Lecture 15: Muscular System Upper Limb Flashcards
Muscles attaching upper limb to trunk
Pectoralis major and minor Serratus anterior Trapezius Latissimus dorsi Rhomboids Levator scapulae
Muscles of upper limb
Scapular Deltoid Arm Forearm Hand
Rotator cuff
Subscapularis Supraspinatus Infraspinatus Teres minor Function: reinforce shoulder joint capsule (except the inferior aspect) and stabilize the joint
Supraspinatus
Origin: supraspinous fossa
Insertion: greater tubercle of humerus
Function: prime mover for abduction of shoulder for first 30 degrees
Nerve: branch of brachial plexus
Infraspinatus
Origin: infraspinous fossa
Insertion: greater tubercle of humerus
Function: lateral rotation of shoulder
Nerve: branch of brachial plexus
Subscapularis
Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Function: prime mover for medial rotation of shoulder
Nerve: 2 branches of brachial plexus
Deltoid
Origin: clavicle, acromian, spine of scapula (U shaped)
Insertion: deltoid tuberosity
Function: prime mover of abduction of shoulder from 30-90 degrees
Nerve: axillary nerve of brachial plexus
Muscles of arm
Contains 2 compartments made by humerus and extensions of deep fascia/inter-muscular septum attaching to humerus
Anterior compartment
Posterior compartment
Anterior compartment of arm
Biceps brachii Brachialis Coracobrachialis Mainly flex shoulder/elbow joints Innervated by musculocutaneous nerve of brachial plexus
Posterior compartment of arm
Triceps brachii
Mainly extend shoulder/elbow joints
Innervated by radial nerve of brachial plexus
Biceps brachii
2 heads
Origin: long head - above glenoid fossa, short head - corocoid process
Insertion: radial tuberosity
Function: flexor of elbow, weak flexor of shoulder, prime mover for supination of forearm
Nerve: musculocutaneous nerve
Brachialis
Origin: anterior surface of humerus
Insertion: ulnar tuberosity
Function: prime mover for flexion of elbow
Nerve: musculocutaneous nerve
Triceps brachii
3 heads
Origin: long head - scapula below glenoid fossa, lateral/medial head - posterior surface of humerus
Insertion: olecranon process
Function: prime mover for extension of elbow, only long head extends shoulder
Nerve: radial nerve
Muscles of forearm
Has anterior and posterior compartments
Divided by radius, ulna, interosseous membrane, extension of deep fascia attaching to radius
Anterior compartment of forearm
Subdivided into superficial (pronator teres, flexor carpi radialis), intermediate (flexor digitorum superficialis), deep (flexor digitorum profundus, flexor pollicis longus) layer
Most common origin: medial epicondyle of humerus (common flexor tendon)
Insertion: radius, metacarpals, phalanges
Involved in pronation of forearm, flexion of wrist and fingers
Innervated by median or ulnar nerves
Posterior compartment of forearm
Subdivided into superficial (brachioradialis, extensor digitorum, extensor carpi ulnaris) and deep (supinator, extensor indicis, abductor pollicis) layer
Most common origin: lateral epicondyle of humerus (common extensor tendon)
Insertion: radius, metacarpals, phalanges
Involved in supination of forearm, extension of fingers and wrist
Innervated by radial nerve
Extensor hood or dorsal digital expansion
Tendons of extensor muscles form triangular expansion on dorsal proximal phalanges
Receives tendons of lumbricals and interossei muscles
Inserts to middle and distal phalanges
Extensor retinaculum
Holds tendons of muscles in the posterior compartment by thickening of deep fascia
Passes behind wrist
Pronator teres
Superficial layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: shaft or radius
Function: prime mover for pronation of forearm
Nerve: median nerve
Flexor carpi radialis
Superficial layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: 2nd and 3rd metacarpal bone
Function: flexion of wrist, abduction of wrist (radial deviation)
Nerve: median nerve
Flexor retinaculum
Thick band of dense connective tissue
Transversely passes in front of wrist
Holds all muscles of anterior compartment of forearm to increase overall efficiency
Flexor digitorum superficialis
Intermediate layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: tendons splits into 4 and inserts to middle phalange of fingers 2-5
Function: flexor of wrist, flexor of metacarpal phalangeal joints and proximal interphalangeal joints
Nerve: median nerve
Flexor digitorum profundus
Deep layer of anterior compartment of forearm
Origin: ulna
Insertion: distal phalangeal of fingers 2-5
