Lecture 4: Part 4 (the back) Flashcards
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
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
Structure 8:
Erector Spinae
Structure 7:
Posterior Superior Iliac Spines (PSIS): dimples at bottom of back
Structure 5:
Site of Sacrum (below dimples of PSIS, above buttcrack)
structure 11:
medial borders of scapulae
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*
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
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)
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)
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)
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)
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)
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)
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.)
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
- what 3 muscles
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
-
Muscles that rotate to ipsilateral (same) side –
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
B) Spinal accessory nerve
C) Dorsal scapular nerve
D) Greater occipital nerve
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
