Muscles of Facial Expression  

    Originate in fascia or bones of skull and insert into the skin. Move the skin rather than a joint when they contract.

Muscle

Origin

Insertion Action
Buccinator Maxilla and Mandible Orbicularis oris Compresses cheeks
Corrugator supercilii Orbital rim of frontal bone eyebrow Pulls skin inferiorly and anteriorly; wrinkles brow
Depressor anguli oris Mandible Angle of mouth Depresses corner of mouth
Depressor labii inferioris Mandible Skin of lower lip Depresses lower lip
Frontalis Galea aponeurotica Skin of eyebrow and bridge of nose Raises eyebrows, wrinkles forehead
Levator labii superioris Maxilla  orbicularis oris Elevates upper lip
Levator palpebrae superioris Tendinous band around optic foramen upper eyelid Elevates upper eyelid
Mentalis Mandible Skin of chin Elevates and protrudes lower lip
Occipitalis Occipital and Temporal Galea aponeurotica Tenses and retracts scalp
Orbicularis oris Maxillary bone and mandible lips Compresses, purses lips
Orbicularis oculi Medial margin of orbit Skin around eyelids Closes eye
Platysma Upper thorax between cartilage of second rib and acromion of scapula Mandible and skin of cheek Tenses skin of neck, depresses mandible
Risorious Fascia over parotid gland angle of mouth Draws corner of mouth to the side
Zygomaticus major Zygomatic bone Angle of mouth  Retracts and elevates corner of mouth

 

Extrinsic Eye 

    The movement of the eyeballs are controlled by three pairs of extrinsic muscles. The superior and inferior recti muscles control vertical movements and the lateral and medial recti muscles move the eyeball laterally. The superior oblique muscle moves the eyeball inferiorly and laterally and the inferior oblique muscle moves the eyeball superiorly and laterally.

Muscle

Origin

Insertion Action
Superior rectus Sphenoid bone around optic canal Superior surface of eyeball Eye looks up
Inferior rectus As above Inferior, medial surface of eye Eye looks down
Lateral rectus As above Lateral surface of eyeball Eye rotates laterally
Medial rectus As above Medial surface of eyeball Eye rotates medially
Superior oblique As above Superior, lateral surface of eyeball Eye rolls, looks down and to the side
Inferior oblique Maxillary bone at anterior portion of orbit Inferior, lateral surface of eyeball Eye rolls, looks up and to the side

 

Muscles of Mastication

   These four muscles move the mandible and are involved in chewing. Three of them, masseter, temporalis and medial pterygoid are powerful closers of the joint and account for the strenth of the bite. The medial and lateral pterygoids move the mandible from side to side and also protrude the mandible.

Muscle

Origin

Insertion Action
Masseter zygomatic arch Mandible Elevates mandible
Temporalis Temporal and frontal bones Mandible Elevates mandible
Medial pterygoid Sphenoid (Lateral pterygoid plate) Mandible Elevates mandible; moves mandible side to side
Lateral pterygoid Sphenoid (Lateral pterygoid plate) Mandible Opens jaws, protrudes mandible; moves mandible side to side

 

Muscles of the Floor of the Mouth

    These muscles are part of the suprahyoid (above the hyoid) group of muscles. Together with the infrahyoid muscles (discussed below) these muscles fix the hyoid bone and this enables the hyoid bone to serve as a firm base for the attachment of the tongue. As a group these muscles also elevate the hyoid bone, the floor of the oral cavity, and tongue during swallowing.

Muscle

Origin

Insertion Action
Digastric Anterior belly from mandible and posterior belly from temporal Hyoid  Elevates hyoid and/or depresses mandible
Stylohyoid Temporal (styloid process) Hyoid Elevates larynx
Mylohyoid Mandible Hyoid Elevates hyoid and floor of mouth; depresses mandible

 

Extrinsic Muscles of the Larynx

    The extrinsic muscles of the larynx are also called infrahyoid muscles because they lie inferior to the hyoid bone. These muscles are sometimes called "strap" muscles because of their ribbonlike appearance. These muscles depress the hyoid bone and larynx during swallowing and speech.

Muscle

Origin

Insertion Action
Omohyoid Central tendon attaches to clavicle and 1st rib One belly attaches to hyoid; second to scapula Depresses hyoid and larynx
Sternohyoid Clavicle and Sternum Hyoid As above
Sternothyroid Sternum Thyroid cartilage As above
Thyrohyoid Thyroid cartilage Hyoid Depresses hyoid; elevates thyroid

 

Muscles that Move the Head 

    Balance and movement of the head on the atlanto-occipital joint involves the action of several neck muscles. One example of these muscles is the sternocleidomastoid muscles.

Muscle

Origin

Insertion Action
Sternocleidomastoid Sternum and clavicle Temporal (mastoid process) Together, flexes the neck; alone, one side bends head toward shoulder and turns face to opposite side

 

Muscles that Move the Abdominal Wall

    Four muscles contribute to the abdominal wall. Three are flat, the external oblique, the internal oblique and the transversus abdominis, and one is a straplike muscle, the rectus abdominis.  The fibers in each of these muscles run in a cross direction from one another in a way that maximizes the strength of the three muscles together (think of plywood). The aponeuroses of three muscles,  external oblique, internal oblique and transversus abdominis meet at the midline to form the linea alba. The linea alba is a tough fibrous band of tissue that extends from the xiphoid process to the pubic symphysis.

