Functional Anatomy of the Hand

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska and Jess Bell  

Introduction

The hand contains a number of joints that allow complex actions, such as manipulating, gripping and grasping objects. Optimal hand function requires adequate strength, sensation, range of motion, and dexterity. When one or more of these components are injured or impaired, an individual's participation in daily activities may be significantly limited. However, even a partial recovery of hand function can positively impact independence. This article discusses the key anatomical structures of the hand that enable functional movements, including the bony structures, articulations, ligaments, muscles, nerves and the vascular supply.

Key Terms

Axes: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: sagittal passing from posterior to anterior, frontal passing from left to right, and vertical passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion.

Bursae: reduce friction between the moving parts of the joints. A bursa is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, synovial, and sub-muscular.

Capsule: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."

Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. For example, the closed pack position for the interphalangeal joints is full extension.

Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations.

Ligament: fibrous connective tissue that holds the bones together.

Open (loose) pack position: position with the least joint congruency where joint stability is reduced.

Planes of movement: describe how the body moves. Up and down movements (flexion/extension) occur in the sagittal plane. Sideway movements (abduction/adduction) occur in the frontal plane. The transverse plane movements are rotational (internal and external rotation).

Hand Structure

The human hand includes 27 bones. There are:

• eight carpal bones
• five metacarpal bones
• fourteen digital bones, including the fingers and thumb

The bony segments of the hand are arranged in a series of longitudinal and transverse arches. The bones of the five digital rays are part of the longitudinal arches. The proximal transverse arch is made up of carpal bones. The distal transverse arch is made up of the metacarpal heads of the fingers.

The Carpus (Carpal Bones)

Proximal row:

• Scaphoid (navicular): most lateral bone of the proximal row. The palmar surface contains the scaphoid tubercle and the floor of the anatomical snuffbox.
• Lunate: articulates with the scaphoid on its lateral side and the triquetrum on its medial side.
• Triquetrum: other names include triquetral, triangular, or cuneiform bone. It is a triangular / pyramidal-shaped bone located on the medial side of the wrist. It has multiple articular surfaces: the lunate articulates on its lateral side, the pisiform on its anterior side and the hamate on its distal side.
• Pisiform: the smallest carpal bone. It only articulates with the triquetrum.

Distal row:

• Trapezium: located on the radial side of the distal row of the carpal bones. It has four articulations for the first metacarpal, second metacarpal, scaphoid and trapezoid bones. The articulation between the trapezium and first metacarpal provides significant mobility in the hand, enabling thumb opposition.
• Trapezoid: also known as the lesser multangular bone. This is the smallest bone of the distal row of the carpal bones. It gives structure to the palm.
• Capitate: the largest and most central carpal bone. It articulates with the bases of the second and third metacarpal bones, forming part of the common carpometacarpal joint in the hand. In addition, it articulates with the scaphoid and lunate on its proximal surface, the trapezoid on its lateral surface, and the hamate on its medial surface.
• Hamate: sits on the medial side of the distal row of carpal bones. The hook of the hamate is a bony process extending from the palmar surface. This bone forms the medial border of the carpal tunnel.

The Metacarpus (Metacarpal Bones)

There are five metacarpal bones. The metacarpals make up the metacarpus. Each metacarpal bone articulates with one or more carpal bones:

• First metacarpal articulates with the trapezium
• Second metacarpal articulates with the trapezium, trapezoid and capitate
• Third metacarpal articulates with the capitate
• Fourth and fifth metacarpals articulate with the hamate

Additionally, the second to fifth metacarpals articulate with each other.

The Phalanges

The long finger bones are known as phalanges (singular = phalanx). While the thumb (pollex) only has distal and proximal phalanges, the other fingers have distal, middle and proximal phalanges. The middle and proximal phalanges have a base (proximal), body, and head (distal).

The thumb: the typical position of the thumb is pronation and approximately 80 degrees of flexion in relation to the other metacarpals of the hand. This position allows opposition of the thumb to the digits.

The index finger: the second and most important finger of the hand. It is able to abduct, adduct, flex and extend. The index finger participates in precision pinch and directional grip.

