8 8 Major Skeletal Muscles What muscle names

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8. 8 Major Skeletal Muscles

8. 8 Major Skeletal Muscles

What muscle names tell us Relative size v Shape v Location v Action v

What muscle names tell us Relative size v Shape v Location v Action v Number of attachments v Direction of fibers v

Examples Zygomaticus – originates at the zygomatic bone v Gluteus maximus – originates in

Examples Zygomaticus – originates at the zygomatic bone v Gluteus maximus – originates in the gluteal region and is a large muscle v Tibialis anterior – originates on the anterior surface of the tibia v

Muscles of Facial Expression

Muscles of Facial Expression

Epicranus Origin – occipital bone v Insertion – skin and muscles around eye v

Epicranus Origin – occipital bone v Insertion – skin and muscles around eye v Action – raises eyebrow v

Orbicularis oculi Origin – maxillary and frontal bones v Insertion – skin around eye

Orbicularis oculi Origin – maxillary and frontal bones v Insertion – skin around eye v Action – closes eye v

Orbicularis oris Origin – muscles near the mouth v Insertion – skin of lips

Orbicularis oris Origin – muscles near the mouth v Insertion – skin of lips v Action – closes and protrudes lips v

Buccinator Origin – outer surfaces of maxilla and mandible v Insertion – orbicularis oris

Buccinator Origin – outer surfaces of maxilla and mandible v Insertion – orbicularis oris v Action – compresses cheeks inward v

Zygomaticus Origin – zygomatic bone v Insertion – orbicularis oris v Action – raises

Zygomaticus Origin – zygomatic bone v Insertion – orbicularis oris v Action – raises corner of mouth v

Platysma Origin – fascia in upper chest v Insertion – lower border of mandible

Platysma Origin – fascia in upper chest v Insertion – lower border of mandible v Action – draws angle of mouth downward v

Muscles of Mastication

Muscles of Mastication

Masseter Origin – lower border of zygomatic arch v Insertion – lateral surface of

Masseter Origin – lower border of zygomatic arch v Insertion – lateral surface of mandible v Action – closes jaw v

Temporalis Origin – temporal bone v Insertion – coronoid process and lateral surface of

Temporalis Origin – temporal bone v Insertion – coronoid process and lateral surface of mandible v Action – closes jaw v

Muscles that move the head

Muscles that move the head

Sternocleidomastoid Origin – anterior surface of sternum and upper surface of clavicle v Insertion

Sternocleidomastoid Origin – anterior surface of sternum and upper surface of clavicle v Insertion – mastoid process of temporal bone v Action – pulls head to one side, pulls head toward chest, or raises sternum v

Splenius capitis Origin – spinous processes of lower cervical and upper thoracic vertebrae v

Splenius capitis Origin – spinous processes of lower cervical and upper thoracic vertebrae v Insertion – mastoid process of temporal bone v Action – rotates head, bends head to one side, or brings head into an upright position. v

Semispinalis capitis Origin – processes of lower cervical and upper thoracic vertebrae v Insertion

Semispinalis capitis Origin – processes of lower cervical and upper thoracic vertebrae v Insertion – occipital bone v Action – extends head, bends head to one side, or rotates head. v

Muscles that move the pectoral girdle Closely associated with those that move the arm.

Muscles that move the pectoral girdle Closely associated with those that move the arm. v Many of these move the scapula up and down, back and forth. v

Muscles that move the pectoral girdle

Muscles that move the pectoral girdle

Trapezius Origin – occipital bone and spines of cervical and thoracic vertebrae v Insertion

Trapezius Origin – occipital bone and spines of cervical and thoracic vertebrae v Insertion – clavicle; spine and acromion process of scapula v Action – rotate scapula and raises arm, raises scapula, pulls scapula medially or pulls scapula and shoulder downward. v

Rhomboideus major Origin – spines of upper thoracic vertebrae v Insertion – medial border

Rhomboideus major Origin – spines of upper thoracic vertebrae v Insertion – medial border of scapula v Action – raises and adducts scapula v

Levator scapula Origin – transverse process of cervical vertebrae v Insertion – medial margin

Levator scapula Origin – transverse process of cervical vertebrae v Insertion – medial margin of scapula v Action – elevates scapula v

Serratus anterior Origin – outer surface of upper ribs v Insertion – ventral surface

Serratus anterior Origin – outer surface of upper ribs v Insertion – ventral surface of scapula v Action – pulls scapula anteriorly and downward v

Pectoralis minor Origin – sternal ends of upper ribs v Insertion – coracoid process

Pectoralis minor Origin – sternal ends of upper ribs v Insertion – coracoid process of scapula v Action – pulls scapula anteriorly and downward or raises ribs v

Muscles that move the arm Arm is freely movable. v Muscles are grouped by

Muscles that move the arm Arm is freely movable. v Muscles are grouped by their primary action. v Flexion – flexors v Extension – extensors v Abduction – abductors v Rotation - rotators v

Flexors Coracobrachialis v Pectoralis major v

Flexors Coracobrachialis v Pectoralis major v

Coracobrachialis

Coracobrachialis

Extensors Teres major v Latissimus dorsi v

Extensors Teres major v Latissimus dorsi v

Abductors Supraspinatus v Deltoid v

Abductors Supraspinatus v Deltoid v

Rotators Subscapularis v Infraspinatus v Teres minor v

Rotators Subscapularis v Infraspinatus v Teres minor v

Muscles that move the forearm Most forearm movement is accomplished by muscles that connect

Muscles that move the forearm Most forearm movement is accomplished by muscles that connect the radius or ulna to the humerus or pectoral girdle. v Again, we have flexors, extensors and rotators. v

Flexors Biceps brachii v Brachialis v Brachioradialis v

Flexors Biceps brachii v Brachialis v Brachioradialis v

Extensor v Triceps brachii

Extensor v Triceps brachii

Rotators Supinator v Pronator teres v Pronator quadratus v

Rotators Supinator v Pronator teres v Pronator quadratus v

Muscles that move the hand v v v Flexors Anterior side Flexor carpi radialis

Muscles that move the hand v v v Flexors Anterior side Flexor carpi radialis Flexor carpi ulnaris Palmaris longus Flexor digitorum profundus v v v Extensors Posterior side Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris Extensor digitorum

Muscles of the abdominal wall External oblique v Internal oblique v Transversus abdominis v

Muscles of the abdominal wall External oblique v Internal oblique v Transversus abdominis v Rectus abdominis v

Muscles of the pelvic outlet v v Pelvic diaphragm Levator ani v v Urogenital

Muscles of the pelvic outlet v v Pelvic diaphragm Levator ani v v Urogenital diaphragm Superficial transversus perinei Bulbospongiosus Ischiocavernosus

Muscles that move thigh Anterior group v v Psoas major Iliacus Posterior group v

Muscles that move thigh Anterior group v v Psoas major Iliacus Posterior group v v Gluteus maximus Gluteus medius Gluteus minimus Tensor fasciae latae

Muscles that move the leg Flex the knee v v Biceps femoris Semitendinosus Semimembranosus

Muscles that move the leg Flex the knee v v Biceps femoris Semitendinosus Semimembranosus Sartorius Extend the knee v v v Quadriceps femoris group, consisting of: Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius

Muscles that move the foot Dorsal flexors v v v Tibialis anterior Fibularis Extensor

Muscles that move the foot Dorsal flexors v v v Tibialis anterior Fibularis Extensor digitorum Plantar flexors v v v Gastrocnemius Soleus Flexor digitorum longus