Hand Anatomy: Carpal Tunnel and Flexor Retinaculum

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Questions and Answers

What is the function of the bare parts of the fingers?

Assist in flexion of the fingers

Act as windows for Lumbricals (correct)

Protect underlying tissues

Provide grip strength

Which structure is described as having separate synovial sheaths?

Other fingers' synovial sheaths (correct)

Digital nerves

Muscles of the hand

Tendons of the flexor digitorum profundus

What do the synovial sheaths in the fingers primarily cover?

The lumbrical muscles

The flexor tendons in their resting position (correct)

The bones of the fingers

The extensor tendons

What anatomical feature do the Lumbricals support in the fingers?

Flexion at the metacarpophalangeal joints (C) Signup and view all the answers

Which statement is true regarding the covered and uncovered portions of the fingers?

Uncovered parts represent specific functional zones (D) Signup and view all the answers

Which fingers possess complete sheaths according to the information provided?

Thumb and little finger (C) Signup and view all the answers

What type of sheath do the other fingers have?

Separate synovial sheath lining the fibrous flexor sheath (D) Signup and view all the answers

How many fingers possess complete sheaths?

Two fingers (D) Signup and view all the answers

The presence of separate synovial sheaths means that:

There is a distinction for flexibility in fingers (B) Signup and view all the answers

Which finger is NOT mentioned as having a complete sheath?

Middle finger (B) Signup and view all the answers

What is the main function of the synovial sheath in fingers?

To facilitate smooth movement of tendons (B) Signup and view all the answers

Which statement is true regarding the fingers with complete sheaths?

They allow for greater grip strength. (C) Signup and view all the answers

What characterizes the fibrous flexor sheath?

It is distinct for each finger with certain exceptions. (C) Signup and view all the answers

Which aspect of the fingers does the synovial sheath primarily affect?

Tendon movement (A) Signup and view all the answers

In terms of anatomical structure, the term 'complete sheath' refers to a sheath that:

Encloses a tendon entirely (D) Signup and view all the answers

What are the main structures protected by the flexor retinaculum in the wrist?

Flexor tendons and the median nerve (C) Signup and view all the answers

Which of the following bones is NOT part of the lateral attachment of the flexor retinaculum?

Pisiform (C) Signup and view all the answers

In which structure do the tendons of the superficialis and profundus group together?

Common flexor sheath (D) Signup and view all the answers

What unique feature does the flexor pollicis longus and flexor carpi radialis exhibit in relation to their sheaths?

They have separate sheaths. (C) Signup and view all the answers

Where do the ulnar artery and nerve pass in relation to the flexor retinaculum?

Over the flexor retinaculum (D) Signup and view all the answers

What type of structure is the common flexor sheath described as?

Open laterally and arranged in rows (A) Signup and view all the answers

Study Notes

Hand Anatomy: Flexor Retinaculum and Carpal Tunnel

The flexor retinaculum is a strong fibrous band covering structures passing through the carpal tunnel.
The carpal tunnel is a narrow passageway in the wrist containing flexor tendons and nerves.
Medial attachment of the flexor retinaculum: pisiform and hook of hamate
Lateral attachment of the flexor retinaculum: scaphoid and trapezium
Eight tendons of flexor superficialis and profundus share a common flexor sheath in two rows that open laterally.
Flexor pollicis longus and flexor carpi radialis have separate sheaths.
The ulnar artery and nerve pass above the flexor retinaculum in Guyon's canal.

Synovial Flexor Sheath

Only the thumb and little finger have complete synovial sheaths.
Other fingers have separate synovial sheaths lining the fibrous flexor sheath.
Bare parts of the tendons are windows for lumbricals.

Digital Attachment of Long Tendons

Branches of tendons insert into the dorsal digital expansion of the hand.
Common digital artery

Extensor Expansion

The extensor tendon's expansion across the metacarpophalangeal joint is called the extensor hood.
This area provides insertion points for lumbricals, interossei, extensor indicis, and extensor digiti minimi muscles.

Thenar Muscles

These muscles are located at the base of the thumb.
Include abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and adductor pollicis
The origin is the flexor retinaculum with scaphoid and trapezium.
The insertion of these muscles is lateral to the base of the proximal phalanx.
These muscles are innervated by the recurrent branch of the median nerve.
Thenar muscles are used to abduct and flex the thumb.

Hypothenar Muscles

These muscles are located at the base of the little finger.
Include abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi
Origin of these muscles are the flexor retinaculum and hook of hamate
Insertion of these muscles is to the ulnar side of the 5th metacarpal
These muscles are innervated by the deep branch of the ulnar nerve.
Hypothenar muscles act on little finger–abduction, flexion, and opposition.

Palmaris Brevis Muscle

Origin is the palmar aponeurosis.
Insertion is on the skin of the ulnar border over the hypothenar base.
Its action is to improve grip by steadying the skin on the ulnar side.
Innervation by the superficial palmar branch of the ulnar nerve.

Interossei Muscles

Palmar interossei muscles adduct the fingers towards the middle finger.
Dorsal interossei abduct the fingers away from the middle finger.
Both muscle groups originate from the metacarpals and insert into the extensor expansion and proximal phalanx.
Both are innervated by the deep branch of the ulnar nerve

Lumbricals

The origin of the lumbrical muscles is from the radial side of four profundus tendons.
Their insertion is into the extensor expansion on the lateral side of the 2nd to 5th fingers.
Innervation of these muscles is by median nerve and the deep branch of ulnar nerve.
Lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints.

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Description

Explore the intricate anatomy of the hand, focusing on the flexor retinaculum and the carpal tunnel. This quiz delves into their anatomical attachments, the structures they encompass, and their functional significance in hand movements. Understand the relationships between tendons, nerves, and their synovial sheaths.