Hand and Fascial Spaces Flashcards
What form the hypothenar and thenar eminences?
Thenar = bulge of tissue around thumb hypothenar = bulge of tissue around pinky
What is the midpalmar compartment?
The area between the hypothenar and thenar eminences. A compartment is defined as an area of the body enclosed by fascia or connective tissue and contains muscles, blood vessels, nerves, etc
How many phalanges are there for each digit? What type of bone are they?
Metacarpals and phalanges are all miniature long bones. The thumb has two phalanges and all the other digits have 3
Where are the digits connected most distally? How do phalanges connect?
The metacarpophalangeal ligaments connect as 4 digits with the transverse metacarpal ligament, which include a palmar ligament/plate for the flexor tendons to run. Ligaments also connect interphalangeal ligaments
For finger movements, what are abduction and adduction in relation to?
The plane of the palm for the thumb, through the middle finger for the other digits
What makes the carpometacarpal joint of the thumb different from the other digits?
Flexion, abduction, adduction, and extension can happen at that joint -> it is a moving joint. Joints of other digits cannot do that.
What are MP and IP joints?
MP = metacarpophalangeal, between metacarpals and proximal phalanx IP = interphalangeal, between proximal and intermediate; intermediate and distal phalanges
They are all synovial joints
What are the origin, insertion, innervation, and action of the abductor pollicis brevis muscle?
Origin: Flexor retinaculum, scaphoid, trapezium
Insertion: Sesamoid bone of metacarpal I, proximal phalanx, and extensor expansion on posterior thumb
Innervation: Median nerve (recurrent)
Action: Abduction and flexion of proximal phalanx
Most lateral muscle of thenar compartment
What are the origin, insertion, innervation, and action of the flexor pollicis brevis muscle?
Origin: Flexor retinaculum, trapezium
Insertion: Sesamoid bone of metacarpal I, proximal phalanx, and extensor expansion on posterior thumb
Innervation: Median nerve (recurrent)
Action: Flexion of proximal phalanx
What are the origin, insertion, innervation, and action of the opponens pollicis muscle?
Origin: Flexor retinaculum, trapezium
Insertion: Lateral side of first metacarpal
Innervation: Median nerve (recurrent)
Action: Rotates our thumb during opposition -> lets us have opposable thumb to grasp things
What supplies blood to the thumb and lateral first digit?
Branches of the radial artery, called princeps pollicis for thumb and radialis indicis for lateral digit II. The radial artery in general crosses deep to the adductor pollicis to supply the skin and subcutaneous tissue of the thumb
What is the superficial palmar arch?
Blood mostly supplied by ulnar artery but partially from radial artery through anastomoses, supplies blood to digits (digital arteries), thenar eminenance, and superficial palm (palmar digitals).
What are the origin, insertion, innervation, and action of the palmaris brevis muscle?
Origin: Flexor retinaculum, palmar aponeurosis
Insertion: Ulnar side of palm
Innervation: SUPERFICIAL branch of ulnar nerve
Action: Draws skin from ulnar side of palm to middle of palm, deepening hollow
What are the origin, insertion, innervation, and action of the abductor digiti minimi muscle?
Origin: Pisiform
Insertion: Proximal phalanx of 5th digit
Innervation: Deep branch of ulnar nerve
Action: Abduction of digit V
What are the origin, insertion, innervation, and action of the flexor digiti minimi muscle?
Origin: Hamate
Insertion: Proximal phalanx of digit 5
Innervation: Deep branch of ulnar nerve
Action: Flexion of digit 5 at proximal phalanx
What are the origin, insertion, innervation, and action of the opponens digiti minimi muscle?
Origin: Hamate
Insertion: 5th metacarpal
Innervation: Deep branch of ulnar nerve
Action: Draws 5th metacarpal anteriorly to contact thumb during opposition, but cannot rotate it
What forms the superficial palmar arch?
Vessels from the ulnar artery, supply the medial 3 and 1/2 digits. Also has help from the radial artery in forming the superficial arch
What supplies blood to the hypothenar compartment?
