(3) Back Myology Flashcards
Shapes of Skeletal (Striated) Muscle
What are the different shapes of skeletal muscle?
A. Flat
B. Pennate
C. Fusiform
D. Digastric
Shapes of Skeletal (Striated) Muscle
Describe Flat Muscle
Broad, thin and expansive

Shapes of Skeletal (Striated) Muscle
Describe Pennate Muscles
-What are the three types?
“Feather Like”
- Unipennate (tendon on one side, muscle on the other)
- Bipennate (muscle on either side of tendon)
- Multipennate (multiple feathered)

Shapes of Skeletal (Striated) Muscle
Describe Fusiform Muscles
What are the three types?
*Spindle shaped with thick central region and tapered ends
- Bicipital muscles (muscle with two heads)
- Tricipital muscles (muscles with three heads)
- Quadracipital muscles (muscles with four heads)

Shapes of Skeletal (Striated) Muscle
Describe Digastric Muscles
What are the 5 types?
*Muscles with two bellies
- Multiventral : broken up by tendon
- Multicaudal : muscles with multiple tendons
- Serrated muscles : muscles with a serrated edge
- Circular or Sphincteral muscles : surrounding an opening
- Quadrate muscles: equal sided

What are the functions of skeletal muscle?
- Agonist
- Antagonist
- Synergist
- Fixator

What does an agonist do?
Activates a specific movement of the body
What does an antagonist do?
Opposes the action of the agonist
What does a synergist do?
Complements the action of the agonist and prevents the movement of an intervening joint when the agonist passes more than one joint
What does a fixator do?
Stabilizes the joints, or the proximal part of a joint while the distal portion is in motion
HN:
The superficial three layers are extrinsic and innervated by __________ or __________
Anterior Ramus; Cranial Nerve
HN:
The deep three layers are intrinsic and are innvervated by ______________
Posterior Rami
How are the six layers of the back muscles organized?

Layer 1 (Extrinsic)
What are the muscles in this layer?
Trapezius M.
Latissimus Dorsi M.

Layer 1 (Extrinsic)
Trapezius M.
Origin:
Spinous process of C7-T12
Ligamentum Nuchae
External Occipital Protuberance and medial 1/3 of Superior Nuchal Line of Occipital B.

Layer 1 (Extrinsic)
Trapezius M.
Insertion?
Lateral 1/3 of the clavicle
Acromion
Scapular Spine

Layer 1 (Extrinsic)
Trapezius M.
Action?
Whole muscle: Rotate point of the glenoid cavity superiorly, retract scapula
Upper fibers: Elevate scapula
Lower fibers: Depress scapula
Layer 1 (Extrinsic)
Trapezius M.
Innervation?
Spinal accessory N (CN XI)

Layer 1 (Extrinsic)
Latissimus Dorsi M.
Origin?
Spinous processes of T6-T12
Ribs 9-12
Illiac Crest
Spinous processes of L1-5
Median Sacral Crest via Thoracolumbar fascia

Layer 1 (Extrinsic)
Latissimus Dorsi M.
Insertion?
Floor of the humeral intertubercular groove

Layer 1 (Extrinsic)
Latissimus Dorsi M.
Action?
Extend, ADuct and medially rotate the HUMERUS
Rotate the glenoid cavity inferiorly

Layer 1 (Extrinsic)
Latissimus Dorsi M.
Innervation?
Thoracodorsal N.

What are the muscles in Layer 2 (extrinsic)?
- Rhomboid Major M.
- Rhomboid Minor M.
- Levator Scapulae M.

How many muscles are in Layer 2?
3!!!

Layer 2 (Extrinsic)
Rhomboid Major M.
Origin?
Spinous processes of T2-T5

Layer 2 (extrinsic)
Rhomboid Major M.
Insertion?
Medial border of scapula (inferior to scapular spine)

Layer 2: (extrinsic)
Rhomboid Major M.
Action?
Retract and elevate the scapula
Rotate the glenoid cavity inferiorly
Layer 2: (extrinsic)
Rhomboid Major M.
Innervation?
Dorsal Scapular N.

