The hand (manus)

Question 1

Bones of the Hand

Answer 1

1. Carpal Bones: The wrist consists of eight carpal bones arranged in two rows:
   - Proximal Row: Scaphoid, Lunate, Triquetrum, Pisiform.
   - Distal Row: Trapezium, Trapezoid, Capitate, Hamate.
2. Metacarpal Bones: There are five metacarpal bones (I-V) that form the middle part of the hand, each corresponding to a digit.
3. Phalanges: Each finger has three phalanges (proximal, middle, distal), while the thumb has two (proximal and distal).

Question 2

Muscles of the Hand

Answer 2

The muscles of the hand can be categorized into intrinsic and extrinsic muscles:

1. Intrinsic Muscles: These are located within the hand and are responsible for fine motor movements. They include:
   - Thenar Muscles: Abductor pollicis brevis, Flexor pollicis brevis, Opponens pollicis.
   - Hypothenar Muscles: Abductor digiti minimi, Flexor digiti minimi brevis, Opponens digiti minimi.
   - Lumbricals: Four muscles that flex the metacarpophalangeal joints while extending the interphalangeal joints.
   - Interossei Muscles: Dorsal and palmar interossei that facilitate abduction and adduction of the fingers.
2. Extrinsic Muscles: These originate in the forearm and insert into the hand. They include flexors and extensors:
   - Flexors: Flexor digitorum superficialis, Flexor digitorum profundus, Flexor pollicis longus.
   - Extensors: Extensor digitorum, Extensor indicis, Extensor digiti minimi, Abductor pollicis longus, Extensor pollicis longus, Extensor pollicis brevis

Question 3

Joints of the Hand

Answer 3

Wrist Joint (Articulatio Radiocarpea): A biaxial joint allowing flexion, extension, abduction, and adduction.
- Articular surfaces include the distal radius and the proximal row of carpal bones (except the pisiform).
- Supported by ligaments such as the collateral ligaments.

2. Intercarpal Joints: Joints between the carpal bones allowing slight gliding movements.
3. Carpometacarpal Joints: Joints between the carpal bones and metacarpals. The carpometacarpal joint of the thumb (saddle joint) allows for a wide range of motion.
4. Metacarpophalangeal Joints (MCP): Joints between the metacarpals and phalanges, allowing flexion, extension, abduction, and adduction.
5. Interphalangeal Joints (PIP and DIP): Joints between the phalanges, allowing flexion and extension

Question 4

Ligaments of the Hand

Answer 4

Collateral Ligaments: Stabilize the metacarpophalangeal and interphalangeal joints.
- Palmar Ligaments: Provide support to the joints and prevent hyperextension.
- Retinacula: Such as the flexor retinaculum, which forms the carpal tunnel, housing the median nerve and flexor tendons

Question 5

Blood Vessels of the Hand

Answer 5

Arteries:
- Radial Artery: Supplies the lateral aspect of the hand and contributes to the superficial and deep palmar arches.
- Ulnar Artery: Supplies the medial aspect and forms the superficial palmar arch.
- Palmar Arches: Superficial and deep arches supply digital arteries to the fingers.

2. Veins:
   - Superficial Veins: Include the cephalic (lateral) and basilic (medial) veins.
   - Deep Veins: Accompany the arteries and include radial and ulnar veins

Question 6

Nerves of the Hand

Answer 6

Median Nerve: Innervates most of the flexor muscles in the forearm and the thenar muscles, as well as the first two lumbricals. It provides sensory innervation to the palmar side of the thumb, index, middle, and half of the ring finger.

2. Ulnar Nerve: Innervates the hypothenar muscles, interossei, and the third and fourth lumbricals. It provides sensory innervation to the palmar side of the little finger and half of the ring finger.
3. Radial Nerve: Innervates the extensor muscles of the forearm and provides sensory innervation to the posterior aspect of the hand.