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Anatomy: The Hand (Lecture 6)

From now on I'm going to read through the lecture notes and post about it instead of going to Brons lectures. What I'm doing is simply looking up each item that appears on his powerpoint slides.

Quiz Questions:
1. Which hand muscles act to clench your thumb against your index finger?
2. Name the fibrous band which arches over the carpus making the CARPAL TUNNEL
(through which the Flexor tendons of the digits and the median nerve pass).
3. Which thumb muscle is deep to the other two?
a. Abductor pollicis brevis
b. Flexor pollicis brevis
c. Opponens pollicis
4. Which two muscles work together to allow us to flex the metacarpal phalangeal joints while we extend the interphalangeal joints?
5. Between which two bones in the hand do you find a saddle joint?
6. What kind of joint is found between the metacarpals and the phalanges?
7. Which muscles connect into the dorsal extensor expansion?
8. Damage to which nerve causes you to loose your power grip?

1. the 1st dorsal interosseus and adductor pollicis both act to clench thumb against index finger
2. Flexor retinaculum. (are there other names?)
3. c. opponens is deep to the others on both the thenar and hypothenar sides
4. The so called "tata muscles": the lumbricals and interossei
5. Between the trapezium and metacarpal 1, allowing wide ROM for the thumb
6. Condyloid: an ovoid articular surface or condyle is received into an elliptical cavity in such a manner as to permit of flexion, extension, adduction, abduction, and circumduction, but no axial rotation.
7. the interossei and lumbricals
8. the median nerve

Palmar aponeurosis-
--a sheet of CT that covers the tendons in the palm (Brons)
---central portion in middle of the palm, triangular in shape, of great strength and thickness.
--apex is continuous with the lower margin of the transverse carpal ligament
--apex receives the expanded tendon of the Palmaris longus.
--base divides below into four slips, one for each finger. Each slip gives off superficial fibers to the skin of the palm and finger, those to the palm joining the skin at the furrow corresponding to the metacarpophalangeal articulations, and those to the fingers passing into the skin at the transverse fold at the bases of the fingers.
--The deeper part of each slip subdivides into two processes, which are inserted into the fibrous sheaths of the Flexor tendons. From the sides of these processes offsets are attached to the transverse metacarpal ligament.
--By this arrangement short channels are formed on the front of the heads of the metacarpal bones; through these the Flexor tendons pass. The intervals between the four slips transmit the digital vessels and nerves, and the tendons of the Lumbricales.
--At the points of division into the slips mentioned, numerous strong, transverse fasciculi bind the separate processes together.
--central part is intimately bound to the integument by dense fibroareolar tissue forming the superficial palmar fascia, and gives origin by its medial margin to the Palmaris brevis.
--covers the superficial volar arch, the tendons of the Flexor muscles, and the branches of the median and ulnar nerves
--on either side it gives off a septum, which is continuous with the interosseous aponeurosis, and separates the intermediate from the collateral groups of muscles.

Superficial transverse (metacarpal) ligatment
--runs across the palmar side of the MCP (metacarpalphalangeal) joints (Brons)
--a ligament of the intermetacarpal articulations joint which runs beneath the deep transverse metacarpal ligament (wikipedia)

Tendon coverings
--fibrous flexor sheaths enclose flexor tendons in fingers
--synovial sheaths around tendons
--flexor retinaculum and transverse carpal ligament

synovium = the soft tissue that lines the non-cartilaginous surfaces within joints with cavities (synovial joints). The word synovium comes from a Latin word meaning "with egg," because the synovial fluid in joints that have a cavity between the bearing surfaces is like egg white.

--is superficial to the transverse carpal ligament, both work together

==a strong, fibrous band which arches over the carpus making the CARPAL TUNNEL
(through which the Flexor tendons of the digits and the median nerve pass)
--attached medially to pisiform and the hamulus (HOOK) of the hamate bone, laterally to the tubercle of the scaphoid, and to the medial part of the volar surface and the ridge of the trapezium.
--continuous, above, with the volar carpal ligament; and below, with the palmar aponeurosis. It is crossed by the ulnar vessels and nerve, and the cutaneous branches of the median and ulnar nerves.
--at its lateral end is the tendon of the Flexor carpi radialis, which lies in the groove on the greater multangular between the attachments of the ligament to the bone.
--on its volar surface the tendons of the Palmaris longus and Flexor carpi ulnaris are partly inserted; below, it gives origin to the short muscles of the thumb and little finger.

Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis

Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi

On both sides of the hand, the opponens muscle is deep to the other two and is the one that most directly allows the thumb to oppose the pinkie. Also on both sides of the palm the flexor is closer the the midline of the hand, and the abductor is on the edge of the palm.