Layer 2 (extrinsic)
Rhomboid Minor M.
Origin?
Spinos process of C7-T1
Lower part of the Ligamentum Nuchae

Layer 2: (extrinsic)
Rhomboid Minor M.
Insertion?
Medial border of scapula
(at scapulat spine)

Layer 2 (extrinsic)
Rhomboid Minor M.
Action?
Retract and elevate scapula
Rotate the glenoid cavity inferiorly

Layer 2 (extrinsic)
Rhomboid Minor M.
Innervation?
Dorsal Scapular N.

Layer 2 (extrinsic)
Levator Scapulae M.
Origin?
Posterior tubercules of transverse processes C1-4

Layer 2 (extrinsic)
Levator Scapulae M.
Insertion?
Medial border of scapula
*superior to scapular spine

Layer 2 (extrinsic)
Levator Scapulae M.
Action?
Elevate scapula
Rotate the glenoid cavity inferiorly
When scapula is fixed, extends and laterally flexes the neck

Layer 2 (extrinsic)
Levator Scapulae M.
Innervation?
Dorsal Scapular N.

What are the muscles of layer 3?
Serratus Posterior Superior M.
Serratus Posterior Inferior M.

Layer 3 (extrinsic)
Serratus Posterior Superior M.
Origin?
Nuchal L.
Spinous Processes C7-T3

Layer 3 (extrinsic)
Serratus Posterior Superior M.
Insertion?
Superior surfaces of ribs 2-5

Layer 3 (extrinsic)
Serratus Posterior Superior M.
Action?
Elevate ribs with forced inspiration
*primarily proprioceptive

Layer 3 (extrinsic)
Serratus Posterior Superior M.
Innervation?
Intercostal N.

Layer 3 (extrinsic)
Serratus Posterior Inferior M.
Origin?
Spinous processes T11-L2

Layer 3 (extrinsic)
Serratus Posterior Inferior M.
Insertion?
Inferior surface of ribs 8-12

Layer 3 (extrinsic)
Serratus Posterior Inferior M.
Innervation?
Anterior Rami T9-12

Layer 3 (extrinsic)
Serratus Posterior Inferior M.
Action?
Depress ribs with forced expiration
*primarily proprioceptive

Layer 4 (intrinsic)
What are the muscles of layer 4?
- Splenius Capitus M.
- Splenius Cervicis M.

Layer 4 (Intrinsic)
Splenius Capitus M.
Origin?
*Origins not CRITICAL for written exam, more FYI kind of thing
Lower 1/2 Ligamentum Nuchae, Spinous Process C7-T3

Layer 4 (Intrinsic)
Splenius Capitis M.
Insertion?
Mastoid Process of Temporal B.
Lateral 1/3 superior nuchal line of the occipital B.

Layer 4 (intrinsic)
Splenius Capitis M.
ACTION?
Extend the neck when working bilaterally,
Laterally flex the neck
Rotate face

Layer 4: Intrinsic
Splenius Capitis M.
INNERVATION?
Posterior Rami C3-5
Layer 4 (intrinsic)
Splenius Cervicis M.
origin?
Spinous processes T3-6

Layer 4 (intrinsic)
Splenius Cervicis M.
Insertion?
Transverse processes C1-3

Layer 4(intrinsic)
Splenius Cervicis M.
Action?
Extend the neck when working bilaterally
Laterally flex the nexk and rotate face toward when working unilaterally

Layer 4 (intrinsic)
Splenius Cervicis M.
Innvervation?
Posterior Rami C5-7

What are the muscles in Layer 5?
- Iliocostalis
- Longissimus
- Spinalis

What is the action of the erector spinae group?
Maintain erect posture and extend the vertebral column and head when working bilaterally
Laterally flex the vertebral column when working unilaterally

What is the innervation of the erector spinae group?
Segmentally innvervated by Posterior Rami of spinal nerves
Layer 5 (Intrinsic)
Iliocostalis
What are the three divisions?
- Iliocostalis Lumborum M.
- Iliocostalis Thoracis M.
- Iliocostalis Cervicis M.

Layer 5 (intrinsic)
Longissimus
What are the three divisions?
- Longissimus Thoracis M.
- Longissimus Cervicis M.
- Longissimus Capitis M.

Layer 5 (Intrinsic)
Spinalis
What are the three divisions?
- Spinalis Thoracis M.
- Spinalis Cervicis M.
- Spinalis Capitis M.