Muscle

Origin

Insertion Action
Rectus abdominis Pubic (crest and symphysis) Cartilage of ribs (5-7) and xiphoid process Flexes vertebral column, depresses ribs and compresses abdomen
External abdominal oblique External and inferior borders of ribs 5-12 Iliac crest and linea alba Compresses abdomen; depresses ribs; flexes, laterally flexes or rotates vertebral column
Internal abdominal oblique Lumbodorsal fascia and iliac crest Inferior surfaces of ribs 9-12, costal cartilages 8-10, linea alba, and pubis As above
Transversus abdominis Cartilages of inferior ribs, iliac crest, and lumbodorsal fascia Linea alba and pubis Compresses abdomen

 

Muscles Used in Ventilation (Breathing)

    These muscles alter the size of the thoracic cavity during breathing. The diaphragm is the most important. It is domed shaped and consists of two parts: a peripheral muscular portion and a tendinous central portion called the central tendon upon which the muscle fibers insert. Two other muscles, external intercostals and internal intercostals, occupy the spaces between the ribs. The fibers of the external intercostals run obliquely inferiorly and anteriorly and the fibers of the internal intercostals run obliquely inferiorly and posteriorly.

Muscle

Origin

Insertion Action
Diaphragm Xiphoid process, ribs 7-12 and associated costal cartilages, and lumbar vertebrae Central tendinous sheet Contraction expands thoracic cavity, compresses abdominopelvic cavity
External intercostals inferior border of each rib Superior border of next rib below Elevates ribs 
Internal intercostals Superior border of each rib  Inferior b order of previous rib above Depress ribs
Quadratus lumborum Iliac crest and iliolumbar ligament Twelfth rib and transverse processes of L1 to L4 Together they depress ribs; one side alone produces lateral flexion of vertebral column

 

Muscles of the Pelvic Floor

    The levator ani muscle along with a second muscle forms the pelvic floor. These muscles form the pelvic diaphragm which supports and maintains the position of the pelvic viscera. The levator ani muscle is divisible into two parts, the pubococcygeus and iliococcygeus muscles.

Muscle

Origin

Insertion Action
Levator ani Pubis and ischial spine Coccyx and median raphe Tenses floor of pelvis, supports pelvic organs, flexes coccyx, elevates and retracts anus
External anal sphincter Via tendon from coccyx Encircles anal opening Closes anal opening

Muscles that Move the Pectoral Girdle

    These muscles can be grouped into the anterior muscles the move the pectoral girdle and the posterior muscles. The muscles stablize the pectoral girdle so that it can serve as a stable platform on which the humerus can move. These muscles will also adjust the position of the pectoral girdle and particularly the scapula to allow for a wider range of movements for the humerus.

    The anterior muscles are the subclavius, pectoralis minor and the serratus anterior and the posterior muscles are the trapezius, levator scapulae, rhomboideus major and rhomboideus minor.

Muscle

Origin Insertion Action
Subclavius First rib Clavicle Depresses and protracts shoulder
Pectoralis minor Ventral surfaces of ribs 3-5 Scapula Depresses and protracts shoulder, rotates scapula downward, elevates ribs
Serratus anterior Anterior and superior margins of ribs 1-9 Scapula Protracts shoulder and rotates scapula upward
Trapezius Occipital bone, ligamentum nuchae, spinous processes of thoracic vertebrae Clavicle and scapula May elevate, retract, depress, or rotate scapula upward; elevate clavicle; extend neck
Levator scapulae First 4 cervicle vertebrae Scapula Elevates scapula
Rhomboideus major Spines of T2 -T5 Scapula  adducts scapula and rotates it downward
Rhomboideus minor Spines of C7 and T1 Scapula As above

 

Muscles that Move the Arm

    Nine muscles cross the shoulder joint. Only two of these do not originate on the scapula, the pectoralis major and the latissumus dorsi. Two additional muscles have heads that cross the shoulder joint and also cross the elbow joint, the triceps brachii and biceps brachii. These two muscles will be treated in the next group. Four muscles the subscapularis, supraspinatus, infraspinatus and teres minor for the rotator (musclotendinous) cuff which helps to stabilize the shoulder joint.

Muscle

Origin Insertion Action
Pectoralis major Clavicle and sternum Humerus Flexion, adduction and medially rotation of arm
Latissimus dorsi Spines of lower thoracic and all lumbar vertebrae, ribs 8-12, lumbodorsal fascia Humerus Extension, adduction and medially rotation of the arm
Deltoid Clavicle and scapula Humerus Abduction at shoulder, also extension, flexion, medial and lateral rotation
Subscapularis Scapula Humerus Medial rotation at shoulder joint
Supraspinatus Scapula Humerus Abduction at shoulder joint
Infraspinatus Scapula Humerus Lateral rotation at shoulder joint
Teres major Scapula Humerus Extension, adduction and medial rotation at shoulder joint
Teres minor Scapula Humerus Lateral rotation at shoulder joint
Coracobrachialis Scapula Humerus Adduction and flexion at shoulder joint

 

Muscles that Move the Forearm

    These muscles are involved of flexion and extension of the forearm at the elbow joint.

