Thenar eminence

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Thenar eminence
The mucous sheaths of the tendons on the front of the wrist and digits.
Transverse section across the wrist and digits. (Muscles of thumb labeled at upper left.)
Latin	eminentia thenaris
Gray's	subject #126 546
Origin
Insertion
Artery:
Nerve:	median nerve
Action:	control movement of the thumb
Dorlands /Elsevier	t_07/12801990

The thenar eminence is the body of muscle on the palm of the human hand just beneath the thumb. The skin overlying this region is the area stimulated when trying to elicit a palmomental reflex.

Contents 1 Muscles 2 Mnemonic 3 See also 4 Additional images 5 References 6 External links

[edit] Muscles

The muscles in this location are usually innervated by the recurrent branch of the median nerve. They all control movement of the thumb.

The following three muscles are considered part of the thenar eminence:^[1]

• Abductor pollicis brevis abducts the thumb. This muscle is the most proximal of the thenar group.

• Flexor pollicis brevis, which lies next to the abductor, will flex the thumb, curling it up in the palm.

• Opponens pollicis lies deep to abductor pollicis brevis. As its name suggests it opposes the thumb, bringing it against the fingers. This is a very important movement, as most of our dexterity comes from this action.

The innervation of these muscles by the median nerve is unusual, as most of the intrinsic muscles on the palm of the hand are supplied by the ulnar nerve. The lateral two lumbrical muscles are the other exception.

Another muscle that controls movement of the thumb is adductor pollicis. It lies deeper and more distal to flexor pollicis brevis. Despite its name, its main action is mainly rotation and opposition. It is not in the thenar group of muscles, so is supplied by the ulnar nerve.^[2]

[edit] Mnemonic

A good way to remember what muscles are in the thenar eminence is "OAF"; oafs have big thenar eminences. 'O' = opponens, 'A' = abductor, 'F' = flexor. There is only one opponens. The other two muscles each have a long partner and thus are called "brevis."

Meat-LOAF: the "M" in the word "Meat" helps you remember that the LOAF muscles of the hand are innervated by the Median Nerve

ABOF (pronounced "above") the Law muscles. The law states muscles of the hand are supplied by ulnar nerve. However, ABOF the Law muscles are supplied by MEDIAN nerve. 'AB' = abductor, 'O' = Opponens, 'F' = Flexor, Law 'L' = Lateral Lumbricals (2).

[edit] See also

• Hypothenar eminence

[edit] Additional images

[edit] References

[edit] External links

• Norman/Georgetown lesson5mus&tendonsofhand

v • d • e List of muscles of upper limbs VERTEBRAL COLUMN trapezius - latissimus dorsi - rhomboid (major, minor) - levator scapulae THORACIC WALLS pectoralis major - pectoralis minor - subclavius - serratus anterior SHOULDER deltoid - rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) - teres major ARM anterior compartment: coracobrachialis - biceps brachii - brachialis posterior compartment: triceps brachii - anconeus FOREARM anterior compartment: superf. - pronator teres - palmaris longus - flexor carpi radialis - flexor carpi ulnaris - flexor digitorum superficialis anterior compartment: deep - pronator quadratus - flexor digitorum profundus - flexor pollicis longus posterior compartment: superf. - mobile wad (brachioradialis, extensor carpi radialis longus and brevis) - extensor digitorum, - extensor digiti minimi - extensor carpi ulnaris posterior compartment: deep - supinator - anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) - extensor indicis HAND lateral volar - thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis) - adductor pollicis medial volar - hypothenar (opponens digiti minimi, flexor digiti minimi brevis, abductor minimi digiti) - palmaris brevis intermediate - lumbrical - interossei (dorsal, palmar)