Hand and Wrist Anatomy PDF

XY2141: Hand and Wrist Gemma-Louise Tibbitts PA-R [email protected] Learning Outcomes Describe the bones and regions of the wrist, hand and fingers Identify and name the joints of the wrist and fingers Describe and demonstrate the movements of the wrist (radiocarpal), metacarpophala...

XY2141: Hand and Wrist Gemma-Louise Tibbitts PA-R [email protected] Learning Outcomes Describe the bones and regions of the wrist, hand and fingers Identify and name the joints of the wrist and fingers Describe and demonstrate the movements of the wrist (radiocarpal), metacarpophalangeal and interphalangeal joints and those of the thumb Name the intrinsic (short) muscles and function across the wrist and within the hand Discuss the blood supply and innervation to the wrist and hand Apply anatomical knowledge to clinical correlations related to the wrist, hand and fingers The Hand The hand is the most distal part of the upper limb. It is subdivided into three parts: The wrist (carpus) The palm (metacarpus) The digits (fingers) Index Middle Ring Resting position - fingers form a flexed arcade, with the Little little finger flexed the most and the index finger the Thumb least Surfaces and regions of the Hand Palmar surface - palm side Dorsal surface - back of the hand Ulnar side - towards the little finger Radial side - towards the thumb Heel - area of the hand at the bases of the metacarpal bones on the palmar side Bones of the Hand There are 27 bones of the hand 5 4 5 5 8 Carpal bones - (wrist bones) 8 small, irregularly shaped bones that work together to allow for movement of the wrist. Starting at the thumb and moving in an anticlockwise direction Scaphoid So Lunate Long Triquetrum To Pisiform Pinky Hamate Here Capitate Comes Trapezoid The Trapezium Thumb Carpal bones - (wrist bones) Proximal row of carpal bones: Scaphoid - articulates proximally with the radius to form the radial border of the carpal tunnel. Lunate - articulates proximally with the radius Triquetrum - lies on the medial side of the proximal row of carpal bones Pisiform - forms the ulnar border of the carpal tunnel Carpal bones - (wrist bones) Distal row of carpal bones: Hamate - articulates with 4 carpal bones and the 4th and 5th metacarpals Capitate - largest carpal bone, articulates with 4 carpal bones and the 3rd metacarpal Trapezoid - articulates with 3 carpal bones and the 2nd metacarpal Trapezium - articulates with the scaphoid and the trapezoid as well as the 1st and 2nd metacarpal. The trapezium has a distinct tubercle on the palmar surface which projects anteriorly. Clinical relevance - Scaphoid bone fracture The scaphoid bone is the most commonly fractured carpal bone - typically by falling on an outstretched hand. Fracture passes through the narrowest part of the bone. Pain is typically felt in and around the ‘anatomical snuffbox’ - triangular depression found on the lateral aspect of the dorsum. Scaphoid bone Anatomical snuffbox fracture Metacarpal bones - (palm bones) Each palm has 5 metacarpal bones that articulate proximally with one of the with one of the distal carpal bones forming a carpometacarpal joint. They also articulate distally with the phalanges forming a metacarpophalangeal joint. Each metacarpal has a head, body and base Our knuckles are formed by the head of each metacarpal The first metacarpal bone is separated from all Metacarpo- the other metacarpal bones which form the base Head phalangeal joint of the hand. This allows free movement of the Body Carpometacarpal first metacarpal, independent of all the other Base joint metacarpals bones. Phalanges (bones that make up the fingers) The term phalange originates from the Greek work ‘phalanx’ which means a compact body of heavily armed men in battle array (Greek military formation). In other words the bones that make up our fingers are lined up in a similar way to the way soldiers stand side by side, several rows deep. Each finger apart from the thumb has 3 phalanges - proximal, intermediate and distal The thumb (pollux) only has 2 phalanges There are 14 phalanges in total that make up the bones of the fingers and thumb Distal phalanges These are the bones that run from the intermediate phalanges until the end of the hand - (thumb is an exception)- 5 Intermediate phalanges These are the bones that run from the proximal