The long finger: centrally positioned. It is involved in power grip and precision movements.

The ring finger: weak and only randomly used in precision grip or pinch manoeuvres. In the case of amputation, it has been argued that "the loss of the ring finger [results] in the least amount of impairment to the hand."

The small finger: the weakest of all fingers, but important in grasping while spanning an object because of its ability to abduct.

Bones, Articulations and Kinematics of the Hand

Bones and Articulations

Bones	Articulations	Characteristics	Key palpation points
Distal row of carpal bones and the proximal bases of the five metacarpal bones	The carpometacarpal joints (CMC): The first CMC (1CMC, also known as the CMC of the thumb, trapeziometacarpal (TMCJ) joint: located between the trapezium and the base of the first metacarpal The second CMC (2CMC) joint: located between the trapezoid and the base of the second metacarpal The third CMC (3CMC) joint: located between the capitate and the base of the third metacarpal The fourth CMC (4 CMC) joint: located between the hamate and the base of the fourth metacarpal The fifth CMC (5 CMC) joint: located between the hamate and the base of the fifth metacarpal.	The CMC joints permit opposition of the thumb and cupping of the palm. The mobility of the CMC joints increases from the radial to the ulnar side of the hand. 1CMC (TMCJ) is located on the radial aspect of the wrist. It does not have any bony stabilisers. Instead, stability is provided by five internal ligaments. These are the dorsal radial ligament, posterior oblique ligament, first intermetacarpal ligament, ulnar collateral ligament, and anterior oblique ligament. 2CMC and 3CMC: belong to the central column of the hand, relatively rigid. 1CMC, 4CMC, 5CMC: relative mobility, with 4CMC and 5CMC contributing the most to hand mobility.	To palpate the first CMC joint, place the patient's hand on the side with the radial side up. Slide your finger along the patient's thumb down to the first metacarpal. You will feel a divot (indentation) just below the first metacarpal. The trapezium is located just below this indentation - the first metacarpal articulates with the trapezium. The trapezoid is located between the trapezium and the capitate. It articulates with the second metacarpal. To find the capitate, slide your finger down the patient's middle finger to reach the third metacarpal bone. You have located the capitate when your finger drops into a divot (indentation) - the capitate articulates with the third metacarpal. To palpate the hamate, first locate the hook of the hamate. Turn the patient's hand with the palmar (volar) side up and place your finger on the hypothenar region. You can palpate the hook and the hamate in the hypothenar eminence. The hook of the hamate is tender, and even gentle compression may be unpleasant for the patient. The fourth and the fifth metacarpals articulate with the hamate.
Metacarpal bones and the proximal phalanges	Metacarpophalangeal (MCP) joints	Considered the most important joints for hand function, as they contribute 77% of the total arc of finger flexion	To locate the proximal phalanges, look at the joints associated with them. Flex the patient's finger. The proximal phalanx is located between the proximal and the middle knuckle of the finger or between the palmar and the middle crease of the finger. The joint space of the MCP joint is located around 1 cm distal to the tip of the knuckle.
Proximal, middle, and distal phalanges	Interphalangeal joints PIP: proximal interphalangeal joint between the proximal and middle phalanges DIP: distal interphalangeal joints between the middle and distal phalanges	The function of the interphalangeal joints of the hand is to permit fine motor movements in the digits, including flexion towards the palm.	The PIP and DIP joint space correspond to the flexor crease.

Hand Kinematics

There are seven fundamental manoeuvres needed for basic hand function. These manoeuvres involve specific motions which must occur at the wrist, thumb and fingers:

1. The precision pinch, or the terminal pinch, is used to pick up a small object, like a pen.
   • Motion required: flexion of the interphalangeal (IP) joint of the thumb and the distal IP (DIP) joint of the index finger.
2. The oppositional pinch, or the subterminal pinch with thumb opposition. The pulp of the index finger connects with the pulp of the thumb - e.g. to hold a piece of paper.
   • Motion required: extension of the IP and DIP joints.
3. The key pinch requires a "stable post", which is usually provided by the index finger, as well as sufficient length of the digit and a metacarpophalangeal joint (MCP) - e.g. to hold a key
   • Motion required: thumb adduction to the radial aspect of the middle phalanx of the index finger.
4. The chuck grip, or a directional grip, allows the index finger, long finger, and thumb to hold cylindrical objects. This grip is usually associated with the application of a rotational and axial force to the object - e.g. using a screwdriver.
   • Motion required: combined index finger, long finger, and thumb motion.
5. The hook grip is used to hold items, such as a briefcase, by its handle. This grip does not require any thumb function.
   • Motion required: finger flexion at the IP joints and extension at the MCP joints.
6. The power grasp is used to grip a club or a bat.
   • Motion required: finger and thumb flexion, thumb opposition relative to the other digits.
7. The span grasp requires stability at the thumb, metacarpophalangeal (MCP) and interphalangeal (IP) joints. The span grasp is used when grasping a ball.
   • Motion required: 30 degrees of flexion at the DIP joints and the proximal IP (PIP) joints, thumb abduction towards the palm.

Joint	Type of joint	Plane of movement	Motion	Kinematics	Closed pack position	Open pack position
Carpometacarpal joints (CMC)	1CMC: Synovial, saddle joint. 2CMC/3CMC: Synovial, planar joints. But synarthrotic with almost no movement under physiological conditions. 4CMC/5CMC: Synovial, saddle joint.	1CMC: Flexion/extension occurs in the frontal plane as the thumb is rotated at 90 degrees in relation to the plane of the hand Abduction/adduction occurs in the sagittal plane External/internal rotation (axial rotation) where the axis is the length of the thumb Thumb opposition: all thumb movements combined together 2CMC/3CMC: Nonaxial, translational movements 4CMC/5CMC: Sagittal (flexion/extension) Frontal (abduction/adduction)	1CMC: Flexion/extension Abduction/adduction Axial rotation 2CMC/3CMC: Nonaxial, translational movements only 4CMC/5CMC: Flexion/extension Abduction/adduction	1CMC: Flexion/extension: total motion of 40-50 degrees Abduction/adduction: total motion of 80 degrees Axial rotation: total motion of 70-110 degrees 2CMC/3CMC: Nonaxial, translational movements only 4CMC: Flexion/extension: 10/0 degrees Abduction/adduction: 5/0 degrees 5CMC: Flexion/extension: 20/0 degrees Abduction/adduction: 13/0 degrees	1CMC: maximum opposition 4CMC/5CMC: full flexion	1CMC: slight flexion 4CMC/5CMC: halfway between flexion and extension
Metacarpophalangeal (MCP) joints	Condyloid joint	Sagittal Frontal	Flexion/extension, Abduction/adduction, Mild to moderate rotation of the digit	Thumb MCP: Flexion/extension: 55 degrees/35 degrees Abduction/adduction: 25-30 degrees total range Second to fifth MCP: Flexion: 90 degrees Extension: 10-30 degrees Abduction/adduction: 25-30 degrees	Thumb MCP: maximum opposition Second to fifth MCP: full flexion	Slight flexion
Interphalangeal joints (IP) PIP DIP	Hinge	Sagittal	Flexion/extension	Thumb: Flexion: 90 degrees Extension: 10-15 degrees Second to fifth PIP: Flexion: 70-100 degrees (depends on the digit, with digit 5 having the least flexion range of motion) Extension: 2-5 degrees Second to fifth DIP: Flexion: 50 degrees Extension: 15 degrees	Full extension	Slight flexion

Hand Passive Range of Motion

Please watch this video if you want to learn about the passive range of motion assessment for the thumb using a goniometer:

Please watch this video if you want to learn about the passive range of motion assessment for the fingers using a goniometer:

