Muscle Anatomy

Question 1

Sternocleidomastoid

Answer 1

Innervation: Accessory nerve, Cranial Nerve 11
Origin: sternal end of the clavicle and manubrium
Insertion: mastoid region of the skull
Action: bilaterally flexes neck. unilaterally turns face to opposite side

Question 2

Semispinalis Capitis

Answer 2

Innervation: Spinal Nerves
Origin: articular process of the inferior cervical vertebrae and the transverse process of the superior thoracic vertebrae
Insertion: Occipital bone
Action: bilaterally extends head. Unilaterally flexes neck to same side

Question 3

Splenius Capitis

Answer 3

Innervation: cervical spinal nerves
Origin: Spinous process/ligaments of inferior cervical vertebrae
Insertion: Mastoid process (temporal bone) occipital bone
Action: bilateral extend head. unilaterally laterally flexes neck to same side

Question 4

Longissimus cervicis

Answer 4

Origin: transverse processes of superior thoracic vertebrae
Insertion: transverse process of middle and superior cervical vertebrae
Action:
Bilateral extend head
Unilateral laterally flexes neck to same side

 Innervation: cervical and thoracic spinal nerves

Question 5

Longissimus thoracis

Answer 5

Origin: transverse process of all thoracic and lumbar vertebrae
Insertion: transverse processes of all thoracic vertebrae
Action:
Bilateral extension of spine
Unilaterally: lateral flexion of spine

 Innervation: thoracic and lumbar spinal nerves

Question 6

Thyrohyoid

Answer 6

Origin: thyroid cartilage of larynx
Insertion: hyoid bone
Action: elevates thyroid, depresses hyoid bone
Innervation: hypoglossal nerve

Question 7

Scalenes (anterior, middle, posterior)

Answer 7

Origin: transverse processes of C2- C7
Insertion: first and second ribs
Action: elevates ribs 1 & 2
Innervation: cervical spinal nerves

Question 8

Spinalis

Answer 8

Medial column of erector spinae
Made up of three divisions (spinalis thoracis, spinalis cervicis, and spinalis capitis)

Question 9

Longissimus

Answer 9

Intermediate column of erector spinae
Made up of three divisions (longissimus thoracis, longissimus cervicis, longissimus capitits)

Question 10

Iliocostalis

Answer 10

Lateral column of erector spinae
Made up of three divisions (iliocostalis lumborum, iliocostalis thoracis, iliocostalis cervicis)

Question 11

Rectus abdominis

Answer 11

Origin: pubic crest, pubic symphysis
Insertion: cartilages of ribs 5-7, xiphoid process
Action: flexion of spine, compression of abdominal viscera
Innervation: spinal nerves (T 7-T 12)

Question 12

External oblique

Answer 12

Origin: sternum, ribs (5-12)
Insertion: linea alba, iliac crest
Action:
Bilaterally: flexion of the spine, compress the abdomen;
Unilaterally: flexes trunk to same side, rotates to opposite side
Innervation: lower intercostal, ilioinguinal nerves

Question 13

Internal oblique

Answer 13

Origin: iliac crest, lumbodorsal fascia
Insertion: inferior ribs, linea alba
Action: compresses abdomen, depresses ribs, flexes spine
Innervation: lower intercostal, ilioinguinal nerves

Question 14

Transverse abdominis – deep to internal oblique

Answer 14

Origin: lateral inguinal ligament, inner iliac crest
Insertion: linea alba, pubis
Action: compression of abdomen
Innervation: first lumbar nerve (T 7- L1), iliohypogastric (T12-L1), ilioinguinal (T12-L1)

Question 15

Diaphragm

Answer 15

Origin: cartilage of ribs 7-12, xiphoid process, lumbar vertebrae
Insertion: anterior longitudinal ligament (vertebral column)
Action: expands thoracic cavity, compresses abdominal cavity
Innervation: phrenic nerve (C3-5)

Question 16

Internal Intercostals

Answer 16

Origin: superior border of ribs 2-12
Insertion: inferior of ribs above (1-11)
Action: depresses ribs (forced expiration)
Innervation: intercostal nerves