Study guide 3- deltoid and scapular region

1. In relation to the superior transverse scapular ligament, where will you find the suprascapular nerve and suprascapular artery?

Both course through the suprascapular notch. The superior transverse scapular ligament passes over the suprascapular notch to create the suprascapular foramen. The suprascapular artery passes over the transverse scapular ligament, while the suprascapular nerve passes underneath the superior transverse scapular ligament and through the suprascapular foramen. (The ARMY goes over the bridge and the NAVY goes under the bridge).

Axillary nerve:

Originates from the posterior cord of the brachial plexus and exits the axilla by passing through the quadrangular space in the posterior wall of the axilla, and enters the posterior scapular region. The axillary nerve innervates the deltoids and teres minor. It has a cutaneous branch which carries general sensation from the skin over the inferior part of the deltoid muscle.

Radial nerve

Originates from the posterior cord of the brachial plexus. It passes out of the axilla and into the posterior compartment of the arm by passing through the triangular interval between the inferior border of the teres major muscle, the long head of the triceps brachii muscle, and the shaft of the humerus. The radial nerve innervates all of the muscles in the posterior compartment of the arm and forearm, and the skin of the posterior aspect of the arm and forearm, the inferio-lateral surface of the arm, and the dorsal-lateral surface of the hand.

Lower subscapular nerve

Originates from the posterior cord of the brachial plexus. This nerve innervates the muscles associated with the posterior wall of the axilla, passing inferiorly along the posterior wall and innervates the subscapularis and teres major muscles. (Upper subscapular nerve which originates in a similar are as the lower subscapular nerve also innervates the subscapularis muscle).

Suprascapular nerve

Originates in the proximal neck from the superior trunk of the brachial plexus and passes posterolaterally from its origin, through the suprascapular foramen (located on the superior border of the scapula directly medial to the coracoid process) to reach the posterior scapular region. It innervates the supraspinatus muscle and then passes through the greater scapular notch (between the root of the spine of the scapula and the glenoid cavity), to terminate in and innervate the infraspinatus muscle. The suprascapular nerve has no cutaneous branches.

1. From what structure(s) does the glenohumeral joint gets its stability?

Stability is provided by the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis), the long head of the biceps brachii muscle, related bony processes, and extracapsular ligaments

1. From what structure(s) does the glenohumeral joint gets its stability?

Stability is provided by the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis), the long head of the biceps brachii muscle, related bony processes, and extracapsular ligaments.

1. Remember that mobility is not possible without stability. Therefore, what do you think is the impact of a clavicle fracture on shoulder movement? Show an understanding of the anatomy of the shoulder in your answer.

The clavicle is the only TRUE joint attachment of the shoulder complex to the axial skeleton (the scapulothoracic joint isn't a true joint and doesn't have any real joint stability). So if the clavicle is fractured, the shoulder complex will have difficulty performing movement. In a sense, the origin of the complex can't stay stable, so the rest of the complex can't perform movement as intended.

What structures make up the borders of the quadrangular space

The quadrangular space is a passageway for nerves and vessels (specifically, the axillary nerve and posterior circumflex humeral artery) passing from the anterior regions of the shoulder (the axilla) to the posterior scapular region. The structural borders of the quadrangular space are as follows: the inferior margin of the teres minor, the surgical neck of the humerus (or the medial border of the bone), the superior margin of the teres major, and the lateral margin of the long head of the triceps brachii. Inside the quadrangular space you can find the axillary nerve and the posterior circumflex humeral artery as they leave the axilla and travel posteriorly to innervate and supply nearby muscles.

What anatomical structures are involved in the shoulder subluxation?

The scapula, humerus, and clavicle form 3 synovial joints of the shoulder and the subacromial and scaluar-thoracal joint. The size of the glenoid cavity is impacted by the glenoid labrum. The skeletal muscles (and their tendons) of the supraspinatus, infraspinatus, teres minor and subscapularis (rotator cuff muscles) provide stability to the joint. As do the glenohumeral, coracohumeral, coracoacromial, and acromiohumeral ligaments. The acromioclavicular ligament also supports the shoulder capsule. Often times, subluxation occurs when the muscles loosen due to non-use or denervation (like with hemiplegia after a stroke) and the constant pull of gravity on the ligaments (especially the glenohumeral ligament) stretches them out, which decreases stability of the shoulder joint and leads to subluxation of the humeral head out of the glenoid cavity. Individuals can be prone to subluxation based on the size/shape of the cavity and glenoid labrum.

1. Which joints make up the "shoulder complex"?

The sternoclavicular, acromioclavicular, and glenohumeral joints make up the shoulder complex. The scapulothoracic joint is a "pseudo" joint that is also involved, but does not share the same joint properties as the other three and so is not always included as a bony joint making up the complex.

1. What muscles make up the rotator cuff? What characteristics do these four muscles share?

The subscapularis, supraspinatus, infraspinatus, and teres minor muscles the 4 muscles that make up the rotator cuff. Each of them originates on the scapula and inserts on the humerus and the GH joint capsule. These 4 muscles are responsible for much the joint stability (particularly dynamic stability) of the GH (they hold the head of the humerus in the glenoid fossa). Additionally, all four muscles share a root level at C5 and C6.

What structures make up the borders of the triangular interval?

The triangular interval is bordered by the long head of triceps brachii, the humerus bone, and the teres major muscle. Inside the triangular interval you can find the radial nerve as it leaves the axilla and travels posteriorly to wrap around the posterior humerus bone.

1What is shoulder (glenohumeral) subluxation?

a. Shoulder subluxation is a partial or incomplete dislocation of the glenohumeral joint where the humeral head slips out of the glenoid cavity. b.

1. Describe the location of the posterior humeral circumflex artery. Then explain shoulder quadrilateral space syndrome. And finally, explain why volleyball players might be at risk of injuring the PCHA and developing shoulder quadrilateral space syndrome.

a. The PCHA arises from the distal third of the axillary artery and runs with the axillary nerve through the quadrilateral space, which is bound by the teres major inferiorly, the long head of the triceps medially, the teres minor superiorly, and the surgical neck of the humerus laterally. b. When the space within the quadrilateral space of the shoulder tightens (due to edema from repetitive motion/injury or physical compression of heavy straps, or bulky muscles in an overhead position), the muscles/humerus can compress the axillary nerve and PCHA, causing injury. c. When the humerus is in full shoulder extension overhead, as it is for serving, setting, and blocking in volleyball, it is at increased risk of stretching the axillary nerve and PCHA and causing injury (quadrilateral space syndrome). Here's a resource on this for you

lateral head of brachii

highlighted muscle

1. Where can you find the tendon of the long head of the biceps brachii muscle?

originates from the supraglenoid tubercle and passes through the joint capsule laterally and the inferiorly through the intertubercular groove. The easiest place to find the tendon is in the intertubercular groove.

middle facet of humerus

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