Week 4: Arm/Forearm mm. Flashcards
Includes origins and insertions
Palmar interossei
palmar interossei
Three muscles located on the palmar surface of the metacarpal bones, with the exception of the 1st and 2nd metacarpals.
Origin
Metacarpals 2: ulnar aspect.
Metacarpals 4 to 5: radial aspect.
Insertion
Proximal phalanx 2: ulnar aspect.
Proximal phalanges 4 to 5: radial aspect.
Innervation
Ulnar nerve.
dorsal interossei
the four dorsal interossei are intrinsic muscles of the hand belonging to the midpalmar muscle group; they are bipennate, intermetatarsal muscles that act on the fingers.
Origin
Metacarpals 1 to 5: shafts.
Insertion
Proximal phalanx of fingers 2 to 5: bases.
Dorsal extensor expansions of fingers 2 to 5.
Innervation Ulnar nerve (C8, T1).
opponens digiti minimi
Proximal attachments
Hook of the hamate and the ulnar border of the flexor retinaculum.
Distal attachments
Ulnar border of the fifth metacarpal.
Surface anatomy
Contributes to the bulk of the hypothenar eminence. This muscle lies underneath the flexor digiti minimi and blends with its neighbors to a variable degree.
Nerve supply
Deep branch of the ulnar nerve (C8, T1).
lumbricals
The lumbricals are four slender intrinsic muscles found in the palmar aspect of the hand.
Origin
Tendons of flexor digitorum profundus.
Insertion
Extensor apparatus of fingers 2 to 5.
Innervation Median nerve (C8, T1)
Action
Extend the interphalangeal (IP) joints while flexing the metacarpophalangeal (MCP) joints.
Flexor Digiti Minimi brevis
An intrinsic muscle of the hand, it belongs to the hypothenar muscle group.
Origin
Hamate: hook
Flexor retinaculum.
Insertion
Proximal phalanx of the little finger: base.
Innervation Ulnar nerve (C8, T1).
Actions
Flexes the metacarpophalangeal (MCP) joint of the little finger.
Assists with opposition of the little finger.
abductor digiti minimi
Proximal attachments
Pisiform and ulnar border of the flexor retinaculum.
Distal attachments
Ulnar side of the base of the proximal phalanx of the little finger; ulnar border of the extensor apparatus of the little finger.
Surface anatomy
Contributes to the bulk of the hypothenar eminence on the ulnar border of the fifth metacarpal.
Nerve supply
Deep branch of the ulnar nerve (C8, T1).
adductor pollicis
just deep to the bifurcated tendon of FDS on the palmar side of hand
Proximal attachment
Transverse head: distal two-thirds of the palmar surface of the third metacarpal.
Oblique head: volar surface of the capitate, the bases of the second and third metacarpals, the palmar carpal ligaments, and the tendon sheath of flexor carpi radialis.
Distal attachment
Medial aspect of the base of the proximal phalanx and the medial sesamoid of the metacarpophalangeal joint of the thumb.
Innervation Ulnar nerve (C8, T1).
Blood supply
Superficial palmar branches of the radial artery.
Flexor pollicis brevis
Proximal attachments
Superficial part: from the flexor retinaculum and tubercle of the trapezium.
Deep part: from the trapezoid and capitate.
Distal attachments
Through the radial sesamoid over the metacarpophalangeal joint of the thumb to the base of the proximal phalanx.
Surface anatomy
It contributes to the medial bulk of the thenar eminence and can be palpated on the ulnar palmar aspect of the thenar eminence.
abductor pollicis brevis
Proximal attachments
Flexor retinaculum; tubercles of scaphoid and trapezium.
Distal attachments
Radial aspect of the base of the proximal phalanx of the thumb and the extensor apparatus of the thumb.
Surface anatomy
It contributes to the anterolateral bulk of the thenar eminence and can be directly palpated over the muscle belly.
Nerve supply Median nerve (C8, T1).
opponens pollicis
Proximal attachments
Flexor retinaculum and tubercle of the trapezium.
Distal attachments
Palmar aspect of the radial border of the first metacarpal (thumb).
