula
Pectoralis minor and subclavius
Depress and abduct shoulder

27. Figure 7-18 Muscles That Position the Pectoral Girdle.

28. Figure 7-18 Muscles That Position the Pectoral Girdle.

29. Muscles That Move the Arm (7-11)
Deltoid
Major abductor of the arm
Supraspinatus assists at beginning of movement
Subscapularis, teres major, infraspinatus, and teres minor
Rotate the arm
Pectoralis major
Flexes the arm at the shoulder
Latissimus dorsi
Extends the arm at the shoulder

30. Figure 7-19 Muscles That Move the Arm.

31. Figure 7-19 Muscles That Move the Arm.

32. Rotator Cuff (7-11)
Tendons of four muscles form a supportive capsule around the shoulder joint called the rotator cuff
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Common site of sports injuries such as a muscle strain (tear or break in muscle)

33. Animation: A&P Flix: Rotator cuff muscles: An overview (a)

34. Animation: A&P Flix: Rotator cuff muscles: An overview (b)

35. Muscles Moving the Forearm and Wrist (7-11)
Biceps brachii
Flexes the elbow and supinates forearm
Triceps brachii
Extends elbow
Brachialis and brachioradialis
Flex elbow
Flexor carpi ulnaris, flexor carpi radialis, and palmaris longus
Flex wrist

36. Figure 7-20 Muscles That Move the Forearm and Wrist.

37. Muscles Moving the Forearm and Wrist cont. (7-11)
Extensor carpi radialis and extensor carpi ulnaris
Extend wrist
Pronators and the supinator
Rotate radius

38. Figure 7-20 Muscles That Move the Forearm and Wrist.

39. Muscles That Move the Hand (7-11)
Extensor digitorum and flexor digitorum
Extends and flexes fingers respectively
Abductor pollicis and extensor pollicis
Abducts and extends thumb respectively
Muscles located in the forearm
Only tendons cross the wrists
Wide bands of connective tissue hold tendons in place
Inflammation of this tissue can result in carpal tunnel syndrome

40. Muscles of the Pelvis and Lower Limbs (7-11)
Divided into three functional groups
Muscles that work across the hip joint to move the thigh
Muscles that work across the knee joint to move the leg
Muscles that work across various joints of the foot to move the ankles, feet, and toes

41. Muscles That Move the Thigh (7-11)
Gluteal group
Covers lateral surface of iliac bones
Includes the gluteus maximus, the largest and most posterior
Produces extension, rotation, and abduction at hip joint
Adductors
Include the adductor magnus, adductor brevis, adductor longus, the pectineus, and the gracilis
Largest hip flexor is the iliopsoas
Composed of the psoas major and the iliacus

42. Figure 7-21a-b Muscles That Move the Thigh.

43. Figure 7-21c Muscles That Move the Thigh.
Iliopsoas Group
Psoas major
Iliacus L5 L5
Adductor Group
Pectineus
Adductor brevis
Adductor longus
Adductor magnus
Gracilis c
Anterior view of the
Iliopsoas and
adductor groups
Figure 7-21c Muscles That Move the Thigh.

44. Muscles That Move the Leg (7-11)
Flexors are on posterior and medial surfaces
Three are collectively known as the hamstrings
Biceps femoris, semimembranosus, and semitendinosus
Sartorius crosses hip and knee joints and produces lateral rotation at the hip
Popliteus unlocks the knee joint
Extensors are on anterior and lateral surfaces
Collectively known as the quadriceps femoris
Includes the rectus femoris and the three vastus muscles

45. Figure 7-22 Muscles That Move the Leg.

46. Figure 7-22 Muscles That Move the Leg.

47. Muscles That Move the Foot (7-11)
Gastrocnemius
Largest muscle of the calf
Assisted by the underlying soleus
They share a common calcaneal tendon
Both muscles are plantar flexors
Fibularis, or peroneus muscles
Produce eversion and plantar flexion
Tibialis muscles
Cause inversion of the foot
Tibialis anterior is largest and produces dorsiflexion

48. Muscles That Move the Toes (7-11)
Originate on surface of the tibia, fibula, or both
Tendons surrounded by synovial tendon sheaths at ankle
Sheaths stabilized by retinacula
Smaller intrinsic muscles originate on tarsal and metatarsal bones
Contractions move the toes

49. Figure 7-23a Muscles That Move the Foot and Toes.

50. Figure 7-23b-d Muscles That Move the Foot and Toes.

51. Four Effects of Aging on Skeletal Muscle (7-12)
Skeletal muscle fibers become smaller in diameter
Skeletal muscles become less elastic
Increasing fibrous tissue (fibrosis) makes muscle less flexible
Tolerance for exercise decreases
Tendency to tire quickly
Decrease in thermoregulation
Ability to recover from injury is decreased

52. Exercise Engages Multiple Systems (7-13)
Muscular system
Active muscles consume oxygen and generate CO2 and heat
Cardiovascular system
Increases heart rate and speeds up delivery of oxygen
Respiratory system
Increases rate and depth of respiration
Integumentary system
Dilation of blood vessels and sweating combine to increase cooling
Nervous and endocrine systems
Control heart rate, respiratory rate, and release of stored energy