Hand Flashcards
What is a tendon?
Made of fibrous connective tissue and connects bone to muscle
What is a ligament?
Made of fibrous connective tissue and connects bone to bone
What are the 2 main compartments of the arm?
Thenar and midpalmar space
What are the two septa of the hand and where are they?
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Medial - extends from the palmar aponeurosis to the little finger metacarpal
Lateral - extends from the palmar aponeurosis to the middle finger metacarpal
What are the muscular compartments of the hand?
- Hypothenar compartment (elongated prominence associated with the little finger)
- Central compartment (contains lots of tendons)
- Thenar compartment (muscle compartment at the base of the thumb)
- Adductor compartment (small compartment – essentially just a single muscle)
What is a septum?
essentially a wall between two structures
Where else are septa found in the hand?
between the tendons
What do digitorium muscles act on?
The four digits other than the thumb
Which muscles are in the superficial anterior compartment of the arm?
- Pronator teres (PT)
- Flexor carpi radialis (FCR)
- Palmaris longus (PL)
- Flexor digitorum superficialis (FDS)
- Flexor carpi ulnaris (FCU)
Which muscles are in the deep anterior compartment of the arm?
- Flexor digitorum profundus (FDP)
- Flexor pollicis longus (FCP)
- Pronator quadratus (PQ)
Where do most of the flexors originate from?
common flexor tendon
What does the palmaris longus tendon fan out into?
The palmar aponeurosis (this is present even when PL isn’t)
Where can extensor muscles originate?
Interosseous membrane, ulnar/radius and common extensor tendon
What are the groups of intrinsic muscles of the hand?
- thenars
- adductors
- hypothenars
- interossei
- lumbricals
What are the thenar muscles?
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
What are the adductor intrinsic hand muscle(s)?
adductor pollicis
What are the hypothenar muscles?
- Abductor digit minimi
- Flexor digiti minimi
- Opponens digiti minimi
What are the interossei/lumbricals?
-Lumbricals – flex the MCP’s, extend the IPJs
Palmar interossei – adduct the digits (“PAD”)
Dorsal interossei – abduct the digits (“DAB”)
What are interossei?
muscles that have attachments between bones
What are extrinsic and intrinsic muscles of the hand?
Extrinsic - muscle belly is located on the forearm. Intrinsic - smaller muscles located within the hand
Which muscles cause abduction. adduction. extension, flexion and opposition of the thumb?
Abduction: APL, APB
Adduction: Adductor pollicis, first dorsal interosseous
Extension: EPL, EPB, APL
Flexion: FPL, FPB
Opposition: Opponens pollicis
Where is adductor pollicis?
A single muscle that has a broad attachment on the middle metacarpal. Muscle fibres combine at the end of the first phalanx of the thumb
What is the nerve supplying the adductor pollicis?
ulnar - all other thenars are supplied by median
What are the lumbricals?
Muscles that are coming off the long tendons from flexor digitorum profundus (deep)
Where do the lumbrical muscles converge?
At a tendon a little more distally
How many interossei are there dorsally and palmar and what do they do?
dorsal - 4 (dorsal one pulls the fingers apart in relation to the axial line)
palmar - 3
What is special about the little finger in terms of adduction and abduction?
The little finger has its own digiti minimi (adductor that is not an interosseous muscle). The dorsal interossei will abduct the fingers. The palmar interossei adduct to close the fingers
What are the different joints in the hand?
- Distal radio-ulnar joint
- Wrist joint
- Intercarpal joints
- Carpo-metacarpal and inter-metacarpal joints
- Metacarpo-phalangeal joints
- Interphalangeal joints
What kind of movement occurs at intercarpal joints?
gliding
What is unique about the skin on the palms and sole of the feet?
It is very tough due to grasping and gripping, the cornified layer is much thicker (plantar-palmar skin)
Where is the palmar aponeurosis?
- underneath the fascia in a fan shaped structure
What does the palmar aponeurosis cover?
- longer flexor tendons of the hand
What is the palmar aponeurosis continuous with?
- proximally with the flexor retinaculum
- distally with the fibrous digital sheaths
What do fibrous digital sheaths contain?
flexor tendons and synovial sheaths
Where does the palmar aponeurosis originate from?
Originates at the wrist region, and is a continuation of palmaris longus tendon (some people don’t have this bu the aponeurosis still exists)
What are the lumbricals?
