Anatomy of Muscles of Back and Arm PDF

Anatomy of Muscles of the back and Arm Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt  Intended Learning Outcomes (ILOs) 1. Recognize muscles of the back. 2. Enumerate layers forming the back. 3...

Anatomy of Muscles of the back and Arm Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt  Intended Learning Outcomes (ILOs) 1. Recognize muscles of the back. 2. Enumerate layers forming the back. 3. Recognize muscles of the arm. 4. Enumerate actions of muscles of the arm. 5. Compare between muscles of anterior and posterior compartments of the arm. 6. Enumerate changes at the level of coracobrachialis.  Agenda 1. What are the layers of the back muscles? 2. What are the functions of back muscles? 3. What are the origin and insertion of arm muscles? 4. What are the actions of arm muscles? 5. What are nerves supplying arm muscles?  Muscles of the back They are arranged into 3 layers: 1) Superficial layer: Trapezius Latissimus dorsi Levator scapulae Rhomboid minor Rhomboid major 2) Intermediate layer: Levator costarum Serratus posterior superior Serratus posterior inferior 3) Deep layer: Splenius group (splenius capitis & splenius cervicis). Erector spinae group. Transverse spinalis.  Muscles of the back Superficial layer Intermediate layer deep layer  Intermediate layer of back muscles Levator Costarum Origin: Transverse processes of C7-T11 vertebrae. Insertion: Ribs (below origin). Innervation: Dorsal rami of thoracic spinal nerves. Action: Raise ribs in inspiration. Serratus Posterior Superior Origin: Spines of lower 2 cervical and upper 2 thoracic vertebrae. Insertion: Upper ribs (2-5). Innervation: Intercostal nerves. Action: Raise ribs in inspiration. Serratus Posterior Inferior Origin: Spines of lower 2 thoracic and upper 2 lumbar vertebrae. Intercostal nerve Insertion: Lower 4 ribs. Innervation: Intercostal nerves. Action: Lowers ribs in expiration. Intermediate layer of back muscles  Deep layer of back muscles Splenius capitis & Splenius cervicis Located deep to trapezius. Origin: from vertebral spines. Insertion: according to name (capitis to the skull & cervicis to the cervical ribs). Action: Extend neck and head in bilateral action. Rotate the neck. Erector Spinae Three columns of muscles lie parallel to each other Spinalis (medial) -Longissimus (intermediate)-Iliocostalis (lateral) Transverse spinalis Origin: From transverse processes Insertion: Spines of vertebrae above Divided into: a. Semispinalis b. Multifidus c. Rotators Action: Extend trunk in bilateral action. Rotate in unilateral action  Deep layer of back muscles Splenius capitis & Splenius cervicis Located deep to trapezius. Origin: from vertebral spines. Insertion: according to name (capitis to the skull & cervicis to the cervical ribs). Action: Extend neck and head in bilateral action. Rotate the neck. Erector Spinae Three columns of muscles lie parallel to each other Spinalis (medial) -Longissimus (intermediate) Iliocostalis (lateral) Transverse spinalis Origin: From transverse processes Insertion: Spines of vertebrae above Divided into: a. Semispinalis b. Multifidus c. Rotators Action: Extend trunk in bilateral action. Rotate in unilateral action  Quiz Which of the following muscles forms the intermediate layer of back muscles ? A) splenius capitis muscle. B) serratus posterior superior muscle. C) semispinalis capitis muscle. D) trapezius muscle. E) levator scapulae muscle. answer is B  Muscles of the Arm Anterior compartment of the arm posterior compartment of the arm  Muscles of the Arm Biceps Brachii Origin: By 2 heads 1- The long head; From the supraglenoid tubercle of the scapula (within the capsule of the shoulder joint) (intracapsular extra-synovial). 2- The short head; From the tip of the coracoid process in common with the coracobrachialis muscle. Insertion: 1. Into the radial tuberosity by a tendon. 2-Into the deep fascia of the forearm by the bicipital aponeurosis. Nerve supply: Musculocutaneous nerve. Action: 1- Both heads: supination and flexion of the forearm. 2-The short head: Flexion of the shoulder joint. 3-The long head: Stabilize the head of the humerus. Bicipital tendon  Muscles of the Arm Coracobrachialis Origin: From the tip of the coracoid process, with the short head of the biceps. Insertion: Into the middle part of the medial border of the humerus. Nerve supply: Musculocutaneous nerve. Action: flexion and adduction of the arm.  Muscles of the Arm Changes at the level of insertion of coracobrachialis: Median nerve crosses the brachial artery (from the lateral to the medial). Ulnar nerve pierces the medial intermuscular septum. Radial nerve pierces the lateral intermuscular septum.  Muscles of the Arm Brachialis Origin: From the lower 1/2 of the front of the humerus. Insertion: Into the ulnar tuberosity. Nerve supply: Musculocutaneous and Radial nerve. Action: Flexion of the forearm. Biceps brachialis  Muscles of the Arm Triceps: Origin: it arises by 3 heads 1- Long head: From the infraglenoid tubercle of the scapula. 2- Lateral head: From the upper 1 |2 of the posterior surface of the shaft of the humerus. 3- Medial head: From the posterior surface of the lower 1|2 of the shaft of the humerus. Insertion: In a common tendon into the olecranon process of the ulna. Nerve supply: radial nerve. Action: It is a powerful extensor of the elbow joint. Nerve Supply of muscles of the Arm Radial nerve Musculocutaneous nerve  Quiz Which of the following muscles is supplied by both radial and musculocutaneous nerves? A) long head of biceps muscle. B) coracobrachialis muscle. C) brachialis muscle. D) lateral head of triceps muscle. E) deltoid muscle. answer is c