OMM: Musculoskeletal & Autonomic Nervous System

SItS = Supraspinatus, Infraspinatus, Teres minor, Subscapularis

Four muscles wrap the humeral head like a sleeve, holding it in the shallow glenoid socket. Supraspinatus initiates abduction (first 15 degrees), infraspinatus and teres minor externally rotate, subscapularis internally rotates. They stabilize the ball in the socket during every arm movement.

Supraspinatus tears first because it runs through the subacromial space (between acromion and humeral head). Every time you raise your arm, it gets pinched. Decades of pinching = fraying = tear.

Impingement tests (Neer, Hawkins) compress supraspinatus against acromion. Empty can test isolates it specifically.

Two big muscles pulling the arm toward the body:

• Pectoralis Major (lateral & medial pectoral nerves) pulls from the front
• Latissimus Dorsi (thoracodorsal nerve) pulls from behind

• Primary flexor: Anterior deltoid
• Primary abductor: Middle deltoid
• Primary extensors: Posterior deltoid, Teres major, Latissimus dorsi
• Normal abduction: 180 degrees

Artery goes BETWEEN scalenes. Vein goes ANTERIOR to them.

Anterior scalene is the dividing wall. Subclavian artery passes between anterior and middle scalenes (same path as brachial plexus). Subclavian vein passes in front of the anterior scalene (separate path). This anatomy creates three compression zones for TOS.

Numbness, tingling, pain in arm/hand + positive provocative tests at specific compression points

Neurovascular bundle (brachial plexus + subclavian artery/vein) travels through three narrow spaces:

1. Scalene triangle (between anterior and middle scalenes)
2. Costoclavicular space (between clavicle and 1st rib)
3. Interpectoral space (under pec minor)

Compression at any of these = TOS.

Tests by compression site:

• Scalene triangle: Adson test (deep breath + head turn toward affected side) + Reverse Adson (head turn away)
• Costoclavicular: Military posture test (retract + depress shoulders)
• Interpectoral: Wright's test (arm hyperabduction) + Roos test (arms abducted, elbows flexed, open/close hands 3 min)

Which direction? Almost always anterior (95%).

Arm in abduction + external rotation (falling on outstretched hand) levers humeral head forward. Posterior structures weaker than anterior. Head slides out the front.

• Anterior dislocation: Most common. Mechanism = fall on outstretched hand. Nerve at risk = axillary nerve (deltoid paralysis, lateral shoulder numbness "regimental badge").
• Posterior dislocation: Etiology = SEIZURES (also electrocution). Posterior muscles overpower anterior. X-ray = "light bulb sign."

Terminology:

• Subluxed: Partially out, surfaces still touching, often self-reduces
• Dislocated: Completely out, zero contact, needs reduction
• Separated: AC joint ligaments torn, clavicle floats up (different joint entirely)

These test INSTABILITY (will it dislocate again?), not acute dislocation.

• Anterior apprehension: Shoulder abducted 90 degrees, externally rotated. Positive = feels like it will pop out the front.
• Posterior apprehension: Shoulder flexed 90 degrees, internally rotated, adducted. Positive = feels like it will slide out the back.

Supraspinatus compressed under acromion. Pain with overhead movement.

• Neer: Forward flex arm past 90 degrees, push down. Pain = positive.
• Hawkins: Arm at 90 degrees forward flex, internally rotate. Pain = positive. More sensitive than Neer.
• Empty can (Jobe's): Arms 90 degrees abduction, 30 degrees forward, thumbs down. Resist downward. Pain/weakness = supraspinatus.
• Drop arm: Abduct 90 degrees, slowly lower. Can't control descent = TEAR (get MRI).

Pain in the bicipital groove (anterior shoulder)

• Speed's test: Shoulder flexed 90, elbow flexed, forearm supinated. Resist shoulder flexion. Pain = biceps tendinitis.
• Yergason's test: Elbow flexed 90 at side, forearm pronated. Patient supinates against resistance. Pain = biceps tendinitis.

• Painful Arc Syndrome = another name for supraspinatus tendonitis
• Adhesive Capsulitis (frozen shoulder) = develops from prolonged immobilization or guarding

"Waiter's tip" position in a newborn after difficult delivery.

Excessive lateral neck flexion away from shoulder (head pulled one way, shoulder pulled other way) stretches C5-C6 roots. These roots supply deltoid, biceps, brachialis, brachioradialis, supraspinatus, infraspinatus. All gone.

Result: Arm hangs adducted, internally rotated, elbow extended, forearm pronated. Gravity wins because the muscles holding the arm UP are dead.