Muscles that come off the long tendons from flexor digitorum profundus
Where do the lumbricals converge?
At a distal tendon
- This tendon on the anterior surface of the palm goes round posteriorly, and attaches to the tendinous structures posteriorly.
- This allows these muscles to flex the metacarpal phalangeal joint, and extend the fingers (important in graduated movements of the fingers).
What are the annular and cruciform pulley?
ligaments of the tendon sheath
annular - bands
cruciform - cross shaped
What is the anterior tendinous anatomy of the hand?
- Fibrous digital sheath
- Osseo-fibrous tunnels
- In the tunnels run the long flexor tendons and their synovial sheaths
- Annular and cruciform pulleys
What does the synovial sheath do? Describe its association with the tendons
As groups of tendon pass under the flexor retinaculum into the carpal tunnel, they are covered with a synovial sheath.
Synovial sheaths wrap around the tendons. They continue right up into the little finger and thumb. The sheath stops for the middle three fingers (they have a separate sheath surrounding them).
What are the tendons of the posterior surface of the hand?
- Extensor retinaculum (at - Synovial tendon sheaths
- Inter-tendinous bands - Extensor expansions
- Lumbricals and interossei attach to the expansions
- Extensor digitorum, EI, EDM
What is the role of the extensor retinaculum?
Not as thick as the flexor retinaculum but holds the tendon down
Why do tendons have sheaths?
They act as lubricants
What happens to the tendons in the hand as they move closer to the digits?
They are linked by the inter-tendinous bands
Where do flexor digitorum profundus and superficialis attach?
- Flexor digitorum superficialis attaches into the middle phalanx
- The flexor digitorum profundus goes to the distal phalanx
- In order to do that, it has to pierce the FDS – this allows the FDP to go through
What are the movements of the carpometacarpal and intermetacarpal joints?
- flexion and extension
- radial and ulnar deviation
- circumduction
What are the movements of the metacarophalangeal joints?
- flexion and extension
- abduction and adduction
What movements of the interphalangeal joints?
Flexion and extension only
What are the interphalangeal joints?
proximal and distal
What are collateral ligaments and volar plates (palmar ligaments)?
There are collateral ligaments, which help to prevent over-extension and over-flexion (particularly in the interphalangeal joints).
The volar plates (palmar ligaments) are important for preventing over-extension of the joints as well.
Describe the extensor tendon anatomy on the posterior surface of the hand
- When talking about the dorsal (posterior) surface of the hand, we see extensor tendons
- The extensor tendon fans out into a hood (to become to extensor expansion)
- The lumbricals and the interossei attach in these regions
- The lumbricals will pull on the extensor expansion, helping to straighten the fingers
- The interossei can make a contribution to this movement
What is the arterial supply of the hand?
- The radial and ulnar arteries supply the hand
- Each of these provides contribution to arterial arches in the hand
- Most commonly, the ulnar provides larger supply to the superficial palmar arch
- It also branches later into the deep palmar branch
- The superficial arch branches off into 3 common palmar digital arteries
- The radial supply is larger to the deep palmar arch
- Anastamoses with deep palmar branch of ulnar artery to form deep branch
- deep arch fives off the palmar metacarpal arteries
Where is the radial artery found in the hand?
floor of anatomical snuff box
Describe the venous drainage of the hand
- Superficial and deep systems
- There is a superficial palmar arch and a deep palmar arch.
- It is rarely a single vein – often at least a pair.
There are digital branches that feed into the venous arches - Venous arches ultimately drain into the deep veins (radial and ulnar veins)
What are the superficial veins of the hand?
Posteriorly is the dorsal venous arch. This arch gives rise to the two major superficial veins of the forearm and arm (the cephalic vein and the basilic vein).
What are the main nerves of the forearm?
ulnar, radial and median
What do the median, ulnar and radial nerve do?
Median nerve
- Main nerve of the anterior compartment of forearm
- Some supply to hand intrinsic muscles
Ulnar nerve
- Main nerve of the hand
- Some of anterior compartment (FCU, half of FDP)
Radial nerve
- Posterior compartment of the forearm
- Some sensory component to the hand
- No supply to intrinsic muscles of the hand
Where does the median nerve enter the hand?
Through the carpal tunnel
What does the median nerve provide motor and sensory supply to?
