Hand

What is the palmar aponeurosis?

A thick, triangular sheet of fibrous tissue in the palm that protects underlying nerves, blood vessels, and flexor tendons

An extension of the palmaris longus

What tendons travel through the palmar aponeurosis?

Flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP), and flexor digitorum longus (FDL)

What is dupuytren’s contracture?

Viking hand; a benign hand condition where connective tissue beneath the palm's skin thickens and shortens, pulling the ring and little fingers inward; tends to pull more on ulnar side of hand, curling fingers in at MCP and PIP; occurs usually in men in 50 years or older

What are the fascial compartments of the hand?

Thenar, hypothenar, central, and adductor (deepest) compartments

What does it mean to be an extrinsic muscle of the hand ?

The muscles act on the hand but are not in the hand

The long flexor muscle bellies are in the anterior forearm; the long extensor muscle bellies in posterior forearm; tendons pass to digits through central compartments

What are the intrinsic muscles in the hand?

Thenar muscles, adductor pollicis, hypothenar muscles, lumbricals, & interossei

What are the thenar muscles?

Abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, adductor pollicis

What are the attachments of the abductor pollicis brevis?

Flexor retinaculum, tubercles of scaphoid and trapezium to lateral side of base of proximal phaIanx of thumb

What is the action of the abductor pollicis brevis?

Abducts thumb and helps with opposition

What innervates the abductor pollicis brevis?

Recurrent branch of median nerve C8/T1

What are the attachments of the flexor pollicis brevis?

Flexor retinaculum, tubercles of scaphoid and trapezium to lateral side of base of proximal phaIanx of thumb (2 heads & FPL runs in between)

What is the action of the flexor pollicis brevis?

Flexes thumb

What innervates the flexor pollicis brevis?

Recurrent branch of median nerve C8/TI

What are the attachments of the opponens pollicis?

Flexor retinaculum, tubercles of scaphoid and trapezium to lateral side of 1st MC

What is the action of the opponens pollicis?

Draws 1st MC and medially rotates toward center of palm

What innervates the opponens pollicis?

Recurrent branch of median nerve C8/TI

What are the attachments of the adductor pollicis?

2 heads separated by radial artery as it goes into hand to form deep palmar arch

Oblique head: base of 2nd/3rd MC, capitate, and adjacent carpals

Transverse head: anterior surface of shaft of 3rd MC

…to medial side of base of proximal phalanx of thumb (sesamoid bone)

What is the action of the adductor pollicis?

Adducts thumb toward lateral border of palm

What innervates the adductor pollicis?

Deep branch of ulnar nerve C8/T1

What is unique about the movements of the digits?

They are relative to the middle finger and the middle finger abducts in two directions

What are the hypothenar muscles?

Abductor digiti minimi, flexor digiti minimi (brevis), opponens digiti minimi

What are the attachments of the adbuctor digiti minimi?

Pisiform to medial side of base of proximal phalanx of 5th digit

What is the action of the adbuctor digiti minimi?

Abducts the 5th digit; assists in flexion of the proximal phalanx

What innervates the adbuctor digiti minimi?

Deep branch of ulnar nerve C8/T1

What are the attachments of the flexor digiti minimi?

Hook of hamate and flexor retinaculum to medial side of base of proximal phalanx of 5th digit

What is the action of the flexor digiti minimi?

Flexes proximal phalanx of 5th digit

What innervates the flexor digiti minimi?

Deep branch of ulnar nerve C8/T1

What are the attachments of the opponens digiti minimi?

Hook of hamate and flexor retinaculum to medial border of 5th MC

What is the action of the opponens digiti minimi?

Draws 5th MC anterior and rotates it, bringing 5th digit into opposition with thumb

What innervates the opponens digiti minimi?

Deep branch of ulnar nerve C8/T1

What are the short muscles of the hand?

Lumbricals, palmar interossei, dorsal interossei

What are the attachments of the lumbricals?

1st & 2nd: lateral 2 tendons of FDP to lateral sides of extensor expansions of the 2nd and 3rd digits; crosses MCP and goes around posterior and bledns with extensor expansions (unipennate)

3rd & 4th: medial 3 tendons of FDP to lateral sides of extensor expansions of the 4th and 5th digits (bipennate)

What is the action of the lumbricals?

1st & 2nd: Flexes MCP and extends IP joints of digits 2 and 3

3rd & 4th: Flexes fingers at MCP joints and extend IP joints of digits 4 and 5

How many digits can adduct and abduct?

Adduction - 3

Abduction - 4

What is a way to remember the digit adductors and abductors?

3 PADS 4 DADs

3 palmar interossei that adducts the fingers

4 dorsal interossei that abducts the fingers

What are the attachments of the palmar interossei?

Palmar surfaces of 2nd, 4th, and 5th MC (unipennate) to base of proximal phalanges; extensor expansions of 2nd, 4th, and 5th digits

What is the action of the palmar interossei?

Adducts 2nd, 4th, and 5th digits & aids lumbricals

What innervates the palmar interossei?

Deep branch of ulnar nerve C8/T1

What are the attachments of the dorsal interossei?

Adjacent sides of 2 MCs (bipennate) to base of proximal phalanges, extensor expansions of 2nd-4th digits

What is the action of the dorsal interossei?

Abducts 2nd-4th digits from axial line; helps lumbricals

What innervates the dorsal interossei?

