Anatomy of Upper Limb

Question 1

Upper Limb Movements

Answer 1

Shoulder movements: above 90 degrees abduction requires abduction of the scapula (glenohumeral joint can only go 90 degrees)
Can also circumduct glenohumeral joint
Achieve long axis rotation of humerus and easily seen when arm bent
At elbow: two joints ulnarhumeral joint that allows flexion and extension only, and then the radiohumeral joint allows for long axis rotation and flexion and extension
Radius rotates around the ulna

Question 2

Hand/Wrist Movements

Answer 2

Wrist – F and E, adduction and abduction (think anatomical position in relation to these)
Circumduction at the wrist because can do all four movements

Hand: adduction and abduction is relative to the middle finger (2nd digit in foot)
Abduction powered by dorsal interossei (no palmar attached because only in adduction)
Thumb is rotated 90 degrees when hands are relaxed and can pivot it around at carpal and metacarpal joint
Orient yourself to the thumbnail to tell which direction; move thumb in relation to its nail
Can also long axis rotation = opposition via opponens pollicis

Question 3

Intrinsic Muscles and Extensor Hood of Phalanges

Answer 3

Flexor digitorum profundus tendon inserts on the middle phalanx, but the flexor digitorum superficialis tendon goes between the FDP tendon and inserts on the distal phalanx

Extensor hood is a CT covering that binds the tendons to the skeleton as well as serves as an insertion point for interosseous and lumbricle muscles

Actions: Interossei and lumbricals help flex the MCP joint and extend the IP joints

Question 4

Precision Grip

Answer 4

Contraction of FDP alone flexes digits so that tips digit into palm

Precision grip requires:
partial flexion of IP joints
lower levels of FDP contraction
passive tension in lumbricals (ulnar and median nn.)
or active force by interossei (ulnar n.)

Contraction of digitorum profundus = arched view (OK sign) and without the influence of the interossei muscle you can bend all 3 joints at the same time; anytime trying to bring tips of finger it is hard without lumbricles and interossei

Question 5

Types of Nerve Injuries

Answer 5

Avulsion = pull root out of spinal cord
Rupture: father out from CNS
Neuroma: spinal nerve torn and partially healed
Neuropraxia: nerve damaged by stretching; usually traction injuries and can recover well

Question 6

Testing Myotomes

Answer 6

C5: abduction of arm
C5/6: flexion of elbow
C7: elbow extension
C8: flexion of digits (gripping)
T1: adduction or abduction of fingers (hold piece of paper between fingers)

Question 7

Bicipital Reflex

Answer 7

Bicipital reflex = tests C6 spinal nerve and musculocutanous nerve
Patient can be unconscious

Question 8

Triceps Reflex

Answer 8

Triceps reflex: test above olecranon and arm should jerk in response
Patient must be conscious
Tests radial nerve and C7 spinal nerve

Question 9

Dermatomes of Overlap

Answer 9

C4 – Acromioclavicular joint 
C5 – Upper lateral arm
C6 – Pad of thumb (I)
C7 – Pad of middle finger (III)
C8 – Pad of little finger (V)
T1 – Medial elbow
T2 – Axilla

Question 10

Cutaneous Nerves: Shoulder

Answer 10

Supraclavicular nn - cervical plexus

Question 11

Cutaneous Nerves: Arm

Answer 11

• Intercostobrachial n. is extension of 2nd intercostal n.
• Medial cutaneous n. of the arm - medial cord of brachial plexus
• Posterior cutaneous n of the arm - radial n.
• Superior lateral cutaneous n. of arm - axillary n.
• Inferior lateral cutaneous n. of arm - radial n.

Question 12

Cutaneous Nerves: Forearm

Answer 12

• Posterior cutaneous n. of the forearm - radial n.
• Lateral cutaneous n. of the forearm - musculocutaneous n.
  Medial cutaneous n. of the forearm - medial cord of brachial plexus

Question 13

Cutaneous Nerves: Hand

Answer 13

Superficial branch of radial n.
Ulnar n.
Median n.

