Functional Anatomy of the Hand

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska  

Introduction

The hand, positioned at the end of the upper limb, combines complex joints that allow manipulation, grip and grasp. The normal hand function depends on adequate strength, sensation, range of motion, and dexterity in order to allow an individual to engage in daily activities and occupations independently. When one or more of these components are damaged or impaired, the person's participation in everyday life may be severely limited. However, even a partial recovery of hand function may greatly impact a person's independence.

This article discusses the key anatomical structures of the hand, 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 structure of the human hand includes 27 bones: eight carpal bones, five metacarpal bones, and fourteen digital bones, including 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. There are two transverse arches: the proximal and the distal. The proximal transverse arch is made up of carpal bones. The metacarpal heads of the fingers belong to the distal transverse arch.

The Carpus (Carpal Bones)

Proximal row:

The scaphoid (navicular): belongs to the proximal row of the carpal bones. Located the most laterally. Its palmar surface contains the tubercle, the muscles' attachment point and the anatomical snuffbox floor.

The lunate: part of the proximal row of the carpal bones. It articulates with the scaphoid on the lateral and the triquetrum on the medial side.

The triquetrum: other names include triquetral, triangular, or cuneiform bone. It is a triangular and pyramidal-shaped bone located in the proximal row, on the medial side of the wrist. It contains multiple articulation surfaces: lateral for the lunate, anterior for the pisiform, and distal for the hamate.

Distal raw:

The trapezium: located in the distal row of the carpal bones, on its radial side. It has four articulations for the first metacarpal, second metacarpal, scaphoid and trapezoid bones. This bone is part of the mechanism responsible for the wide mobility of the human hand, where the articulation between the first metacarpal and the trapezium allows for the opposable thumbs function.

The trapezoid: The lesser multangular bone is another name for this bone. This is the smallest bone of the distal row of the carpal bones. It gives structure to the palm of the hand.

The capitate: the largest and most central carpal bone belonging to the distal row. It articulates with the bases of the 2nd and 3rd metacarpal bones, forming part of the common carpometacarpal joint in the hand. In addition, it articulates with the following: scaphoid and lunate on the proximal, trapezoid on the lateral, and the hamate on the medial surfaces.

The hamate: sits on the medial side of the distal row of carpal bones. The hook of the hamate is the bony process extending from the palmar surface. This carpal bone forms the medial border of the carpal tunnel.

The Metacarpus (Metacarpal Bones)

Five 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
• The third metacarpal articulates with the capitate
• The fourth and fifth metacarpal articulate with the hamate

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

The Phalanges

Long finger bones are known as phalanges. Apart from the thumb (the pollex), which only has distal and proximal bones, each phalanx has three bones: the distal, middle and proximal phalanx. The middle and proximal phalanges consist of a base, a body, and the head, which is the distal part of the phalanx.

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

The index finger: second the 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: is centrally positioned, which makes it involved in power grip and precision movements.

The ring finger: weak and only randomly used in precision grip or pinch manoeuvres. When lost, it leads to the least amount of impairment in the hand.

The small finger: the weakest of all fingers, but important in grasping while spanning an object manoeuvre due to 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 Proximal bases of five metacarpal bones	The carpometacarpal joints (CMC): The first CMC (1CMC) joint or trapeziometacarpal (TMCJ) joint-the CMC of the thumb: between the trapezium and the base of the first metacarpal The second CMC (2CMC) joint: between the trapezoid and the base of the second metacarpal The third CMC (3CMC) joint: between the capitate and the base of the third metacarpal The fourth CMC (4 CMC) joint: between the hamate and the base of the fourth metacarpal The fifth CMC (5 CMC) joint: 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 radial to ulnar sides of the hand. 1CMC (TMCJ) is located on the radial aspect of the wrist. It does not contain bony stabilizers. Instead, the stability is provided by five internal ligaments: dorsal radial, posterior oblique, the first intermetacarpal, ulnar collateral, and anterior oblique ligaments. 2CMC and 3CMC: belong to the central column of the hand, relatively rigid. 1CMC, 4CMC, 5 CMC: relative mobility, with 4CMC and 5CMC contributing the most to hand mobility.	Place the patient's hand on the side with the radial side up to palpate the first CMC joint. Slide your finger along the patient's thumb down to the first metacarpal. Just below the first metacarpa,l you will feel a divot. The trapezium bone is located just below it. The first metacarpal articulates with the trapezium. The trapezoid bone is located between the trapezium and the capitate. It articulates with the second metacarpal. To find the capitate, slide your finger down along the middle finger to reach the third metacarpal bone. When your finger drops into a duvet (indentation), you have located the capitate bone. It articulates with the third metacarpal. To palpate the hamate bone, 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 bone in the hypothenar eminence. The hook of the hamate is tender, and gentle compression on the bone may be unpleasant for the patient. The fourth and the fifth metacarpals articulate with the hamate.
Metacarpal bones Proximal phalanges	Metacarpophalangeal (MCP) joints	Considered being 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 this finger or between the palmar crease and the middle crease of the finger. The joint space of the MCP joint is located at about one centimetre distal to the tip of the knuckle.
Proximal, middle, and distal phalanges	Interphalangeal joints PIP: proximal interphalangeal joint between 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. It includes providing flexion towards the palm.	The PIP and DIP joint space correspond to the flexor crease.