Abduction/adduction are perpendicular to the palm
Flexion/extension are parallel to the palm

=intrinsic muscles in the fingers
--four small, worm-like muscles on each hand
--unusual in that they do not attach to bone
A: flexion at the metacarpophalangeal joints, while maintaining extension at the interphalangeal joints (tata! along with the interossei)
O: (proximal) tendons of the flexor digitorum profundus
I: dorsal extensor expansions (on the back of the hand)
N: 1,2 innervated by median nerve
N: 3,4 innervated by ulnar nerve
--flexor pollicis longus does not have a lumbrical
--note opponens muscles of thenars and hypothenars (??what about it?)
--similar muscles exist on the foot

I: bases of proximal phalanges, sesamoid bone here and at flexor pollicis

I: bases of proximal phalanges
A: adduct fingers to midline (PAD AND DAB)

I: bases of proximal phalanges
A: abduct fingers from midline (spread fingers)
--1st dorsal interosseus and adductor pollicis both act to clench thumb against index finger***

--LI 4 (acupuncture point between thumb and forefinger) is located on 1st dorsal interosseus

--lateral and central slips

I: PIP (proximal interphalangeal p ? joint)

I: DIP (distal interphalangeal p ? joint)

--The trapezium and metacarpal 1 form a SADDLE JOINT which gives the thumb flexibility.
--Metacarpals 4 and 5 are more mobile than 2 and 3 due to differences in conformation of carpal articular surfaces.
--MCP (metacarpal-phalangeal joints) are condyloid, allow flexion/extension and adduction/abduction
--IP (interphalangeal) joints are bi-condyloid facets that allow only flexion/extension

--Palmar ligaments = thickened anterior portions of MCP and IP joints (Brons)
--(Wikipedia version): The palmar carpal ligament (also volar carpal ligament) is a term that is often used in anatomy to describe the thickened portion of antebrachial fascia on the anterior of the wrist. It is officially unnamed. The palmar carpal ligament is a different structure to the flexor retinaculum of the hand, but the two are frequently confused. The palmar calpar ligament lies superficial and proximal to the flexor retinaculum. The ulnar nerve and the ulnar artery run through the ulnar canal, which is deep to the palmar carpal ligament and superficial to the flexor retinaculum. The palmar carpal ligament is continuous with the extensor retinaculum of the hand, which is located on the posterior side of the wrist.
--Deep transverse ligaments = interconnect MCP joints (except thumb, big toe)
--Collateral ligaments = support all MCP and IP joints, are tightened during flexion so limit adduction and abduction, but not in extended position.
--retinacular ligaments = link ligaments = the borders of extensor expansions, they link IP joints to flex or extend together

--supplies the skin on 3.5 digits
--forearm muscles: pronator teres, palmaris longus, flexor carpi radialis, flexor digitorum superficialis and half of profundus, pronator quadratus and flexor policis longus
--hand muscles: thenar muscles and lumbricals 1 & 2
--the power grip: damage this nerve and loose your grip

--median nerve goes thru it
--flexors digitorum superficialis and profundus
--flexor pollicis longus
--flexor carpi radialis

--tunnel size shrinks due to inflammation, dislocation of carpal bones or arthritis
--compression of median nerve
--Sx: loss of sensation in 3.5 digits, thoss of fx of thenars and lumbricals 1, 2, thenar wasting "ape hand"

--ulnar nerve
--radial and ulnar arteries
--palmaris longus
--flexor carpi ulnaris

--supplies skin on 1.5 digis=ts, ulnar side of palm & dorsum of hand
--forearm muscles: flexor carpi ulnaris and 1/2 of flexor digitorum profundus
--hand muscles: hypothenars, adductor pollicis, lumbricals 3, 4, dorsal and palmar interossei
--precision grip: intrinsic hand muscles produce fine muovements of the fingers

--space between pisiform and hook of hamate, normally covered by ligament
--structures in Guyon tunnel: ulnar nerve (deep & superficial), artery and veins

--claw hand due to lack of MC-P flexion and IP extension in fingers
--two fingers remain extended because 2 lumbricals innervated by median nerve
--atrophy of interossei
--cutaneous loss of 1.5 digits

= area of skin innervated by one spinal segment

= area of muscle innervated by one spinal segment
--usually 2-3 segments per muscle



( 9 comments — Leave a comment )
Oct. 17th, 2007 06:09 am (UTC)
Alright, maybe someoen can finally help me... I've asked doctors, nurses, etc... no dice.

What is the name of the webbing between your thumb and forefinger? You know, the part of the body for snorting coke.
Oct. 17th, 2007 04:16 pm (UTC)
I don't know! There is a well known acupuncture/acupressure point there, used for treating headaches. But anyway, I'll let you know when I find out.
Oct. 19th, 2007 08:13 pm (UTC)
Yay. A part of the body perfect for headache relief and snorting coke!
Oct. 19th, 2007 11:06 pm (UTC)
FYI: It's the LI-5 acupuncture point, too.
Sep. 14th, 2009 11:33 pm (UTC)
its called the anatomical snuffbox between the tendons of the fingers and thumb
Sep. 16th, 2010 04:55 am (UTC)
In my med school anat class they refer to that as the "anatomical snuffbox" look it up.
Sep. 16th, 2010 05:58 am (UTC)
Zzzzzt wrong! Snuffbox is NOT the web. Who taught you anatomy? What med skule you go to?
Oct. 13th, 2009 03:49 am (UTC)
skin between thumb and index finger
Hi, my professors all just call that area the web space. Also, its not called the anatomical snuff box. The anatomical snuff box (or radial fossa) is the indent dorsal to the carpometacarpal joint when the thumb is in radial abduction or extension. The snuff box is bordered by the extensor pollicis longus, and the extensor pollicis brevis.
Oct. 13th, 2009 03:55 am (UTC)
Re: skin between thumb and index finger
Hi there. Thanks for the correction. In fact I am gratified to report that I now know what the snuffbox is, and am not worried anymore about the name of the web. And I did not end up skipping all the rest of the Brons lectures, in fact by the end I had an appreciation of the man and his way of teaching. But it was certainly difficult for me at first. Are you a student? Or??
( 9 comments — Leave a comment )



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