Your Muscular System Exam Assignment Is To Describe Location

Your Muscular System Examassignmentis To Describe Location Superior

Your muscular system exam/assignment is to describe location (superior & inferior attachments, action and innervations) of the following muscles: Deltoid, Triceps brachii, Biceps brachii, Coracobrachialis, Brachialis, Brachioradialis, Sternocleidomastoid, Trapezius, Latissimus Dorsi, Supraspinatus, Infraspinatus, Subscapularis, Sartorius, Iliotibial tract/band, Tensor Fascia Lata. Additionally, describe the Glenohumeral joint including its anatomy, ligaments, and movements.

Paper For Above instruction

The human muscular system is a complex network of muscles responsible for movement, stability, and posture. Understanding the specific locations, attachments, actions, and innervations of individual muscles provides essential insight into their functional roles and interactions within the musculoskeletal system. This paper systematically explores these characteristics for selected muscles, focusing on their superior and inferior attachments, actions, and nerve supplies. Additionally, the anatomy and movements of the glenohumeral joint are examined, providing a comprehensive overview of shoulder biomechanics.

Muscles of the Upper Limb and Shoulder

Deltoid: The deltoid muscle is located on the shoulder and covers the glenohumeral joint. Its superior attachment is on the acromion of the scapula, and its inferior attachment is on the deltoid tuberosity of the humerus. The muscle's actions include shoulder abduction, anterior fibers flex and medially rotate the shoulder, while posterior fibers extend and laterally rotate the arm. Innervation is via the axillary nerve (C5-C6).

Triceps brachii: Positioned on the posterior aspect of the upper arm, the triceps brachii has superior attachments on the infraglenoid tubercle of the scapula (long head), posterior humeral shaft (lateral head), and distal posterior humerus (medial head). Inferior attachments are all converging on the olecranon process of the ulna. Its primary action is extending the elbow, with the long head also assisting in shoulder extension and adduction. Innervated by the radial nerve (C6-C8).

Biceps brachii: Situated at the anterior arm, the long head originates from the supraglenoid tubercle of the scapula, while the short head originates from the coracoid process. Both attachments are inferior to the shoulder joint—on the radial tuberosity and bicipital aponeurosis. The biceps facilitate forearm flexion, supination, and shoulder flexion. Innervation is via the musculocutaneous nerve (C5-C6).

Coracobrachialis: Originates from the coracoid process of the scapula and inserts on the middle third of the medial humerus. It functions in shoulder adduction and flexion, innervated by the musculocutaneous nerve (C5-C7).

Brachialis: The brachialis muscle arises from the distal anterior surface of the humerus (superior attachment) and inserts on the coronoid process and tuberosity of the ulna (inferior attachment). It is a primary flexor of the elbow, innervated by the musculocutaneous nerve (C5-C6).

Brachioradialis: Located on the lateral aspect of the forearm, originating from the lateral supracondylar ridge of the humerus and inserting on the styloid process of the radius. It assists in flexion of the elbow, especially in mid-pronated forearm, innervated by the radial nerve (C5-C6).

Sternocleidomastoid: This neck muscle originates from the manubrium of the sternum and clavicle (superior attachments). It inserts on the mastoid process of the temporal bone. The muscle acts to flex and rotate the neck; when both sides contract, it flexes the neck; unilaterally, it rotates the head to the opposite side. Innervated by the accessory nerve (cranial nerve XI) and facial nerve (C2-C3).

Trapezius: Originates from the occipital bone, ligamentum nuchae, and spinous processes of cervical and thoracic vertebrae (superior attachments). Its inferior attachment is on the lateral clavicle, acromion, and spine of scapula. The trapezius elevates, retracts, and depresses the scapula, and assists in tilting the head backward. Innervated by the accessory nerve (cranial nerve XI).

Latissimus dorsi: Originates from the spinous processes of T7-L5, sacrum, iliac crest, and ribs (superior attachments). Its inferior attachment is on the intertubercular groove of the humerus. It extends, adducts, and medially rotates the shoulder; it is innervated by the thoracodorsal nerve (C6-C8).