Hand Kinematics

Hand biomechanics consists of seven fundamental manoeuvres needed for basic functions. They 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 thumb's interphalangeal (IP) joint and the distal IP (DIP) joint of the index finger.
2. The oppositional pinch, or the subterminal pinch with the thumb opposition. The index finger's pulp connects with the thumb's pulp needed to hold a piece of paper.
   • Motion required: Extension of the IP and DIP joints.
3. The key pinch requires stability provided by the index finger, the optimal length of the digit and a metacarpal phalangeal joint (MCP).
   • Motion required: thumb adduction to the radial aspect of the index finger’s middle phalanx.
4. The chuck grip, or a directional grip, is used to perform the action that requires an application of rotational and axial forces, like when using a screwdriver.
   • Motion required: a combined index finger, long finger, and thumb motion.
5. The hook grip allows one to hold a briefcase by its handle. No thumb function is required in this manoeuvre.
   • Motion required: finger flexion at the IP joints and extension at the MCP joints.
6. The power grasp is needed to grip a club or a bat.
   • Motion required: fingers and thumb flexion, thumb opposition relative to the other digits
7. The span grasp manoeuvre is based on the stability of the thumb, metacarpophalangeal (MCP) and interphalangeal (IP) joints. The span grasp is utilised when grabbing a ball.
   • Motion required: 30 degrees flexion of 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
The carpometacarpal joints (CMC)	1CMC: Synovial, saddle joint. 2CMC/3CMC: 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

Watch this video to learn about the thumb passive range of motion assessment using a goniometer:

Watch this video to learn about the fingers' passive range of motion assessment using a goniometer:

Ligaments of the Hand

Ligaments Supporting 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 stabilizer of 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	The 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 the thumb from side-to-side movement
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 thumb metacarpal bone to the index finger metacarpal
Dorsoradial ligament (DRL)	Dorsoradial tubercle of the trapezium	Dorsal edge of the base of the thumb metacarpal.	The strongest and stiffest of TMCJ ligaments The primary stabiliser of the TMCJ. Proprioceptive function due to 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) four medial metacarpal bases	CMC joint stabilisers
Dorsal carpometacarpal ligaments	Dorsal surfaces of the distal row of carpal bones: 2CMC:trapezium and trapezoid 3CMC:trapezoid and capitate 4CMC:capitate and hamate 5CMC:hamate	Dorsal 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 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 The palmar surface of the base of the adjacent proximal phalanx	Blends with the collateral ligament	Prevents hyperextension of the MCP joint

Ligaments Supporting Interphalangeal Joints

Key ligament	Origin	Insertion	Action/role
Collateral ligaments Accessory ligament (AL)	Head of the more proximal phalanx	Volar third of the middle phalanx bases AL: Attaches to the fibres of the palmar ligament	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

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

• Annular pulleys are well-defined thickened tendon sheath areas going across the tendons.
• Cruciform pulleys provide the necessary flexibility for the approximation of the annular pulley at flexion and maintain the integrity of the flexor sheaths.

You can read more on the hand pulleys here.

Muscles of the Hand

Hand muscles can be grouped into the extrinsic and intrinsic divisions:

• Extrinsic division: muscles that originate on 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:
  • The interossei: dorsal interossei,palmar interossei
  • The lumbricals
  • The hypothenar muscles controlling the fifth finger: flexor digiti minimi brevis, abductor digiti minimi, opponens digiti minimi
  • The thenar muscles controlling the thumb: flexor pollicis brevis, opponens pollicis, abductor pollicis brevis

Hand muscles can also be grouped according to their function into finger flexors, extensors, abductors and adductors.

The table below presents the hand muscles according to their function:

Fingers Flexors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	The 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	The first palmar interosseous: the medial side of the second metacarpal The second and third interossei: the lateral side of the fourth and fifth metacarpals	The proximal phalanx on the same side and the extensor apparatus		Flexion of the 2,4 and 5 MCP joints Assist in the extension of the IP joints Assist in adduction in 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 When interossei are paralyzed, the lumbrical can initiate flexion of the proximal phalanx.
Flexor digitorum profundus	Ulnar shaft The interosseous membrane	Distal phalanges of fingers two to five through four tendons	Lateral part (fingers 2and 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	The anterior surface of the shaft of the radius	Distal phalanx of the thumb	The 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	The 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	The shaft of the first metacarpal	Recurrent branch of the median nerve	Flexion of the CMC joint of the thumbOpposition of the thumb to the other fingers
Flexor digiti minimi brevis	Hamate Flexor retinaculum	The base of the proximal phalanx of the fifth finger.	Deep branch of the ulnar nerve	Flexion of the MCP joint of the fifth finger.

