Lecture 4: Part 4 (the back) Flashcards by Emmalee Kent

Surface Landmarks of Back

what is #13?
- how can it be identified?
- what vertebral level is this located at?
- site of what other structure?

Surface Landmarks of Back

Nuchal Groove
- divet you can palpate above C7
- where cervical vertebrae are, covered by nuchal ligament
- site of nuchal ligament

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Surface Landmarks of Back

what is structure #12?
what vertebral structure is located here?

Surface Landmarks of Back

Structure 12 - Vertebra Prominens: the spinous process of C7

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Structure 8:

Erector Spinae

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Structure 7:

Posterior Superior Iliac Spines (PSIS): dimples at bottom of back

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Structure 5:

Site of Sacrum (below dimples of PSIS, above buttcrack)

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structure 11:

medial borders of scapulae

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Extrinsic Back Muscles:

muscles you see first when you ______
located ____, but ______
- act as _____ and control movment of ______ and ______
in embryology, these muscles ______
have unique _______
-Superficial: (2)*
-Intermediate: (3)*
-Deep: (2)*

Extrinsic Back Muscles: “false back muscles”

muscles you see when you first remove skin and subcutaneous tissue
located in the back but do not act on the back (do not have a function or movement control of the vertebral column)
- act as accessory respiratory muscles and control movements of shoulder and arm
in embryology, these muscles formed elsewhere and then rotated to the back
have unique innervations
-Superficial: Trapezius and Latissimus Dorsi*
-Intermediate: Levator scapulae, Rhomboid minor, and Rhomboid major*
-Deep: Serratus posterior superior and Serratus posterior inferior*

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Extrinsic Back Muscles: Superficial Group

2 superficial back muscles (and what they look like)

Extrinsic Back Muscles:

2 superficial back muscles: Trapezius and Latissimus Dorsi
- the 2 large “sheet” muscles you encounter first in dissection

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Trapezius:

what type of back muscles? (extrinsic or intrinsic)
- subtype?
goes from _____ down ______ until _____
fiber direction: _______
actions: (4)
innervation:

Trapezius:

extrinsic back muscle
- superficial layer
goes from external occipital protruberance down all spinous processes until T12
fiber direction: fibers point down to the spine of the scapula
actions: elevates, depresses, retracts and rotates the scapula
innervation: spinal accessory nerve (CNX1)

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Latissimus Dorsi

What type of back muscle (extrinsic or intrinsic)?
- what subgroup?
attaches to _____ and ______ (origin)
fiber direction: points to ______
- inserts on _____
has a sheet like tendon called _____ - allows latissimus dorsi to have ______
action: (3)
innervation:

Latissimus Dorsi

extrinsic back muscle
- superficial
attaches to lumbar and some of lower thoracic spinous processes (origin)
fiber direction: points to anterior surface of arm (near bicep tendon)
- attaches to lesser tuberosity of the humerus (insertion)
has a sheet like tendon called an thoracolumbar fascia aponeurosis - this allows latissimus dorsi to have an expansive attachment
action: extends, adducts, and medially rotates humerus
innervation: thoracodorsal nerve (C6-C8)

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Extrinsic Back Muscles: Intermediate Group

3 Intermediate extrinsic back muscles:
- all associated with _____
- all innervated by _____

Extrinsic Back Muscles: Intermediate Layer

3 Intermediate extrinsic back muscles: levator scapulae, rhomboid minor, rhomboid major
- all associated with the scapula
- all innervated by dorsal scapular nerve (C5)

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Levator Scapulae:

what type of back muscle (extrinsic or intrinsic) ?
- what subgroup ?
Origin: ______
Insertion (distal attachments): ______
Action: _____ and ______
Innervation: ______ and ______, and ______

Levator Scapulae:

Extrinsic back muscle
- intermediate group (the highest one)
Origin: posterior tubercle of transverse process of cervical vertebrae 1 to 4.
Insertion (distal attachments): Medial border of the scapula between spine and superior angle.
Action: Elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula
Innervation: ventral primary rami of C3 and C4 and dorsal scapular nerve (C5)

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Rhomboid Major:

What type of back muscle (extrinsic or intrinsic)?
- what subgroup?
Origin (Proximal Attachment): _____
Insertion (Distal attachment): _____
Action: 3 main actions:
- also assists serratus anterior with _____
Innervation: _____

Rhomboid Major

Extrinsic back muscle
- intermediate layer (lowest one - “minor rides on top of the major”)
Origin (Proximal Attachment): Spinous Processes T2-T5
Insertion (Distal attachment): Medial border of scapula inferior to spine
Action: Elevates and retracts scapula and rotate its glenoid cavity inferiorly; also assists serratus anterior to fix scapula to thoracic wall
Innervation: Dorsal Scapular Nerve (C5)