Ligaments of the Hand

Ligaments Supporting the Carpometacarpal Joints

Trapeziometacarpal Joint (TMCJ) Ligaments

Key ligaments	Origin	Insertion	Action/role
Anterior oblique ligament (AOL) ("beak ligament"): Deep Superficial	Palmar tubercle of the trapezium	Volar beak of the first metacarpal base at the palmar and ulnar surface	A static stabiliser of the TMCJ. Prevents dorsoradial subluxation of thumb metacarpal during key pinch. Degeneration of AOL frequently leads to osteoarthritis of the first CMC joint.
Posterior oblique ligament (POL)	Dorsal-ulnar aspect of the trapezium	Dorsal-ulnar aspect of the thumb metacarpal and the palmar-ulnar tubercle	Secondary role in CMC joint stability. Prevents radial translation.
Ulnar collateral ligament (UCL)	Distal and ulnar margin of the flexor retinaculum insertion onto the trapezial ridge	Superficial and ulnar to the superficial anterior oblique ligament on the volar-ulnar tubercle of the first metacarpal base	Prevents side-to-side movements of the thumb
First intermetacarpal ligament (1stIMCL)	Dorsoradial aspect of the second metacarpal, radial to the extensor carpi radialis longus tendon insertion	Volar-ulnar tubercle of the first metacarpal base	Connects the metacarpal of the thumb to the metacarpal of the index finger.
Dorsoradial ligament (DRL)	Dorsoradial tubercle of the trapezium	Dorsal edge of the base of the thumb metacarpal.	The strongest and stiffest of the TMCJ ligaments. The primary stabiliser of the TMCJ. Also has a proprioceptive function due to its rich innervation.

Carpometacarpal Joints 2-5 (2CMC-5CMC) Ligaments

Key ligaments	Origin	Insertion	Action/role
Palmar (volar) carpometacarpal ligaments	Palmar (volar) surfaces of the distal row of carpal bones: 2CMC: trapezium and trapezoid 3CMC: trapezium/trapezoid, capitate, hamate 4CMC: capitate and hamate 5CMC: hamate	Palmar (volar) surface of the four medial metacarpal bases	CMC joint stabilisers
Dorsal carpometacarpal ligaments	Dorsal surfaces of the distal row of the carpal bones: 2CMC: trapezium and trapezoid 3CMC: trapezoid and capitate 4CMC: capitate and hamate 5CMC: hamate	Four medial metacarpal bases
Interosseous ligament: Lateral band (LB) Medial band (MB)	Inferior aspect of the distal margins of the capitate and hamate bones: LB: capitate MB: hamate	Third and fourth metacarpal bases: LB: third metacarpal base MB: fourth metacarpal base

Ligaments Supporting the Metacarpophalangeal Joints

Key ligaments	Origin	Insertion	Action/role
Collateral ligaments: Proper collateral ligaments (PCL) Accessory collateral ligaments (ACL)	PCL: posterior tubercles on the dorsolateral aspect of the metacarpal head ACL: proximal to the metacarpal head	PCL: palmar aspect of the adjacent proximal phalanx, distal to the base ACL: distal third of the palmar (volar) plate	Stabilise the joint medially and laterally. Limit flexion and extension.
Deep transverse metacarpal ligaments (2-5MCP only)	Run across the palmar aspect of the second to fifth metacarpophalangeal joints.		Stabilise the transverse metacarpal arch.
Palmar ligament (volar plate)	The palmar aspect of the metacarpal neck and the palmar surface of the base of the adjacent proximal phalanx	Blends with the collateral ligament	Prevents hyperextension of the MCP joint.

Ligaments Supporting the Interphalangeal Joints

Key ligament	Origin	Insertion	Action/role
Collateral ligaments divide into: Proper collateral ligament (PCL) Accessory ligament (AL)	PCL/AL: Dorsal proximal phalangeal heads	PCL: Volar third of the middle phalanx bases AL: Volar plate	Provide radio-ulnar stability. Prevent excessive adduction-abduction movements of the interphalangeal joints.
Palmar ligament (volar plate)	The palmar surface of the base of the distal phalanx	Blends with the accessory collateral ligaments	Prevents hyperextension of each IP joint.

