L5 Anatomy

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Questions and Answers

What type of joint is the shoulder joint classified as?

  • Pivot
  • Ball and Socket (correct)
  • Hinge
  • Saddle

Which part of the shoulder joint is described as the weakest?

  • Glenohumeral ligaments
  • Coracoacromial ligament
  • Upper part of the fibrous capsule
  • Lower and medial parts of the capsule (correct)

What fibrous structure deepens the glenoid cavity of the shoulder joint?

  • Rotator cuff
  • Scapular fossa
  • Synovial membrane
  • Glenoid labrum (correct)

Which ligaments are considered thickenings of the fibrous capsule of the shoulder joint?

<p>Glenohumeral ligaments (B)</p> Signup and view all the answers

What is the role of the coracoacromial ligament?

<p>Resists superior dislocation of the humerus (B)</p> Signup and view all the answers

Which muscle initiates the first 15 degrees of shoulder flexion?

<p>Supraspinatus (B)</p> Signup and view all the answers

Which muscles are responsible for lateral rotation of the shoulder joint?

<p>Teres minor and Infraspinatus (A)</p> Signup and view all the answers

What does the transverse humeral ligament connect?

<p>Intertubercular groove of the humerus (B)</p> Signup and view all the answers

What is the most common cause of anterior dislocation of the gleno-humeral joint in athletes?

<p>Excessive extension and lateral rotation of the humerus (D)</p> Signup and view all the answers

Which nerve is most likely injured during an anterior dislocation of the shoulder joint?

<p>Axillary nerve (A)</p> Signup and view all the answers

What symptom is NOT typically associated with a shoulder dislocation?

<p>Severe bruising of the forearm (C)</p> Signup and view all the answers

Which muscle is involved in flexion of the elbow joint?

<p>Coracobrachialis (C), Brachialis (D)</p> Signup and view all the answers

What is the action of the triceps brachii muscle?

<p>Extension of the elbow joint (A)</p> Signup and view all the answers

Which of the following statements about the musculocutaneous nerve is true?

<p>It supplies the coracobrachialis, biceps, and brachialis muscles (D)</p> Signup and view all the answers

During an anterior dislocation, where does the humeral head typically come to lie?

<p>Inferior to the glenoid cavity and anterior to the infra-glenoid tubercle (C)</p> Signup and view all the answers

Which of the following is a symptom that might occur due to injury of the upper lateral cutaneous nerve of the arm?

<p>Pins and needles in the skin of the upper arm (D)</p> Signup and view all the answers

Which muscle is primarily responsible for weak lateral rotation in the context of shoulder dislocation?

<p>Teres minor (C)</p> Signup and view all the answers

What immediate symptom is indicative of injury to the axillary nerve following shoulder dislocation?

<p>Weakness in shoulder abduction (B)</p> Signup and view all the answers

Which joint receives the humeral head following an anterior dislocation?

<p>Inferior part of the joint capsule (D)</p> Signup and view all the answers

Which of the following actions is primarily affected due to the musculocutaneous nerve injury?

<p>Flexion of the elbow (A)</p> Signup and view all the answers

Which nerve could potentially lead to 'pins and needles' sensation in the upper arm if injured?

<p>Upper lateral cutaneous nerve (B)</p> Signup and view all the answers

How is excessive lateral rotation of the humerus related to shoulder dislocation?

<p>It decreases the stability of the joint (D)</p> Signup and view all the answers

What characteristic distinguishes the triceps brachii from the muscles in front of the arm?

<p>It is responsible for elbow extension (D)</p> Signup and view all the answers

What is the primary function of the glenoid labrum in the shoulder joint?

<p>To increase the depth of the glenoid cavity for better fit (A)</p> Signup and view all the answers

Which muscle action is associated with the posterior fibers of the deltoid?

<p>Extension and lateral rotation of the shoulder (C)</p> Signup and view all the answers

What anatomical structure is primarily involved in the stability of the shoulder joint during dislocation?

<p>Joint capsule (C)</p> Signup and view all the answers

Which of these statements accurately describes the coracohumeral ligament?

<p>It runs between the coracoid process and the greater tubercle of the humerus (A)</p> Signup and view all the answers

Which muscle assists in flexion of the elbow joint alongside the biceps brachii?

<p>Brachialis (D)</p> Signup and view all the answers

Which muscle primarily contributes to maintaining shoulder stability during lateral rotation?

<p>Infraspinatus (B)</p> Signup and view all the answers

What role does the transverse humeral ligament serve in relation to the biceps tendon?

<p>It allows for the tendon to pass through the intertubercular groove (C)</p> Signup and view all the answers

Which muscle groups are involved in shoulder adduction?

<p>Latissimus dorsi and subscapularis (D)</p> Signup and view all the answers

Where does the humeral attachment of the fibrous capsule occur?