Surface anatomy
Contributes to the bulk of the thenar eminence. Lies underneath the abductor pollicis brevis and thus is difficult to palpate.
Extensor pollicis brevis
Proximal attachment
Posterior surface of the ulna and the interosseous membrane.
Distal attachment
Distal phalanx of the thumb.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
abductor pollicis longus
Proximal attachment
Posterior surfaces of the ulna and the radius and the interosseous membrane.
Distal attachment
Lateral aspect of the base of the first metacarpal.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
Extensor Pollicis longus
Proximal attachment
Posterior surface of the ulna and the interosseous membrane.
Distal attachment
Distal phalanx of the thumb.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
extensor indicis
Proximal attachment
Posterior surface of the ulna (distal to extensor pollicis longus) and the interosseous membrane.
Distal attachment
Dorsal surface of the base of the middle phalanx (central slip) and distal phalanx (lateral bands) of the index digit.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
Supinator
Proximal attachment
Lateral epicondyle of the humerus, the radial collateral ligament, the supinator crest of the ulna, and the radial collateral and annular ligaments.
Distal attachment
Proximal portion of the anterolateral surface of the radius.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Radial recurrent artery from the radial artery.
extensor digiti minimi
Proximal attachment
Lateral epicondyle of the humerus via the common extensor tendon and the ulnar aspect of extensor digitorum.
Distal attachment
Central slip: dorsal surface of the base of the middle phalanx of the fifth digit.
Lateral bands: via two slips to the dorsal surface of the base of the distal phalanx of the fifth digit.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
extensor carpi ulnaris
Proximal attachment
Lateral epicondyle of the humerus via the common extensor tendon.
Distal attachment
Tubercles on the medial side of the base of the fifth metacarpal.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
extensor digitorum
Proximal attachment
Lateral epicondyle of the humerus via the common extensor tendon.
Distal attachment
Main attachment: dorsal aspect of the base of the proximal phalanx of each of the four digits.
Central slip: dorsal aspect of the base of the middle phalanx of each of the four digits.
Lateral bands: via two slips to the dorsal aspect of the base of the distal phalanx of each of the four digits.
Innervation Radial nerve (C6, 7, 8).
Blood supply
Posterior interosseous artery from the ulnar artery.
Extensor Carpi Radialis longus
Lateral epicondyle of the humerus via the common extensor tendon and the radial collateral ligament of the elbow.
Distal attachment
Dorsal surface of the base of the third metacarpal.
Innervation Radial nerve (C6, 7).
Blood supply
Radial recurrent artery from the radial artery.
Brachioradialis is a muscle of the arm that acts on the elbow joint.
Origin
Humerus: lateral supracondylar ridge.
Insertion
Radius: styloid process.
Innervation Radial nerve (C5, 6, 7).
Actions
Flexes the elbow (when the forearm is in neutral position).
Supinates the elbow joint.
Pronator quadratus is a muscle of the forearm.
Origin
Ulna: oblique ridge on the shaft.
Insertion
Radius: anterior surface of shaft.
Innervation Median nerve (C8, T1).
Actions
It pronates the forearm.
A muscle of the forearm, flexor pollicis longus. Its tendon passes into the hand and acts on the wrist and thumb.
Compartment
It is located in the anterior compartment of the forearm.
Origin
Radial shaft: anterior surface.
Insertion
Distal phalanx of the thumb: base.
Innervation Median nerve (C8, T1).
Actions
Flexes the interphalangeal (IP) and metacarpophalangeal (MCP) joints of the thumb.
Weak flexor of the wrist.
Flexor digitorum profundus (deep to flexor carpi ulnaris) is a muscle of the forearm that splits into four tendons and acts on the wrist and finger joints.
Compartment
It is located in the anterior compartment of the forearm.
Origin
Ulna: shaft.
Interosseous membrane.
Insertion
Distal phalanges of fingers 2 to 4: bases.
Innervation
Ulnar nerve supplies the ulnar half.
Median nerve (C8 and T1) supplies the radial half.
Actions
Flexes the distal interphalangeal (DIP), proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the fingers and also the wrist joint.
