VH Dissector: Upper Limb: Hand
VH Dissector: Upper Limb: Hand
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Arteries of the Hand
Arteries of the Hand
Add the dorsal carpal arch. The dorsal carpal branch of the radial artery anastomoses with the dorsal carpal branch of the ulnar artery and the anterior and posterior interosseous arteries to form the dorsal carpal arch. The branching from the radial artery is seen in the 3D cadaver, but because of it's caliber, the remaining arch is not visualized. It transversely crosses the distal carpals. From this arch arise three dorsal metacarpal arteries which pass distally over the second to fourth metacarpals before bifurcating into dorsal digital arteries to adjacent sides of the index, middle, ring and little fingers.
Add the deep palmar arch. In the hand the radial artery passes between the heads of the first dorsal interosseous muscle and between the heads of adductor pollicis to terminate in the deep palmar arch through which it usually anastomoses with a deep branch of the ulnar artery. This usually complete arch runs transversely across the bases of the metacarpals in the palm deep to the long flexor tendons and lumbricals. Three palmar metacarpal arteries arise from the deep palmar arch and run distally on the interosseous muscles to anastomose with the common palmar digital arteries.
Add the superficial palmar arch. This arterial arch is superficial to all of the structures of the palm except the aponeurosis and palmaris brevis. It is the continuation of the ulnar artery beyond the flexor retinaculum and gives rise to four common palmar digital arteries. On the radial side it may anastomose with the superficial palmar branch of the radial artery (one third of cases) or the arteria princeps pollicis, arteria radialis indicis, or median artery (one third) to complete the arch. The remaining third of superficial palmar arches are derived from the ulnar artery alone
Nerves of the Hand
Nerves of the Hand
Add the radial nerve which supplies no muscles of the hand. The superficial branch supplies skin and fascia over the lateral two-thirds of the dorsum of the hand, the dorsum of the thumb, and proximal parts of the lateral two and one-half fingers..
Add the median nerve which enters the hand via the carpal tunnel, deep to the flexor retinaculum, between the tendons of the flexor digitorum superficialis and the tendon of the flexor carpi radialis. The median nerve supplies motor fibers to 2.5 thenar muscles and the first and second lumbrical muscles. It sends cutaneous, sensory fibers to the entire palmar surfaces and sides of the thumb, index finger, middle finger, and lateral half of the ringer finger; and to the dorsum of the distal halves of these fingers.
Add the ulnar nerve which is just proximal to the wrist the ulnar nerve gives off a palmar cutaneous branch which supplies the skin of the medial side of the palm. It also gives off a dorsal cutaneous branch which supplies the medial half of the dorsum of the hand, little finger, and the medial half of the ring. The ulnar nerve ends by dividing into a superficial and deep branch. The superficial branch supplies cutaneous fibers to the palmar surfaces of the little finger and the medial half of the ring finger. The deep branch supplies motor fibers to the hypothenar muscles, medial two lumbricals, adductor pollicis, deep head of flexor pollicis brevis, and all of the intersosseous muscles.
Interosseus and Lumbrical Muscles
Interosseus and Lumbrical Muscles
Add the Dorsal Interossei Muscles. Each dorsal interossei (there are four of them) originates from two heads one from each of the adjacent metacarpal bones. Example: 1st dorsal interosseous muscle arises from the first and second metacarpal bones. The 1st dorsal interosseous muscle inserts into the extensor expansion on the proximal phalanx of the 2nd digit. The 2nd and 3rd interossei insert on the medial and lateral aspect of the proximal phalanx of the middle finger. The 4th interosseous inserts on the ulnar side of the ring finger. The deep branch of the ulnar nerve (C8, T1) innervates all four of the dorsal interossei muscles. Each abducts the fingers using the middle finger as the midline. It also helps to flex the metacarpophalangeal joints and extend the interphalangeal joints.
We can remember the actions of the palmar and dorsal interossei muscles through the memory of P.A.D and D.A.B.
P.A.D – Palmar Interossei ADduct
D.A.B – Dorsal Inersossei ABduct
Add the Palmar Interosseous Muscles.
First palmar interosseous muscle- it originates from the ulnar and palmar surfaces of the second metacarpal. It inserts on the ulnar aspect of the extensor expansion of the second digit. It is innervated by the the deep branch of the ulnar nerve (C8, T1). The first palmar interosseous adducts the index finger at the MP joint.
Second palmar interosseous muscle- it originates on the radial side of the fourth metacarpal. It inserts on the radial aspect of the extensor expansion of the fourth digit. It is innervated by the deep branch of the ulnar nerve. The second palmar interosseous adducts the ring finger at the MP joint.
Third palmar interosseous muscle- it originates on the radial side of the fifth metacarpal. It inserts on the radial aspect of the extensor apparatus of the fifth digit. It is innervated by the deep branch of the ulnar nerve. The third palmar interosseous adducts the little finger at the MP joint.
