The thenar muscles are capable of various thumb movements abduction, adduction, flexion, and opposition. Origin - flexor retinaculum, tubercle of trapezium boneįunction - thumb flexion, abduction, and medial rotation resulting in a combined movement called opposition Insertion - radial sesamoid bone and base of the proximal phalanx (superficial head), base of first phalanx, radial sesamoid bone (deep head) Origin - flexor retinaculum, tubercle of trapezium (superficial head), trapezoid and capitate bones (deep head) Insertion - base of proximal phalanx, ulnar sesamoid boneįunction - thumb adduction (moving towards the hand) Origin - palmar base of third metacarpal (transverse head), capitate bone and palmar bases of second and third metacarpals (oblique head)
Innervation - Recurrent branch of median nerve (C8, T1)įunction - thumb abduction (moving away from the hand) at carpometacarpal joint 1 Insertion - base of the proximal phalanx 1 (via radial sesamoid bone) Origin - tubercles of the scaphoid and trapezium flexor retinaculum Key Facts about thenar muscles Abductor pollicis brevis Use the following mnemonic to easily remember them They form the ‘ball’ or ‘fleshy’ part of the thumb known as the thenar eminence, and are named as follows: abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, and opponens pollicis. The thenar muscles are four in total they are evident and easy to palpate on the radial side of the palmar surface of the hand, at the base of the thumb. It also facilitates the passage of tendons and various neurovascular structures from the forearm to the hand. It is capable of various movements like flexion, extension, abduction and adduction. Palmar venous arches: Receives palmar metacarpal and digital veins. Gives rise to cephalic and basilic veins. They include: palmar arches (superficial, deep), palmar digital arteries (common, proper), dorsal carpal arch, dorsal metacarpal arteries, dorsal digital arteries, principal artery of the thumb.ĭorsal venous network of hand: predominant drainage route of the hand (also receiving palmar venous return via perforating veins). Mnemonic: Ulnar nerve supplies all intrinsic muscles of the hand except the LOAF muscles ( Lateral two lumbricals, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis)Īll the branches originate from the radial and ulnar arteries. Ulnar nerve and its branches (superficial, deep and dorsal) innervate the hypothenar and metacarpal groups Radial nerve provides cutaneous innervation along the outisde of the thumb. Median nerve and its branches (common and proper palmar digital nerves) predominantly supply the thenar muscles. Metacarpal group: lumbircals, palmar interossei, dorsal interossei Hypothenar group: abductor digiti minimi, flexor digiti minimi, opponens digiti minimi, palmaris brevis Thenar group: abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, opponens pollicis Phalanges: proximal, middle, distal phalanges Key facts about the anatomy of the hand BonesĬarpals: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate The other major contributors are actually the forearm muscles, which project tendons towards the hand via an equally complex and flexible anatomical structure, called the wrist.Ī solid understanding of the hand requires good grasp (pun intended) of its entire anatomy, so in this page we will look at all of the above structures. However, the intrinsic muscles of the hand are only partially responsible for all its range of motion. The hand itself consists of specific bones onto which various muscles are attached, and a collection of neurovascular structures responsible for drainage and innervation. It is strong enough to allow climbers to tackle any mountain, but also sufficiently precise for the manipulation of some of the world’s smallest objects and the performance of complex actions. The human hand, the most distal part of the upper limb, is a remarkable feat of engineering and evolution.
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