Anatomy Flashcards
Anatomical planes
Median:
- midline plane that divides into L and R halves
Sagittal:
- divides into L and R parts
- infinite number of sagittal planes parallel to mid-sagittal plane
Coronal:
- divides into front and back
- aka frontal plane
Transverse:
- divides into top and bottom
- aka horizontal plane, aka axial plane
Levator scapula
spacular elevation
dorsal scapular n.
Rhomboid minor/major
scapular elevation, retraction
dorsal scapular n.
Latissumis dorsum
arm extension, adduction, medial rotation
thoracodorsal n.
Deltoids
arm abduction
axillary n.
Trapezius
upper fibers: scapular elevation, upward rotation
middle fibers: scapular retraction
lower fibers: scapular depression, upward rotation
accessory n.
Intermediate back muscles
serratus posterior superior, serratus posterior inferior
respiratory muscles
Deep/intrinsic intermediate muscles
erector spinae: spinalis, iliocostalis, longissimus
vertebral column and head movements
Shoulder ligaments, muscles
Ligaments:
- acromioclavicular ligament (weak)
- coracoacromial ligament (weak)
- coracoclavicular ligament (strong) <- if torn, you get a 3rd degree shoulder separation
Rotator cuff muscles:
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
Supraspinatus
rotator cuff muscle; initial abduction (0˚-15˚)
suprascapular n.
empty can test
- supraspinatus travels deep to the coracoacromial arch; the proximity of the bones and ligaments of this arch makes the supraspinatus easily injured
- most commonly injured rotator cuff muscle
Infraspinatus
rotator cuff; lateral rotation of arm
suprascapular n.
Subscapularis
medial rotation of arm
upper and lower subscapular n.
Teres minor
lateral rotation
axillary n.
Teres major
medial rotation, extension
lower subscapular n.
Axillary n.
C6, C7 (posterior cord of brachial plexus)
innervates deltoid, teres minor
innervates skin of lateral upper arm
injured in humerus fracture of surgical neck
Axillary foramens
Suprascapular foramen - suprascapular n.
Quadrangular space - axillary n., posterior circumflex humeral a.
Triangular space - circumflex scapular a.
Triangular interval - radial n., profunda brachii a. (mid-shaft humeral fracture)
Pectoralis major
arm adduction, flexion, medial rotation
medial & lateral pectoral n.
Pectoralis minor
shoulder depression, scapular protraction, forced inspiration
medial pectoral n.
Subclavicus
clavicular depression
n. to sublavicus
Serratus anterior
spacular protraction and rotation, holds scapula to thoracic wall
long thoracic n.
winged scapula
Clavipectoral/Deltopectoral triangle
hole in clavipectoral fascia that allows cephalic vein to exit axilla
Veins down arm/forearm
medial cubital vein ==> cephalic v. (lateral) + basilic v. (medial)
basilic v. ==> axillary v. ==> subclavian v.
Axillary artery
starts at 1st rib and ends below teres major
3 parts:
1. 1st rib to superior aspect of pectoralis minor
2. superior aspect of pec minor to inferior aspect
3. inferior aspect of pec minor to teres major
1st part of axillary a.
superior thoracic a.
2nd part of axillary a.
thoraco-acromial a.
lateral thoracic a.
3rd part of axillary a.
subscapular a.
- circumflex scapular a.
- thoracodorsal a.
anterior circumflex humoral a.
posterior circumflex humoral a.
Subclavian artery
above axillary artery:
suprascapular a.
dorsal scapular a.
creates anastamoses with 3rd part of axillary a.
Axillary lymph nodes
[humeral (lateral) + pectoral (anterior) + subscapular (posterior) nodes] ==> central nodes ==> apical nodes
Coracobrachialis
arm flexion
- attaches to coracoid process and midshaft of humerus
musculocutaneous n.
Brachialis
forearm flexion
musculocutaneous n.
Biceps brachii
short and long head (long head tendon more commonly ruptured <- popeye sign)
forearm flexion and supination; accessory muscle for arm flexion
musculocutaneous n.
Triceps brachii
forearm extension
long head also does arm extension and adduction
radial n.