Additional Structures

Pulleys of the Hand

The pulleys of the hand are thickened areas of the flexor tendon sheath. This sheath holds the flexor tendons near the bone and converts the force generated in the muscle-tendon unit into movement at the phalanges. This system helps maintain the tracking of the flexor tendons during flexion and extension. There are two types of pulley systems in the hand:

• Annular pulleys: well-defined thickened areas of tendon sheath going across the tendons.
• Cruciform pulleys: help with approximation of the annular pulley during flexion and maintain the integrity of the flexor sheaths.

You can read more on the hand pulleys here.

Muscles of the Hand

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

• Extrinsic division: muscles that originate at the forearm
• Intrinsic division: muscles that originate within the hand. Collectively, they contribute to around 50% of grip strength, and they are divided into four groups:
  • Interossei (dorsal interossei and palmar interossei)
  • Lumbricals
  • Hypothenar muscles controlling the fifth finger (flexor digiti minimi brevis, abductor digiti minimi, opponens digiti minimi)
  • Thenar muscles controlling the thumb (flexor pollicis brevis, opponens pollicis, abductor pollicis brevis)

The hand muscles can also be grouped according to their function: finger flexors, extensors, abductors and adductors. The tables below describe the hand muscles according to their function.

Finger Flexors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	Bases of the proximal phalanges and the extensor apparatus	Ulnar nerve	Abduct the fingers. Assist in flexion of the MCP joints. Assist in extension of the IP joints.
Palmar interossei	First palmar interosseous: medial side of the second metacarpal. Second and third interossei: lateral side of the fourth and fifth metacarpals	Proximal phalanx on the same side and the extensor apparatus		Flexion of the second, fourth and fifth MCP joints. Assist in the extension of the IP joints. Assist in adduction at the MCP joints.
Lumbricals	Tendons of the flexor digitorum profundus	Extensor apparatus on the second to fifth fingers	First and second lumbricals: Median nerve. Third and fourth lumbricals: Ulnar nerve	Flexion of MCP joints. Extension of the IP joints. The lumbricals can initiate flexion of the proximal phalanx when the interossei are paralysed.
Flexor digitorum profundus	Ulnar shaft, interosseous membrane	Distal phalanges of fingers two to five through four tendons	Lateral part (fingers 2 and 3): Anterior interosseous nerve (branch of the median nerve) Medial part (fingers 4 and 5): Ulnar nerve	Flexion of the MCP, PIP, and DIP joints.
Flexor pollicis longus	Anterior surface of the shaft of the radius and interosseous membrane	Distal phalanx of the thumb	Anterior interosseous nerve	Flexion of the thumb MCP and IP joints.
Flexor digitorum superficialis (FDS) Humeroulnar head (HUH) Radial head (RH)	HUH: medial epicondyle via the common flexor tendon and the coronoid process RH: radial tuberosity	HUH/RH: middle phalanges of fingers two to five	Median nerve	Flexion of the MCP and PIP joints.
Flexor pollicis brevis Superficial head (SH) Deep head (DH)	Trapezium, flexor retinaculum	Base of the proximal phalanx of the thumb	SH: Median nerve DH: Median and ulnar nerves	Flexion of the CMC and MCP joints of the thumb.
Opponens pollicis	Trapezium, flexor retinaculum	Shaft of the first metacarpal	Recurrent branch of the median nerve	Flexion of the CMC joint of the thumb.Opposition of the thumb to the other fingers.
Flexor digiti minimi brevis	Hamate, flexor retinaculum	Base of the proximal phalanx of the fifth finger	Deep branch of the ulnar nerve	Flexion of the MCP joint of the fifth finger.

