1. Naming Skeletal Muscle

2. Types of Muscles
Most often body movements are the result of the activity of pairs or teams of muscles acting together or against each other
Muscles that oppose or reverse a movement are antagonists
E.g. the biceps is antagonized by the triceps
The muscle that has the major responsibility for causing a particular movement is called the prime mover

3. Types of Muscle
The muscles that help prime movers by producing the same movement or by reducing undesirable or unnecessary movement are called synergist (syn= together, erg = work)
Fixators are specialized synergists. They act to hold a bone still or to stabilize the origin of a prime mover so all the tension can be used to move the insertion bone
e.g. the muscles that anchor the scapula

4. Naming Skeletal Muscles
Muscles are named on the basis of several criteria, each of which focuses on a particular structural or functional characteristic

5. Naming Skeletal Muscles
Direction of the muscle fibers: muscles are named in reference to some imaginary line, usually the midline of the body or the long axis of a limb bone
- Rectus: (straight) its fibers run parallel to that imaginary line
- Oblique: (slanted) its fiber run obliquely to the imaginary line
Oblique
Rectus

6. Naming Skeletal Muscles
2. Relative size of the muscle:
Maximus: largest
Minimus: smallest
Longus: long
e.g. gluteus Maximus
3. Location of the muscle: some muscles are named for the bone with which they are associated
e.g. temporalis and frontalis

7. Naming Skeletal Muscles
4. Number of origins: When the term biceps, triceps or quadriceps forms part of a muscle name, one can assume that the muscle has two, three, or four origins 5. Location of the muscle’s origin and insertion: Muscles are named for their attachment sites. e.g. sternocleidomastoid muscle: has its origin on the sternum and clavicle and inserts on the mastoid process of the temporal bone

8. Naming Skeletal Muscles
6. Shape of the muscle:
Deltoid: triangular
7. Action of the muscle: When muscles are named for their actions, terms such as flexor, extensor and adductor appear in their names

9. Head Muscles

10. Facial Muscles
Frontalis: covers the frontal bone. This muscle allows you to raise your eyebrows
Orbicularis Oculi: fibers that run in circles around the eyes. It allows you to close your eyes, squint, blink and wink
- Orbicularis: circling
- Oculi: eyelike

11. Facial Muscles
Orbicularis Oris: The circular muscle of the lip, it is often called the “kissing” muscle
- Oris: Mouth
Buccinator (Bu’si-nator): runs horizontally across the cheek and inserts into the orbicularis oris, it flattens the cheek. It is also listed as a chewing muscle

12. Facial Muscles
Zygomaticus: extends from the corner of the mouth to the cheek bone. It is often referred to as the smiling muscle

13. Chewing Muscles
Masseter: Covers the angle of the lower jaw as it runs from the zygomatic process of the temporal bone to the mandible. This muscle closes the jaw by elevating the mandible
Temporalis: is a fan-shaped muscle overlying the temporal bone. It inserts into the mandible and acts as a synergist of the masseter in closing the jaw

14. Trunk and Neck Muscles
Anterior Muscle

15. Sternocleidomastoid
The paired muscles are two headed muscles, one found on each side of the neck.
One arises from the sternum and the other arises from the clavicle
The heads fuse before inserting into the mastoid process of the temporal bone
When both muscles contract together, they flex your neck
If just one muscle contracts, the head is rotated towards the opposite side

16. Pectoralis Major
A large fan-shaped muscle covering the upper part of the chest
Its origin is from the shoulder girdle and the first six ribs and inserts on the proximal end of the humerus
It is the prime mover for shoulder flexion and adduction

17. Intercostal Muscles Deep muscles found between the ribs
The external intercostals are important in breathing because they help to raise the rib cage for breathing air in
The internal intercostals depress the rib cage, which helps to move air out of the lungs when you exhale

18. Muscles of the Abdominal Girdle
Rectus abdominis: the paired strap-like muscles are the most superficial muscles of the abdomen.
They run from the pubis to the rib cage
Their main function is to flex the vertebral column
They also compress the abdominal contents and are involved in forced breathing

19. Muscles of the Abdominal Girdle
External oblique: are paired superficial muscles that make up the lateral walls of the abdomen
Their fibers run downward and medially from the last eight ribs and insert into the ilium
They flex the vertebral column but they also rotate the trunk and bend it laterally

20. Muscles of the Abdominal Girdle
Internal oblique: Paired muscles deep to the external obliques
Their fiber run at right angles to those of the external obliques
They raise from the iliac crest and insert into the last three ribs
Their functions are the same as those of the external obliques