Musculocutaneous n.
C5, C6, C7 (lateral cord of brachial plexus)
pierces coracobrachialis and goes between biceps and brachialis; ends as cutaneous nerve of lateral forearm
coracobrachialis, brachialis, biceps bracii
Radial n.
C5, C6, C7, C8, T1 (posterior cord of brachial plexus)
posterior cord of brachial plexus, travels through triangular interval and goes along radial groove on humerus
innervates triceps brachii, posterior forearm muscles (extensors)
Brachial a.
continuation of axillary artery, from bottom of teres major to cubital fossa (radius neck)
branches into profunda brachii a. (triceps), which passes through triangular interval
profunda brachii a. ==> radial & middle collateral a.
Afferent vs. efferent neurons
Afferent = sensory
- dorsal root ganglion (posterior)
- somatic: pain, touch, proprioception
- visceral: organs
Efferent = motor
- ventral root (anterior)
- somatic: skeletal muscle
- visceral: smooth muscle, cardiac muscle, glands
Spinal nerves & vertebrae
spinal nerves C1-C7 emerge superior to pedicle of corresponding vertebrae
spinal nerves C8, T1-T12, L1-L5, S1-S5, Co emerge inferior to pedicle of corresponding vertebrae
Cauda equina
nerve roots suspended in CSF, below L2
spinal cord ends around L1-L2 (lumbar cistern)
- lumbar punctures ideally between L3-L4 or L4-L5
- anatomical landmark for L4: iliac crest
Brachial plexus
Real Teachers Drink Cold Beer:
- Roots (C5-C8, T1)
- Trunks (superior, middle, inferior)
- Divisions (anterior, posterior)
- Cords (lateral, posterior, medial)
- Branches (musculocutaneous, median, radial, axillary, ulnar)
3 musketeers assassinated 5 rats, 5 mice, and 2 unicorns
- musculocutaneous: C5, C6, C7
- axillary: C5, C6
- radial: C5, C6, C7, C8, T1
- medial: C5, C6, C7, C8, T1
- ulnar: C8, T1
Brachial plexus: Lateral cord
- lateral pectoral n.
- musculocutaneous n.
- lateral root of median n.
Brachial plexus: Medial cord
- median n.
- medial pectoral n.
- ulnar n.
- medial cutaneous n.
Brachial plexus: Posterior cord
- superior subscapular n.
- inferior subscapular n.
- thoracodorsal n.
- axillary n.
- radial n.
Injury to posterior cord would present with:
- atrophy of posterior axillary muscles
- atrophy of shoulder muscles
- inability to extend arm/forearm
- wrist drop
Erb-Duchenne Paralysis
- traction injury to upper trunk of brachial plexus (C5, C6)
- axillary n. completely affected
- adducted shoulder, extended elbow, internally rotated arm, waiter’s tip hand
Klumpke Paralysis
- traction injury to lower trunk of brachial plexus (C8, T1)
- caused by excessive abduction of arm (hanging injury)
- ulnar n. completely affected
- median n. and radial n. also affected
- complete claw hand (4 digits affected) <- opposite actions of lumbricals
Radiculopathy vs. peripheral nerve injuries
Radiculopathy = damage to nerve roots where they leave the spine
- check dermatomes, myotomes, reflexes
Peripheral nerve injuries = damage in peripheries
- check specific nerve functions (motor & sensory)
Cubital fossa contains:
from medial to lateral:
1. ulnar n. (posterior to humerus)
2. median n. (middle of cubital fossa)
3. brachial a.
4. biceps tendon (attaches to radius)
5. radial n. (anterior to humerus)
superior: median cubital v.
Superficial anterior muscles of forearm
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
median n. innervates all of them except flexor carpi ulnaris, which is innervated by the ulnar n.
Attachment: medial epicondyle of humerus
- golfer’s elbow
Pronator teres
forearm flexion and pronation
median n.
Flexor carpi radialis
wrist abduction and flexion
median n.
Palmaris longus
wrist flexion
median n.
Flexor carpi ulnaris
wrist adduction and flexion
ulnar n.