Function: prime mover for flexion of wrist and all joints in fingers
Nerve: fingers 2-3 - median nerve, fingers 4-5 - ulnar nerve
Flexor pollicis longus
Deep layer of anterior compartment of forearm
Origin: radius
Insertion: distal phalange of thumb
Function: prime mover for flexion of thumb
Nerve: median nerve
Brachioradialis
*Physically sits in anterior compartment and flexes forearm, but is innervated by radial nerve
Origin: lateral epicondyle of humerus
Insertion: styloid process of radius
Function: flexion of elbow (prime mover from 90-110 degrees)
Nerve: radial nerve
Extensor digitorum
Superficial layer of posterior compartment of forearm
Origin: lateral epicondyle of humerus
Insertion: middle and distal phalange of fingers 2-5
Function: prime mover for extension of fingers and wrist
Nerve: radial nerve
Extensor carpi ulnaris
Superficial layer of posterior compartment of forearm
Origin: lateral epicondyle of humerus
Insertion: 5th metacarpal bone
Function: extension of wrist and adduction of wrist (ulnar deviation)
Nerve: radial nerve
Supinator
Deep layer of posterior compartment of forearm Origin: ulna and humerus Insertion: radius Function: supination of forearm Nerve: radial nerve
Extensor indicis
Deep layer of posterior compartment of forearm
Origin: ulna
Insertion: middle and distal phalange of index finger
Function: extends index finger independently
Nerve: radial nerve
Abductor pollicis longus
Deep layer of posterior compartment of forearm
Origin: posterior shaft of ulna
Insertion: 1st metacarpal bone and proximal phalange of thumb
Function: prime mover for abduction of thumb
Nerve: radial nerve
Intrinsic muscles of hand
19 muscles
3 groups:
Thenar
Hypothenar
Central (lumbricals, palmar/dorsal interossei, adductor pollicis)
Mainly innervated by ulnar nerve, some by median nerve
Thenar group of hand
Origin: carpal bones
Insertion: 1st metacarpal bone or proximal phalanage of thumb
Function: forms thenar eminence at base of thumb and moves thumb (abduction, flexion, opposition)
Nerve: median nerve
Hypothenar group of hand
Origin: carpal bone
Insertion: 5th metacarpal bone or proximal phalange of 5th finger
Function: forms hypothenar eminence at base of pinky and moves pinky (abduction, flexion, opposition)
Nerve: ulnar nerve
Central group of hand
Deep to the thickening of deep fascia of palm of hand = palmar aponeurosis
Protects soft tissues at the center of the palm
Contains adductor pollicis (only muscle in central group that moves thumb), lumbricals, dorsal and palmar interossei
Lumbricals
4 superficial worm-like muscles underneath palmar aponeurosis of hand
Origin: tendon of flexor digitorum profundus
Insertion: middle and distal phalange of fingers 2-5
Function: flexion of metacarpal phalangeal joints, and extension of proximal and distal interphalangeal joints (tata movement)
Nerve: half by median, and half by ulnar nerve
Interossei
Origin: metacarpal bone
Insertion: middle and distal phalange of fingers 2-5
Function: palmar - adduction of fingers (2, 4, 5), dorsal - abduction of fingers (2-4)
Nerve: ulnar nerve
Transitional areas of upper limb
Major blood vessels and nerves pass from one region to the next
Axilla
Cubital fossa
Carpal tunnel
Axilla
Pyramidal space between root of neck and shoulder (armpit)
Axillary artery and vein, cords of brachial plexus pass through
Has 4 walls, base, apex
Anterior wall: pectorialis major and minor
Medial wall: thoracic wall (until 5th rib) and serratus anterior muscle
Posterior wall: subscapularis, teres major, latissimus dorsi, scapula
Lateral wall: intertubercular groove of humerus
Base: skin of armpit
Apex: behind middle third of clavicle
Cubital fossa
In front of elbow
Median and radial nerves, and brachial artery pass through
Triangular space
Lateral: brachioradialis muscle
Medial: pronator teres
Superior: imaginary line joining medial and lateral epicondyles of humerus
Carpal tunnel
Wrist
Fibro-osseous tunnel by carpal bones and thickening of deep fascia (flexor retinaculum) in front of wrist
Contains tendons of flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, median nerve
Carpal tunnel syndrome
All tendons are double wrapped by synovial membrane which produces fluid to minimize friction between tendons and flexor retinaculum
Overuse of muscles causes tendons and membranes to be inflammed causing swelling which compresses the median nerve
Causes weakness in thenar muscles
Also caused by pregnancy, hypothyroidism, collagen vascular disease