Important relations
The lumbricals arise from the tendons of flexor digitorum profundus.
Flexor digitorum superficialis, a muscle of the forearm that originates from two heads and distally divides into four tendons; it acts on the wrist and finger joints.
Compartment
It is located in the anterior compartment of the forearm.
Origin
Humeroulnar head
Humerus: medial epicondyle (via common flexor tendon).
Ulna: coronoid process.
Radial head
Radial tuberosity.
Insertion
Middle phalanges 2 to 5: shafts.
Innervation Median nerve (C7, 8 and T1).
Actions
Flexes the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints as well as the wrist joint.
Flexor carpi ulnaris is a muscle of the forearm that acts on the wrist joint; a sesamoid bone, the pisiform forms in its tendon.
Compartment
It is located in the anterior compartment of the forearm.
Origin
Humeral: medial epicondyle (via the common flexor tendon).
Ulna: head.
Insertion
Hamate: hook.
5th metacarpal: base.
Innervation Ulnar nerve (C7, 8).
Actions
Flexes the wrist and adducts (ulnar deviation) the wrist.
Palmaris Longus, a muscle of the forearm and hand, it is frequently absent.
Compartment
Anterior compartment of the forearm.
Origin
Humerus: medial epicondyle (via the common flexor tendon).
Insertion
Flexor retinaculum.
Palmar aponeurosis.
Innervation Median nerve (C7, C8).
Actions
Flexor carpi radialis is a fusiform muscle of the forearm that acts on the wrist joint.
Compartment
It is located in the anterior compartment of the forearm.
Origin
Humerus: medial epicondyle (via the common flexor tendon).
Insertion
Metacarpals 2 to 3: bases.
Innervation Median nerve (C6, 7).
Actions
Flexes the wrist.
Abducts (radially deviates) the wrist.
Pronator teres is a muscle of the forearm.
Origin
Humerus: medial epicondyle (via common flexor tendon)
Ulna: coronoid process.
Insertion
Radius: lateral surface of shaft.
Innervation Median nerve (C6, 7).
Actions
It pronates the forearm.
Weak flexor of the elbow.
A triangular muscle of the forearm, anconeus acts on the elbow joint.
Origin
Humerus: lateral epicondyle.
Insertion
Ulna: shaft and olecranon.
Innervation Radial nerve (C7, 8).
Actions
It assists extension of the elbow.
Triceps brachii is a muscle of the posterior arm that acts on the shoulder and elbow joints.
It has three heads, medial, lateral, and long, which converge distally on a common tendon.
Compartment
It occupies the extensor compartment (back) of the arm.
Origin
Long head
Scapula: infraglenoid tubercle.
Medial head
Humerus: shaft (medial surface).
Lateral head
Humerus: shaft (lateral surface).
Insertion
Ulna: olecranon.
Innervation Radial nerve (C6, 7, 8).
Actions
The three heads acting together powerfully extend the elbow.
Acting individually the long head produces weak extension of the shoulder and assists in stabilization of the shoulder joint.
A muscle of the anterior arm, coracobrachialis acts on the shoulder joint.
Origin
Scapula: coracoid process.
Insertion
Humerus: shaft (medial surface).
Innervation Musculocutaneous nerve (C5, 6, 7).
Actions
It flexes the shoulder and rotates it medially.
Biceps Brachii
coracoid process and supraglenoid tubercle
Musculocutaneous N. C5, 6
supinates forearm, flexes elbow joint and shoulder joint
Brachialis is a muscle of the anterior arm that acts on the elbow joint.
Origin
Humerus: shaft (anterior surface).
Insertion
Ulna: coronoid process and tuberosity.
Innervation Musculocutaneous nerve (C5, 6). Radial nerve (C7).
Actions
Flexes the elbow, with the forearm pronated or supinated.
A muscle of the anterior arm, coracobrachialis acts on the shoulder joint.
Origin
Scapula: coracoid process.
Insertion
Humerus: shaft (medial surface).
Innervation Musculocutaneous nerve (C5, 6, 7).
Actions
It flexes the shoulder and rotates it medially.
