Muscles for Notes PDF

Pectoral Region MUSCLES OF PECTORAL REGION 1- Pectoralis major muscle (Fig. 35): It is the superficial muscle of the pectoral region which extends laterally to form the anterior wall of the axilla. -Origin: It arises by 2 heads:...

Pectoral Region MUSCLES OF PECTORAL REGION 1- Pectoralis major muscle (Fig. 35): It is the superficial muscle of the pectoral region which extends laterally to form the anterior wall of the axilla. -Origin: It arises by 2 heads: 1. Clavicular head: arises from the anterior surface of the medial 112 of the clavicle. 2. Sternocostal head: it is larger and it arises from :. Anterior surface of the sternum. Front of the upper 6 costal cartilages.. Aponeurosis of external abdominal oblique muscle. - Insertion: It is inserted by a bilaminar tendon into the lateral lip of the intertubercular (bicipital) groove as follow: - Nerve supply: Lateral and medial pectoral nerves. -Action: As a whole, the muscle adducts and medially rotates the arm. The clavicular head flexes the arm. The strenocostal head extends the flexed arm and comes to work in swimming, rowing and climbing. II- Pectoralis minor (Fig. 35): Deep to the middle part of the pectoralis major. -Origin: From the outer surfaces of the 3rd, 4th and 5th ribs near their costal cartilages. -Insertion: Into the medial border and the upper surface of the coracoid process. - Nerve supply: Medial pectoral nerve. -Action: Protraction of the shoulder girdle Depression of the shoulder With fixed scapula, it can raise the ribs in forced inspiration  Pectoral Region III- Subclavius (Fig. 35): It is a slender muscle presents just below the clavicle. -Origin: From the upper surface of the 1 st costo-chondral junction. - Insertion: Into a groove on the lower surface of the middle third of the clavicle. - Nerve supply: Nerve to subclavius (CS). -Action: It steadies the clavicle thus preventing excessive movements of the shoulder girdle. Pectoralis major m. I IClavicular head Sternocostal head of Pectoralis minor m. greater 6th rib tubercle (lateral lip of intertubercula groove) Costal arch Fig. (35): Muscles of pectoral region  Muscles of the Back CHAPTER3 I LOs: By the end of the lectures, the student should be able to: List the muscles of the back. Locate the site of attachment of the back muscles. Mention the nerve supply & actions of the back muscles. Recall boundaries and contents of lumbar triangle and triangle of auscultation. Interpret some clinical problem related to lumbar triangle. Interpret clinical problem related to the nerve supply to trapezius. MUSCLES CONNECTING THE UPPER LIMB WITH VERTEBRAL COLUMN (Muscles of the Back) These are the muscles of the upper limb situated in the back and connect the limb to the vertebral column. They are supplied by the anterior primary rami of the spinal nerves and they are arranged into two layers as follows (Fig. 36): 1- Muscles of the superficial layer: Consists of two muscles: 1. The trapezius 2. The latissimus dorsi 2-Muscles of the deep layer: Consists of three muscles: 1. The levator scapulae 2. The rhomboideus major 3. The rhomboideus minor Levator scapulae Seventh cervical......_.......... vertebra major Fig. 36: Muscles :of the back J  Muscles of the Back 1- Muscles of the Superficial Layer a) Trapezius (Fig. 37): It is a large triangular muscle covering the upper half of the back. The two muscles of both sides form together the outline of a trapezium. -Origin: Back of the skull: from the external occipital protuberance and the medial third of the superior nuchal line. Back of the neck: from the ligamentum nuchae and the spine of the i h cervical vertebra. Back of thorax: from the spines of all thoracic vertebrae and their supraspinous ligaments. -Insertion: It has a V-shaped insertion as follows: The upper fibers: they are inserted into the posterior border of the lateral third of the clavicle. Middle fibers: they are inserted into the medial border of the acromion and the upper lip of the crest of the spine of the scapula. Lower fibers: they are inserted into a rough tubercle on the crest of the spine of the scapula (near the root of the spine). N.B. The insertion of the trapezius is surrounded by the v-shaped origin of deltoid muscle. - Nerve supply: Motor: spinal root of accessory nerve. Sensory: Cervical nerves number 3 and 4 (C3 and 4). -Action: It maintains the level of the shoulder. Its upper fibers elevate the shoulder girdle. The upper and lower fibers of trapezius rotate the scapula so that the glenoid cavity looks upwards to put the arm above the head. Acting with rhomboids, its middle fibers retract the scapula and brace back the shoulder. Applied anatomy: Paralysis of the trapezius leads to shoulder drop. b) Latissimus dorsi (Fig. 38): It is large triangular flat muscle covering the lower half of the back down to the iliac crest. It has wide origin and narrow tendon of insertion.  