Deep branch of ulnar nerve C8/T1

What is the path of the median nerve?

Root of medial and lateral cord then travels down medial brachium, through cubital fossa (TAN), innervates forearm muscles (PFP), goes into deep compartment and gives off interosseous branch

Interosseous nerve innervates muscles on medial side of hand, gives off palmar cutaneous branch (sensory), goes through carpal tunnel into hand and passes thenar compartment, gives off recurrent branch that loops around to innervate thenar muscles and innervates first 2 lumbricals (proper)

What does the motor component of the median nerve supply?

Thenar muscles

What does the sensory component of the median nerve supply?

Lateral palmar surface and sides of 1st 3 ½ digits and dorsum of distal halves of these digits

How many tendons go through carpal tunnel and from what muscles?

9 tendons:

4 from FDS

4 from FDP

1 form F

(+ 1 median nerve)

What is carpal tunnel syndrome?

When the median nerve is compressed as it passes through the carpal tunnel, causing numbness, tingling, and weakness in the hand and finger

What are symptoms of carpal tunnel syndrome?

Inability to oppose thumb, numbness/ "pins and needles" sensation, shock-like sensations radiating to the fingers, hand weakness and clumsiness, pain that can travel up the forearm

Where does the ulnar nerve travel?

Medial-posterior to median nerve, posterior compartment of brachium, behind medial epicondyle, enters anterior compartment and innervates FCU and half of…., goes through Guyon’s canal b/w hook of hamate and pisiform, splits into superficial and deep nerves, gives off dorsal and palmar branches before entering the hand

Superficial branch innervates superficial muscles while deep branch innervated PADs and DADs, thenar compartment, and deep ulnar muscles

What does the motor component of the ulnar nerve supply?

Medial 2 lumbricals, 3 hypothenar muscles, 7 interossei, adductor pollicis, (occasionally ?) deep part of FPB; also supplies wrist, intercarpal, CMC and IMC joints

What does the sensory component of the ulnar nerve supply?

Skin of palmar and distal dorsal aspects of medial 1 ½ digits and adjacent palm (dorsal and palmar cutaneous branch)

What is Guyon's canal syndrome?

Compression of the ulnar nerve as it passes through the canal in the wrist caused by repetitive pressure on the base of the palm of hand, trauma, and anatomical growths like cysts

What are the signs of Guyon’s canal syndrome?

Ulnar “claw hand”: IP flexion & hyperextension at MCP joint

Tingling or numbness in the little finger and the ulnar half (inner side) of the ring finger, weakness in grip, clumsiness, difficulty spreading or bringing the fingers together, and atropy of hand muscles

What is the pathway of the radial nerve?

From posterior cord and posterior division of all trunk, innervates anterior forearm, emerges b/w brachioradialis and brachialis, gives off into superficial and deep branches (posterior interossei nerve)

Deep branch goes through posterior compartment and innervates supinator, travels deep to brachioradialis and supplies no hand muscles

What are the dorsal components of the radial nerve?

None; it doesn’t innervate any hand muscle

What are the sensory components of the radial nerve?

Superficial branch supplies skin and fascia over lateral 2/3 of dorsum of hand, dorsum of thumb, and proximal parts of the lateral 2/3 digits

What is the path of the ulnar and radial artery into the hand?

Radial: By crossing the floor of the snuff box

Ulnar: After traveling through forearm, it passes anterior flexor retinaculum

Both: Contribute to the formation of superficial and deep palmar arches

Where does the venae comitantes and dorsal digital veins drain?

Venae comitantes: Into deep veins of the forearm

DDV: Into a dorsal venous network that leads to the cephalic vein (laterally) and basilic vein (medially)

Label the blue joint

Distal interphalangeal joint (DIP)

Label the purple joint

Proximal interphalangeal joint (PIP)

Label the yellow joint

Metacarpophalangeal joint (MCP)

(your knuckles!)

Label the orange joint

Interphalangeal joint (IP)

Label the green joint

Carpometacarpal joint (CMC) of thumb

Describe the joints of the hand

Plane synovial joints; allow gliding and sliding movements to help increase ROM of wrist joint

Describe the capsule and ligaments of the joints of the hand?

Fibrous capsule lined with synovial membrane that are continuous b/w inter/midcarpal and CMC joints

Bones of each row are connected by dorsal, palmar, and interossei ulnar ligaments

2 rows are connected by dorsal, palmar, radial, and ulnar ligaments

Describe the CMC joint of the thumb

Saddle synovial joint located at the trapezium and base of 1st, 2nd and 5th digits; fibrous loose capsule lined by synovial membrane; allows flexion, extension, ab/aduction, opposition, and circumduction of thumb; common site of arthritis

What innervates the CMC joint of the thumb?

Anterior interosseous (median), posterior interosseous (radial), and dorsal/deep branch of ulnar nerve

Describe the MCP joints

Condyloid synovial joints; fibrous capsules w/ synovial membrane; triangular collateral ligaments on sides; articulates with palmar ligaments; innervated by digital nerves from ulnar and median nerves

Describe the IP joints

Uniaxial hinge synovial joints; reinforced dorsally by extensor expansions of the digits; only allow flexion and extension

What are extensor expansions of the hand?

A complex, triangular band of connective tissue on the back of the fingers that allows the extensor muscles, lumbricals, and interossei to coordinate precise extension, flexion, and fine movements at each finger joint