The three palmar interossei adduct the fingers relative to the midline of the long finger. Through their attachments to the extensor expansion, they contribute to flexion of the MP and extension of PIP and DIP joints. They also have a role in isolated rotation of a digit
Add the Lumbrical Muscles (Four of them): All of them originate from the tendon of the flexor digitorum profundus (they have the same innervations as flexor digitorum profundus). They insert on the radial side of the 2nd, 3rd, 4th, and 5th extensor expansion, respectively. Each lumbrical is named for the digit it inserts into (E.G. the first lumbrical inserts on the second digit all the way to the fourth lumbrical inserts on the fifth digit. The lateral two lumbricals are innervated by the median nerve and the medial two are innervated by the deep branch of the ulnar nerve. They flex the metacarpophalngeal joints and help extend the interphalangeal joints.
The tendons of these muscles pass in a common sheath deep to the flexor retinaculum. They then pass deep to the palmar aponeurosis and enter the osseofibrous tunnels digital tunnels. The palmar aponeurosis is the strong, well defined triangular part of the deep fascia covering the soft tissue of the hand. It overlies the long flexor tendons of the palm. The proximal end of the palmar aponeurosis is continuous with the flexor retinaculum.
Observe that there are two tendons in each osseofibrous tunnel. In order that these tendons can slide freely over each other during movements of the fingers, each tendon is covered with a synovial membrane. Near the base of the proximal phalanx, the tendon of the flexor digitorum superficialis splits and surrounds the tendon of the flexor digitorum profundus. The halves of the tendon of the flexor digitorum superficialis insert into the margins of the middle phalanx. The tendon of the flexor digitorum profundus, after passing through the split in the tendon of the flexor digitorum superficialis, passes distally to insert into the base of the distal phalanx.
Muscles of the Hand
Muscles of the Hand
The intrinsic muscles of the hand are on the palmar aspect and are innervated by branches of the ulnar and median nerves. They can be divided into three groups: thumb or thenar muscles, the little finger or hypothenar, and the lumbrical and interosseous muscles. The long flexor tendons of the extrinsic muscles arise from in the forearm and pass through the hand to the digits.
Thumb or Thenar Muscles
Thumb or Thenar Muscles
The short muscles of the thumb: there are four thenar muscles that are chiefly responsible for the movement termed opposition of the thumb. 2 ½ are supplied by the recurrent branch of the median nerve and 1 ½ are supplied by the deep branch of the ulnar nerve.
Add the Adductor Pollicis muscle.
Origin (two heads of origin) - Oblique Head- capitate bone and base of the 2nd and 3rd metacarpal bones; Transverse Head- palmar surface of the 3rd metacarpal bone
Insertion - Ulnar side of the base of the proximal phalanx of the thumb
Innervation - Deep Branch of Ulnar Nerve (C8, T1)
Action - Adduction of the thumb
Add the Opponens Pollicis muscle.
Origin - Flexor retinaculum and scaphoid and trapezium bones
Insertion - Lateral border of the first metacarpal
Innervation - Recurent Branch of Median Nerve and sometimes a small branch of the ulnar nerve (C8, T1)
Action - Opposition of the thumb with the other fingers
Add the Flexor Pollicis Brevis muscle. (Not identified in this cadaver)
Origin (two heads of origin) - Superficial Head - flexor retinaculum and trapezium and scaphoid bones. Deep Head - trapezoid and capitiate bones
Insertion - Radial side of the base of the proximal phalanx of the thumb
Innervation - Superficial Head - Recurrent Branch of Median Nerve. Deep Head - Deep Branch of Ulnar Nerve
Action - Flexes proximal phalanx of the thumb
Add the Abductor Pollicis Brevis muscle. (Not identified in this cadaver)
Origin - Flexor retinaculum, scaphoid bone, and trapezium bone
Insertion - Lateral side of base of the proximal phalanx of the thumb
Innervation - Recurrent Branch of Median Nerve
Action - Abduction of the thumb
Opposition is the most important movement of the thumb. Opposition involves extension, then abduction, flexion, and medial rotation and usually adduction. Opposition occurs at the 1st carpometacarpal joint. If the median nerve is severed in the forearm or at the wrist, the thumb cannot be opposed.
Muscles of the Little Finger or Hypothenar Muscles
Muscles of the Little Finger or Hypothenar Muscles
Short muscles of the little finger: the three hypothenar muscles lie in the hypothenar compartment of the palm; they produce the hypothenar eminence; they are all supplied by the deep branch of the ulnar nerve.
Add the Opponens Digiti Minimi muscle.
Origin - Hook of the Hamate bone and flexor retinaculum
Insertion - Ulnar side of the fifth metacarpal bone
Innervation - Deep Branch of Ulnar Nerve
Action - Opposition of the little finger to the thumb
Add the Flexor Digiti Minimi muscle.
Origin - Hook of the Hamate bone and flexor retinaculum
Insertion - Medial side of base of the proximal phalanx of the little finger
Innervation - Deep Branch of Ulnar Nerve
Action - Flexion of the little finger at the metacarpophalangeal joint
Add the Abductor Digiti Minimi muscle.
Origin - Pisiform bone
Insertion - Medial side of base of proximal phalanx of little finger
Innervation - Deep Branch of Ulnar Nerve
Action - Abduction of the little finger
Credits:
Credits:
VH Dissector steps modified for Drexel Dissector by Dr. Haviva Goldman from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.
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