<p>Around the anatomical neck (C)</p> Signup and view all the answers

What is unique about the lower and medial parts of the capsule in the shoulder joint?

<p>They are lax and weakest (A)</p> Signup and view all the answers

What is a significant characteristic of the gleno-humeral ligaments?

<p>They are considered thickenings of the fibrous capsule (D)</p> Signup and view all the answers

What initiates the first 15 degrees of shoulder flexion?

<p>Supraspinatus (C)</p> Signup and view all the answers

What is the structural significance of the scapular attachments of the fibrous capsule?

<p>They provide a firm anchoring to the scapula (A)</p> Signup and view all the answers

Flashcards

Shoulder Joint Type

A synovial joint, allowing for a wide range of motion.

Shoulder Joint Shape

A ball-and-socket joint, providing both rotational and angular movement.

Shoulder Joint Bones

Simple, consisting of the scapula and humerus, forming a socket and ball.

Glenoid Labrum Function

Deepens the glenoid cavity, improving the fit of the humeral head.

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Glenohumeral Ligaments

Strengthen anterior capsule of the shoulder.

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Coracohumeral Ligament Function

Resist inferior shoulder dislocation.

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Coracoacromial Ligament Function

Prevents upward displacement of the humeral head.

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Shoulder Flexion Muscles

Anterior deltoid, pectoralis major, coracobrachialis, and biceps brachii.

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Shoulder Dislocation Cause

Shoulder dislocation often results from forceful extension and lateral rotation of the humerus, potentially combined with a blow to the humerus during abduction.

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Immediate Shoulder Dislocation Symptom

Immediate symptoms of shoulder dislocation include significant swelling, extreme pain, and difficulty moving the shoulder; injury to nerves can also lead to numbness or prickling feelings in the affected area.

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Anterior Shoulder Dislocation

Most common shoulder dislocation, involving the humerus head sliding/displacing inferiorly, and anteriorly relative to the socket.

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Teres Minor Muscle Function

This muscle assists in lateral rotation of the shoulder; nerve injury from a dislocation can lead to weakened lateral rotation movements

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Axillary Nerve Role

The nerve supplying muscles of the shoulder and the skin covering the shoulder and the lateral part of the upper arm.

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Biceps Brachii Muscle Action

A muscle that flexes the elbow.

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Triceps Brachii Muscle Action

Muscle that extends the elbow joint

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Musculocutaneous Nerve Function

Provides movement and sensation to the muscles in front of the upper arm, and the lateral portion of the forearm.

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Shoulder Joint Type

A synovial joint, allowing free movement.

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Glenoid Labrum Function

Deepens the glenoid cavity for a better fit of the humeral head.

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Shoulder Joint Shape

A ball-and-socket joint, enabling a wide range of movement.

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Glenohumeral Ligaments

Ligaments strengthening the shoulder joint's anterior side.

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Coracohumeral Ligament Function

Supports the shoulder joint to prevent dislocation, mainly during dependent arm position.

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Shoulder Flexion Muscles

Deltoid (anterior), pectoralis major, coracobrachialis, and biceps brachii.

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Coracoacromial Ligament Function

Prevents the humeral head from moving upward.

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Shoulder Adduction Muscles

Teres major, latissimus dorsi, pectoralis major, long head of triceps.

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Shoulder Abduction Muscles

Deltoid (middle fibers, primarily), Supraspinatus (initially).

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Fibrous Capsule attachment

The fibrous capsule surrounds the anatomical neck and is weakly attached ½” below its medial side, thereby creating a gap for the tendon of the long head of biceps.

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Shoulder Dislocation Cause

Shoulder dislocation often happens from forceful extension and sideways rotation of the upper arm bone (humerus).

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Immediate Shoulder Dislocation Symptom

Quick signs include shoulder swelling, extreme pain, trouble moving the shoulder, and possible numbness or tingling from nerve damage.

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Anterior Shoulder Dislocation

The most common type where the upper arm bone shifts down and in front of the shoulder socket.

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Teres Minor Muscle Function

Helps rotate the shoulder outwards. Its function can get impaired due to shoulder dislocation.

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Axillary Nerve Role

Controls shoulder muscles and feeling in the shoulder and upper outside arm area.

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Biceps Brachii Muscle Action

Muscle that bends the elbow.

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Triceps Brachii Muscle Action

Muscle responsible for straightening the elbow.

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Musculocutaneous Nerve Function

Controls muscles in the front of the upper arm and feeling on the front of the forearm.

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Latissimus Dorsi Function

Large back muscle that helps extend and adduct the arm.

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Teres Major Muscle

A shoulder muscle that assists in extending the arm backward.