Muscle

Origin Insertion Action
Biceps brachii Scapula Radius Flexion at elbow and shoulder, supinates forearm
Brachialis Humerus Ulna Flexes elbow
Brachioradialis Humerus Radius Flexes elbow
Triceps brachii Scapula and Humerus Ulna Extends elbow
Anconeus Humerus Ulna Extends elbow

 

Muscles that Move the Wrist, Hand and Digits

    This group is know as the extrinsic muscles that move the wrist, hand and digits because they originate outside the hand and insert within it. There are also intrinsic muscles of the hand which will not be covered in this course. These muscles can be divided into two groups on the basis of location and function. The muscle of the anterior compartment (arm in anatomical position) function as flexors while the muscles of the posterior compartment function as extensors.

Muscle

Origin Insertion Action
Flexor carpi radialis Humerus Metacarpals 2 and 3 Flexes and abducts wrist
Palmaris longus Humerus Flexor retinaculum and palmar aponeurosis Flexes wrist
Flexor digitorum superficialis Humerus, ulna and radius Middle phalanges of fingers 2-5 Flexion at proximal interphalangeal joint, metocarpophalangeal joint and wrist joint
Flexor digitorum profundus Ulna Distal phalanges of fingers 2-5 Flexion at distal and proximal interphalangeal joints, metocarpophalangeal joint and wrist joint
Flexor carpi ulnaris Humerus and ulna Pisiform, hamate and metacarpal 5 Flexes and adducts wrist
Extensor carpi radialis Humerus Metacarpal 2 and 3 Extends and abducts wrist
Extensor digitorum Humerus Posterior surfaces of phalanges of finger 2-5 Extension at joints of fingers and wrist
Extensor digiti minimi Humerus Posterior surface of proximal phalanx of little finger Extends joint of little finger
Extensor carpi ulnaris Humerus and ulna Metacarpal 5 Extends and adducts wrist

Muscles that Move the Femur

    These muscles are larger and more powerful than those of the upper limb because they provide stability, enable locomotion and maintain posture.

Muscle Origin Insertion Action
Psoas major Vertebrae T12-L5 Femur Flexes hip and/or lumbar spine
Illiacus Ilium Femur As above

Gluteus maximus Ilium, sacrum, coccyx and lumbodorsal fascia Iliotibial tract and femur Extension and lateral rotation at the hip
Gluteus medius Ilium Femur Abduction and medial rotation at the hip
Gluteus minimus Ilium Femur As above
Tensor fasciae latae Ilium Iliotibial tract Flexion and medial rotation at hip; tenses fascia lata

Piriformis Sacrum Femur Lateral rotation and abduction at thigh
Obturator internus Lateral and medial margins of obturator foramen Femur Lateral rotation at the hip
Obturator externus As above Femur As above
Superior gemellus Ischium Femur As above
Inferior gemellus Ischium Femur As above
Quadratus femoris Ischium Femur As above
Adductor longus Pubis Femur Adduction, flexion, and medial rotation at hip
Adductor brevis Pubis Femur As above
Adductor magnus Pubis and Ischium Femur As above but also inferior portion produces extension and lateral rotation at hip
Pectineus Pubis Femur Flexion, medial rotation and adduction at hip

 

Muscles that Move the Leg   

Muscle Origin Insertion Action
Rectus femoris Ilium Tibia Extends knee; flexes hip
Vastus lateralis Femur Tibia Extends knee
Vastus medialis Femur Tibia Extends knee
Vastus intermedius Femur Tibia Extends knee
Gracilis Pubis Tibia Flexes knee; adduction and medial rotation at hip
Sartorius Ilium Tibia Flexes knee; flexion and lateral rotation at hip
Biceps femoris Ischium and Femur Fibula and tibia Flexes knee; extends and laterally rotates hip
Semitendinosus Ischium Tibia Flexes knee; medially rotates leg; extends hip
Semimembranosus Ischium Tibia As above

 

Muscles that Move the Foot and Toes

Muscle Origin Insertion Action
Tibialis anterior Tibia First metatarsal and first cuneiform Dorsiflexes ankle and inverts foot
Extensor hallucis longus Fibula Distal phalanx of great toe  extends joints of great toe
Extensor digitorum longus Tibia and fibula  phalanges of toes 2-5  extends joints of toes 2-5
Peroneus longus Tibia and fibula First metatarsal and first cuneiform Plantar flexes ankle and everts foot
Peroneus brevis Fibula Fifth metatarsal Plantar flexes ankle and everts foot
Gastrocnemius Femur Calcaneus (via calcaneal tendon) Plantar flexes ankle; inverts and adducts foot; flexes knee
Soleus Fibula and tibia Calcaneus (via calcaneal tendon) Plantar flexes ankle