Hand Flashcards
[10-minute video]: an easy way to remember hand and arm muscles [Part 1]
[8-minute video]: an easy way to remember hand and arm muscles [Part 2]
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State the dermatome of the:
(a) Thumb
(b) Small finger
(c) Middle finger
(a) Thumb: C6
(b) Small finger: C8
(c) Middle finger: C7
[Diagram]
State the characteristic features of the skin of the palm.
- It is thick to withstand wear and tear during work.
- It is richly supplied by the sweat glands but contains no hair or sebaceous glands.
- It is immobile as it is firmly attached to the underlying palmar aponeurosis.
- It presents several longitudinal and transverse creases where the skin is firmly bound to the deep fascia.
What are the two important features of the superficial fascia of the palm?
- Palmaris brevis, a subcutaneous muscle [innervated by the superficial branch of the ulnar nerve]
- Thickens to form a superficial transverse metacarpal ligament, which stretches across the roots of fingers over the digital nerve and vessels
- Note: the palmar aponeurosis is considered a part of the deep fascia of the palm.
The palmar fascia is specialized to form three structures, namely:
- flexor retinaculum
- palmar aponeurosis
- fibrous flexor sheaths of digits
State the functions of palmar aponeurosis.
- Helps to improve the grip of hand by fixing the skin.
- Protects the underlying tendons, nerves, and vessels.
What is the function of the fibrous flexor sheaths?
They hold the tendons in position during flexion of digits.
List the groups of the intrinsic muscles of the hand.
- Thenar muscles
- Hypothenar muscles
- Lumbricals
- Interossei
The thenar muscles are arranged around the polex (thumb). List the thenar muscles.
Abductor pollicis brevis (lies laterally)
Flexor pollicis brevis (lies medially)
Opponens pollicis (deep to abductor pollicis brevis)
[Diagram]
(a) State the function of each of the thenar muscles.
(b) What is the nerve supply of the thenar muscles?
(a) Functions:
~ Flexor pollicis brevis: flex the metacarpophalangeal and carpometacarpal joints
~ Abductor pollicis brevis: abduct the thumb
~ Opponens pollicis: produce opposition of thumb
~ [Diagram]
(b) All are supplied by the recurrent branch of the median nerve.
Name the three hypothenar muscles.
- Abductor digiti minimi [lies medially]
- Flexor digiti minimi [lies laterally]
- Opponens digiti minimi [lies deep to abductor digiti minimi and flexor digiti minimi]
- [Diagram]
(a) State the action of each of the hypothenar muscles.
(b) What is the nerve supply of the hypothenar muscles?
(a) Functions:
~ abductor digiti minimi: abduction and flexion of the 5th finger at the metacarpophalangeal joint
~ flexor digiti minimi: flexion of the 5th finger at the metacarpophalangeal joint
~ opponens digiti minimi: flexion, lateral rotation and opposition of 5th finger
(b) All of them are supplied by the deep branch of ulnar nerve (C8, T1).
The flexor pollicis brevis has dual nerve supply: superficial head by the median nerve and deep head by the deep branch of the ulnar nerve. TRUE or FALSE?
Discuss the following under the adductor pollicis muscle:
origin, insertion, nerve supply, action
Origin:
1. Oblique head arises from anterior aspects of capitate bone and bases of second and third metacarpal bones—forming a crescentic shape.
2. Transverse head arises from ridge on distal two-third of the anterior surface of the shaft of the third metacarpal.
[Diagram: Two heads of adductor pollicis]
Insertion: Medial side of the base of proximal phalanx of the thumb (tendon has a sesamoid bone)
Nerve supply: Deep branch of the ulnar nerve
Actions: Adduction of the thumb to provide power to the grip