Finger Extensors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	Bases of the proximal phalanges and the extensor apparatus	Ulnar nerve	Abduct the fingers. Assist in flexion of the MCP joints. Assist in the extension of the IP joints.
Palmar interossei	First palmar interosseous: medial side of the second metacarpal. Second and third interossei: lateral side of the fourth and fifth metacarpals	Proximal phalanx on the same side and the extensor apparatus		Flexion of the second, fourth and fifth MCP joints. Assist in the extension of the IP joints. Assist in adduction at the MCP joints.
Lumbricals	Tendons of the flexor digitorum profundus	Extensor apparatus on the second to fifth fingers	First and second lumbricals: Median nerve Third and fourth lumbricals: Ulnar nerve	Flexion of MCP joints. Assist in the extension of the IP joints. When the interossei are paralysed, the lumbricals can initiate flexion of the proximal phalanx.
Extensor indicis	Shaft of the ulna and the interosseous membrane	Extensor apparatus of the index finger	Posterior interosseous nerve	Extension of the finger at the MCP and IP joints
Extensor pollicis brevis	Shaft of the radius and the interosseous membrane	Base of the proximal phalanx of the thumb		Thumb extension at the CMC and the MCP joints
Extensor pollicis longus	Shaft of the radius and the interosseous membrane	Base of the distal phalanx of the thumb		Extension of the CMC, MCP, and IP joints
Extensor digiti minimi	Lateral epicondyle of the humerus via the common extensor tendon	Extensor apparatus of the fifth finger		Extension of the fifth finger at the MCP and IP joints
Extensor digitorum	Lateral epicondyle via the common extensor tendon	Extensor expansions of fingers two to five via four tendons		Extension of the MCP and IP joints of the second to fifth fingers

Finger Abductors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	Bases of the proximal phalanges and the extensor apparatus	Ulnar nerve	Abduct the MCP joints of the fingers. Assist in flexion of the MCP joints. Assist in the extension of the IP joints.
Abductor digiti minimi	Pisiform and the flexor retinaculum	Base of the proximal phalanx of the fifth finger and the extensor apparatus	Deep branch of the ulnar nerve	Abducts the fifth MCP joint.
Abductor pollicis longus	Posterior aspect of the radius and the ulna and the interosseous membrane	Base of the first metacarpal	Posterior interosseous nerve	Abducts the thumb at the CMC joint.
Abductor pollicis brevis	Scaphoid, trapezium, and flexor retinaculum	The base of the proximal phalanx of the thumb and the extensor apparatus.	Recurrent branch of the median nerve	Abducts the thumb at the CMC and MCP joints.

Finger Adductors

Muscle	Origin	Insertion	Innervation	Action
Palmar interossei	First palmar interosseous: medial side of the second metacarpal. Second and third interossei: lateral side of the fourth and fifth metacarpals	Proximal phalanx on the same side and the extensor apparatus	Ulnar nerve	Flexion of the second, fourth and fifth MCP joints. Assist in the extension of the IP joints. Assist in adduction at the MCP joints.
Adductor pollicis : Oblique head (OH) Transverse head (TH)	OH: bases of the second and third metacarpals, trapezoid, and capitate TH: third metacarpal shaft	OH/TH: the base of the proximal phalanx of the thumb	Deep branch of the ulnar nerve	Adduct the thumb at the CMC and MCP joints.

Opposition

Opposition is the movement that brings the tip of the thumb to the tip of any other finger. It is essential for the pinch grip, where a person holds an object between the thumb and finger.

Muscle	Origin	Insertion	Innervation	Action
Opponens digiti minimi	Hamate and the flexor retinaculum	Shaft of the fifth metacarpal	Deep branch of ulnar nerve	Opposes the fifth finger to the thumb
Opponens pollicis	Tubercle of trapezium and the flexor retinaculum	Radial border of the first metacarpal shaft	Recurrent branch of median nerve	Opposition of the thumb to the other fingers. Flexion of the CMC joint of the thumb.
Palmaris brevis	Palmar aponeurosis	Skin of the palm on the ulnar border	Superficial branch of the ulnar nerve	Tenses the skin on the ulnar side to aid grip.

Innervation of the Hand

Hand innervation is highly variable due to anatomical variations within the ulnar and median nerves. For example, anastomoses in the hand "may result in confusing clinical, surgical, and electromyographic findings in cases of median or ulnar damage or entrapment." Of all the nerves innervating the hand, the median nerve has the most variations in its formation.

