Extensor Expansions Flashcards
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Questions and Answers

The extensor expansions are formed by the tendons of what?

the tendons of extensor digitorum longus & brevis muscles

The ___ ___ __ tendons of digits 2, 3, 4 & 5 divide into (3) slips.

extensor digitorum longus

Where does the central slip of the tendons insert?

base of middle phalanx

Where do the 2 lateral slips of the extensor tendons converge?

<p>over distal end of middle phalanx</p> Signup and view all the answers

What passes distally to insert on the base of the distal phalanx?

<p>terminal slip</p> Signup and view all the answers

At what level do the tendons of extensor digitorum brevis join extensor digitorum longus?

<p>MPJs on fibular side just proximal to their division into 3 slips</p> Signup and view all the answers

What tendons contribute to the lateral aspect of the expansion for the 5th digit?

<p>abductor digiti minimi &amp; flexor digiti minimi</p> Signup and view all the answers

How many fibrous sheaths hold the long & short extensor tendons in place?

<p>2</p> Signup and view all the answers

What is the name of the strong fibrous structure formed by the fibrous sheaths?

<p>extensor hoods</p> Signup and view all the answers

What is the more proximal part of the extensor hoods called?

<p>extensor sling</p> Signup and view all the answers

The distal part of the extensor hood is formed mostly from expansions of what?

<p>tendons of lumbrical muscles</p> Signup and view all the answers

What do interosseous muscles contribute to the formation of?

<p>sling but NOT THE WING</p> Signup and view all the answers

What is the function of extensor digitorum longus when acting alone?

<p>it tightens the sling &amp; loosens the wing</p> Signup and view all the answers

When the muscle contracts, the ___ ___ is pulled against the metatarsal head, resulting in extension of MPJs.

<p>plantar plate</p> Signup and view all the answers

Which joints cannot be extended by the wing portion of extensor hood?

<p>interphalangeal joints</p> Signup and view all the answers

What do lumbrical muscles do upon contraction?

<p>tighten wing &amp; loosen sling</p> Signup and view all the answers

Name another muscle that contributes to the function of the extensor hood.

<p>flexor digitorum longus muscle</p> Signup and view all the answers

What is the function of interosseous muscles?

<p>abduction/adduction</p> Signup and view all the answers

What is a controversial function of the interosseous muscles?

<p>some consider them to function as lumbricals</p> Signup and view all the answers

On the 1st digit, only the tendon of which muscle is attached to the extensor expansion?

<p>tendon of extensor hallucis longus</p> Signup and view all the answers

What is attached to the deep transverse ligament on the lateral side of the 1st digit?

<p>plantar plate</p> Signup and view all the answers

Extensor expansion of the hallux has a wing & sling present, but lumbricals & interossei do not contribute to them.

<p>True</p> Signup and view all the answers

On the medial side of the extensor expansion of hallux, the wing & sling are formed by ___ ___.

<p>abductor hallucis</p> Signup and view all the answers

On the lateral side of the extensor expansion of hallux, which muscles are involved?

<p>adductor hallucis &amp; flexor hallucis brevis</p> Signup and view all the answers

Study Notes

Extensor Expansions Overview

  • Extensor expansions are formed by tendons of the extensor digitorum longus and brevis muscles, analogous to those in fingers.

Extensor Digitorum Longus Functionality

  • Tendons of extensor digitorum longus for digits 2-5 split into three slips; the central slip attaches to the base of the middle phalanx.
  • Lateral slips converge over the distal end of the middle phalanx, reforming into the terminal slip that inserts on the base of the distal phalanx.

Tendon Interactions

  • Tendons of extensor digitorum brevis merge with extensor digitorum longus near the metatarsophalangeal joints, with the 5th digit receiving contributions from abductor digiti minimi and flexor digiti minimi.

Fibrous Sheaths and Structure

  • Long and short extensor tendons are secured by two fibrous sheaths, creating an extensor hood, with the more proximal section termed the extensor sling.
  • The extensor sling attaches to the plantar plate via fibers encircling the digit.

Components of Extensor Hood

  • The distal portion of the extensor hood is the extensor wing, mainly derived from lumbrical muscle tendon expansions.
  • Interosseous muscles aid in forming the sling but not the wing.

Muscle Functions

  • Extensor digitorum longus tightens the sling and loosens the wing upon contraction, allowing plantar plate tension and extension at metatarsophalangeal joints; however, it does not extend interphalangeal joints.
  • Lumbrical muscles tighten the wing and loosen the sling, facilitating proximal flexion at metatarsophalangeal joints while keeping distal joints extended. Flexor digitorum longus also supports this function due to its link with lumbricals.

Interosseous Muscles

  • Interosseous muscles are agreed to function in abduction and adduction.
  • Controversy exists regarding their role in extending interphalangeal joints and flexing metatarsophalangeal joints, with some considering their effectiveness only post-lumbrical action.

First Digit Specifics

  • Only the tendon of extensor hallucis longus attaches to the extensor expansion of the first digit, while the plantar plate connects to the deep transverse ligament on the lateral side.

Hallux Characteristics

  • The extensor expansion of the hallux features a wing and sling, with no contribution from lumbricals or interossei.
  • The medial side's wing and sling arise from the abductor hallucis; the lateral side's structure is formed by the adductor hallucis and flexor hallucis brevis.

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Test your knowledge of extensor expansions with this set of flashcards. Each card focuses on important details regarding the tendons involved, including their structure and function. Perfect for students studying human anatomy.

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