Supraspinatus: Arises from the supraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. It abduction of the arm and stabilizes the shoulder joint. Innervated mainly by the suprascapular nerve (C5-C6).

Infraspinatus: Originates from the infraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. Its primary action is lateral rotation of the arm, and it stabilizes the shoulder joint. Innervated by the suprascapular nerve (C5-C6).

Subscapularis: Originates from the subscapular fossa and inserts on the lesser tubercle of the humerus. Its main function is medial rotation of the arm, and it stabilizes the shoulder. Innervated by the upper and lower subscapular nerves (C5-C6).

Sartorius: The longest muscle in the body, originating from the anterior superior iliac spine and inserting on the medial tibia (pes anserinus). It flexes, abducts, and laterally rotates the hip, as well as flexing the knee. Innervated by the femoral nerve (L2-L4).

Iliotibial tract/band: A thickening of the fascia lata, running along the lateral thigh from the iliac crest to the lateral condyle of the tibia. It stabilizes the knee and assists in hip abduction and extension. Innervated by the superior gluteal nerve.

Tensor fascia lata: Originates from the anterior iliac crest and anterior superior iliac spine, inserting into the iliotibial tract. It aids in thigh abduction, medial rotation, and stabilization of the hip. Innervated by the superior gluteal nerve.

Glenohumeral Joint (Shoulder Joint) Anatomy and Movement

The glenohumeral joint is a highly mobile ball-and-socket joint formed by the articulation of the head of the humerus with the glenoid fossa of the scapula. It is stabilized by a complex arrangement of ligaments, tendons, and the rotator cuff muscles. The joint capsule is relatively loose, allowing extensive range of motion but requiring reinforcement from surrounding structures.

Major ligaments include the glenohumeral ligaments (superior, middle, and inferior), the coracohumeral ligament, and the transverse humeral ligament, which help stabilize the joint during movement. The rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) provide dynamic stability by holding the humeral head within the glenoid cavity.

The shoulder permits a wide range of movements, including flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction. These movements result from the coordinated actions of muscles crossing the shoulder joint, with the rotator cuff muscles playing a crucial role in stability during movement.

Understanding the anatomy and mechanics of the glenohumeral joint is essential for diagnosing and treating shoulder injuries and pathologies, such as rotator cuff tears, impingements, and dislocations.

Conclusion

The detailed analysis of the muscles' attachments, actions, and innervations underscores their specific roles in upper limb movements and stability. Coupled with a comprehensive understanding of the glenohumeral joint's anatomy and biomechanics, this knowledge facilitates effective clinical assessment, intervention, and rehabilitation strategies in musculoskeletal health and sports medicine.

References

• Gray, H., & Standring, S. (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st Edition. Elsevier.
• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy. 7th Edition. Wolters Kluwer.
• Netter, F. H. (2018). Netter's Atlas of Human Anatomy. 7th Edition. Elsevier.
• Snell, R. S. (2018). Clinical Anatomy by Regions. 9th Edition. Wolters Kluwer.
• Kumar, A., & Khandelwal, S. (2015). Anatomy, Shoulder. In StatPearls. StatPearls Publishing.
• Ellenbecker, T. S., & Cools, A. (2018). Rehabilitation of Shoulder Instability. In Journal of Athletic Training, 53(10), 1008–1012.
• Yamamoto, N., et al. (2020). Anatomy and Function of the Rotator Cuff. In Orthopaedic Journal of Sports Medicine, 8(11), 1–12.
• Burkhart, S. S., et al. (2010). Shoulder Instability and the Rotator Cuff. In Clinical Sports Medicine, 29(4), 565–585.
• McGahan, J. P., et al. (2018). Ultrasonography of the Shoulder. In Ultrasound Clinics, 13(2), 163–177.
• Levangie, P. K., & Norkin, C. C. (2011). Joint Structure and Function: A Comprehensive Analysis. F.A. Davis Company.