Spinal muscles Flashcards
Why are the superficial and intermediate back muscles defined as extrinsic muscles?
They don’t develop embryologically in the back
Why are the deep back muscles defined as intrinsic muscles?
They develop embryologically in the back
Generally, where do all of the superficial back muscles originate and attach to, and why?
Originate from vertebral column
Attach to shoulder bones
Because they are associated with movements of upper limb
Where is trapezius, and what are its sites of origin and attachment?
1
Originates from skull, nuchal ligament (ligament at back of neck that is continuous with supraspinous ligament), spinous processes C7-T12
Attaches to clavicle, acromion process, scapula spine
What nerve innervates trapezius, and what are its 3 motor actions?
Innervated by accessory nerve
Upper fibres: Elevate and rotate scapula during arm abduction
Middle fibres: Retract scapula
Lower fibres: Pull inferiorly/depress scapula
What is the nuchal ligament, and which superficial back muscle originates from here?
ligament at back of neck that is continuous with supraspinous ligament
Origin site of trapezius
Where is latissimus dorsi, and what are its sites of origin and attachment?
5
Originates from iliac crest, spinous processes T6-T12, thoracolumbar fascia
Attaches to bicipital groove/intertubercular sulcus of humerus
Which nerve innervates latissimus dorsi, and what are its 3 motor actions?
Thoracodorsal nerve
Upper arm extension, adduction, medial rotation
Where is levator scapulae, and what are its origin and attachment sites?
11
Originates from transverse processes of C1-C4
Attaches to scapula medial border
Which nerve innervates levator scapulae, and what is its motor action?
Innervated by dorsal scapular nerve
Elevates scapula
Is rhomboid minor or major more superficial?
Rhomboid minor is superficial to rhomboid major
Where is rhomboid minor, and what are its origin and attachment sites?
10
Originates from spinous processes C7-T11
Attaches to scapula medial border at level of scapula spine
Which nerve innervates rhomboid minor, and what are its 2 motor actions?
Dorsal scapular nerve
Retracts/pulls inferiorly scapula
Rotates scapula
Where is rhomboid major, and what are its origin and attachment sites?
7
Originates from spinous processes T2-T5
Attaches to medial border of scapula
Which nerve innervates rhomboid major, and what are its 2 motor actions?
Dorsal scapular nerve
Rotates scapula
Retracts/pulls inferiorly scapula
What are the 2 intermediate back muscles, and what nerve innervates them and what is their motor action?
Serratus posterior superior: Elevates ribs 2-5
Serratus posterior inferior:
Depresses ribs 9-12
Innervated by intercostal nerve
Where is serratus posterior superior, and what are its origin and attachment sites?
8
Originates from lower part of nuchal ligament and cervical spine
Attaches to ribs 2-5
Which 2 muscles is serratus posterior superior directly deep to?
Rhomboid major and minor
Where is serratus posterior inferior, and what are its origin and attachment sites?
15
Originates from thoracic and lumbar spine
Attaches to ribs 9-12
Which muscle is serratus posterior inferior directly deep to, and directly inferior to?
Directly deep to latissimus dorsi
Directly inferior to serratus anterior
How does the direction of muscles fibres in serratus posterior superior and inferior determine what direction they pull the ribs in?
Serratus posterior superior: Fibres run inferolateral, so when they contract they will pull ribs up
Serratus posterior inferior: Fibres run superolateral, so when they contract they will pull ribs down
In the deep back, what are the 2 spinotransversales, and what is the function of these muscles?
Splenius capitis
Splenius cervicis
Movements of head and neck
Which group of deep back muscles control movements of head and neck?
Spinotransversales:
Splenius capitis
Splenius cervicis
Where is splenius capitis, and what are its origin and attachment sites?
13
Originates from lower aspect of nuchal ligament and spinous processes C7-T4
Attaches to mastoid process and occipital bone of skull
Which 2 posterior rami innervate splenius capitis?
C3 and C4
Where is splenius cervicis, and what are its origin and attachment sites?
12
Originates from spinous processes T3-T6
Attaches to transverse processes C1-C3
Which posterior rami innervate splenius cervicis?
Posterior rami of lower cervical nerves
Which 3 deep back muscles form a column called the erector spinae, and where is the erector spinae, and why are they all included in this group?
10
Iliocostalis
Longissimus
Spinalis
They all originate from common tendon origin
Where is iliocostalis cervicis, and what part of iliocostalis does it arise from, and what are the attachment sites?
4
Arises from costal angles (angle where rib changes direction to form cage shape) of ribs 3-6
Attaches to transverse processes C4-C6
What are the 2 main motor actions of iliocostalis cervicis?
Lateral flexion (unilateral action of one side of spine only) and extension of lower cervical spine (bilateral)
Where is iliocostalis thoracis, and what part of iliocostalis does it arise from, and what are the attachment sites?
6
Arises from costal angles of ribs 7-12
Attaches to angles of ribs 1-6 and C7 transverse process
What are the 2 motor actions of iliocostalis thoracis?
Lateral flexion (unilateral) and extension (bilateral) of thoracic spine
Where is iliocostalis lumborum, where does it arise from in the iliocostalis and where does it attach?
Arises from common erector spinae tendon
Attaches to angles of ribs 7-12
What are the 2 motor actions of iliocostalis lumborum?
Lateral extension and flexion of lumbar spine
List the erector spinae muscles from most lateral to most medial?
Iliocostalis, longissimus, spinalis
Where is longissimus capitis, where does it arise from and where does it attach?
1
Arises from transverse processes T1-T5
Attaches to transverse processes C4-C7, then inserts onto lateral surface of mastoid process of temporal bone
What are the 2 main actions of longissimus capitis?
Bilateral contraction: Head and neck extension
Unilateral contraction: Ipsilateral head and neck lateral flexion and rotation
Where is longissimus cervicis, where does it arise from and where does it attach?
5
Arises from transverse processes T1-T5
Attaches to transverse processes C2-C6
Where is longissimus thoracis?
7
What are the overall 2 functions of longissimus muscles acting together?
Spine extension
Ipsilateral spine lateral flexion
Where is spinalis, and what are the 3 divisions?
Spinalis capitis: 2
Spinalis cervicis: 3
Spinalis thoracis: 9
What are the 2 main actions of spinalis?
Bilateral contraction: Extension of head, cervical spine, thoracic spine
Unilateral contraction: Ipsilateral lateral flexion of head, cervical spine, thoracic spine
