Short Muscles Of Hand – Origin, Nerve Supply, Functions

Short Muscles Of Hand

Short Muscles Of Hand/The thenar muscles are three short muscles located at the base of the thumb. The muscle bellies produce a bulge, known as the thenar eminence. They are responsible for the fine movements of the thumb. The median nerve innervates all the thenar muscles.

Short Muscles Of Hand

Thenar Muscles of Hand

Opponents policies 

  • Function: Opposition of the thumb
  • Origin: Flexor retinaculum  and tubercle of trapezium
  • Insertion: Lateral aspect of the first metacarpal
  • Innervation: Recurrent branch of the median nerve (C8, T1)

Abductor policies Brevis

  • Function: Abduction of the thumb at the metacarpophalangeal joint
  • Origin: Flexor retinaculum  and tubercle of the scaphoid
  • Insertion: Lateral aspect of proximal phalanx of the first finger
  • Innervation: Recurrent branch of the median nerve (C8, T1)

Flexor policies Brevis 

  • Function: Flexion of the thumb at the metacarpophalangeal joint
  • Origin: Flexor retinaculum  and tubercle of trapezium
  • Insertion: Lateral aspect of proximal phalanx of the first finger
  • Innervation: Recurrent branch of the median nerve (C8, T1)

Adductor Compartment

Adductor pollicus 

  • Function: Adduction of the thumb
  • Origin: Second, third metacarpal, and capitate
  • Insertion: Proximal phalanx and extensor expansion of 1st finger
  • Innervation: Deep branch of ulnar nerve (C8, T1)

Hypothenar Muscles of Hand

Abductor digiti minimi

  • Function: Abduction of the little finger at the metacarpophalangeal joint
  • Origin: Pisiform
  • Insertion: Medial aspect of proximal phalanx of fifth finger
  • Innervation: Deep branch of ulnar nerve (C8, T1)

Flexor digiti minimi brevis

  • Function: Flexion of the little finger at the metacarpophalangeal joint
  • Origin: Flexor retinaculum and hook of hamate
  • Insertion: Medial aspect of proximal phalanx of fifth finger
  • Innervation: Deep branch of ulnar nerve (C8, T1)

Opponens digiti minimi

  • Function: Opposition of the little finger
  • Origin: Flexor retinaculum and hook of hamate
  • Insertion: Medial aspect of fifth metacarpal
  • Innervation: Deep branch of ulnar nerve (C8, T1)

Short Muscles Of Hand

Lubricants 

  • Function: Flexion of the metacarpophalangeal joints with extension of the interphalangeal joints
  • Origin: Arise from tendons of flexor digitorum profundus. First 2 are unipennate, and the third and fourth are bipennate
  • Insertion: Extensor expansions of second, third, fourth, and fifth finger
  • Innervation: Median nerve (C8, T1) for the lateral 2 lumbricals, deep branch of ulnar nerve (C8, T1) for the medial 2 lumbricals

Dorsal interossei 

  • Function: Abduction of the second, third, and fourth finger away from the axial line
  • Origin: Adjacent metacarpals
  • Insertion: Extensor expansions and proximal phalanges of the second, third, and fourth fingers
  • Innervation: Deep branch of ulnar nerve (C8, T1)

Palmar interossei

  • Function: Adduction of the second, third, and fourth finger towards the axial line
  • Origin: Palmar surfaces of second, fourth, and fifth metacarpals
  • Insertion: Extensor expansions and proximal phalanges of the second, fourth, and fifth fingers
  • Innervation: Deep branch of ulnar nerve (C8, T1)

 