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Rhomboid Minor

What type of back muscle (extrinsic or intrinsic)?
- what subgroup?
Origin (Proximal Attachment): _____
Insertion (Distal attachment): _____
Action: 3 main actions:
- also assists serratus anterior with _____
Innervation: _____

Rhomboid Minor:

Extrinsic back muscle
- intermediate group (rides on top of major)
Origin (proximal attachments): Spinous process of C7-T1 vertebrae.
Insertion (distal attachments): Medial border of scapula superior to spine (below levator scapulae)
Action: Elevates and retracts scapula and rotate its glenoid cavity inferiorly; also assists serratus anterior to fix scapula to thoracic wall
Innervation: Dorsal Scapular Nerve (C5)

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Extrinsic back muscles: Deep layer

2 deep extrinsic back muscles: _______ and _______
located underneath ______
function:
- if robust, this means _____

Extrinsic back muscles: Deep layer

2 deep extrinsic back muscles: serratus posterior superior and serratus posterior inferior
located underneath the rhomboids
- very thin muscles
function: 2° respiratory muscles
- if robust, this means patient likely has a problem with inspiration (ie COPD, emphysema, ect.)

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Serratus Posterior Superior:

Extrinsic or instrinsic back muscle?
- what subgroup?
Origin: _______
insertion: ______
innervation: _____
Function: _______

Serratus Posterior Superior:

Extrinsic back muscle
- deep layer (underneath rhomboids)
Origin: Nuchal ligament, spinous processes of vertebrae C7-T3
insertion: Superior borders of ribs 2-5
innervation: 2nd-5th Intercostal nerves
Function: Elevates ribs (inspiration)

Serratus Posterior Inferior:

Extrinsic or instrinsic back muscle?
- what subgroup?
Origin: _______
insertion: ______
innervation: _____
Function: _______

Serratus Posterior Inferior:

Extrinsic back muscle
- deep extrinsic back muscle (underneath latissimus dorsi)
Origin: spinous processes of vertebrae T11-L2
insertion: Inferior borders of ribs 9-12
innervation: Anterior rami of spinal nerves T8-T12 (a.k.a. 8th-11th Intercostal nerves + 12th “subcostal” intercostal nerve)
Function: Depresses ribs/ Draws ribs inferoposteriorly (expiration)

In a cross (axial) section:

which extrinsic back muscles can we see and where are they located?
where are the intrinsic back muscles located in relation to this?

In a cross (axial) section:

can see the superficial extrinsic back muscles (trapezius and latissimus dorsi)
- located between the transverse process and the spinous process
the intrinsic back muscles are located deep to the extrinsic back muscles
- located between the rib and spinous process in this cross-section

Intrinsic back muscles

true or false back muscles? (and why)
innervation?
act to?
layers? (and subtypes)

Intrinsic back muscles

true back muscles
- have a unifying innervation and act on the vertebral column (as well as where they attach - perhaps the head, perhaps the ribs, ect.)
innervated by dorsal segmental rami ONLY
- the dorsal segmental rami are going to leave the intervertebral foramen and push there way through all the intrinsic back muscles while dropping off motor innervation, and then keep going through the deep investing fascia and superficial fascia and finally up to the skin to supply a dermatome (because dorsal segmental rami are mixed system)
Action - move the vertebral column
- maintain posture and control movements of vertebral column and head
superficial layer
- splenius cervicis
- splenius capitus
intermediate layer = erector spinae muscles
- spinalis
- longissimus
- iliocostalis
deep layer = transversalis group
- multifidus

Intrinsic Back Muscles: Superficial Layer

2 muscles
where they insert/attach
innervation
action

Intrinsic Back Muscles: Superficial Layer

Splenius capitus
- from spinous processes of C7-T4 to mastoid process
- moves neck
  - when bilateral -> head and neck extension
  - when unilateral ->ipsilateral head rotation
Splenius cervicis
- from spinous processes of T3-T6 to transverse processes of C1-C3
- moves neck
  - when bilateral -> head and neck extension
  - when unilateral ->ipsilateral head rotation
Both innervated by dorsal segmental rami

*note that Splenius Capitis/Cervicis is different from semispinalis capitis/cervicis (semispinalis is deeper and note that capitis attached to cap/head while cervicis

Splenius Capitis

true or false back muscle?
- what layer?
origin:
insertion:
action:
innervation:

Splenius Capitis

true or false back muscle: intrinsic (true)
- superficial layer
origin: spinous processes of C7-T4
insertion: mastoid process (on occipital bone)
action: moves neck
- when bilateral -> head and neck extension
- when unilateral -> ipsilateral head rotation
innervation: dorsal segmental rami of middle cervical nerves