Claw hand in a newborn. MCP extended, IP joints flexed.

Arm yanked UPWARD during delivery (opposite of Erb's) stretches C8-T1 roots. These roots supply all intrinsic hand muscles (lumbricals, interossei). Without intrinsics, long flexors dominate unopposed. Fingers claw.

Result: MCP hyperextension + IP flexion = claw hand. Wrist flexed.

Nerve = Long Thoracic Nerve. Muscle = Serratus Anterior.

Kill the nerve, the scapula wings out. Ask patient to push against a wall and scapula pops off their back.

Can't EXTEND 4th and 5th fingers when asked.

Ulnar nerve controls interossei + lumbricals 3-4. Without them, extensors hyperextend MCPs and flexors curl the IPs. Ask patient to extend all fingers: ring/pinky stay curled.

Froment's sign: Patient holds paper between thumb and index. Without adductor pollicis (ulnar), they compensate by flexing thumb IP. Flexed IP = positive Froment's = ulnar nerve dead.

Can't FLEX digits 1-3 when asked to make a fist.

Median nerve controls FDS and part of FDP (to index and middle). Ask patient to make a fist. Digits 1-3 stay extended while 4-5 flex normally (ulnar does those). Looks like a Pope giving a blessing.

Wrist hangs limp, can't lift it up.

Radial nerve controls ALL wrist and finger extensors (ECRB, ECRL, ECU, EDC). Kill the radial nerve, nothing can lift the wrist. Flexors unopposed, wrist drops.

Thenar eminence wasted, thumb stuck adducted, can't oppose.

Long-standing median nerve compression starves the thenar muscles (APB, opponens pollicis, FPB). Muscles atrophy over months/years. Thumb loses opposition. Hand looks like an ape's.

Numbness in thumb, index, middle, and lateral half of ring finger. Worse at night.

Carpal tunnel = tight space (carpal bones on floor, flexor retinaculum on top). Median nerve passes through. Repetitive motion swells tendons. Pressure builds. Median nerve crushed. Paresthesias in median territory. Worse at night because wrist flexes during sleep.

What's spared: Palmar cutaneous branch exits BEFORE the tunnel. Base of thenar eminence sensation stays normal. Numb fingertips + normal palm = CTS.

Muscles affected (chronic): Thenar muscles (APB, opponens, FPB) + lumbricals I-II.

Tests:

• Tinel's: Tap over carpal tunnel. Tingling shoots into median fingers = positive.
• Phalen's: Flex both wrists fully (reverse prayer), hold 30-60 sec. Reproduces paresthesias = positive.
• Reverse Phalen's (Prayer test): Extend both wrists fully. Same principle.

Long-standing CTS = thenar atrophy = ape hand deformity.

• Tennis elbow = Lateral Epicondylitis: Wrist extensors attach at lateral epicondyle. Repetitive extension overloads them.
• Golfer's elbow = Medial Epicondylitis: Wrist flexors attach at medial epicondyle. Repetitive flexion overloads them.

Angle formed by intersection of humerus axis and forearm axis.

• Normal: Males 5 degrees, Females 10-12 degrees
• Cubitus Valgus: Angle > 15 degrees = ABDuction of the ulna
• Cubitus Varus: Angle < 3 degrees = ADDuction of the ulna

Pain at radial styloid with Finkelstein's test.

Test: Patient makes fist with thumb tucked inside, then ulnar deviate the wrist. Pain at radial styloid = positive.

Muscles: APL (Abductor Pollicis Longus) + EPB (Extensor Pollicis Brevis). First dorsal compartment.

PIP hyperextension + DIP flexion. Associated with Rheumatoid Arthritis.

RA attacks flexor sheath and pulleys. PIP stuck in hyperextension, DIP compensates into flexion.

PIP flexion + DIP extension. Associated with Rheumatoid Arthritis.

RA destroys the central slip of the extensor tendon at PIP. Loss of PIP extension. DIP compensates by hyperextending. Looks like pushing a button.

Palmar fascia contracture. Fingers (ring and pinky first) progressively flex and won't straighten.

Abnormal fibroblast activity. Collagen cords form and shorten. Pull fingers into permanent flexion over months/years.

Pattern goes lateral to medial as you descend the cervical spine:

Radial head stuck anteriorly. Moves freely in supination, RESTRICTED in pronation.

Pronation requires radial head to move posteriorly. Stuck anteriorly, can't move back. Supination (anterior movement) is free because it's already there.

Etiology: Falling BACKWARDS onto a SUPINATED forearm.

HVLA: Flexion + supination + adduction.

Radial head stuck posteriorly. Moves freely in pronation, RESTRICTED in supination.