Question 14

Erb-Duchenne Palsy

Answer 14

damage to root of C5 and C6
from traumatic lateral neck bending
during childbirth
from fall on shoulder

Question 15

Erb-Duchenne Palsy: Nerves and Muscles Affected

Answer 15

Nerves downstream:

• Suprascapular n,
• Axillary n.
• Musculocutaneous n.
• Radial n. (partial)

Paralysis or weakness:
Deltoid and supraspinatus: arm adducted, cannot abduct
Infraspinatus: arm medially rotated by pec. major and latissimus dorsi, cannot laterally rotate
Biceps, brachialis: elbow extended, cannot flex, forearm pronate ad fingers extended, waiter’s tip” position (medial rotation)

Question 16

Klumpke’s Palsy

Answer 16

Damage to roots of C8 and T1

From traumatic hyperabduction of arm during childbirth or grabbing object in fall
Paralysis or weakness of short muscles of hand
“Claw hand” and wasting

Also can be from thoracic outlet syndrome, when it will be accompanied by poor circulation in arm due to compression of the subclavian artery as well as nerve roots

Question 17

Klumpke’s Palsy: Nerves and Muscles Affected

Answer 17

T1 controls most intrinsic hand muscles (via ulnar n.); unopposed flexors (profundus) and extensors leads to hyper extended MP joints and flexed IP joints (claw hand); also wasting of the hand muscles

Wasting of non-thenar intrinsic hand muscles

Horner’s syndrome: distinguishes between proximal ulnar nerve lesion and inferior brachial plexus lesion
Interrupted sympathetic innervation of head because T1-L2 and unopposed constriction of pupil

Question 18

Axillary Nerve Damage

Answer 18

Common Causes

• Fracture of surgical neck of humerus
• Dislocation of glenohumeral joint
• Improper use of crutches

Axillary nerve runs under head of humerus and then out the quadrangular space through the deltoid
If you dislocated head of humerus and will slide posteriorly and inferiorly and this movement will stretch the axillary nerve and impinge it
Proximal humerus fractures from improper use of crutches

Sensory: loss of sensation on “regimental badge”, (superior lateral cutaneous nerve)
Motor: weakness/paralysis of deltoid with possibly atrophy

Question 19

Median Nerve Muscles

Answer 19

1/2 LOAF
L- lumbricles 2/4
O- opponens pollicis
A – abductor pollicis brevis
F- flexor pollicis brevis

All flexors in the forearm except flexor carpi ulnaris and medial ½ of digitorum profundus (ulnar nerve)

*Ulnar nerve innervates the two muscles named above + adductor pollicis (transverse and oblique), opponens digit minimi, flexor digit minimi, and abductor digit minimi

Question 20

Musculocutaneous Nerve

Answer 20

Motor: biceps, coracobrachialis and brachialis
Symptoms: weak elbow flexion and forearm supination

Sensory: lateral cutaneous n. of forearm
Symptoms: loss of sensation on lateral radial aspect of forearm

Question 21

Ligament of Struthers Syndrome

Answer 21

Weakness of all median n. muscles, including pronator teres, 1/2 LOAF, all forearm muscles except flexor carpi ulnaris and 1/2 of digitorum profundus (ulnar head portion)
Thenar eminence wasting, “ape hand”
Benediction Hand, sensory loss over thenar eminence

Question 22

Pronator Teres Syndrome

Answer 22

Compression due to pronator teres on the median nerve, but spares pronator teres and affects downstream mm., especially thenar mm., Benediction hand
Pain on pronation, sensory loss over thenar eminence, Thenar eminence wasting, “ape hand”
Benediction Hand, sensory loss over thenar eminence

Question 23

Anterior Interosseous Nerve and Carpal Tunnel Syndrome

Answer 23

Median Nerve Neuropathies

Anterior interosseous nerve
Weak flexion of 1st IP joint (cannot make OK sign with thumb and index)

Carpal tunnel syndrome
Thenar eminence wasting, “ape hand”
Spares sensory to thenar eminence, palmar branch arise in forearm and median cutaneous branch doesn’t go through the tunnel
Ulnar nerve is spared because goes through Guyon’s tunnel

Question 24

Proximal Median Nerve Injury

Answer 24

Highest injuries (above elbow) results in loss of pronation and medial deviation during wrist flexion

Question 25

Flexor Pollicis Longus

Answer 25

FPL only flexor of thumb IP joint Innervated by anterior interosseous n., branch of median n., in forearm. Denervated by ant. inteross. n. palsy (compression, cutting) or median n. in cubital fossa or above Lesion: unable to make the OK sign; Interphalangeal joint of thumb not able to bend because flexor pollicis longus can only do that

