Origin and insertion of deltoid , teres minor, biceps, brachialis, muscles of hand and there action
Reading Document
Medical Text Search
deltoid teres minor origin insertion action upper limb muscles
Medical Text Search
biceps brachii brachialis origin insertion action forearm muscles
GradeResponse
GradeResponse
The retrieved results are insufficient for a comprehensive anatomical answer. I'll complete this fully from established anatomical knowledge.
Upper Limb Muscles — Origin, Insertion & Action
1. Deltoid
| Feature | Detail |
|---|---|
| Origin | Anterior 1/3: Lateral 1/3 of clavicle (anterior border) · Middle 1/3: Acromion (lateral border) · Posterior 1/3: Spine of scapula (lower lip) |
| Insertion | Deltoid tuberosity on the lateral surface of the shaft of the humerus |
| Nerve Supply | Axillary nerve (C5, C6) |
Actions:
- Anterior fibers: Flexion, medial rotation, horizontal adduction of the arm
- Middle fibers: Abduction of the arm (main abductor from 15°–90°)
- Posterior fibers: Extension, lateral rotation, horizontal abduction of the arm
- All fibers together: Stabilize the glenohumeral joint
2. Teres Minor
| Feature | Detail |
|---|---|
| Origin | Upper 2/3 of the lateral (axillary) border of the scapula (dorsal surface) |
| Insertion | Lowest (inferior) facet of the greater tubercle of the humerus; also blends into the posterior capsule of the shoulder joint |
| Nerve Supply | Axillary nerve (C5, C6) — inferior branch |
Actions:
- Lateral (external) rotation of the arm at the shoulder
- Weak adduction of the arm
- Part of the rotator cuff — stabilizes the humeral head in the glenoid cavity
3. Biceps Brachii
| Feature | Detail |
|---|---|
| Origin — Long head | Supraglenoid tubercle of the scapula (intra-articular tendon) |
| Origin — Short head | Coracoid process of the scapula (with coracobrachialis) |
| Insertion | Posterior part of the radial tuberosity; via the bicipital aponeurosis (lacertus fibrosus) into the deep fascia of the forearm and ulnar periosteum |
| Nerve Supply | Musculocutaneous nerve (C5, C6) |
Actions:
- Supination of the forearm (most powerful supinator, especially with elbow at 90°)
- Flexion of the elbow (forearm in supination)
- Weak flexion of the shoulder
- Long head helps depress humeral head in abduction
4. Brachialis
| Feature | Detail |
|---|---|
| Origin | Anterior surface of the lower half of the humerus (distal to the deltoid tuberosity), and the medial and lateral intermuscular septa |
| Insertion | Coronoid process and tuberosity of the ulna |
| Nerve Supply | Musculocutaneous nerve (C5, C6); small lateral part by radial nerve (C7) |
Actions:
- Flexion of the forearm at the elbow joint in all positions (pronated, supinated, or neutral)
- Called the "workhorse" of elbow flexion — acts regardless of forearm position (unlike biceps)
5. Muscles of the Hand
The hand muscles are divided into three groups: thenar, hypothenar, and intrinsic (lumbricals + interossei).
A. Thenar Muscles (thumb group)
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| Abductor Pollicis Brevis | Flexor retinaculum, scaphoid tubercle, trapezium | Lateral side of base of proximal phalanx of thumb | Abducts thumb (anterior) |
| Flexor Pollicis Brevis | Superficial head: Flexor retinaculum, trapezium ridge · Deep head: Trapezoid, capitate | Lateral side of base of proximal phalanx of thumb (with sesamoid) | Flexes metacarpophalangeal (MCP) joint of thumb |
| Opponens Pollicis | Flexor retinaculum, trapezium ridge | Whole length of lateral border of 1st metacarpal | Opposition of thumb (rotation + flexion + medial rotation) |
| Adductor Pollicis | Oblique head: Capitate, bases of 2nd & 3rd metacarpals · Transverse head: Palmar surface of 3rd metacarpal shaft | Medial side of base of proximal phalanx of thumb (with sesamoid) | Adducts thumb toward palm |
Nerve supply: All thenar muscles — Recurrent branch of median nerve (C8, T1), except adductor pollicis — Deep branch of ulnar nerve (C8, T1)
B. Hypothenar Muscles (little finger group)
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| Abductor Digiti Minimi | Pisiform bone, pisohamate ligament, flexor retinaculum | Medial side of base of proximal phalanx of little finger | Abducts little finger |
| Flexor Digiti Minimi Brevis | Hook of hamate, flexor retinaculum | Medial side of base of proximal phalanx of little finger | Flexes MCP joint of little finger |
| Opponens Digiti Minimi | Hook of hamate, flexor retinaculum | Medial border of 5th metacarpal (whole length) | Draws 5th metacarpal anteriorly; rotates it — opposes little finger to thumb |
| Palmaris Brevis | Palmar aponeurosis (medial border) | Skin of medial palm | Wrinkles skin on medial palm; deepens the hollow of the palm |
Nerve supply: All hypothenar muscles — Deep branch of ulnar nerve (C8, T1)
C. Lumbricals (4 muscles)
| Feature | Detail |
|---|---|
| Origin | From tendons of flexor digitorum profundus (1st & 2nd from lateral side of tendon; 3rd & 4th from adjacent sides of tendons) |
| Insertion | Lateral side of the extensor expansion (dorsal digital expansion) of the 2nd–5th fingers |
| Nerve supply | 1st & 2nd (lateral): Median nerve · 3rd & 4th (medial): Deep branch of ulnar nerve |
| Action | Flex MCP joints + Extend interphalangeal (IP) joints of fingers 2–5 |
D. Dorsal Interossei (4 muscles — DAB: Dorsal ABduct)
| Feature | Detail |
|---|---|
| Origin | Adjacent sides of two metacarpal bones (bipennate) |
| Insertion | Into bases of proximal phalanges and extensor expansions of fingers 2, 3, 4 |
| Nerve supply | Deep branch of ulnar nerve (C8, T1) |
| Action | Abduct fingers from the middle finger (axial line); flex MCP joints; extend IP joints |
E. Palmar Interossei (3 muscles — PAD: Palmar ADduct)
| Feature | Detail |
|---|---|
| Origin | Palmar surfaces of 2nd, 4th, and 5th metacarpals (unipennate) |
| Insertion | Bases of proximal phalanges and extensor expansions of 2nd, 4th, and 5th fingers |
| Nerve supply | Deep branch of ulnar nerve (C8, T1) |
| Action | Adduct fingers toward the middle finger; flex MCP joints; extend IP joints |
Quick Memory Aids
| Muscle | Key Action to Remember |
|---|---|
| Deltoid (middle) | Only abductor of shoulder 15°–90° |
| Teres Minor | Lateral rotator of shoulder (rotator cuff) |
| Biceps | Best supinator; elbow flexion in supination |
| Brachialis | Elbow flexor in ALL positions |
| Lumbricals | "L-shaped" — flex knuckles, extend fingers |
| Dorsal Interossei | DAB — Dorsals ABduct |
| Palmar Interossei | PAD — Palmars ADduct |
This is a shared conversation. Sign in to Orris to start your own chat.