Back Muscles

Question 1

extrinsic vs intrinsic muscles

Answer 1

extrinsic attach to spine and lateral, intrinsic go up and down spinal cord

Question 2

foramen magnum

Answer 2

hole where your spine enters skull

Question 3

Why do your intervertebral disc get larger down your back?

Answer 3

since your weight is mostly held inferiorly near your sacrum the intervertebral disc need to be larger there to compensate for weight

Question 4

Trapezius muscle

Answer 4

most superficial of the back; proximally attaches to the medial nuchal line, spinous processes C7-T12; distally attaches to the clavicle, acromion, and spine of scapula; innervated by accessory nerve and sternocleidomastoid.

Question 5

What do striations of a muscle show us?

Answer 5

The direction a muscle contracts; for example, the descending trapezius pulls trap up, and ascending trap pulls trap down.

Question 6

Latissimus Dorsi

Answer 6

Proximally attaches to iliac crest, spinous processes of inferior 6 thoracic vertebrae, and inferior 3-4 ribs; distally attaches to intertubercular groove of humerus (bicipital groove); function is to cross shoulder joint and manipulate upper arm/rotate upper arm; this is deeper than trapezius.

Question 7

Rhomboids

Answer 7

consists of two muscles: 1. major attaches proximally to T2-T5; distally attaches to medial border of scapula; innervated by dorsal scapular nerve; 2. minor proximally attaches to C7-T1 and nuchal ligament; distally attaches to medial border of the scapula and also innervated by dorsal scapular nerve.

Question 8

Levator scapulae

Answer 8

This elevates the scapula; distally attaches to the superior angle of the scapula, and medial border of scapula (just above the rhomboid minor) ; proximally attaches deep to C1-C4; innverated by C5 nerve

Question 9

Serratus posterior muscle (2 types)

Answer 9

Two types of this muscle superior and inferior, both are paper thin. The serratus posterior superior attaches proximally to the nuchal ligament, and C7-T3; distally attaches to ribs 2-5; pulls ribs up during inhalation and is innervated by 2nd/5th intercostal nerve.
The serratus posterior inferior nerve attaches proximally to T11-L2; distally attaches to ribs 9-12, and innervated by 9th-11th intercostal nerves; this pulls ribs down during expiration.

Question 10

Splenius muscles (2 types)

Answer 10

1. Splenius capitis - proximally attaches to nuchal ligament and C7-T4; distally attaches to mastoid process and superior nuchal line; innervated by posterior rami of spine nerves.
2. Splenius cervicis - lower proximal attachments at T3-T6; distally attaches to distal transverse processes of C1-C4; also innervated by posterior rami

Question 11

Erector Spinae muscles (made of 3)

Answer 11

1. Iliocostalis - proximal aponeurosis (thin connect collagen) attached to iliac crest and sacrum; distally attaches to angle of ribs and transverse processes; innervated by posterior rami; this is most lateral erector spinae
2. Longissimus - proximal attachments to sacral and lumbar spinous processes; distal attachments ribs and mastoid; innervated by posterior rami
3. Spinalis - proximal attachments to lumbar and thoracic spinous processes; distally to upper thoracic spinous process; innervated by posterior rami

Question 12

What action does semispinalis capitis, semispinalis cervicis, and multifidus participate in?

Answer 12

Stabilization and rotation

Question 13

Why is head extension a compound movement?

Answer 13

It involves a bunch of muscles: Semispinalis Cervicis, semispinalis Iliocostalis, Splenius Cervicis, Levator Scapulae,
Splenius Capitis, Multifidus, Longissiumus Capitus
Semispinalis Capitus, and Trapezius

Question 14

What is importance of odontoid process (dens)?

Answer 14

It is the pivot point for the atlas allowing for rotation

Question 15

Sub occipital triangle

Answer 15

houses the vertebral artery and sub occipital nerve. Protected by four muscles: rectus capitis minor (att. C1 tubercle) and major (att. C2), which make up medial part of triangle. Obliquus capitis inferior (att. C2) makes up the floor of triangle, and obliquus capitis superior (att. transverse of C1) which makes up lateral part of triangle.

Question 16

Which muscles contract to turn head left?

Answer 16

obliquus capitis inferior, rectus capitis major, rectus capitis minor, longissimus capitis, and splenius capitis

Question 17

Which muscles contract to turn head right?

Answer 17

contraction of sternocleidomastoid, and semispinalis capitis

Question 18

Which muscles contract to extend head?

Answer 18

rectus capitis major and minor, obliquus capitis superior

Question 19

Triangle of auscultation

Answer 19

sits on lateral border of trapezius, superior border of latissimus, and inferior border of scapulae; best spot to listen for lungs

Question 20

Lumbar triangle

Answer 20

rest on iliac crest, latissimus makes up the medial border, and lateral border is the abdominal oblique; lots of herniations occur here