Fingers Extensors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	The 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	The first palmar interosseous: the medial side of the second metacarpal The second and third interossei: the lateral side of the fourth and fifth metacarpals	The proximal phalanx on the same side and the extensor apparatus		Flexion of the 2,4 and 5 MCP joints Assist in the extension of the IP joints Assist in adduction in 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 interossei are paralyzed, the lumbrical can initiate flexion of the proximal phalanx.
Extensor indicis	The shaft of the ulna and the interosseous membrane	The extensor apparatus of the index finger	Posterior interosseous nerve	Extension of the finger at the MCP and IP joints
Extensor pollicis brevis	The shaft of the radius and the interosseous membrane	The base of the proximal phalanx of the thumb		Thumb extension at the CMC and the MCP joints
Extensor pollicis longus	The shaft of the radius and the interosseous membrane	The 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

Fingers Abductors

Muscle	Origin	Insertion	Innervation	Action
Dorsal interossei	Adjacent metacarpal shafts	The 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	The base of the proximal phalanx of the fifth finger The extensor apparatus	Deep branch of the ulnar nerve	Abducts the fifth MCP joint
Abductor pollicis longus	The posterior aspect of the radius and the ulna The interosseous membrane	The 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 The extensor apparatus.	Recurrent branch of the median nerve	Abducts the thumb at the CMC and MCP joints

Fingers Adductors

Muscle	Origin	Insertion	Innervation	Action
Palmar interossei	The first palmar interosseous: the medial side of the second metacarpal The second and third interossei: the lateral side of the fourth and fifth metacarpals	The proximal phalanx on the same side and the extensor apparatus	Ulnar nerve	Flexion of the 2,4 and 5 MCP joints Assist in the extension of the IP joints. Assist in adduction in the MCP joints
The adductor pollicis : Oblique head (OH) Transverse head (TH)	OH: the 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 fingers. It is foundational for a pinch grip, where a person holds an object between the thumb and fingers of the hand.

Muscle	Origin	Insertion	Innervation	Action
Opponens digiti minimi	Hamate and the flexor retinaculum	The shaft of the fifth metacarpal	Deep branch of ulnar nerve	Opposes the fifth finger to the thumb
Opponens pollicis	Tubercle of trapezium bone and the flexor retinaculum	Radial border of the first metacarpal	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

The hand innervation is found to be highly variable due to the presence of anatomical variations within the ulnar and the median nerves. Examples of these variations include anastomoses in the hand impacting the management and the outcome of median or ulnar nerve damage or entrapment. Among all nerves innervating the hand, the median nerve presents significant 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	Thumb's radial dorsal aspect Dorsum of the hand
Ulnar nerve	Brachial plexus medial cord	Articular branches Muscular branches The palmar and dorsal cutaneous branches Terminal branches in the hand: Superficial branch of ulnar nerve Deep branch of 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 a 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 The ventral aspect of the index finger

Carpal vascular arches

Vascular Supply of the Hand

The hand receives blood from the radial, ulnar, and interosseous arteries. At the carpal level, the forearm arteries form three dorsal and three palmar arches:

Palmar arches: radiocarpal arch, palmar intercarpal arch, distal palmar arch.

• The radiocarpal arch receives branches from the radial, ulnar, and the anterior interosseous arteries
• The palmar intercarpal arch receives blood supply from the radial, ulnar, and anterior interosseous arteries
• The distal palmar arch receives vascular supply from recurrent arteries ( small branches from the radial and ulnar arteries).

Dorsal arches: dorsal radiocarpal arch, dorsal intercarpal arch, dorsal proximal metacarpal arch.

• The dorsal radiocarpal arch receives contributions from the radial artery, the ulnar artery, and a dorsal branch of the anterior interosseous artery
• The dorsal intercarpal arch receives contributions from the radial, ulnar, and the anterior interosseous arteries
• The dorsal proximal metacarpal arch is located at the carpometacarpal joints and supplies the dorsal skin of the hand

Artery	Origin	Branches	Supply
Radial artery	Terminal branch of 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 brachial artery	Anterior and posterior ulnar recurrent arteries Common interosseous artery Palmar carpal arch Superficial palmar arch Dorsal carpal branch	Four fingers, 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 at the distal interphalangeal joint (DIP) and hyperextension at the proximal interphalangeal joint (PIP). This deformity can be caused by PIP extensors' over-activity or a laxity at the volar plate and 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 results from the rupture of the central slip of the extensor tendon of a finger. Traumatic injury, rheumatoid arthritis, osteoarthritis, prolonged flexion contracture (Dupuytren's contracture), flexor pulley disruptions, and burns are all common causes that can lead to this deformity.
3. Finger pulley injuries are the most common in rock climbers. They are overuse types of injuries that occur during sporting activities due to demands placed on the finger.

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