Nerve	Origin	Branches	Motor fibres	Sensory fibres
Radial nerve	Brachial plexus posterior cord	Superficial branch: lateral branch medial branch Deep branch: posterior interosseous nerve Posterior brachial cutaneous nerve Inferior lateral brachial cutaneous nerve Posterior antebrachial cutaneous nerve Muscular branches	Extrinsic extensors of the hand	Radial dorsal aspect of the thumb, dorsum of the hand
Ulnar nerve	Brachial plexus medial cord	Articular branches Muscular branches Palmar and dorsal cutaneous branches Terminal branches in the hand: Superficial branch of the ulnar nerve Deep branch of the ulnar nerve	The medial half of flexor digitorum profundus, hypothenar muscles, third and fourth lumbricals, the interossei, and adductor pollicis, extensor muscles, and abductor pollicis longus via the posterior interosseous nerve	Dorsomedial and ventromedial aspect of the hand
Median nerve	Brachial plexus lateral and medial cords	Palmar cutaneous branch: Lateral branch Recurrent median nerve Medial branch Common palmar digital nerves Anterior interosseous	Flexor digitorum superficialis, radial half of flexor digitorum profundus, flexor pollicis longus, first and second lumbricals, thenar eminence muscles	Lateral palm, ventral lateral aspects of the thumb and the ventral aspect of the index finger

Carpal vascular arches

Vascular Supply of the Hand

The hand receives its vascular supply from the radial, ulnar, and interosseous arteries. The forearm arteries form three dorsal and three palmar arches at the carpal level.

Palmar arches:

• Radiocarpal arch: receives contributions from the radial, ulnar, and anterior interosseous arteries
• Palmar intercarpal arch: receives contributions from the radial, ulnar, and anterior interosseous arteries
• Distal palmar arch: receives contributions from the recurrent arteries (small branches from the radial and ulnar arteries)

Dorsal arches:

• Dorsal radiocarpal arch: receives contributions from the radial artery, the ulnar artery, and a dorsal branch of the anterior interosseous artery
• Dorsal intercarpal arch: receives contributions from the radial, ulnar, and the anterior interosseous arteries
• Dorsal proximal metacarpal arch: located at the carpometacarpal joints. It receives its supply from communicating branches of the deep palmar arch. It supplies the dorsal skin of the hand.

Artery	Origin	Branches	Supply
Radial artery	Terminal branch of the brachial artery	Muscular branches Radial recurrent artery Palmar carpal branch Dorsal carpal branch Superficial palmar branch Deep palmar branch First dorsal metacarpal artery Princeps pollicis artery Radialis indicis artery	Radial nerve, carpal bones and joints, thumb, and lateral side of the index finger, thenar muscles
Ulnar artery	Terminal branch of the brachial artery	Anterior and posterior ulnar recurrent arteries Common interosseous artery Palmar carpal arch Superficial palmar arch Dorsal carpal branch	Four fingers (not thumb), forearm muscles, ulnar nerve, wrist bones and joints.
Interosseous artery	Common interosseous artery (branch of the ulnar artery)	Anterior and posterior interosseous arteries	Bones and muscles of the forearm

Clinical Relevance

1. Swan neck deformity is a condition characterised by flexion of the distal interphalangeal joint (DIP) and hyperextension of the proximal interphalangeal joint (PIP). This deformity can be caused by overactivity of the PIP extensors or laxity at the volar plate. It is commonly associated with rheumatoid arthritis.
2. Boutonniere deformity is a finger flexion deformity in which the proximal interphalangeal joint (PIP) is flexed, and the distal interphalangeal joint (DIP) is hyperextended. It is caused by the rupture of the central slip of the extensor tendon of a finger. Common causes of this condition are traumatic injury, rheumatoid arthritis, osteoarthritis, prolonged flexion contracture (Dupuytren's contracture), flexor pulley disruptions, and burns.
3. Finger pulley injuries are common in rock climbers. They are an overuse-type injury that occurs during sporting activities due to high demands placed on the fingers.

Resources

• Tan RES, Lahiri A. Vascular Anatomy of the Hand in Relation to Flaps. Hand Clin. 2020 Feb;36(1):1-8
• Physical Exam of the Hand