Anatomy of Upper Limb Flashcards
Upper Limb Movements
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
Hand/Wrist Movements
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
Intrinsic Muscles and Extensor Hood of Phalanges
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
Precision Grip
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
Types of Nerve Injuries
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
Testing Myotomes
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)
Bicipital Reflex
Bicipital reflex = tests C6 spinal nerve and musculocutanous nerve
Patient can be unconscious
Triceps Reflex
Triceps reflex: test above olecranon and arm should jerk in response
Patient must be conscious
Tests radial nerve and C7 spinal nerve
Dermatomes of Overlap
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
Cutaneous Nerves: Shoulder
Supraclavicular nn - cervical plexus
Cutaneous Nerves: Arm
- 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.
Cutaneous Nerves: Forearm
- 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
Cutaneous Nerves: Hand
Superficial branch of radial n.
Ulnar n.
Median n.
Erb-Duchenne Palsy
damage to root of C5 and C6
from traumatic lateral neck bending
during childbirth
from fall on shoulder
Erb-Duchenne Palsy: Nerves and Muscles Affected
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)
Klumpke’s Palsy
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
Klumpke’s Palsy: Nerves and Muscles Affected
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
Axillary Nerve Damage
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
Median Nerve Muscles
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
Musculocutaneous Nerve
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
Ligament of Struthers Syndrome
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
Pronator Teres Syndrome
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
Anterior Interosseous Nerve and Carpal Tunnel Syndrome
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
Proximal Median Nerve Injury
Highest injuries (above elbow) results in loss of pronation and medial deviation during wrist flexion
Flexor Pollicis Longus
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
Testing Flexor Digitorum Profundus and Superficialis
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
Ulnar Nerve Neuropathies
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
Mannerfelt’s Sign
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
Froment’s Sign
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
Test for Deep Branch of Ulnar Nerve
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
Ulnar vs. Median Nerve Tests
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
Ulnar Nerve Palsy
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
Radial Nerve Neuropathies: Upper and Lower Humerus
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
Radial Nerve Neuropathies: Posterior Interosseous and Superficial Radial
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
Radial Nerve Injury
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
Long Thoracic Nerve
Innervates serratus anterior (C5-7)
Lesion: winged scapula
Accessory Nerve (CN XI)
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
