Chapter 69 - Anatomy of the Shoulder, Arm, and Elbow Flashcards
what is the first bone in the body to ossify?
clavicle - 5th week of gestation
it is also the last bone in the body to fuse at like 25 yo
what is the only long bone to ossify via intramembranous ossification?
clavicle
intramembranous ossification occurs without a cartilage precursor
normal shoulder motion is what percentage glenohumeral vs scapulothoracic
2/3 vs 1/3
when does the scapular body ossify?
8th week of gestation
three ossifications centers of the acromion
Meta (base)
meso (middle)
preacromion (tip)
what attaches to the coracoid process?
- coracobrachialis
- short head of the biceps
- pectoralis minor inserts onto the base of the coracoid
what is the average orientation of the glenoid?
5degrees retroverted
average orientation of the humerus
19 degrees of retroversion, 41 degrees of inclination (neck-shaft angle)
primary blood supply to the greater tuberosity
arcuate a via the ascending branch of the anterior humeral circumflex a
primary blood supply to the humeral head
posterior circumflex humeral a (previously thought to be the ascending branch of the anterior circumflex humeral a)
what are the primary SC joint stabilizers to AP translation?
posterior SC joint ligaments
What are the primary SC joint stabilizers to superior/inferior translation?
anterior SC joint ligaments
What ligaments are the primary restraints to AP translation of the AC joint
posterior and superior AC ligaments
what ligaments are the primary restraints to vertical translation of the distal clavicle
coracoclavicular ligaments
- conoid medial
- trapezoid lateral
rotator interval is composed of what?
base of coracoid medially
supraspinatus
subscap
contains: SGHL, Long head of the biceps
what ligament is most active in the position of apprehension for anterior instability (90 abduction, ER)
anterior band of the inferior gleno humeral ligament
primary restraint to anterior-inferior dislocation
role of the posterior band of the IGHL
primary static restraint against posterior inferior translation with the arm internally rotated and adducted
long thoracic nerve palsy
results from axillary dissection or aggressive scalene retraction
-> serratus anterior palsy -> MEDIAL scapular winging (scapular elevstion with medial translation and medial rotation of the inferior pole of the scapula)
spinal accessory nerve palsy
cranial nerve XI
from radical neck dissection or lymph node biopsy
-> trapezius palsy -> LATERAL scapular winging (scapular depression with lateral translation and lateral rotation of the inferior pole of the scapula)
posterior approach to the shoulder
interval:
- teres minor: axillary n
- infraspinatus: suprascapular n
what is buford complex
a cord like MGHL with a sublabral foramen anterosuperiorly just distal to the biceps insertion
what is idiopathic osteonecrosis of the capitellum called?
Panner diesase
Supinator crest
insertion point for the LUCL
on posterolateral ulna
and origin for supinator muscle
sublime tubercle
insertion point for the anterior bundle of medial collateral ligament aka anteromedial facet of the coronoid
Lateral collateral ligament of the elbow
primary restraint to varus force at the elbow
lateral ulnar collateral ligament
primary restraint to posterolateral rotatory instability
Medial collateral ligament - which band primarily resists valgus
anterior band
medial collateral ligament - which band is most dominant in elbow contractures
posterior band
also forms floor of cubital tunnel
name the major arm nerves and the corresponding cords of the brachial plexus
axillay - posterior cord
median - lateral and median cord
musculocutaneous - lateral cord
radial - posterior cord
ulnar - meddial
first motor branch of the ulnar nerve branches where?
distal to the. cubital tunnel
branch to the FCU
median nerve
is medial to the brachial artery
lies anterior to the brachialis at the antecubital fossa
where does the blood supply to the lateral condyle come from?
posterior
what is the only direct source of oxygenated blood to the ulnar n proximal to the cubital tunnel?
inferior ulnar collateral a
kocher approach
between anconeus (radial n) and extensor carpi ulnaris (PIN)
preserve the LCL buy doing your arthroptomy above the equatorial line
what percentage of an axial load goes through the radial head v the ulna
60% radiohumeral, 40% ulnohumeral
most common neurologic complication of elbow arthroscopy?
ulnar nerve palsy
dangers with proximal anterolateral portal
radial n
dangers with proximal anteromedial portal?
medial antebrachial cutaneous n (medial cord, brachial plexus)
what nerve lies close to the anterior capsule at the mis aspect of the radiocapitellar joint?
radial n
where does the ulnar nerve lie in elbow arthroscopy?
directly superficial to the capsule in the posteriomedial gutter