Intrinsic Muscles of the Hand
Muscle Origin Insertion Action Innervation
Muscles acting on the Second through Fifth Digits
Dorsal interossei (4) the ulnar side of 1st MC; both sides of 2nd-4th MC; radial side of 5th MC Tubercle of the proximal phalanx and dorsal aponeurosis: radially on 2nd and 3rd digits, clearly on 3rd and 4th digit Abduct 2nd-4th digits from midline; flex MCP joint, extend PIP and DIP joints Ulnar nerve (C8-T1, anterior)
Palmar interossei (3) the ulnar side of 2nd and radial side of 4th-5th MC Tubercle of the proximal phalanx and dorsal aponeurosis: ulnarly on 2nd digit, radially on 4th and 5th digits Adduct 2nd, 4th, and 5th digits to the midline of the hand. Flex MCP joint and extend PIP and DIP joints Ulnar nerve (C8-T1, anterior)
Lubricants (1 and 2) Tendons of FDP in deep palm radial side of dorsal expansion of 2nd and 3rd digits Flex MCP, extend DIP, PIP Median nerve (C8-T1, anterior)
Lubricants (3 and 4) Tendons of FDP in deep palm radial side of dorsal expansion of 4th and 5th digits Flex MCP, extend DIP, PIP Ulnar nerve (c8-T1, anterior)
Palmaris Brevis ulnar border of palmar aponeurosis The skin over the hypothenar region Corrugates palmar skin Ulnar nerve (C8-T1, anterior)
Abductor digiti minimi Pisiform bone The ulnar side of the base of the 5th proximal phalanx Abduct 5th digit Ulnar nerve (C8-T1, anterior)
Flexor digiti minimi brevis Flexor retinaculum and hamulus The ulnar side of the base of the 5th proximal phalanx Flex 5th MCP joint Ulnar nerve (C8-T1, anterior)
Opponents digiti minimi Flexor retinaculum and hamulus The ulnar side of the base of the 5th MC Flexion and opposition Ulnar nerve (C8-T1, anterior)
Muscles acting on the Thumb
Abductor pollicis brevis (APB) Anterior surface of trapezium, scaphoid the radial aspect of the base of proximal phalanx Abducts thumb Median n. (C8-T1, anterior)
Opponent pollicis Trapezium The anterolateral surface of 1st MC Medially rotates (opposes) thumb Median n. (C8-T1, anterior)
Flexor pollicis brevis
  Superficial head Transverse carpal ligament and trapezium radial side of the base of proximal phalanx Flexes thumb Median n. (C8-T1, anterior)
  Deep head radial side of 2nd MC Ulnar nerve (C8-T1, anterior)
Adductor pollicis
  Oblique head The anterior surface of capitate and 2nd and 3rd MC the ulnar side of the base of proximal phalanx Adducts thumb Ulnar nerve (C8-T1, anterior)
  Transverse head Distal half of 3rd MC
  • Extrinsic (Originate in the forearm)The extrinsic muscles of the hand include the wrist flexors and extensors, which stabilize the wrist in slight dorsiflexion, the Finger Flexors (five deep and four superficial), and the finger extensors
Extrinsic Muscles of the Hand
Muscle Origin Insertion Action Innervation
Muscles acting on the Second through Fifth Digits
Extensor digitorum cominus (EDC) Lateral epicondyle of humerus middle and distal phalanges of index, middle, and ring fingers Extends digits and wrist when the fist is clenched Radial nerve (C7-C8, posterior)
Extensor digiti minimi (EDM) Common extensor tendon All phalanges of the fifth digit Extends the fifth digit Radial nerve (C7-C8, posterior)
Extensor indicis proprius (EIP) Interosseus membrane and ulna middle and distal phalanges of the index finger extends first digit and wrist Radial nerve (C8-T1, posterior)
Flexor digitorum superficialis (FDS) Medial epicondyle The base of the middle phalanx of each digit Flexes PIP, MCP, and wrist joint Median nerve (C8-T1, anterior)
Flexor digitorum profundus (FDP) Anterior proximal ulna and IOM Base of distal phalanx of each digit Flexes DIP, PIP, MCP, and wrist joints -Median n. (C7-T1, anterior) for 2nd-3rd digit
-Ulnar n. (C7-T1, anterior) for 4th-5th
Muscles acting on the thumb
Abductor pollicis longus (APL) Posterior IOM and ulna Base of1st MC, laterally Abducts thumb and wrist Radial n. (C8-T1, posterior)
Extensor pollicis brevis (EPB) Posterior midshaft of radius and IOM Base of proximal phalanx Extends thumb and abducts wrist Radial n. (C8-T1, posterior)
Extensor pollicis Longus (EPL) Posterior surface of IOM and posteriior ulna Base of middle phalanx Extend thumb and abducts wrist Radial n. (C8-T1, posterior)
Flexor pollicis longus (FPL) Anterior mid-radius and IOM Lateral aspect of base of proximal phalanx Flexe thumb, MCP joint, and wrist Median n. (C7-T1, anterior)

Surgical Considerations

The deltoid is a significant factor when considering the anterior surgical approach to gain access to the shoulder joint.  Some of these technical procedures include, but are not limited to the following:

  • Open Bankart repair/capsular reconstructions – indicated in the setting of recurrent anterior (or other directional) instability of the shoulder
  • Shoulder arthroplasty – indicated for cases of post-traumatic deformity, advanced degenerative arthritis, and/or avascular necrosis includes hemiarthroplasty, total shoulder arthroplasty (TSA), reverse total shoulder arthroplasty (TSA)
  • The long head of the biceps tendon (LHBT) – repair versus tenotomy versus tenodesis procedures  indicated in the setting of either LHBT/bicipital groove instability or advanced/end-stage LHBT tendinopathy and degeneration
  • Rotator cuff repair contemporary –  indications remain somewhat controversial although most of these procedures are now being performed arthroscopically popular approaches (as opposed to the deltopectoral approach) include the mini-open approach (lateral deltoid-splitting approach)

References