*note that Splenius Capitis/Cervicis is different from semispinalis capitis/cervicis (semispinalis is deeper and note that capitis attached to cap/head while cervicis attaches to the spine)

Splenius Cervicis

true or false back muscle?
- what layer?
origin:
insertion:
action:
innervation:

Splenius Cervicis

true or false back muscle? intrinsic (true)
- what layer? superficial
origin: spinous processes of T3-T6
insertion: transverse processes C1-C3
action: moves neck
- when bilateral -> head and neck extension
- when unilateral -> ipsilateral head rotation
innervation: dorsal segmental rami of lower cervical nerves

*note that Splenius Capitis/Cervicis is different from semispinalis capitis/cervicis (semispinalis is deeper and note that capitis attached to cap/head while cervicis attaches to the spine)

Spinalis

true or false back muscle?
- what layer?
origin:
insertion:
action:
innervation:

Spinalis

true or false back muscle? intrinsic (true)
- what layer? intermediate (erector spinae muscle group)
origin: spinous processes of inferior vertebral level
insertion: spinous processes of superior vertebral level
action: (all erector Spinae muscles)
- when bilateral -> vertebral extension
- when unilateral -> ipsilateral lateral flexion
innervation: dorsal segmental rami

Longissimus

true or false back muscle?
- what layer?
origin:
insertion:
action:
innervation:

Longissimus

true or false back muscle? intrinsic (true)
what layer? intermediate (erector spinae muscle group; middle one)
origin: transverse process below
insertion: transverse process above
action: (all erector Spinae muscles)
- when bilateral -> vertebral extension
- when unilateral -> ipsilateral lateral flexion
innervation: dorsal segmental rami

_Iliocostalis_ * true or false back muscle? * what layer? * origin: * insertion: * action: \*\*\* * innervation:

_Iliocostalis_ * true or false back muscle? **intrinsic (true)** * what layer? **intermediate (erector spinae muscle group; outer one)** * origin: **iliac crest** * insertion**: ribs** * action: (all erector Spinae muscles) * when bilateral -\> vertebral extension * when unilateral -\> ipsilateral lateral flexion * innervation: **dorsal segmental rami**

_Intrinsic Back Muscles: Intermediate Layer_ * name of group * what 3 muscles * their order from inner/outer * origins and insertions * actions * innervation

_Intrinsic Back Muscles: Intermediate Layer_ * _Erector Spinae Muscles_ * **Spinalis:** from spinous process of inferior vertebral level to spinous processes of superior vertebral level (inner one) * **Longisimus:** from transverse process to transverse processes above (middle one) * **Iliocostalis:** from the iliac crest to the ribs (outer one) * all innervated by **dorsal segmental rami** * action: * when bilateral -\> vertebral extension * when unilateral -\> ipsilateral lateral flexion * \*_erector spinae muscle mneumonic: I Love Spines (from outer to inner)_*

_Intrinsic Back Muscles: Deep Layer_ * Name for group of muscles * example of one of the muscles (mentioned in lecture) * location * action

_Intrinsic Back Muscles: Deep Layer_ * **Transversospinalis group** * location: **between transverse process and spinous process** * example: **Multifidus, semispinalis capitis** * *\*note that Splenius Capitis/Cervicis is different from semispinalis capitis/cervicis (semispinalis is deeper and note that capitis attached to cap/head while cervicis attaches to the spine)* * action: * acting bilaterally: **extension of vertebral column** * acting unilaterally: **contralateral rotation**

_Movement of intrinsic back muscles_ * if erector spinae act bilaterally = * if erector spinae act unilaterally =

_Erector Spinae: (longissimus, spinalis, iliocostalis)_ * **Acting bilaterally:** extend head & neck & vertebral column * **Acting unilaterally:** laterally flex (side bending) of vertebral column * *ex: if use iliocostalis, longissimus, and spinalis on left side = will bend to left* \*the splenius (splenius capitis and splenius cervicis) will also help with this function *\*remember we are talking about EXTENSION with back muscles (bending down forward, like going to bow) -* *flexion is done by anterior muscles (ie rectus abdominis and psoas major)*

_Movement of Intrinsic back muscles_ * _Rotational movements_ * **Muscles that rotate to ipsilateral (same) side** = (3 + 1 other) * **Muscles that rotate to contralateral (opposite) side** = (1 + 2 others)

_Movement of Intrinsic back muscles_ * _Rotational movements_ * **Muscles that rotate to ipsilateral (same) side –** * Erector spinae muscles = Splenius, Iliocostalis, Longissimus * *Internal abdominal oblique* * **Muscles that rotate to contralateral (opposite) side –** * Transversospinal (ie deep muscles = multifidus, semispinalis capitus) * *Sternocleidomastoid* * *External abdominal oblique*