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Study Notes

Shoulder Joint

  • Type: Synovial
  • Shape: Ball and Socket
  • Number of bones: Two (articulating bones)
  • Articular surfaces: Glenoid cavity of scapula, head of humerus
  • Acromion, articular cartilage, coracoid process, scapula, humerus, glenoid are key anatomical structures

Ligaments of the Shoulder

  • Fibrous capsule
  • Scapular attachments: Margins of the glenoid fossa, supraglenoid tubercle with long head of biceps
  • The lower and medial parts of the capsule are lax and weakest (lack muscular support)
  • Humeral attachments: Surround anatomical neck, attached to shaft 1½" below anatomical neck (medially-weak part)
  • Gap in capsule for passage of biceps tendon in inter-tubercular groove
  • Synovial membrane lines inner surface of capsule

Glenoid Labrum

  • Glenoid cavity is shallow, accommodating only 1/3 of humeral head
  • Glenoid cavity deepened by fibrocartilaginous collar (glenoid labrum) attached to its margin
  • Deepens the socket for a better fit of the head

Glenohumeral Ligaments

  • Superior, middle, and inferior glenohumeral ligaments
  • Extend from anterior glenoid margin to lesser tubercle of humerus
  • Considered thickenings of the fibrous capsule of the shoulder joint
  • Strengthen the anterior surface of the capsule

Coracohumeral Ligament

  • Between coracoid process and greater tubercle of humerus
  • Aids in resisting inferior dislocation of the shoulder, particularly in dependent arm positions

Coracoacromial Ligament

  • Between coracoid process and acromion
  • Prevents upward displacement of humeral head

Relations of Shoulder Joint

  • Anterior: Subscapularis
  • Posterior: Infraspinatus, teres minor
  • Superior: Supraspinatus
  • Inferior: Axillary nerve

Movements of the Shoulder

  • Flexion: Anterior fibers of deltoid, pectoralis major, coracobrachialis, biceps brachii
  • Extension: Posterior fibers of deltoid, teres major, latissimus dorsi, long head of triceps
  • Abduction: Supraspinatus (first 15 degrees), middle fibers of deltoid (up to 90 degrees), scapular movement (beyond 90 degrees—trapezius & serratus anterior)
  • Adduction: Subscapularis, pectoralis major, latissimus dorsi, teres major
  • Medial rotation: Subscapularis, pectoralis major, latissimus dorsi, teres major
  • Lateral rotation: Infraspinatus, teres minor, posterior fibers of deltoid

Clinical Anatomy-Shoulder Dislocation

  • Anterior dislocation of the glenohumeral joint most common in athletes
  • Usually caused by excessive extension and lateral rotation of humerus
  • Hard blow to humerus with abducted glenohumeral joint can tilt humeral head inferiorly, dislocating it

Immediate Symptoms of Shoulder Dislocation

  • Immediate swelling within the shoulder region
  • Extremely difficult shoulder movements due to pain and weakness (axillary nerve injury)
  • Loss of abduction from 15 to 90 degrees (deltoid), weak lateral rotation (teres minor)
  • Pins and needles on upper arm skin due to injury to upper lateral cutaneous nerve of the arm (branch of axillary nerve)

Arm Muscles (Anterior)

  • Coracobrachialis
  • Biceps brachii
  • Brachialis
  • Nerve supply: Musculocutaneous nerve
  • Action: Flexion of elbow joint

Arm Muscles (Posterior)

  • Triceps brachii
  • Nerve supply: Radial nerve
  • Action: Extension of elbow joint

Musculocutaneous Nerve

  • Branch of lateral cord (C5, C6, C7)
  • Enters arm by penetrating coracobrachialis muscle
  • Appears laterally to biceps tendon at elbow
  • Penetrates deep fascia, continuing as lateral cutaneous nerve of forearm
  • Supplies coracobrachialis, biceps, and brachialis muscles and skin of lateral forearm

Brachial Artery

  • Continuation of axillary artery at lower border of teres major muscle
  • Main arterial supply to arm
  • Terminates at neck of radius, dividing into radial and ulnar arteries
  • Branches: Profunda brachii, superior ulnar collateral, inferior ulnar collateral, radial, ulnar

Cubital Fossa

  • Triangular depression anterior to elbow joint
  • Laterally: brachioradialis muscle
  • Medially: pronator teres muscle
  • Base: imaginary horizontal line between medial and lateral epicondyles

Cubital Fossa-Roof and Floor

  • Roof: Skin, superficial fascia, median cubital vein, bicipital aponeurosis
  • Floor: Brachialis and supinator muscles

Contents of Cubital Fossa

  • Radial nerve laterally
  • Biceps tendon
  • Brachial artery with terminal branches (radial and ulnar arteries)
  • Median nerve medially

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Shoulder Joint Anatomy Lecture 5 PDF

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