Intermediate & deep anterior muscles of forearm
Intermediate:
- flexor digitorum superficialis
Deep:
- flexor digitorum profundus
- flexor pollicis longus
- pronator quadratus
all innervated by median n. (or anterior interosseous branch of median n.), except for digits 4-5 of flexor digitorum profundus (ulnar n.)
Flexor digitorum superficialis
flexion of digits 2-5 at PIP
median n.
Flexor digitorum profundus
flexion of digits 2-5 at DIP (attach to lumbricals)
- the only muscle that flexes the DIP joints
digits 2-3: anterior interosseous n.
digits 4-5: ulnar n.
Flexor pollicis longus
thumb IP flexion
anterior interosseous n.
Pronator quadratus
forearm pronation
anterior interosseous n.
Median n.
C5, C6, C7, C8, T1 (from lateral and medial cords of brachial plexus)
passes under flexor retinaculum (carpal tunnel)
- palmar branch passes superior to flexor retinaculum <- not affected in carpal tunnel syndrome
sensory: lateral palm + lateral 3.5 digits
motor: anterior forearm flexors (except flexor carpi ulnaris and digits 4-5 of flexor digitorum profundus)
Dupuytren’s disease
abnormal thickening of palmar aponeurosis, causing flexion of MCP joints (4th and 5th digits most commonly affected)
Thenar muscles
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
all innervated by median n.
Hypothenar muscles
- abductor digiti minimi
- flexor digiti minimi
- opponens digiti minimi
- palmaris brevis (wrinkles skin of medial palm)
all innervated by ulnar n.
Lumbricals
connect from flexor digitorum profundus; do MCP flexion and PIP/DIP extension
- claw hand if nerve lesion affects lumbricals
lateral digits 1-2: median n.
medial digis 3-4: ulnar n.
Deep palm muscles
- abductor pollicis
- palmar interossei
- dorsal interossei
all innervated by ulnar n.
Abductor pollicis
abduction of thumb
ulnar n.
Palmar interossei
adduction of digits 2, 4, 5
ulnar n.
Dorsal interossei
Abduction of digits 2, 4, 5
ulnar n.
Tenosynovitis (Trigger finger)
inflammation of synovial sheaths; fingers stuck in flexion
Carpal tunnel
median n. affected
intermediate/deep flexor tendons travel beneath flexor retinaculum:
- flexor pollicis longus
- flexor digitorum superficialis
- flexor digitorum profundus
Tinel’s sign (tapping), Phalen maneuver (wrist flexion for 60s)
Anterior interosseous n. syndrome (AINS)
median n. lesion affecting lateral flexor digitorum profundus and flexor pollicis longus
OK sign is flattened
Pope’s hand
flexor digitorum profundus (lateral) and flexor digitorum superficialis affected
digits 1-2 don’t flex when trying to make a fist
Supracondylar fracture of humerus
most common pediatric elbow fracture
- FOOH
compression of medial n. and brachial a. ==> weak forearm flexors and pronators
Nursemaid’s elbow
radial head subluxation (partial dislocation) at proximal radio-ulnar joint
annular ligament slips over head of radius
Ulnar n.
C8, T1 (from medial cord of brachial plexus)
passes over flexor retinaculum, under Guyon’s canal (ulnar tunnel)
- deep branch goes to palm
- superficial branch goes to digits
sensory: medial palm/dorsum + medial 1.5 digits
motor: flexor carpi ulnaris and digits 4-5 of flexor digitorum profundus
Ulnar claw
loss of medial lumbricals (4-5)
MCP extension + IP flexion
Ulnar paradox: ulnar claw is less severe in proximal lesions (elbow) than distal lesions (wrist) because the IP joints are left intact in proximal lesions
Guyon’s canal syndrome
caused by direct pressure on ulnar n. near wrist (bicyclists)
Anterior forearm/palm arteries
Brachial a. ==> radial a. (lateral) + ulnar a. (medial)
- Radial a. passes by flexor carpi radialis tendon and goes to supply deep palmar arch + lateral 1.5 digits
- Common interosseous a. branches off of ulnar a.
- Ulnar a. goes to supply superficial palmar arch + medial 3.5 digits