17 - MSK Brachial Plexus & Pextoral Girdle Flashcards
What does the brachial plexus innervate, which spinal levels
upper limbs
c5-t1
What is the purpose of nerve plexuses
join at least 2 spinal levels
- b/c require many axons since large muscles
separate anterior flexor and posterior extensor divisions
(what goes to front, what goes to back)
- extensor: axillary and radial
- flexor: ulnar, median, musculocutaneous
What are scalene muscles
three groups of muscles
help with lateral bending of the cervical vertebrae
anterior, middle, posterior
form interscalene triangle when attached to first rib
- brachial plexus has to pass through to gete to armpit or upper limb
What are scalene disorders
scalene hypertrophy: scalene muscles can get bigger, but will pinch the upper nerve roots
- issues with muscles around your shoulder
supernumary rib: tranverse process grows into (extra rib), raises floor of triangle, causing lower nerve roots to have to run under it – t1 issues (hand)
subclavian artery entrapment: vascular issue of upper limb
- vascular entrapment
- long term issue because anatomic based
What is a peripheral nerve injury
saturday night palsy
- brachial plexus compression leading to wrist drop and sensory loss (radial nerve)
can also be caused by improper use of crutches
(when resting weight on armpit)
What is hyperabduction syndrome
vascular issue of the upper limb
when the arm is hyper-abducted, the head of the humerus compresses and places traction on nearby structures that serve the upper limb
pins and needles
must restore blood flow (blood flow issue)
motor and sensory loss are temporary
What are spinal nerve root injuries
damage to upper roots or lower roots of the brachial plexus can result in procimal and distal motor issues
Erb’s: issues with c5 (action on the elbow) and c6 - always abducted
Klumpke’s: arm in the hyperabducted position, motor issues on distal (c7, c8, t1)
What are the two bones on the pectoral girdle
scapula (back) - back and reaches to front
- caracoid process
- glenoid fossa (articulate cartilage)
- acromion
- spine of scapula: attachment site for muscles that originate at scapula
clavicle (front) - articulates with sternum and scapula
What does the pectoral girdle do
serve as an attachment site for upper limb
muscles on the pg serve to stabalize the scapula
- arranged in anterior and posterior
What are the posterior muscles of the PG
trapezius (CN XI) - action on neck – attatch to spine of scapula, has lower fivers from lumbar and thoracic vertebrae –> extend the cervical vertebrae
- upper fibers: elevation of scapula or extension of neck
- middle fibers: retraction of scapula
- lower fibers: rotation of scapula (hyperabduction)
levator scapulae - superior and medial scapula –> to elevate scapula (innervated by dorsal scapular nerves)
- retraction of scapula
rhomboids - allow scapula to be pulled back to midline –> extra reach (innervated by dorsal scapular nerves)
- retraction of scapula
What are the anterior muscles of the PG
originate out front and attach to the scapula
protractors and stabalizers of the scapulaq
- pectoralis minor (coracoid process)
- serratus anterior (medial border
What causes the winged scapula
intact pectoralis minor pulls the carocoid process of the scapula forward
The inactive serratus anterior allows the medial border of the scapula to move backwards
C567
What are the muscles of the thorax that move the humerus
axial muscles
pectoralis major
- flexes and adducts the arm at the shoulder joint
Latissimus dorsi
- extends and adducts the arm at the shoulder joint
What are the muscles of the scapula that move the humerus
What is it innervated by
deltoid muscle
- flexion, extension, abduction of the shoulder
- also participates in the internal and external rotation of the humerus
- abducts the shoulder 20-90 degrees
axillary nerve
What is the shoulder joint called
glenohumeral joint