phalanges until the second joint - 4 Proximal phalanges These are the bones that run from the metacarpals until the first joint - 5 Joints - phalanges In between each phalange is a joint Joints - Interphalangeal joints Synovial hinge joints that sit between the phalanges Since the thumb only has a proximal and distal phalanx, the joint between them is simply known as the interphalangeal joint of the thumb Distal interphalangeal joint Digits 2-5 have a proximal, middle and distal phalanx so they have 2 interphalangeal joints. These are the proximal interphalangeal joint (PIP) Proximal and distal interphalangeal joint (DIP) interphalangeal joint Interphalangeal joint of the thumb Joints - Interphalangeal joints Movements: flexion and extension (flexion is much more achievable than extension in these joints). Extension in PIPJ is up to 2° and in the DIPJ up to 5° Typical range of motion at the proximal interphalangeal joint (PIPJ) and the distal interphalangeal joint (DIPJ) Joints - Metacarpophalangeal joint This joint is an articulation between the metacarpal head and the base of the proximal phalanx. All of the movements at the joint are produced by muscles of the forearm and hand Movements of digits 2-5 = Flexion, extension, adduction, abduction Joints - Metacarpophalangeal joint Movements of the thumb = flexion, extension, adduction, abduction, axial rotation Flexion Extension Adduction Abduction Joints - Radiocarpal joint Radiocarpal joint (main wrist joint) - A synovial joint that lies between the radius and the three proximal carpal bones (scaphoid, lunate and triquetrum) An ellipsoid joint – allows for movement along two planes – back and front, and side to side  Radiocarpal joint movement Flexion Extension Adduction/ulnar flexion Abduction/radial flexion Palmar aponeurosis (Palmar fascia) Transverse fibres of palmar aponeurosis Palmar aponeurosis is a triangular shaped sheet of connective fibres that lie just beneath the skin. It converges near the wrist and radiates out to the base of the fingers. Apex of the triangle is continuous with the palmaris longus tendon. Its function is to protect underlying structures such as the tendons, vessels and nerves. Flexor retinaculum Palmaris longus tendon Clinical relevance - Dupuytren’s contracture Dupuytren’s contracture is caused by proliferation of collagen within the palmar facia. It causes the palmar aponeurosis to thicken and contract, causing the little and ring finger to flex. Treatment is with physiotherapy, steroid injection or even surgical excision of the bands in advanced cases Flexor retinaculum & Carpal tunnel Flexor reticulum is a strong fibrous band on the palmar side that arches over the carpal bones and turns it into a tunnel known as the carpal tunnel Flexor retinaculum Clinical relevance - Carpal Tunnel Syndrome The median nerve travels through the Carpal Tunnel. Pressure on the median nerve within the carpal tunnel causes pain, numbness and tingling in the distribution of the median nerve. Causes: Overuse Swelling of tendons and tendon sheaths (e.g rheumatoid arthritis) Cysts at carpal joints Compressed nerve Flexor reticulum Carpal ligament Carpal arch Carpal tunnel Median nerve Carpal tunnel Muscles The muscles that act on the hand can be divided into two groups: Extrinsic muscles - long muscles that originate in the forearm and insert in the hand, responsible for forcefully gripping Intrinsic muscles - short muscles located within the hand, execute precision movements of the fingers and thumb or fine motor functions of the hand Muscles The intrinsic muscles of the hand consist of five groups: Thenar muscles Hypothenar muscles Lumbricals Palmar interossei Dorsal interossei Thenar muscles Three short muscles located at the base of the thumb, make up the thenar eminence Flexor Pollicis Brevis Abductor Pollicis Brevis Opponens Pollicis Thenar muscles - Flexor Pollicis Brevis Origin: tubercle of the trapezium & flexor retinaculum Insertion: base of the proximal phalanx of the thumb Actions: flexes the metacarpophalangeal joint of the thumb (bends the thumb) Innervation: Median and ulnar nerve Thenar muscles - Abductor Pollicis Brevis Origin: tubercle of the scaphoid and trapezium & flexor retinaculum Insertion: base of the proximal phalanx of the thumb Actions: abducts the thumb (moves the thumb away from the