Supination requires radial head to move anteriorly. Stuck posteriorly, can't come forward. Pronation (posterior movement) is free because it's already there.

Etiology: Falling FORWARD onto a PRONATED forearm.

HVLA: Extension + pronation + abduction.

Decreased carrying angle + restricted wrist/hand adduction.

Distal ulna deviates medially (toward body) = ADDuction. Olecranon deviates LATERALLY (opposite). Carrying angle decreases (cubitus varus).

Increased carrying angle + restricted olecranon lateral glide.

Distal ulna deviates laterally (away from body) = ABDuction. Olecranon deviates MEDIALLY (opposite). Carrying angle increases (cubitus valgus).

Biceps femoris (lateral), semitendinosus, semimembranosus (medial).

Gracilis and sartorius assist but are NOT hamstrings. All three hamstrings also EXTEND the hip.

Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius. All four extend the knee.

ACL:

• Anterior drawer: Knee 90 degrees, pull tibia forward. Positive = anterior translation.
• Lachman's: Knee 20-30 degrees, pull tibia forward. MORE ACCURATE.

PCL:

• Posterior drawer: Knee 90 degrees, push tibia backward.
• Sag sign / Godfrey's: Hip AND knee 90 degrees, support heel. Gravity sags tibia posteriorly. Compare both sides.

Line from ASIS through patella center to tibial tuberosity.

• Normal: 10-15 degrees (females higher: 15-17 degrees)
• Increased (>15): Genu Valgum (knock-knees)
• Decreased (<10): Genu Varum (bow-legs)

OMM: High Q angle + tight IT band + weak VMO = patellofemoral pain syndrome. Valgum = lateral compartment OA risk. Varum = medial compartment OA risk.

Angle of Inclination (Neck-Shaft Angle):

• Normal: 130-135 degrees
• Coxa vara: < 130 degrees (neck bends down)
• Coxa valga: > 135 degrees (neck angles out)

• Spurling test: Extend neck + bend toward painful side + axial compression = reproduces radicular pain
• Neck distraction: Pull head upward = relieves pain. Confirms nerve is the source.
• Imaging: X-ray (bone spurs), MRI (disc bulge, nerve compression), CT (bone detail), EMG/NCS (confirms nerve dysfunction)

Two divisions: Sympathetic (fight or flight) vs Parasympathetic (rest and digest). Both require a 2-neuron chain: preganglionic → ganglion → postganglionic.

Viscerosomatic reflex: Organ dysfunction → afferent signals travel back to spinal cord → sensitize the corresponding somatic segment → you find tenderness, hypertonicity, or skin changes at the body wall level corresponding to the organ's spinal level.

Chapman reflex points: Anterior points on the chest/abdomen wall; posterior points near the paraspinal region. Each point maps to a specific organ. Used for diagnosis AND treatment.

• Find the anterior point → correlate with organ → look for matching symptoms
• Treatment: sustained rotary pressure on the anterior point, then confirm resolution at posterior point
• Posterior points lie in the transverse processes near the organ's corresponding spinal level
• Points are small, tender, firm nodules → like a small BB under the skin

• Rib raising: Stretches the paravertebral muscles → mobilizes ribs → increases SNS outflow. Used in pneumonia with respiratory compromise to improve respiratory drive.
• Chapman point stimulation: Rotary pressure activates the viscerosomatic reflex arc
• Paraspinal ganglionic stimulation: Direct pressure on the sympathetic chain

• Paraspinal inhibition: Sustained pressure on paravertebral muscles → decreases SNS tone. Opposite of rib raising.
• Still technique: Inhibitory technique → calms tissue, decreases SNS activation. Useful when you need to reduce sympathetic overdrive.
• Rib raising (paradox): At lower rib levels (11: 12), Still technique decreases SNS output to the organ

• OA-AA release / Suboccipital release: Targets the vagus nerve (CN X) at its exit from the jugular foramen (C0: C1 level). Increases vagal parasympathetic output to thorax and abdomen.
• C1: C2 manipulation: Same vagal effect as OA-AA release
• Sacral techniques: Target S2: S4 pelvic splanchnics → increases parasympathetic to lower GU/GI
• Cranial techniques: Influence the dorsal vagal nucleus via craniosacral rhythm

• Thoracic lymphatic pump: Moves lymph from thoracic duct into venous circulation. Contraindicated in pneumonia with sepsis risk (could spread bacteria systemically).
• Pedal pump (Dalrymple): Lower extremity lymph drainage
• Splenic pump: Activates immune cells from spleen → useful in infection but also contraindicated if bacteremia risk exists