Deep branches of the ulnar artery
What are the boundaries of the mid palmar compartment?
palmar aponeurosis, interosseous fascia posteriorly, thenar fascia / compartment, and hypothenar fascia / compartment
What are the lumbricals and what is their function?
Wormlike muscle on the radial (lateral) side of FDP tendons (digits II-V). They attach on the extensor expansions, and cause flexion at MP joints and extension at IP
What are the innervations of the lumbricals?
Unipennate lumbricals of digits II and III = median nerve
Bipennate lumbricals of digits IV and V = ulnar nerve
What are the origin, insertion, innervation, and action of the adductor pollicis?
Origin: Oblique head - 2nd and 3rd metacarpals and capitate
Transverse head - 3rd metacarpal
Insertion: Medial sesamoid bone, proximal phalanx, extensor expansion of thumb
Innervation: deep branch of ulnar nerve
Action: adduction of thumb, helps with opposition
Why can you still move your thumb inward when you have CTS?
the adductor pollicis is innervate by the ulnar nerve
What is the function of the palmar interossei and where do they originate and attach? What innervates them?
They function to adduct the fingers towards the middle finger. There is some debate as to whether the thumb one exists. They originate on the palmar side of the digits (Except middle finger) and insert on the side of the base of the proximal phalanx of each finger, as well as the extensor expansion. Innervated by deep branch of ulnar nerve
What is the function of the dorsal interossei and where do they originate and attach? What innervates them?
They function to abduct the fingers. They each have two heads and arise between the metacarpal bones and pull them away from imaginary line through the middle finger. First dorsal interosseous is largest and pulls index finger towards thumb. Only the third digit has attachments on the medial and lateral side. Digit 5 has no attachment of these (that’s why is it has abductor digiti minimi). They also attach to extensor expansion and can have the same function as lumbricals. Innervated by ulnar nerve.
What is the extensor expansion?
Aponeurotic or tendinous fusion of digital extensors, lumbricals, and interossei tendons on dorsal aspecct of digits. Flexion at MP joint causes extension at IP joints when the interossei and lumbrical muscles are active
What are vincula?
Special folds of connective tissue which hold the long flexor tendons at each joint and protect the supplying blood vessels. They provide nutrients to the tendons?
What is the fibrous digital sheath?
The sheath that encloses the tendons and extensors in the fingers, making them much stronger
What muscles does the recurrent medial nerve supply?
Abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and the first and second lumbricals. It is vulnerable to cuts on the thenar eminence because it is superficial distally to flexor retinaculum.
What does the deep branch of the ulnar nerve supply in the hand?
After passing laterally to the pisiform, it supplies all three muscles of the hypothenar compartment, the 3rd and 4th lumbricals, all interossei, and the adductor pollicis.
How does the ulnar nerve supply cutaneous innervation?
Dorsal branch supplies medial 1 and 1/2 digits on dorsal side, superficial branch supplies medial 1 and 1/2 digits on palmar side, after splitting with deep (motor) branch of ulnar nerve
What is the function of the superficial radial nerve in the hand?
Supplies dorsal surface sensation of medial 3 and 1/2 digits, except for distal phalanges (supplied by medial nerve). Remember, this courses through the anatomical snuff box
Where does the deep palmar arch of the radial artery go?
Between the two heads of the 1st dorsal interosseous muscle. Eventually meets with ulnar artery deeply.
What is the lateral fibrous septum?
Also called the oblique palmar septum, extends from third metacarpal to palmar aponeurosis. Definds the boarders of the medial and lateral palmar fascial spaces
What is a fascial space?
Any area between fascial layers of a compartment
Where is the lateral palmar space?
Also called the thenar space, it is lateral to the oblique palmar septum
What is the medial palmar space?
The space medial to the oblique palmar septum.
Why do the palmar spaces matter?
Because the fascia is compartmentalized, the infection can only spread proximally up the arm, but not medially or laterally since the fascia prohibits it.
