MSK Muscles of the upper arm and hand Flashcards
Name the muscles in the anterior and posterior compartment of the arm
Anterior - BBC
Biceps brachii
Brachialis
Coracobrachialis
Posterior
Triceps brachii
What are the attachments and actions of the biceps brachii?
The long head originates from the supraglenoid tubercle
The short head originates from the coracoid process
The biceps attach to the radial tuberosity
Actions:
Main - supination
Flexes arm at elbow and shoulder
What happens when the biceps tendon ruptures?
The long head tendon is one of the most common tendons to rupture (although tendon rupture is rare)
Produces popeye sign when the elbow is flexed - a bulge where the muscle belly is
The patient would not notice much weakness due to the action of brachialis and supinator
What are the attachments and actions of coracobrachialis?
Originates from the coracoid process
Attaches to the medial humeral shaft at the level of the deltoid tuberosity
Actions:
Flexes the arm at the shoulder
What are the attachments and actions of the brachialis?
Originates from medial and lateral surfaces of the humeral shaft
Inserts into the ulna tuberosity
Actions:
Main flexor at the elbow
What are the attachments and actions of triceps brachii?
Long head originates from infraglenoid tubercle
Lateral head originates from humerus (superior to radial groove)
Medial head originates from humeral (inferior to radial groove)
They attach to the olecranon of the ulna
Actions:
Extension at the elbow
What is the innervation of the 4 arm muscles?
BBC are all innervated by musculocutaneous nerve (although brachialis has some radial nerve innervation)
Triceps innervated by radial nerve
What is the difference between intrinsic and extrinsic muscles of the hand?
Extrinsic muscles - located in anterior and posterior forearm and control rude movements and produce grip
Intrinsic muscles - located within the hand and responsible for fine motor movements
Name the intrinsic muscles of the hand
Thenar muscles:
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Hypothenar muscles:
Opponens digiti minimi
Abductor digiti minimi
Flexor digiti minimi brevis
Lumbricals (1-4)
Interossei - dorsal and palmar
Palmaris brevis
Adductor pollicis
What are the attachments and actions of opponens pollicis?
Largest and deepest thenar muscle
Originates from tubercle of the trapezium and inserts into the lateral margin of thumb metacarpal
Actions:
Opposes the thumb
What are the attachments and actions of abductor pollicis brevis?
Found proximal to flexor pollicis brevis
Originates from scaphoid and trapezium tubercles and attaches to lateral side of proximal phalanx
Actions:
Abducts the thumb
What are the attachments and actions of flexor policies brevis?
Most distal thenar muscle
Originates from tubercle of trapezium and attaches to base of proximal phalanx of the thumb
Actions:
Flexers the thumb
What is the innervation of the thenar muscles?
Median nerve
What are the attachments and actions of opponens digiti minimi?
Deep to all the hypothenar muscles
Originates from hook of hamate and inserts on the medial margin of metacarpal 5
Actions:
Opposes little finger
What are the attachments and actions of abductor digiti minimi?
Most superficial hypothenar
Originates from pisiform and tendon of flexor carpi ulnaris and attaches to base of proximal phalanx
Actions:
Abducts the little finger
What are the attachments and actions of flexor digiti minimi brevis?
Originates from hook of hamate and inserts into base of proximal phalanx
Actions:
flexes little finger
What is the innervation of the hypothenar muscles?
Ulnar nerve
What are the attachments and actions of the lumbricals?
There are 4 lumbricals each associated with a finger
They link the extensor and flexor tendons
Each originates from tendon of flexor digitorum profundus and pass dorsally and laterally around each finger to insert into the extensor hood
Actions:
Flex at the metacarpalphalangeal joint
Extend interphalangeal joints
What is the innervation of the lumbricals?
Medial 2 lumbricals (little and ring finger) - ulnar nerve
Lateral 2 lumbricals - median nerve
What happens to the fingers if the lumbricals are denervated?
Ulnar claw - damage to ulnar nerve paralyses the lumbricals of the little and ring finger, so they are bent
Hand of benediction - damage to median nerve, occurs when patient asked to make a fist
What are the attachments and actions of the dorsal interossei?
Most superficial, there are 4 which sit between the metacarpals
Originate from lateral and medial surface of the metacarpals and attach to extensor hood and proximal phalanx of each finger
Actions:
DAM abducts
What are the attachments and actions of the palmar interossei?
There are 3 (the middle finger is missing because it cants adduct anywhere)
Originate from lateral and medial surface of the metacarpals and attach to extensor hood and proximal phalanx of each finger
Actions:
PAM adducts
What is the innervation of the interossei?
Ulnar nerve
What are the attachments and actions of the palmaris brevis?
A small thin muscle found superficially of hypothenar eminence
Originates from palmar aponeurosis and attaches to skin of the medial margin of hand
Actions:
Wrinkles the skin of the hypothenar eminence to deep curve of hand and improve grip
What innervates the palmaris brevis?
Ulnar nerve
What are the attachments and actions of the adductor pollicis?
Large triangular muscle with 2 heads - the radial artery passes anteriorly between the 2 heads forming the deep palmar arch
One head originates from metacarpal 3, the other from capitate and metacarpals 2 and 3
Both attach to base of proximal phalanx of thumb
Actions:
Adducts the thumb
What is the innervation of adductor pollicis?
Ulnar nerve
