Forearm anatomy Flashcards
Describe the elbow joint and the annular ligaments that hold it?
Elbow joint is between the condyle (capitulum and trochlear) of the humerus and the radius/ulnar.
There are 3 annular ligaments that hold it:
- Radial and ulnar collateral ligament
- Annular ligament of radius
A 7-year-boy was brought to our department with pain in the right arm after a fall from a height about 3 hours before admission. On examination, the elbow was found to be markedly swollen with restriction of movement of the right arm. A 4-cm-wide wound was also observed on the flexural aspect of the elbow, indicating severe contamination of the fracture site (Figure 1A). Neurological examination revealed restriction of hand movement and decreased sensations, which suggested the possibility of nerve injuries. Radiography performed at admission showed severe displacement of the right humerus fracture. Overtime, his right arm looked like this: What is your likely diagnosis?
- Volkmann’s contracture
- supracondylar fracture of humerus-> obstructs the brachial artery-> causes ischemia and necrosis of flexors of the forearm
3 year old girl cried in severe pain in her arm after she was pulled from her crib. X ray showed this:
What caused this?
- Radial subluxation due to damage to the radial annular ligament that is not fully developed in children<5. Often occurs with sharp pull of child’s hand
Describe the boundaries of the cubital fossa and the contents.
- Laterally-brachioradialis
- Medially-pronator teres
- Floor-brachialis
Contents (lateral to medial)
- Biceps Brachii tendon, brachial artery, median nerve (medial to BA)
Covered by bicipital aponeurosis
-often clinician places stethoscope over brachial artery in cubital fossa when takin BP
A 54 year old golfer reported pain in medial epicondyle particularly when wrist was flexed and pronated.
A 53 year old tennis player reported pain in lateral epicondyle particularly when wrist was extended and supinated.
What is this due to?
- Medial epicondylitis-found in golfers; where arm is constantly flexed. Causes pain in medial epicondyle upon wrist flexion and pronation
- Lateral epicondylitis-found in tennis players; arm is extended. Causes pain in lateral epicondyle when wrist is extended and supinated
A 57-year-old woman presented with occasional pain, numbness and paralysis in her left hand (4th and 5th fingers) and a palpable, painless mass in the ulnar side of her left elbow. What is this due to?
- Cubital tunnel syndrome (ulnar nerve affected)-particularly upon hitting the funny bone (medial epicondyle) or flexing/extending which causes damage to ulnar nerve beneath medial epicondyle-> numbness/tingling in 4/5 th fingers
Between which artery and vein is a fistula made?
- Radial artery and cephalic vein
Describe the distal end of the radius and distal end of the ulna?
What are the joints between the radius and ulnar?
- Distal end of radius has a radial styloid process, and facets for articulation with scaphoid, lunate
- Distal end of ulna has an ulnar styloid process
Joints:
- Proximal and distal radioulnar joint for pronation and supination
What is this fracture called?
- Galeazzi’s fracture-> distal third of radius affected causing subluxation of ulnar
What is this fracture called?
- Monteggia’s fracture-proximal 1/3 of ulnar has fracture causing anterior dislocation of proximal radius
What is the origin, insertion, innervation and function of the muscles in the anterior compartment of the forearm (most superficial-flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres?
What is the origin, insertion, innervation and function of the muscles in the anterior compartment of the forearm (intermediate-flexor digitorum superficialis)?
What is the origin, insertion, innervation and function of the muscles in the anterior compartment of the forearm (most deep-flexor digitorum profundus, flexor pollicis longus, pronator quadratus)
What is the origin, insertion, innervation and function of the muscles in the posterior compartment of the forearm (most superficial-brachoradialis, extensor carpi radialis longus/extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, anconeus)?
What is the origin, insertion, innervation and function of the muscles in the posterior compartment of the forearm (deep-supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis)?
In the forearm, what is the course of the radial artery and what branches does it give off? Which part of the hand does it supply?
In the forearm, what is the course of the ulnar artery and what branches does it give off? Which part of the hand does it supply?
- Radial artery is found deep to the brachoradialis and in the distal part of the forearm, distal to the flexor carpi radialis (landmark for palpation). It supplies thumb, and 1/2 of index finger. It gives off:
- radial recurrent artery (elbow joint)
- palmar carpal branch
- superficial palmar branch (anastamoses w that of ulnar)
- Ulnar artery is found deep to pronator teres and in distal part of forearm, underneath flexor carpi ulnaris. It supplies medial 3 1/2 of hand. It gives off:
- ulnar recurrent artery (elbow joint)
- palmar/dorsal carpal branch
- superficial palmar branch.
What is the course of the median nerve in the forearm and its branches? What does it supply?
