The origin, insertion, and action(s) of 1. Sternocleidomastoid 2. Trapezius 3. R

ID: 3476301 • Letter: T

Question

The origin, insertion, and action(s) of 1. Sternocleidomastoid 2. Trapezius 3. Rectus abdominis 4. External oblique 5. Internal oblique 6. Erector spinae 7. Deltoid 8. Pectoralis major 9. Latissimus dorsi The origin, insertion, and action(s) of 1. Sternocleidomastoid 2. Trapezius 3. Rectus abdominis 4. External oblique 5. Internal oblique 6. Erector spinae 7. Deltoid 8. Pectoralis major 9. Latissimus dorsi 1. Sternocleidomastoid 2. Trapezius 3. Rectus abdominis 4. External oblique 5. Internal oblique 6. Erector spinae 7. Deltoid 8. Pectoralis major 9. Latissimus dorsi

Explanation / Answer

MUSCLE NAME

ORIGIN

INSERTION

ACTION

STERNOCLEIDOMASTOID

Largest n most superficial neck muscle

Originates at the manubrium of the sternum (sterno) and the clavicle (cleido)

Insertion at the mastoid process of the temporal bone of the skull

-function is to rotate the head to the opposite side

-flexes the neck

-also acts as an accessory muscle of respiration along with scalene muscles of the neck

TRAPEZIUS – diamond shaped muscle

Divided into 3 functional parts - upper (descending), middle(transverse), lower(ascending)

The upper(or descending) fibers of the trapezius originate from the spinous process of C7, the external occipital protuberance, the medial third of the superior nuchal line of the occipital bone (both in the back of the head) and ligamentum nuchae

-The middle fibers, or transverse of the trapezius arise from the spinous process of the seventh cervical (both in the back of the neck), and the spinous processes of the first, second, and third thoracic vertebrae

The inferior (or ascending) fibers of the trapezius arise from the spinous processes of the remaining thoracic vertebrae (T4–T12). From this origin they proceed upward and laterally to converge near the scapula and end in an aponeurosiswhich glides over the smooth triangular surface

The upper fibres are nserted into the posterior border of the lateral third of the clavicle

The middle fibres hey are inserted into the medial margin of the acromion and into the superior lip of the posterior border of the spine of the scapula

The inferior inserted into a tubercle at the apex of this smooth triangular surface.of spine

ITS function is

To move scapula

Support arm

RECTUS ABDOMINIS- LONG FLAT PAIRED MUSCLES OF THE ABDOMEN SEPERATED BY LINEA ALBA

t extends from the pubic symphysiS, pubic crest and pubic tubercle inferiorly, to the xiphoid process and costal cartilagesof ribs V to VII superiorly

It is inserted distally at the costal cartilages of ribs 5-7 and the xiphoid process of the sternum.[2]

The rectus abdominis muscle is contained in the rectus shEATH,

Function is the flexion of the lumbar spine

EXTERNAL OBLIQUE- It is the largest and superficial muscle amongst the 3 lateral anterio abdominal muscle

Originates from the 5-12 RIBS

INSERTS AT THE ILIAC CREST, LINEA ALBA AND PUBIC TUBERCLE

Function is contralateral rotation of torso

INTERNAL OBLIQUE-Its an abdominal muscle below ext oblique and above transverse abdominis

Origin at Inguinal ligament, Iliac crest and the Lumbodorsal fascia

Insertin at linea alba , pectin pubis via conjoint tendons and ribs 10-12

Function is to Bilateral: Compresses abdomen

Unilateral: ipsilateral trunk rotation

ERECTOR SPINAE – BUNDLE OF MUSCLE AND TENDONS

Origin from Spinous processes of T9-T12 thoracic vertebrae medial slope of the dorsal segment of illiac crest

Insertion at the spinous processes of T1 and T2 thoracic vertebrae and the cervical vertebrae

Function – extends the vertebral column

DELTOID – MUSCLE THAT FORMS ROUNDED CONTOUR OF SHOULDER

ORIGIN the anterior border and upper surface of the lateral third of the clavicle, acromion spine of the scapulA

INSERTIN AT deltoid tuberosity of humeruS

FUNCTION – shoulder abduction, flexion and extension

PECTORALIS MAJOR- SITUATED AT CHEST OF HUMAN BODY IS A FAN SHAPED MUSCLE

ORIGIN - Clavicular head: anterior border of the medial half of the clavicle
Sternocostal head: anterior surface of the sternum the superior six costal cartilagesand the aponeurosis of the external oblique muscle

INSERTION Lateral lip of the bicipital groove of the humerus

Clavicular head: flexes the humerus
Sternocostal head: Adducts the humerus
As a whole, adducts and medially rotates the humerus. It also draws the scapula anteriorly and inferiorly

LATTISIMUS DORSI- LARGE FLAT MUSCLE OF THE BACK

ORIGION Spinous processes of vertebraeT7L5, thoracolumbaR fascia, iliac cret, Tinferior 3 or 4 riBS andINFERIO ANGLE scapula

INSERTION Floor of intertubercular groove of the humerus

FUNCTIONS Adducts, extends and internally rotates the arm when the insertion is moved towards the origin. When observing the muscle action of the origin towards the insertion, the lats are a very powerful rotator of the trunk.