hand) Innervation: Median and ulnar nerve Thenar muscles - Opponens Pollicis Origin: tubercle of the trapezium & flexor retinaculum Insertion: 1st metacarpal bone Actions: thumb flexion, abduction, and medial rotation resulting in a combined movement called opposition (allows the tip of the thumb to touch the tips of the other fingers on the same hand) Innervation: Median nerve Adductor pollicis Although found in the thenar region is does not form part of the thenar muscle group One muscle comprised of two heads Origin - palmar base of the second metacarpal bone, third metacarpal bone and the capitate bone Insertion - base of the first proximal phalanx Function - adduction of the thumb Hypothenar muscles Three short muscles located at the base of the little finger (medial side of the palm), makes up the hypothenar eminence Flexor digiti minimi brevis Opponens digiti Abductor digiti minimi minimi Hypothenar muscles - Abductor digiti minimi The most superficial of the hypothenar muscle group Origin: Pisiform and tendon of the flexor carpi ulnaris Insertion: Base of the proximal phalanx of the little finger Actions: Abducts the little finger Innervation: Ulnar nerve Hypothenar muscles - Flexor digiti minimi brevis Lies laterally to the abductor digiti minimi Origin: Hook of hamate and adjacent flexor retinaculum Insertion: Base of the proximal phalanx of the little finger Actions: Flexes the metacarpophalangeal joint of the little finger Innervation: Ulnar nerve Hypothenar muscles - Opponens digiti minimi Lies deep to the other hypothenar muscles Origin: Hook of hamate and associated flexor retinaculum Insertion: Medial margin of metacarpal 5 Actions: Rotates the metacarpal of the little finger towards the palm Innervation: Ulnar nerve Palmaris brevis Thin, short, quadrangular shaped muscle that lies over the hypothenar muscles Origin: Palmar aponeurosis and flexor reticulum Insertion: Dermis of the skin on the medial margin of the hand Action: Helps the hand to form a cup shape which improves grip Innervation: Ulnar nerve Palmaris brevis Mid-hand muscles There are 3 groups of mid-hand muscles Lumbricals - There are 4 lumbricals in the hand, each associated with a finger and found between the metacarpal bones, deep to the palmar fascia They are essential for finger movement. They flex the fingers at the metacarpophalangeal joints and extend them at the interphalangeal joints. These actions allow for the hands to grip. 2 3 1 4 Lumbricals Each lumbrical muscle arises from one or two adjacent tendons of the flexor digitorum profundus muscle Lumbricals 1 and 2 are usually unipennate, meaning their fibers arise obliquely from one tendon. Lumbricals 3 and 4 are bipennate, 2 3 meaning their fibers arise from two 1 4 adjacent tendons Tendons of the flexor digitorum profundus muscle Lumbricals Lumbrical 1 = arises from the radial side of the tendon of the index finger Lumbrical 2 = arises from the radial side of the tendon of the middle finger Lumbrical 3 = arises from the ulnar side of the middle finger tendon and the radial side of the ring finger tendon Lumbrical 4 = arises from the ulnar side of the ring 2 3 finger tendon and the radial side of the little finger 1 4 tendon All pass distally along radial side of corresponding finger and attach onto the lateral margin of the proximal phalanges, digits 2-5 Lumbricals Nerve innervation: 2 1st and 2nd lumbrical supplied by median nerve 3 1 4 3rd and 4th lumbricals supplied by ulnar nerve Dorsal interossei 4 short bipennate muscles found on the dorsal aspect 2 3 4 (back) of the hand. They occupy the space between the 5 metacarpal bones. Think interossei (inbetween) 1 bipennate (feather like) 2 heads that converge distally before attaching onto a central tendon 2 3 4 1 Dorsal interossei - origin and insertion 1 - arises from metacarpal bones 1 & 2. Fibers converge distally before inserting onto the radial side of the base of the 2nd digit proximal phalanx 3 4 2 2 - arises from metacarpal bones 2 & 3. Fibers converge 5 distally before inserting onto the radial side of the base of 1 the 3rd digit proximal phalanx 3 - arises from metacarpal bones 3 & 4. Fibers converge distally before inserting onto the ulnar side of the base of 2 3 4 the 3rd digit proximal phalanx 1 4 - arises from metacarpal bones 4 & 5. Fibers converge distally before inserting