Anatomy 1 Lecture 5: Pectoral Region & Back Muscles PDF

ANATOMY 1 Lecture 5 Pectoral region & Back muscles Dr. Enas Anwar Associate Professor of Anatomy and Embryology Faculty of Medicine, Ain Shams University 1 -Identify muscles attachments, action and nerve supply of pectoral region. -Describe the anatomy of the brea...

ANATOMY 1 Lecture 5 Pectoral region & Back muscles Dr. Enas Anwar Associate Professor of Anatomy and Embryology Faculty of Medicine, Ain Shams University 1 -Identify muscles attachments, action and nerve supply of pectoral region. -Describe the anatomy of the breast. -Identify muscles attachments, action and nerve supply of back muscles (superficial group). 2 3  Muscles of pectoral region are a group of muscles of the upper limb that attach to the sternum and anterior parts of ribs on one end, and to the scapula, clavicle and humerus on the other end. They are involved in movements of the shoulder and arm. 1. Pectoralis major 2. Pectoralis minor 3. Subclavius 4. Serratus anterior 4  Bony features 1. Costal cartilages. 2. Shoulder girdle bones (clavicle & scapula). 3. Clavicle (Sup. & Inf surfaces). 4. Subclavian groove (middle of inferior surface of clavicle). 5. Sternum. 5 Scapula 1. Ant. & Post. Surfaces. 2. Sup., Inf. & Lat angles. 3. Spine (+ Crest of spine). 4. Acromion. 5. Coracoid. 6. Borders (Sup., Med. & Lat.). 6 Upper end of humerus 1. Head 2. Greater & lesser tuberosities. 3. Bicipital groove 7 1-Pectoralis major Origin: clavicular head: medial ½ of clavicle (superior surface). sternocostal head: sternum and upper 6 costal cartilages of ribs (anterior surface). Insertion: lateral edge of bicipital groove of humerus. Innervation: medial pectoral and lateral pectoral nerves. 8  Action: Adduction & medial (internal) rotation of arm at shoulder joint. Clavicular head: Flexion of arm at shoulder joint. Sternocostal head: extend the arm back to the anatomical position. 9 2-Pectoralis minor Origin: 3rd ,4th ,5th ribs close to their costal cartilages. Insertion: Coracoid process of scapula. Innervation: medial pectoral and lateral pectoral nerves. 10  Action: Depression & protraction of scapula. 11 3-Subclavius Origin: First rib (medial end). Insertion: Clavicle (middle of inferior surface in the subclavian groove). Innervation: Nerve to subclavius. Action: Stabilization of clavicle while the shoulder moves the arm. 12 4-Serratus anterior a fan-shaped muscle at the lateral wall of the thorax. Origin: Lateral part of upper 8 ribs. Insertion: Superior angle, medial border & inferior angle of scapula (anterior surface). Innervation: long thoracic nerve. 13 14  Action Protraction & upward rotation (Lateral rotation) of scapula. It also holds the scapula against the ribcage. 15  Applied Anatomy Winging of scapula -Winging of scapula (where the scapula stands out as a wing on pressing forwards with outstretched arm i.e., the medial border of the scapula is not in contact with the thoracic wall). -Tested by : Make the patient push against the wall. -Weakness in abduction of the arm above 90˚. -Cause: Injury of the long thoracic nerve leads to the paralysis of the serratus anterior muscle. 16 All muscles of pectoral region are accessory inspiratory muscle (lift the ribs). 17 18 Which muscle inserts into the coracoid process of the scapula? A) Pectoralis minor B) Pectoralis major C) Subclavius D) Serratus anterior 19 Paralysis of the serratus anterior leads to: A) Winged scapula B) Frozen shoulder C) Scapular elevation E) Clavicle dislocation 20 21  The breasts are paired structures located on the anterior thoracic wall, in the pectoral region. They are present in both males and females. Yet are more prominent in females following puberty. 22  It extends horizontally from the lateral border of sternum to the mid-axillary line. Vertically, it spans between the 2nd and 6th costal cartilages. It lies superficial to the pectoralis major and serratus anterior muscles. 23 It is composed of: Circular body: largest and most prominent part of the breast. Axillary tail: smaller part, runs along the inferior lateral edge of the pectoralis major towards the axilla. Nipple in the center of the areola (pigmented area). 