Joint Positions in Anatomy

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Questions and Answers

Which muscle primarily elevates the scapula?

Trapezius (correct)

Levator Scapulae (correct)

Rhomboid Major

Latissimus Dorsi

What is the primary action of the Latissimus Dorsi?

Rotates the scapula superiorly

Adducts and elevates the humerus

Retracts the scapula

Extends and adducts the humerus (correct)

Which structure serves as the innervation source for the trapezius muscle?

Thoracodorsal nerve

Dorsal scapular nerve

Cervical nerves C3 and C4 (correct)

Spinal Accessory (CN XI) (correct)

What is the primary muscle action of the Flexor Carpi Radialis?

Flexes and abducts hand at wrist Signup and view all the answers

Which muscle acts to retract the scapula?

Rhomboid Minor Signup and view all the answers

Which nerve innervates the Flexor Carpi Ulnaris?

Ulnar nerve Signup and view all the answers

What is the distal attachment point for the Flexor Pollicis Longus?

Base of distal phalanx of thumb Signup and view all the answers

Which of the following muscles is NOT involved in elevating the scapula?

Latissimus Dorsi Signup and view all the answers

Which muscle primarily flexes the middle phalanges at the proximal interphalangeal joints of the middle four digits?

Flexor Digitorum Superficialis Signup and view all the answers

What is the distal attachment of the Trapezius muscle?

Spine of the scapula Signup and view all the answers

Which muscle is responsible for rotating the glenoid cavity superiorly when acting together?

Trapezius Signup and view all the answers

Which of the following muscles is innervated by the median nerve?

Flexor Pollicis Longus Signup and view all the answers

What is the role of the Flexor Digitorum Profundus?

Flexes distal phalanges of digits 4 and 5 Signup and view all the answers

Which anatomical feature is a proximal attachment point for the Latissimus Dorsi?

Spinous processes of the inferior 6 thoracic vertebrae Signup and view all the answers

What distinguishes the Palmaris Longus from the other flexor muscles listed?

Has no distal attachment to bones Signup and view all the answers

Which part of the Flexor Digitorum Profundus is innervated by the ulnar nerve?

Medial part Signup and view all the answers

What is the primary muscle action of the Pronator Quadratus?

Pronates the forearm Signup and view all the answers

Which nerve innervates the Extensor Pollicis Longus?

Posterior interosseous nerve Signup and view all the answers

Which muscle action is associated with the Extensor Pollicis Brevis?

Extends proximal phalanx of the thumb Signup and view all the answers

What is the proximal attachment of the Abductor Pollicis Longus?

Posterior surface of the proximal halves of ulna and radius Signup and view all the answers

Which muscle is responsible for weak flexion of the forearm when in midpronated position?

Brachioradialis Signup and view all the answers

What is the distal attachment of the Extensor Carpi Radialis Longus?

Dorsal aspect of the base of the 2nd metacarpal Signup and view all the answers

What is the muscle action of the Extensor Pollicis Longus?

Extends distal phalanx of the thumb Signup and view all the answers

Which of the following muscles does NOT have the posterior interosseous nerve as its innervation?

Pronator Quadratus Signup and view all the answers

What is the proximal attachment point of the Extensor Carpi Radialis Brevis (ECRB)?

Lateral epicondyle of humerus Signup and view all the answers

Which muscle primarily extends the 5th digit at the metacarpophalangeal joint?

Extensor Digiti Minimi Signup and view all the answers

What action is the Extensor Carpi Ulnaris primarily responsible for?

Supinating the forearm Signup and view all the answers

Which nerve innervates the Extensor Digitorum?

Deep branch of radial nerve Signup and view all the answers

Which muscle is involved in the independent extension of the 2nd digit?

Supinator Signup and view all the answers

What is the muscle action of the Extensor Digiti Minimi?

Extends and adducts the hand at the wrist Signup and view all the answers

The innervation of the Extensor Carpi Ulnaris is primarily from which nerve?

