Muscles

Question 1

External intercostal

Answer 1

Origin: inferior border of ribs
Insertion: Superior border of ribs below
Action: elevates ribs during forced inspiration
Innervation: Intercostal nerve

Question 2

Internal intercostal

Answer 2

Origin: inferior border of ribs
Insertion: superior border of ribs below
Action: interroseous part depresses ribs during forced inspiration, interchondral part elevates the ribs
Innervation: Intercostal nerve

Question 3

Innermost intercostal

Answer 3

Origin: Inferior border of ribs
Insertion: superior border of ribs below
Action: interroseous part depresses ribs during forced inspiration, interchondral part elevates the ribs
Innervation: Intercostal nerve

Question 4

Transversus thoracis

Answer 4

Origin: Posterior surface of lower sternum
Insertion: Internal surface of costal cartilages 2-6
Action: weakly depresses ribs
Innervation: Intercostal nerve

Question 5

Diphragm (3 origins)

Answer 5

Costal: 7-12th ribs
Lumbar medial: L1-L3 vertebral bodies, intervertebral bodies, intervertebral disks, and anterior longitudinal ligament
Lumbar lateral: lateral and medial arcuate ligaments
Sternal: Xiphoid process (posterior surface)
Insertion:Central tendon
Action: principle muscle of respiration (diaphragmatic and thoracic breathing), aids in compression of abdominal viscera.
Innervation: phrenic nerve

Question 6

External oblique

Answer 6

Origin: external surfaces of 5th-12th ribs
Insertion: 1. linea alba 2. pubic tubercle 3. anterior half of iliac crest
Action: compress and support abdominal viscera; flex and rotate trunk contralateral
Innervation: Thoracoabdominal nerves and subcostal nerves

Question 7

Internal oblique

Answer 7

Origin: Thoracolumbar fascia, anterior two thirds of iliac crest and connective tissue deep to inguinal ligament
Insertion: Inferior borders of 10-12th ribs, linea alba, and pubis via conjoint tendon
Action: Compress and support abdominal viscera; flex and rotate trunk. Ipsolateral rotation
Innervation: Thoracoabdominal nerve, subcostal nerve, first lumbar nerve

Question 8

Transverse abdominis

Answer 8

Origin: 1. internal surface of 7-12th costal cartilages. 2. thoracolumbar fascia. 3. iliac crest 4. connective tissue deep to inguinal ligament
Insertion: 1. linea alba with aponeurosis of internal oblique. 2. pubic crest 3. pubis via conjoint tendon
Action: Compresses and supports abdominal viscera
Innervation: Thoracoabdominal nerve, subcostal nerve, and first lumbar nerve

Question 9

Rectus abdominis

Answer 9

Origin: 1. pubic symphysis 2. pubic crest
Insertion: 1. xiphoid process 2. 5-7th costal cartilages
Action: Flexes the trunk (lumbar), compresses abdominal viscera, stabilizes and controls tilt of pelvis (anti lordosis)
Innervation: Thoracoabdominal nerve, subcostal nerve

Question 10

Sternohyoid

Answer 10

Origin: Manubrium of sternum and medial end of clavicle
Insertion: Body of hyoid
Action: Depresses hyoid after elevation during swallowing
Innervation: C1-C3 by a branch of ansa cervicalis

Question 11

Omohyoid

Answer 11

Origin: superior border of scapular near suprascapular notch
Insertion: inferior border of hyoid
Action: depresses, retracts, and steading hyoid
Innervation: C1-C3 by a branch of ansa cervicalis

Question 12

Sternothyroid

Answer 12

Origin: Posterior surface of manubrium of sternum
Insertion: oblique line of thyroid cartilage
Action: Depresses hyoid and elevate larynx
Innervation: C2 and C3 by a branch of ansa cervicalis

Question 13

Thyrohyoid

Answer 13

Origin: Oblique line of thyroid cartilage
Insertion: Inferior border of body and greater horn of hyoid
Action: Depresses hyoid and elevate larynx
Innervation: C1 via hypoglossal nerve

Question 14

Mylohyoid

Answer 14

Origin: Mylohyoid line of mandible
Insertion: Mylohyoid raphe and body of hyoid
Action: elevates hyoid, floor of mouth, and tongue during swallowing and speaking
Innervation: Nerve to mylohyoid, a branch of inferior alveolar nerve

Question 15

Geniohyoid

Answer 15

Origin: Inferior mental spine of mandible
Insertion: Body of hyoid
Action: Pulls hyoid anterosuperiorly, shortens floor of mouth, widens pharynx
Innervation: C1 via hypoglossal nerve

Question 16

Stylohyoid

Answer 16

Origin: Styloid process of temporal bone
Insertion: Body of hyoid
Action: Elevates and retracts hyoid, thus elongating floor of mouth
Innervation: Stylohyoid branch of facial nerve

Question 17

Digastric

Answer 17

Origin: Anterior belly- digastric fossa of mandible
Posterior belly- mastoid notch of temporal bone
Insertion: Intermediate tendon to body and greater horn of hyoid
Action: Working with infrahyoid muscles, depresses mandible against resistance, elevates and steadies hyoid during swallowing and speaking
Innervation: Anterior belly- nerve to mylohyoid, a branch of inferior alveolar nerve
Posterior belly- digastric branch of facial nerve

Question 18

SCM

Answer 18

Origin: lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line
Insertion: Sternal- anterior surface of manubrium of sternum
Action: Contraction- laterally flex neck and rotates it so that face is turned superiorly toward opposite side
Bilateral contraction- Extend neck at atlanto-occipital joint, flexes cervical vertebrae so chin approaches manubrium
Innervation: occipital artery

Question 19

Trapezius

Answer 19

Origin: Medial third of the superior nuchal line, EOP, nuchal ligament, and spinous process C7-T12
Insertion: lateral third of clavicle, acromion, and spine of scapula
Action: Descending part: elevates scap. Ascending part: Depress scap Middle part: Retracts scapula Rotate glenoid cavity superiorly
Innervation: transverse cervical artery

Question 20

Platysma

Answer 20

Origin: Inferior border of mandible, skin, and subcutaneous tissue of lower face
Insertion: Fascia covering superior parts of pectoralis major and deltoid muscles
Action: Draws corners of mouth inferiorly and widens it as in expressions of sadness and fright; draws skin of neck superiorly when teeth are clenched, indication tension
Innervation:Cranial branch of facial nerve