What is the course of the ulnar nerve in forearm and its branches? What does it supply
What is the course of the radial nerve in forearm and its branches? What does it supply
Median nerve
- Leaves cubital fossa and passes between pronator teres and down deep to the flexor digitorum superficialis. It gives off a few branches:
- anterior interosseus nerve (deep compartment of forearm)
- palmar branch in front of flexor retinaculum (skin of palm which is preserved in carpal tunnel syndrome)
Median nerve supplies all muscles in the anterior compartment of forearm except flexor carpi ulnaris and flexor digitorum profundus.(medial half)
Ulnar nerve
- Leaves cubital fossa, and passes behind the medial epicondyle and along the flexor carpi ulnaris. Gives off a few branches
- muscular branches to flexor carpi ulnaris and flexor digitorum profundus
- palmar and dorsal branches to skin.
Radial nerve
- At lateral edge of cubtial fossa, it has a deep branch (posterior compartment of forearm) and superficial branch that provides sensation to dorsum of hand.
- deep branch gives off posterior interosseus nerve (deep posterior compartment of forearm)
What are the bones of the hand?
- Carpals
- Metacarpals (I-IV)
- Phalanges (proximal, middle, distal)
Some lovers try positions that they can’t handle (from thumb to medial)
1st row-scaphoid, lunate, pisiform,
2nd row-trapezium, trapezoid, capitate, hamate
What are the joints in the hand?
- Wrist joint
- carpal joints
- Metacarpophalangeal joint
- Interphalangeal joint-PIP, DIPs
Wrist joint
- between the radius and ulnar, and the scaphoid/lunate/triquetrium/pisiform
Carpal joints
- Between carpals
Metacarpophalageal joints
- Between metacarpals and phalanges (held by palmar ligament and medial and lateral collateral ligaments) as well as deep transverse metacarpal ligaments in between
Which carpal bone is most at risk of avascular necrosis?
- Scaphoid which only receives blood supply from the radial artery is at risk of avascular necrosis when it is fractureed
What are the medial and lateral boundaries of the anatomical snuffbox? Floor?
What runs underneath?
Anatomic snuffbox is a triangular depression with base formed by the carpal bones to the apex in thumb. The floor is the scaphoid, trapezium.
- medial boundaries-abductor pollicis longus, extensor pollicis brevis
- Lateral boundaries-extensor pollicis longus
Radial artery runs obliquely here.
What is the origin, insertion, innervation and function of the hypothenar muscles and thenar muscles?
What is the origin, insertion, innervation of intrinsic muscles of hand (palmaris brevis, dorsal interossei, palmar interossei, adductor pollicis, lumbricals)
In general what is the nerve supply of the hand?
Intrinsic muscles of the hand is supplied by ulnar nerve except for MLOAF (supplied by recurrent medial nerve):
- Lateral 2 lumbricals
- Opponens pollicis
- Abducens pollicis brevis
- Flexor pollicis brevis (thenar muscles)
What is the course and branches of the ulnar artery? What does this supply?
Ulnar artery courses through medial side of wrist and forms the:
- superficial palmar arch-branches off to form the common palmar digital arteries that branch off to form the proper palmar digital arteries at MCP
- Deep palmar arch
Ulnar artery supplies the lateral 3 fingers and medial side of index.
What is the course and branches of the radial artery and what does this supply?
- Radial artery is found on the lateral side of the wrist and passes underneath anatomical snuff box. It also contributes to superficial and deep palmar arches. At the back it gives off:
- Dorsal carpal branch-dorsal metacarpal arteries arise from; these branch into dorsal digital arteries.
- Radialis indices-index finger; princeps pollicips-thumb
What does the ulnar nerve supply?
At the pisiform, ulnar nerve splits into 2 branches:
- deep branch- Intrinsic muscles except for MLOAF
- superficial branch-Sensation to little and half of ring finger
What does the median nerve supply?
Median nerve travels through the flexor retinaculum and gives off 2 branches:
- Recurrent branch-thenar muscles
- Palmar digital branches- sensation of lateral 3 1/2 fingers
What does the radial nerve supply?
- Radial nerves passes through anatomical snuffbox to supply dorsal lateral 3 1/2 of hand
A 28-year-old male patient presented to our emergency department after sustaining a gunshot wound to the right forearm. The entry wound was located on the ulnar-dorsal aspect of his right mid-forearm. The exit wound was located on the volar aspect of the forearm and 3 cm distally to the elbow (Figure 1). Examination revealed absent sensation on his right 5th and ulnar half of the 4th fingers. The metacarpophalangeal joints of his 4th and 5th fingers were extended and the interphalangeal joints of the same fingers were flexed, suggestive of a ‘claw’.
What is damaged here?
Ulnar nerve is damaged at the pisiform therefore causing:
- Loss of supply to intrinsic muscles (except MLOAF)-clawing of fingers especially pinky and ring finger
- loss of sensation to pinky and half of ring finger