CN:
What is a back sprain?
Injury to the ligamentous attachements between bone;
usually due to inadequate stretching before activity
CN:
What is a back strain?
Involves excessive stretching and sometimes tearing of muscle fibers produced by an overly strong muscular contraction.
*Muscle tissue will spasm, or involuntarily contract in response to injury and inflammation as a protective measure
Label the following structures in layer 5:


Layer 6 (intrinsic)
AKA?
Transversospinalis Muscles

Layer 6 (intrinsic)
What are the muscles in this layer?
- Semispinalis Ms.
- Multifidus Ms.
- Rotatores Longus Ms.
- Rotatores Brevis Ms.

Layer 6 (intrinsic)
Semispinalis Ms.
What are the subdivisions of this muscle group?
- Semispinalis Thoracis M.
- Semispinalis Cervicis M.
- Semispinalis Capitis M.

Layer 6: intrinsic
Semispinalis Ms.
What are the actions of these muscles?
Extend spine
Rotate spine away

Layer 6 (Intrinsic)
Semispinalis Ms.
What are these muscles innervated by?
Posterior Rami

Layer 6 (Internal)
Multifidus M.
Action?
Extend spine
Rotate the spine away

Layer 6 (internal)
Multifidous Ms.
Innervation?
Posterior Rami

Layer 6 (intrinsic)
Rotatores Longus M.
How many spinal segments does it span?
2!

Layer 6 (intrinsic)
Rotatores Longus M.
Insertion?
Transverse Processes

Layer 6 (intrinsic)
Rotatores Longus M.
Insertion?
Roots of spinous processes 2 segments suprior

Layer 6 (intrinsic)
Rotatores Longus M.
Action?
Extend the spine
Rotate the spine away
*primarily proprioceptive

Layer 6 (intrinsic)
Rotatores Longus M.
Innveration?
Posterior Rami

Layer 6 (intrinsic)
Rotatores Brevis M.
Where does it extend?
Adjacent spinal segment

Layer 6 (intrinsic)
Rotatores Brevis M.
Origin?
Transverse processes

Layer 6 (intrinsic)
Rotatores Brevis M.
Insertion?
Roots of spinous processes 1 numeric segments superior

Layer 6 (intrinsic)
Rotatores Brevis M.
Action?
Extend the spine
Rotate the spine away
*primarily proprioceptive

Layer 6 (intrinsic)
Rotatores Brevis M.
Innervation?
Posterior Rami

What are the suboccipital muscles?
- Rectus Capitis Posterior
- Rectus Capitis Posterior Minor M.
- Obliquus Capitis Inferior M.
- Obliquus Capitis Superior M.

Rectus Capitis Posterior Major M.
Origin?
Spinous process C2

Rectus Capitis Posterior Major M.
Insertion?
Lateral portion of inferior nuchal line

Rectus Capitis Posterior Major M.
Action?
Extend the head
Rotate face forward

Rectus Capitis Posteior Major M.
Innervation?
Suboccipital N.

What muscle is the medial border of the suboccipital triangle?
Rectus Capitis Posterior Major M.

What is the inferior border of the suboccipital triangle?
Obliquus Capitis Inferior M.

What is the lateral border of the suboccipital triangle?
Obliquus Capitis Superior M.

What are the three muscles that make up the borders of the suboccipital triangle?
Rectus Capitis Posterior M.
Obliquus Capitis Inferior M.
Obliquus Capitis Superior M.

Rectus Capitis Posterior Minor M.
Origin?
Posterior tubercle C1

Rectus Capitis Posterior Minor M.
Insertion?
Below Inferior Nuchal Line

Rectus Capitis Posterior Minor M.
Action?
Extend head

Rectus Capitis Posterior Minor M.
Innervation?
Suboccipital N

Obliquus Capitis Inferior M.
Origin?
Spinous Process C2

Obliquus Capitis Inferior M.
Insertion?
Transverse process C1
*ONLY CAPITUS MUSCLE THAT DOESN”T INSERT ON CAPPPP

Obliquus Capitis Inferior M.
Action?
Rotate the face forward

Obliquus Capitis Inferior M.
Innervation?
Suboccipital N.

Obliquus Capitis Superior M.
Origin?
Transverse process C1

Obliquus Capitis Superior M.
Insertion?
B/w Superior and Inferior Nuchal Lines

Obliquus Capitis Superior M.
Action?
Extend and laterally flex head

Obliquus Capitis Superior M.
Innervation?
Suboccipital N.