onto the ulnar side of the base of the 4th digit proximal phalanx Dorsal interossei - function & innervation Function - Abduction of the index, middle and ring fingers at the metacarpophalangeal joints 2 3 4 5 Innervation - all are innervated by the ulnar nerve 1 2 3 4 1 Palmar interossei 3 unipennate muscles that lie on the palmar surface, occupying the space between the metacarpal bones 3 2 4 1 arises from the ulna side of metacarpal bone 2 and inserts onto the ulna side of the base of the proximal 5 phalanx of digit 2 1 2 arises from the radial side of metacarpal bone 4 and inserts onto the radial side of the base of the proximal phalanx of digit 4 1 2 3 3 arises from the radial side of metacarpal bone 5 and inserts onto the radial side of the base of the proximal phalanx of digit 5 Palmar interossei - function and innervation 3 Function - Abduction of the digits at the 2 4 metacarpophalangeal joints 5 Innervation - Ulnar nerve 1 1 2 3 Intrinsic muscles - Summary Thenar: Hypothenar: Mid-hand: Flexor pollicis brevis Flexor digiti minimi brevis Lumbricals Abductor pollicis brevis Abductor digiti minimi Dorsal interossei Opponens pollicis Opponens digiti minimi Palmar interossei Thenar region: Hypothenar region: Adductor pollicis Palmaris brevis Blood supply of the hand The two main sources of blood supply to the hand are the ulnar and radial arteries, both of which originate from the brachial artery. Both the ulnar and radial arteries branch and continue into the hand forming a complex vascular network that can be divided into palmar and dorsal components Blood supply - Superficial palmar arch Main continuation of the ulnar artery but has a minor supply from the radial artery. Gives rise to the common digital arteries which then divide into the proper digital arteries at the web spaces. These proper digital arteries run either side of the finger to supply the fingers with blood. Blood supply - Deep palmar arch Main continuation of the radial artery but has a minor supply from the ulnar artery. Gives rise to the princeps pollicis artery and the radial artery of index finger. Supplies the deep hand structures The thumb and the radial side of the index finger are exceptions. They receive branches directly from the radial artery before it forms the deep palmar arch Clinical relevance - Allens test Allens test is a test used in clinical practice to check for adequate anastomoses (connections) between the radial and ulnar arteries Venous drainage - dorsal view Just like the arteries the hand contains interconnected networks of superficial and deep veins. Dorsal digital veins drain into the dorsal Dorsal digital veins metacarpal veins which then drains into the dorsal venous network that lies on the back of the hand over the metacarpal bones Dorsal metacarpal Cephalic vein originates from the lateral side veins of the dorsal venous network Dorsal venus network Basilic vein originates from the medial side of the dorsal venous network Cephalic vein Basilic vein Venous drainage - palmar view Deep veins accompany the major arteries of the hand and as a result tend to have the same name as their arterial counterparts Palmar digital veins drain blood from the palmar aspect of the fingers. They empty into both the superficial venous palmar arch and the dorsal digital veins Palmar digital veins Palmar metacarpal veins drain Palmar digital veins into the dorsal metacarpal veins Palmar metacarpal and the deep venous palmar arch veins Superficial venous palmar arch Deep venous palmar arch Innervation of the hand The nerves of the hand and wrist originate from the brachial plexus (located at the root of the neck) There are 3 nerves from the brachial plexus that go on to innervate the hand and wrist. These are the: Median nerve Ulnar nerve Radial nerve Median nerve Ulnar nerve Ulnar nerve Innervation of the hand Median Nerve - supplies sensation to the radial 3 and a half fingers on the palmar aspect and 2 and a half finger nail beds on the dorsal aspect. Also supplies the radial 2/3rds of the palm through the palmar cutaneous branch. Radial Nerve - supplies sensation to the radial 3 and a half fingers on the dorsal surface through the dorsal sensory branch Ulnar Nerve - supplies the Median nerve ulnar 1 and a half fingers on both the palmar and dorsal aspects Ulnar nerve Ulnar nerve References