Posterior interosseous nerve Signup and view all the answers

What is the primary muscle action of the Extensor Indicis?

Supinates the forearm Signup and view all the answers

Which nerve innervates the Abductor Digiti Minimi?

Deep branch of ulnar nerve Signup and view all the answers

Which muscle is responsible for opposing the thumb?

Opponens Pollicis Signup and view all the answers

What is the distal attachment of the Flexor Digiti Minimi Brevis?

Medial border of 5th metacarpal Signup and view all the answers

Which muscle's primary action is to abduct the thumb?

Abductor Pollicis Brevis Signup and view all the answers

What structures provide the proximal attachment for the Opponens Pollicis?

Tubercles of scaphoid and trapezium Signup and view all the answers

Which muscle assists in the flexion of the proximal phalanx of the 5th digit?

Abductor Digiti Minimi Signup and view all the answers

What nerve innervates the Flexor Pollicis Brevis?

Recurrent branch of median nerve Signup and view all the answers

What is the main action performed by the Adductor Pollicis?

Adducts the thumb toward the lateral border of the palm Signup and view all the answers

What is the muscle action of the Dorsal Interossei?

Abduct 2nd-4th digits from the axial line Signup and view all the answers

Which muscles assist in flexing the metacarpophalangeal joints and extending the interphalangeal joints?

Palmar Interossei and Lumbricals Signup and view all the answers

Where does the 3rd and 4th Lumbricals originate from?

Medial three tendons of flexor digitorum profundus Signup and view all the answers

Study Notes

Close-Packed and Open-Packed Positions of Joints

Close-Packed Position: The position of a joint where the articular surfaces of the bones are maximally congruent, creating the strongest joint stability. This position typically requires ligaments and joint capsule to be most taut and stable.
Open-Packed Position: The position of a joint where the articular surfaces are least congruent and allows for greatest joint mobility and movement . Ligaments and joint caps are relatively slack.

Joint Specific Positions.

Zygapophyseal (spine): Extension/Midway between flexion and extension
Temporomandibular: Teeth clenched/Mouth slightly open (freeway space)
Glenohumeral: Abduction (55 degrees), horizontal adduction (30 degrees) / Arm abducted to 90 degrees
Acromioclavicular: Arm resting by side / Arm abducted to 90 degrees
Sternoclavicular: Arm resting by side / Arm resting by side
Ulnohumeral: Flexion (70 degrees), supination (10 degrees) / Elbow flexed 90 degrees
Radiohumeral: Extension/Full extension
Proximal Radioulnar: 5 degrees of supination / 5 degrees of supination
Distal Radioulnar: 5 degrees of supination / Neutral with slight ulnar deviation
Radiocarpal (wrist): Extension with radial deviation / Midway between abduction-adduction and flexion-extension
Carpometacarpal: Full opposition/Neutral with slight ulnar deviation
Metacarpophalangeal: Full flexion/Midway between abduction-adduction and flexion-extension
Interphalangeal: Full extension/Slight flexion
Hip: Full extension, internal rotation, and abduction/70 degrees of flexion, 35 degrees of supination
Tibiofemoral: Full extension and external rotation of tibia/10-30 degrees of flexion, 10-30 degrees of abduction, and 0-5 degrees of external rotation
Talocrural (ankle): Maximum dorsiflexion/10 degrees of plantar flexion, midway between maximum inversion and eversion
Subtalar: Supination/Midway between extremes of range of movement
Midtarsal: Supination/Midway between extremes of range of movement
Tarsometatarsal: Full extension, supination/Midway between extremes of range of movement
Metatarsophalangeal: Full extension/Neutral
Interphalangeal: Full extension/Slight flexion

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Description

Test your knowledge on the close-packed and open-packed positions of joints, as well as specific joint positions such as zygapophyseal and glenohumeral. Understanding these concepts is crucial for learning about joint stability and mobility. Challenge yourself with this informative quiz on anatomical positions!