_Movement of Vertebral Column:_ *Are these bilateral or unilateral movements?* * Flexion/Extension = * Lateral flexion = * Rotation =

_Movement of Vertebral Column:_ *Are these bilateral or unilateral movements?* * Flexion/Extension- **bilateral** * *remember we are talking about EXTENSION with back muscles (bending down forward, like going to bow)* * *flexion is done by anterior muscles (ie rectus abdominis and psoas major)* * Lateral flexion- **unilateral** * Rotation- **unilateral**

_Transversospinalis muscles_ * acting unilaterally will cause = * acting bilaterally will cause =

_Transversospinalis muscles (ie multifidus, semispinalis capitus)_ * acting unilaterally will cause = **contralateral rotation** * acting bilaterally will cause = **extension**

_what do dorsal rami innervate?_ (2)

_Dorsal rami innervate?_ * Intrinsic back muscles * Skin of back

_Question 1:_ A 42 y/o woman complains of pain and stiffness in her neck. She was injured sliding into 2nd base headfirst during a baseball game. Radiographs show no fractures of her spine. However, upon physical examination her right shoulder is drooping and she has difficulty elevating that shoulder. If you ordered an MRI, it would most likely reveal soft tissue damage to which of the following nerves? A) Thoracodorsal nerve * *The thoracodorsal nerve innervates the latissimus dorsi, which has no action on the shoulder girdle.* **B) Spinal accessory nerve - innervates the trapezius, sternocleidomastoid** * *The spinal accessory nerve is the eleventh cranial nerve (CN XI) and innervates both the trapezius and sternocleidomastoid muscles. The loss of CN XI results in drooping of the shoulder due to paralysis of the trapezius. In addition to the clinical findings of the MRI, one can test the innervation of this nerve by asking the patient to shrug his or her shoulders against resistance (testing the trapezius), as well as turning his or her head against resistance (testing the sternocleidomastoid).* C) Dorsal scapular nerve * *The dorsal scapular nerve innervates the levator scapulae muscle, as well as the rhomboids. \*even though the levator scapula does elevate the scapula the trapezius is the workhorse* D) Greater occipital nerve * *The greater occipital nerve is a sensory nerve innervating the posterolateral aspect of the scalp. The axillary nerve is a branch of the brachial plexus and innervates the deltoid and teres minor. It is not involved in shoulder elevation.*

_Question 2:_ If the right dorsal scapular nerve was cut at it's origin, what would result? A. Skin of the upper back on the right side would be numb B. The point of the right shoulder would droop C. Scapular retration on the right would be weakened D. Extension of the right arm would be weakened E. Inability to adduct the right arm

_Question 2:_ If the right dorsal scapular nerve was cut at it's origin, what would result? A. Skin of the upper back on the right side would be numb B. The point of the right shoulder would droop **C. Scapular retration on the right would be weakened** * ***what other muscle that would be affected by this injury?*** * ****levator scapulae** D. Extension of the right arm would be weakened * *latissimus dorsi, teres major and minor are in charge of extending the arm* E. Inability to adduct the right arm * *latissimus dorsi, subscapularis, teres major, pectoralis major, coracobrachialis, etc*

_The triangle of auscultation_ * The triangle of auscultation is a small area of the back where **\_\_\_\_\_, \_\_\_\_\_, and _____ converge** * This area is near the **\_\_\_\_\_** and **becomes enlarged when \_\_\_\_\_** * When a physician places a stethoscope on the triangle of auscultation, **\_\_\_\_\_\_ can be heard clearly**

* The triangle of auscultation is a small area of the back where **three muscles (trapezius, latissimus dorsi, and rhomboideus major)** converge. * This area is near the **scapula** and **becomes enlarged when a person leans forward with arms folded across the chest**. * When a physician places a stethoscope on the triangle of auscultation, **the sounds of the respiratory organs can be clearly heard.**

_Lumbar Triangle:_ * The lumbar triangle is a well-defined triangular space in the _____ region * Also known as the \_\_\_\_\_\_ * its boundaries are: * inferior: \_\_\_\_\_\_ * anteromedial: \_\_\_\_\_\_ * posterolateral: _____ border of the _____ muscle * The triangle has a superior apex, and the floor of the triangle is the \_\_\_\_\_\_\_ * clinical significance =

* The lumbar triangle is a well-defined triangular space in the **posterolateral lumbar region** * Also known as the **inferior lumbar triangle** * its boundaries are: * inferior: **the iliac crest;** * anteromedial: **latissimus dorsi muscle;** * posterolateral: **posterior border of the external oblique muscle.** * The triangle has a superior apex, and the floor of the triangle is the **internal oblique muscle.** * **This area is thinner than the rest of the back and is thus more susceptible to hernias**