24 Anatomical Structure The breast is composed of mammary glands in (15-20 lobules). Each lobule consists of many alveoli drained by a single duct. These ducts converge at the nipple. The mammary glands are surrounded by a connective tissue (fibrous and a fatty components). The breast lies on pectoral fascia that covers pectoralis major muscle. 25 The breast is primarily composed of: A) Mammary glands and connective tissue B) Fatty tissue only C) Muscles and ligaments D) Bone and cartilage E) Tendons and ligaments 26 27 28 5 Muscles 1-Trapezius & latissimus dorsi (most superficial). 2-Rhomboid major, minor & levator scapulae (covered by Trapezius). 29  Bony features 1. Vertebra (body, Spine Transverse process & Spine). 2. Cervical spines. body 3. Nuchal ligament. Anterior Posterior 30 Occipital bone 1. Superior nuchal line. 2. External occipital protuberance. 3. Nuchal ligament. 31 Hipbone Ilium Iliac crest Anterior view Posterior view 32 Trapezius Extends from skull and vertebral column to shoulder girdle. Origin: Upper fibers: Superior nuchal line (medial part), external occipital protuberance & nuchal ligament. Middle fibers: Spines of vertebrae C7- T3. Lower fibers: Spines of vertebrae T4- T12. 33 Insertion: Upper fibers: lateral 1/3 of clavicle. Middle fibers: Crest of spine of scapula & acromion (medial margin). Lower fibers: medial end of scapular spine. Innervation: Spinal accessory nerve (CN XI). 34 35 Action: Upper fibers: Elevation of the scapula. Lower fibers: Depression of the scapula. Upper & lower fibers: Upward rotation of the scapula. Middle fibers: Retraction of the scapula (middle fibers). Bilateral contraction: Extends neck. Unilateral contraction: Ipsilateral side flexion of the neck 36 Latissimus dorsi A broad, flat muscle occupying most of the lower posterior thorax. Origin: Lower 6 thoracic spines. Thoracolumbar fascia. Iliac crest. inferior three ribs. Inferior angle of scapula (dorsal surface). Insertion: Bicipital groove of humerus (floor). Innervation: Thoracodorsal nerve. 37 38  Action: Adduction, extension & medial rotation of arm at shoulder joint. 39 40 Levator scapulae Origin: Upper 4 cervical vertebrae (transverse processes). Insertion: Scapula (posterior surface of medial border between spine and superior angle). Action: Elevation and Down rotation of the scapula Innervation: Dorsal scapular nerve. 41 Rhomboid minor Origin: C7-T1 vertebrae (spines). Insertion: Scapula (posterior surface of medial border at the level of the spine of scapula). Innervation: Dorsal scapular nerve. Rhomboid major Origin: T2-T5 vertebrae (spines). Insertion: Scapula (posterior surface of medial border between the scapula spine and inferior angle). Innervation: Dorsal scapular nerve. 42  Action of Rhomboids: Retraction and Down rotation of scapula. 43 The action of the latissimus dorsi muscle includes: A) Adduction of the arm B) Abduction of the arm C) Lateral rotation of the arm D) Retraction of the scapula 44 The action of rhomboid muscles includes: A) Retraction and downward rotation of the scapula. B) Elevation and upward rotation of the scapula. C) Depression of the scapula. D) Protraction of the scapula. E) Lateral rotation of the arm. 45 Assignment 4 46 A patient presents with pain and weakness when attempting to push open a heavy door. Upon physical examination, there is noticeable difficulty in scapular protraction. Which muscle is likely affected? A) Serratus anterior B) Rhomboid major C) Latissimus dorsi D) Subclavius 47 48 1. The pectoralis major muscle is responsible for the lateral rotation of the arm. 2. The serratus anterior muscle inserts into the lateral border of the scapula. 3. Paralysis of the serratus anterior muscle can result in winged scapula. 4. The pectoralis minor muscle is innervated by the medial and lateral pectoral nerves. 5. The breast is located between the 3rd and 7th costal cartilages. 49 6. The latissimus dorsi muscle is involved in the medial rotation of the arm. 7. The acromioclavicular joint is a plane synovial joint. 8. The rhomboid muscles are responsible for protraction and lateral rotation of the scapula. 9. The subclavius muscle inserts into the coracoid process of the scapula. 10. The spinal accessory nerve innervates the trapezius muscle. 50 Mention the name of the muscles and their attachments. 51 52