Shoulder, Back Flashcards
retract the scapula:
what 3 muscles do this?
what innervates them?
- 3 muscles retract the scapula: the levator scapulae, the rhomboid major, and the rhomboid minor.
- The levator scapulae also helps elevate the scapula (hence the name).
- All innervated by the dorsal scapular nerve (C5)
elevate the scapula:
What muscle? Innervated by what nerve?
- Levator scapulae elevates the scapula (also retracts scapula)
- Innervated by dorsal scapular nerve
protract the scapula:
what muscle does this? What happens when can’t?
-
serratus anterior = a protractor of the scapula
- Innervated by long thoracic nerve. When lesioned, muscle is paralyzed, get winged scapula.
what’s interesting about pectoralis major muscle?
- The pectoralis major muscle is the only muscle of the body innervated by all five spinal cord segments of the brachial plexus (insignificant but cool)
- Innervated by both the medial pectoral nerve (C8 & T1) and the lateral pectoral nerve (C5-C7)
latissumus dorsi
- innervation?
- actions?
- Innervated by thoracodorsal nerve (C6-C8)
- 3 actions:
- Adducts the arm at the shoulder (glenohumeral) joint.
- Medially rotates the arm at the shoulder (glenohumeral) joint.
- Extends the arm at the shoulder (glenohumeral) joint.
subscapularis muscle:
what does it do, and what two nerves innervate it?
- Medial rotator of arm at the shoulder
- Innervated by both the lower subscapular nerve and the upper subscapular nerve (C5,6, collateral nerves from posterior cord)
- (The upper subscapular nerve only does that. Lower subscapular also innervates teres major.)
rotator cuff:
What is it? What innervates it?
- The rotator cuff is a group of 4 muscles (SITS) that come together as tendons to form a covering around the head of the humerus.
- The rotator cuff attaches the humerus to the shoulder blade and helps to lift and rotate your arm.
- The supraspinatus does first 15* of abduction, and the other three do rotation (SITS-AEEI)
-
3 of the 4 rotator cuff muscles are innervated by collateral nerves
- The supraspinatus and infraspinatus are innervated by the suprascapular nerve.
- The subscapularis is innervated by the upper and lower subscapular nerves.
- The only rotator cuff muscle not innervated by a collateral nerve is the teres minor, which is innervated by the axillary nerve (a terminal nerve).
- Mnemonic: SITS-AEEI
what are the 4 rotator cuff muscles
- Supraspinatus – Abduction
- Infraspinatus – External rotation
- Teres minor – External rotation
- Subscapularis – Internal rotation
abduction of the arm
- What does first 15*?
- What takes over after?
- First 15* = supraspinatus (part of rotator cuff)
- Then deltoid takes over
divisions of vertebral column
how many vertebrae?
how many spinal nerves?
- 33 vertebrae, 31 spinal nerves
where do cervical spinal nerves exit?
where do thoracic, lumbar, sacral, coccygeal spinal nerves exit?
- cervical exit above
- thoracic, lumbar, sacral, coccygeal exit below
landmarks of vertebral column:
- conas medullaris
- cauda equina
- meninges
- filumn terminale
- conus medullaris = tapered end of the spinal cord, consisting of the sacral and coccygeal spinal cord segments. At L2.
- cauda equina = horse’s tail = the roots of the spinal nerves for the lower lumbar, sacral, and coccygeal spinal regions run together
- meninges = protective covering lining the inside of the spinal column, terminates at S2 and is anchored by the filum terminale to the first coccygeal vertebra.
- filum terminale = derivative from the meninges, anchors to coccygeal vertebra
describe these vertebral structures
- Vertebrae are composed of:
- vertebral body = weightbearing part of the bone
-
vertebral arch = contains various processes for articulating with other vertebrae and allowing muscles to move the vertebrae.
- The arch originates from the body with two short pedicles, which each give off a transverse process that serves as an attachment point for muscles and—in the case of thoracic vertebrae—ribs.
- The pedicles also give off laminae, which fuse in the midline to form a spinous process, another attachment point for muscles.
- Between the vertebral body and arch is the spinal canal, which contains the spinal cord, surrounded by meninges.
- superior and inferior articular processes connect to the vertebrae above and below, respectively, at zygapophyseal or facet joints (make back flexible)
What connects vertebral bodies?
What is that structure made of?
- intervertebral discs
- composed of rings of fibrocartilage (annulus fibrosus) surrounding a somewhat gelatinous center (nucleus pulposus, the only postnatal remnant of the notochord).
which joints connect vertebral arches?
- The vertebral arches are connected by zygapophyseal aka facet joints.
through what space do spinal nerves leave the vertebral column?
-
intervertebral aka neural foramina
- Enclosed between the superior and inferior vertebral notches of adjacent vertebrae