Lecture 15 - Forearm and Hand 1 Flashcards
How many carpal, metacarpal and phalanx bones are there in the hand?
8 Carpal bones
5 Metacarpal bones
14 Phalanges (2 in thumb, 3 in other fingers)
Describe the arrangement of the 8 carpal bones
The carpal bones are arranged into a proximal and distal row, with there being 4 bones in each row
What are the 4 bones in each of the proximal and distal row of the carpal bones?
Proximal: Scaphoid, Lunate, Triquetral, Pisiform
Distal: Trapezium, Trapezoideum, Capitate, Hamate
What kind of joint is the wrist joint?
It’s an Ellipsoid joint, which is biaxial allowing for flexion, extension, adduction and abduction
What bones form the midcarpal joint, and what function does this joint have?
Midcarpal joint is formed by the proximal and distal row of carpals.
This joint increases the range of flexion/extension of the carpus.
Describe the naming system for the wrist (sides and aspects)
What is the origin of Flexor carpi ulnaris, and flexor carpi radialis, and where do they insert?
Also, what movement do they perform on the wrist joint?
They both originate at the medial epicondyle of humerus.
Flexor carpi ulnaris inserts into the base of the 5th metacarpal, whilst Flexor carpi radialis inserts into the base of metacarpals 2 and 3.
They both flex and abduct the wrist joint.
What muscles flexes both the interphalangeal amd metacarpophalangeal joints of the thumb?
Flexor pollicis longus
What muscle flexes both the interphalangeal and metacarpophalangeal joints of the index, middle, ring, and little fingers of the hand?
Flexor digitorum profundas
What are the extensors of the wrist in the posterior compartment of the forearm? And where do these originate?
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
They originate from the lateral epicondyle of the humerus
Where does the Extensor carpi radialis brevis insert?
Base of metacarpals 2 and 3
Where does extensor carpi radialis longus insert?
Base of metacarpal 2
Where does extensor carpi ulnaris insert?
Base of metacarapl 5
Which muscles peform wrist flexion?
Flexor carpi radialis
Flexor carpi ulnaris
Which muscles perform wrist extension?
Extensor carpi radialis longus and brevis
Extensor carpi ulnaris
How can the muscles of the wrist work together?
They act in pairs, with one being the agonist and the other an antagonist. And they also act as synergists to cancel out unwanted movement.
Which muscles which move the wrist are found on the ulnar side of the forearm?
Flexor carpi ulnaris
Extensor carpi ulnaris
Which muscles which move the wrist are found on the radial side of the forearm?
Flexor carpi radialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Describe the carpometacarpal joints (CMJ)
Also include which ones have a greater, and smaller ROM
The carpometacarpal joints consists of a series of four medial plane joints.
There is a greater range of movement for the CMJ with metacarpals 4 and 5
There is less movment than CMJ at metacarpals 2 and 3 (with index and middle finger)
What kind of joint is the carpometacarpal joint of metacarpal 1?
This is the thumb joint. Its a saddle joint between trapezium and metacarpal 1.
This joint allows flexion, extension, adduction, abduction and opposition.
(this joint commonly becomes osteoartritic)
How is the thumb set? As in, what position does the thumb have to be in in order for the palmar surface to be facing anteriorly?
The thumb is set at 90 degrees to the plane of the palm.
Describe how flexion, extension and abduction and adduction would look like for the thumb
Flexion of thumb draws it across hand, opposite is extension.
Abduction pulls thumb away from plane of hand, opposite of this is adduction
Opposition is just touching the tips of the other four fingers with the thumb
Describe the metacarpophalangeal joints
They are biaxial (ellipsoidal joints) allowing for:
Flexion, extension, abduction and adduction
How many interphalangeal joints are there? And also, describe this joint.
There are two in each finger, and one in the thumb. Proximal is the proximal interphalangeal joint, and distal is the distal interphalangeal joint.
These are hinge joints, which allow for flexioin and extension
Flexion of the MCP and IP joints allows for what kind of grip?
Hook/power grip
Flexion of the MCP and extension of IP joints allows for what kind of grip?
Precision grip
What are the extrinsic muscles of the thumb?
Flexor pollicis longus
- Lateral side of forearm
- Attaches to base of distal phalanx
Extensor pollicis longus and brevis
- Oblique bellies
- Attach to base of proximal (EPB) and distal (EPL) phalanges
Abductor pollicis longus
- Adjacent to EPB
- Attaches to base of metacarpal 1
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What anterior and posterior tendons make up the anatomical snuff box?
Anteriorly then tendons are of:
- Extensor pollicis brevis
- Abductor pollicis longus
Posteriorly the tendon of
- Extensor pollicis longus
Which artery runs through the snuff box?
Radial artery
What are the intrinsic muscles of the thumb?
Thenar eminence, made up of three muscles (all inneravted by the median nerve)
- Flexor pollicis brevis
- Abductor pollicis brevis
- Opponens pollicis (helps more with opposition)
Adductor pollicis (innervated by the ulnar nerve)
Describe the location of flexor pollicis brevis, and where it inserts
It is on the medial side of thenar eminence, and it inserts into proximal phalanx
Describe the location of Abductor pollicis brevis, and where it inserts
Lateral side of thenar eminence, inserts into proximal phalanx
Describe the location of Opponens pollicis, and where it inserts
Inserts into lateral border and lateral part of the front of the shaft of metacarpal 1
Describe the location, structure and insertion of adductor pollicis
Adductor pollicis comes off the capitate and 3rd metacarpal and inserts into the base of the proximal phalanx of thumb
It arises by two heads, an oblique head and a transverse head
What are the extrinsic flexors of the fingers?
Flexor digitorum superficialis (FDS)
Flexor digitorum profundus (FDP)
Both originate from the medial epicondyle
What is the origin and insertion for flexor digitorum superficialis?
Originates at the humeroulnar and radial heal, and inserts into the proximal phalanges (and also basees of middle phalanges)
What is the origin of flexor digitorum profundas?
Arises from anterior ulnar and interosseseous membrane, and inserts into the base of the distal phalanges