21. Muscles of the Abdominal Girdle
Transversus abdominis: The deepest muscle of the abdominal wall and has fibers that run horizontally across the abdomen
It raises from the lower ribs and iliac crest and inserts into the pubis
This muscle compresses the abdominal contents

22. Transversus abdominis
Which one is which?
Transversus abdominis
Internal Oblique
External Oblique

23. Trunk and Neck Muscles
Posterior Muscle

24. Trapezius (Trah-pee-ze-us)
These muscles are the most superficial muscles of the posterior neck and upper trunk
When seen together, they form a diamond or kite-shaped muscle mass
These muscles are antagonists of the sternocleidomastoids
They also can elevate, depress, adduct and stabilize the scapula

25. Latissimus Dorsi
The large, flat muscle pair that covers the lower back
It originates on the lower spine and ilium and then sweeps superiorly to insert into the proximal end of the humerus
It extends and adducts the shoulder and help maintain upright posture

26. Erector Spinae (spi’na)
It is a prime mover of back extension.
Each erector spinae is a composite muscle consisting of three muscle columns that collectively span the entire length of the vertebral column
They act as powerful back extensors and also provide resistance that helps control the action of bending over at the waist

27. Deltoid
They are fleshy, triangle-shaped muscles that form the rounded shape of your shoulders
The deltoids are the prime movers of arm abduction
It is the antagonist of latissimus dorsi

28. Muscles of the upper limb

29. Upper Limb Muscles The upper limb muscles fall into three groups:
Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus
E.g. the pectoralis major, latissimus dorsi and deltoid
2. Muscles that cause movement at the elbow joint
E.g. Biceps, Triceps
3. Muscles of the forearm, which insert on the hand bones and cause their movement

30. Biceps Brachii (bra’ke-i)
It originates by two heads from the shoulder girdle and inserts into the radial tuberosity.
It is the powerful prime mover for flexion of the forearm and acts to supinate the forearm

31. Triceps Brachii The only muscle fleshing out the posterior humerus.
Its three heads arise from the shoulder girdle and proximal humerus and it inserts into the olecranon process of the ulna

32. Muscles of the lower limb

33. Iliopsoas (il’e-o-so’us)
A fused muscle composed of two muscles
It runs from the iliac bone and lower vertebrae deep inside the pelvis to insert on the lesser trochanter of the femur
It is a prime mover of hip flexion
It also acts as a postural muscle to keep the upper body from falling backward when standing up

34. Adductor Muscles
The muscle of the adductor group form the muscle mass at the medial side of each thigh
They adduct the thighs together
The adductors have their origin on the pelvis and insert on the femur

35. Gluteus Maximus
It is a superficial muscle of the hip that forms most of the flesh of the buttock
It is a powerful hip extensor that acts to bring the thigh in a straight line with the pelvis
It originates from the sacrum and iliac bones and runs to insert on the gluteal tuberosity of the femur

36. Gluteus Medius
It runs from the ilium to the femur, beneath the gluteus maximus for most of its length
It is a hip abductor and is important in steadying the pelvis during walking
It is an important site for giving intramuscular injections

37. Sartorius A thin, strap-like muscle
It runs obliquely across the thigh from the anterior iliac crest to the medial side of the tibia
It is a weak thigh flexor

38. Quadriceps Group
It consists of four muscles: one rectus femoris and three vastus muscles
The rectus femoris originates on the pelvis
The vastus muscles originates from the femur
The four muscles insert into the tibial tuberosity
The group as a whole acts to extend the knee powerfully

39. Hamstring Group
The muscles forming the muscle mass of the posterior thigh are the hamstrings
It extends the thigh and flexes the knee
The group consists of three muscles, the biceps femoris, semimembranosus and semitendinosus which originate on the ischial tuberosity and run down the thigh to insert on both sides of the proximal tibia

40. Tibialis Anterior
It is a superficial muscle on the anterior leg. It arises from the upper tibia and then parallels the anterior crest as it runs to the tarsal bones where it inserts by a long tendon
It acts to dorsiflex and invert the foot

41. Peroneus Muscles
The peroneus muscles of this group are found on the lateral part of the leg
They arise from the fibula and insert into the metatarsal bones of the foot
The group as a whole plantar flexes and everts the foot

42. Gastrocnemius (gas’trok-ne’meus)
It is a two bellied muscle that forms the curved calf of the posterior leg
It arises by two heads, one from each side of the distal femur, and inserts through the large Achilles tendon into the heel of the foot
It is also known as the toe dancers muscle