Question 26

Testing Flexor Digitorum Profundus and Superficialis

Answer 26

FDS supplied in cubital fossa by median nerve Test by holding all other fingers down except middle finger and have patient flex FDP supplied by anterior interosseous nerve Test by holding down the middle finger up to the PIP joint, and have patient flex the PIP joint of the middle finger

Question 27

Ulnar Nerve Neuropathies

Answer 27

``` Elbow Loss of dexterity, decreased grip and pinch strength Weakness in adduction at wrist Ulnar claw hand, Froment sign Digit IV-V numbness ``` Forearm Loss of dexterity, decreased grip and pinch strength Ulnar claw hand, Froment sign Digit IV-V numbness Wrist Mannerfelt’s and Froment’s signs Weakness in finger abduction

Question 28

Mannerfelt's Sign

Answer 28

Testing ulnar nerve function using the pinch testMannerfelt’s sign reflects dorsal interosseous weakness Mannerfelt’s sign - Patient employing forceful precision grip between tips of index finger and thumb displays hyperflexion of index finger PIP joint because flexors of PIP joint are weakly opposed; dorsal interosseous weakness Ulnar nerve affected

Question 29

Froment's Sign

Answer 29

Testing nerve function using the pinch testFroment’s sign reveals adductor pollicis m. weakness Froment’s sign - Patient employing forceful “precision grip” between tips of index finger and thumb displays flexion of thumb IP joint because adductor pollicis is compromised but FPL is still functioning ulnar nerve affected

Question 30

Test for Deep Branch of Ulnar Nerve

Answer 30

``` Ulnar nerve (deep branch) – knocks out interosseous muscles (which flex MP joints), and 2/4 lumbricles Only way to flex the fingers is to recruit the digitorum profundus and superficialis when interosseous muscles aren’t working Flexion with fingers straight can only be achieved with interossei Hold object between straight fingers and can see how much resistance they can generate ```

Question 31

Ulnar vs. Median Nerve Tests

Answer 31

To test ulnar nerve: Can you pinch grip with forefinger and thumb without flexing your thumb IP joint? Froment’s (flexed IP joint) finds median’s (FPL) fine, ulnar nerve is not To test median nerve: Can you flex your thumb IP joint? = Can you make a round OK sign? Flat thumb shows ulnar nerve is fine, median nerve is not

Question 32

Ulnar Nerve Palsy

Answer 32

loss of ulnar nerve function loss of most of the intrinsic muscles of the hand long term - claw hand = intrinsic minus hand due to hyperextension of MCP joints flexion of IP joints lack of interossei & lumbricals NB also atrophy of 1st dorsal interosseous

Question 33

Radial Nerve Neuropathies: Upper and Lower Humerus

Answer 33

``` Upper humerus (Crutch & Sat. night palsy) Weakness in all elbow and wrist extensors, weak wrist abduction and extension Numbness on dorsum of hand radial side ``` Lower humerus Triceps spared (elbow extension retained) Lose brachioradialis (negligible effect on elbow flexion) Lose ECRL&B (weak wrist abduction) Lose wrist extensors (wrist drop) Numbness on dorsum of hand radial side

Question 34

Radial Nerve Neuropathies: Posterior Interosseous and Superficial Radial

Answer 34

Posterior interosseous: Brachioradialis and triceps functioning, but wrist drop Sensation normal on hand radial side dorsum Superficial radial n.: No motor symptoms Numbness hand radial side dorsum

Question 35

Radial Nerve Injury

Answer 35

Common Causes - Fracture of humerus - Improper use of crutches - “Saturday night” palsy Sensory - loss of sensation on lateral elbow, posterior forearm and dorsum of hand Motor Triceps, brachioradialis, supinator and extensors of wrist and fingers - If lesion beyond humerus, triceps not effected “Wrist drop” - patient unable to extend wrist

Question 36

Long Thoracic Nerve

Answer 36

Innervates serratus anterior (C5-7) | Lesion: winged scapula

Question 37

Accessory Nerve (CN XI)

Answer 37

Provided motor innervation to trapezius m. Common causes of injury: Surgery in posterior triangle of neck Penetrating wound in neck Blunt trauma to neck Profound weakness in shrugging/lifting shoulders