Motor:
- Thenar muscles (APB, FPB, OP)
- Lumbricals I and II
Sensory:
- Palmar surface of thumb, IF, MF and half of RF
- Some of the dorsal surface of those digits
What does the ulnar nerve supply?
The ulnar nerve only supplies one and a half muscles (FCU) and the ulnar half of flexor digitorum profundus. Then it supplies all of the other intrinsic muscles of the hand.
What do the superficial (sensory) and deep (motor) branches of the ulnar nerve supply?
Superficial:
- Palmar surfaces of LF and half of RF
Deep:
- Hypothenar muscles
- Adductor pollicis
- Lumbricals III and IV (medial two)
- All the interossei (palmar and dorsal)
What does the radial nerve do?
The radial nerve supplies all the posterior muscles of the arm and forearm. It has no motor supply in the hand, but it does have some sensory supply.
Divides just above the level of the elbow into:
- Deep branch – the posterior interosseous nerve (motor)
- Superficial branch – the superficial radial nerve (sensory)
- No motor supply in the hand
- Sensory supply to the dorsum of the hand
Where does the ulnar enter the hand?
- The ulnar nerve doesn’t pass through the carpal tunnel
- The ulnar nerve goes through a small medial space
- This is called Guyon’s tunnel
Where does the carpal tunnel attach?
Scaphoid, trapezoid, pisiform, hamate (form a gutter)
What are the different types of grip?
- power grip: grasping firmly
- precision grip: grasping with a graded grip
- hook grip: for carrying
Which muscles are used in power grips, precision grips and hook grips?
power: long flexors of finger and thumb, intrinsic muscles of palm, wrist extensors
precision: long flexors and extensors, intrinsic muscles of hand
hook: long flexors of digits
What is the palmar fascia?
- The palmar fascia is the fascia of the hand that lies in the palm
- There are specialisations of the palmar fascia that form the palmar aponeurosis and fibrous digital sheaths
What are the fibrous digital sheaths?
Tubes that contain the flexor tendons and their sheaths
Where do dorsal digital veins drain?
Into dorsal venous arches on the dorsum of the hand - most venous drainage of hand is superficial
Describe the arrangement of the fascia
- The fibrous digital sheaths are a continuation of the palmar fascia
- These sheaths extend from the level of the metacarpal head to the base of the distal phalanx in each digit
- Together with the underlying bone they form osseo-fibrous tunnels through which the long flexor tendons and their synovial sheaths run
- Parts of the fibrous digital sheath form condensations called pulleys, which allow for more functional use of the long flexor tendons -(annular and cruciform pulleys)
Describe the tendinous arrangement on the dorsum of the hand
- On the dorsum of the hand, the long extensor tendons to the digits are joined by inter-tendinous bands
- To some extent, these bands prevent free movement of one extensor tendon independently of the others
- At the level of the metacarpals the long extensor tendons flatten to form extensor expansions.
- These expansions form a hood on the back of the digit
- The lumbricals and the interossei attach to this extensor expansion
- The extensor expansions are intricately involved in the movements of the digits.
- The extensor digitorum extends the MCP joint as well as the IP joints. It also plays some part in extending the wrist joint after maximal extension of the digits.
What do the two branches of the ulnar nerve supply?
Palmar cutaneous branch – supplies the medial palm of the hand
Dorsal cutaneous branch – supplies the medial half of the dorsum of the hand, including the little and ring fingers
Where do secondary ossfication (growth) centres for the metacarpals and phalanges develop?
Thumb metacarpal develops at its base whilst the growth centres of the other 4 MCs develop at their heads.
The phalanges develop at their bases.
What is Allen’s test?
- This is a visual test for relative contribution of radial and ulnar arteries to the hand
- Subject asked to raise the hand and make a clenched fist
- Examiner compresses both the radial and ulnar arteries
- When the fist is released the palmar skin appears pale
- The examiner released either one of the arteries and notes the time for the return of hand colour
What happens to the tendons of FDP and FDS after passing wrist joint?
Which tendons have their own synovial sheaths?
- Enters a common synovial sheath
- The tendons then pass to their respective digit via a digital synovial sheath, which is contained within the fibrous digital sheath
- The digital synovial sheaths of the index, middle and ring fingers are separate from the common synovial sheath
- Those of the little finger and thumb are continuous with the common sheath
- The long tendon of the thumb, flexor pollicis longus, has its own synovial sheath at the flexor retinaculum. It then runs to the distal phalanx of the thumb.