Muscles of the Back 45.," External occipital-----'""' protuberance Superior fibers Superior nuchal line------=:::... of trapezius Nuchal ligament C7 Middle fibers of trapezius Acromion processes of Scapula vertebrae Inferior fibers of trapezius 512 Fig. 37: Back view attachments of trapezius - Fig. 38: Back view showing attachments of latissimus dorsi  Muscles of the Back -Origin: It arises by: 1. Fleshy fibers from: Posterior third of the outer lip of iliac crest. Spines of the lower 6 thoracic vertebrae, undercover of the trapezius. Thoraco-lumbar fascia Outer surface of lower 4 ribs Few fibers from the dorsal aspect of the inferior angle of the scapula. - Insertion: into the floor of the bicipital groove. - Nerve supply: thoraco-dorsal nerve (nerve to latissimus dorsi). -Action: Extension, medial rotation & adduction of the arm (rowing and swimming). Acting with sternocostal part of pectoralis major, it pulls the trunk upwards as in climbing, (acting from insertion) Through its attachment to the ribs, it assists in violent expiration as in coughing. N.B.: 1. The upper border of the muscle crosses over the inferior angle of the scapula and has triple relation to the teres major (Fig. 39) as follows: first, it lies behind the teres major, then it curves below the teres major. At its insertion, it comes in front of the teres major. 2. The latissimus dorsi, at its insertion, usually fuses with teres major forming the posterior axillary fold. - Related triangles: 1- Triangle of auscultation (Fig. 40): It is located medial to the lower part of the scapula. a. Boundaries: Above: lateral border of the trapezius. Below: upper border of the latissimus dorsi. Laterally: lower part of the medial border of the scapula b. The floor is formed by: Rhomboideus major Sixth and seventh ribs and the space in between Breath sounds are clearly heard (auscultated) on this triangle, hence its name. 2- Lumbar triangle (Fig. 40): it I situated just above the iliac crest and might be a site of hernia (lumbar hernia). a. Boundaries: Below: iliac crest. Medially: lateral border of latissimus dorsi. Laterally: vertical posterior border of external abdominal oblique muscle. b. The floor is formed by the internal abdominal oblique and tranversus abdominis muscles.  Muscles of the Back Intertubercular sulcus Pectoralis ----+-. major Latissimus -w.-T"\. dorsi major Lumbar--=*Ht triangle Latissimus i dorsi Fig. 39: Triple relation between latissimus Fig. 40: Triangles related to dorsi and teres major (Anterior view) latissimus dorsi (Back view)  Muscles of the Back 2- Muscles of the deep layer (Figs. 41, 42, 43): a) Levator scapulae (Fig. 41): - Origin: it arises by 4 slips from the transverse processes of the upper 4 cervical vertebrae. 2n - 24 - Insertion: into the dorsal surface of the medial border of the scapula above the root of the spine. - Nerve supply: Nerve to rhomboids (dorsal scapular nerve, CS) Fibers from C3 and 4 -Action: Acting with the upper fibers of trapezius, it elevates the shoulder girdle. Rotates the scapula so that the glenoid cavity looks downwards. Retracts the scapula. b) Rhomboideus minor (Fig. 43): - Origin: from the lower part of ligamentum nuchae, the spines of the ih cervical and the 1st thoracic vertebrae. - Insertion: into the dorsal surface of the medial border of the scapula opposite the root of the spine. - Nerve supply: nerve to rhomboids (dorsal scapular nerve, CS). - C7 -Action: Tr - Rotates the scapula so that the glenoid cavity looks downwards (acting with the levator scapulae). ↑ Retracts the scapula (acting with the middle fibers of trapezius). ! ↑ Adduction med border c) Rhomboideus major (Fig. 42): - Origin: from the spines of the 2nd, 3rd, 4th and sth thoracic vertebrae and their supraspinous ligaments. - Insertion: into the dorsal surface of the medial border of the scapula from the root of the spine to the inferior angle. - Nerve supply: nerve to rhomboids (dorsal scapular nerve, CS). -Action: the same as the rhomboideus minor. Tr  Muscles of the Back Superficial Deep :;..;p.---·Teres minor Fig. 41: Muscles of the back (Deep layer) & attachments of levator scapulae Rhomboid minor m. Fig. 43: Attachments of rhomboid minor Fig. 42: Attachments of rhomboid major  Shoulder Region CHAPTER4 I LOs: By the end of the lectures, the student should be able to: List the muscles of the shoulder region Locate the site of attachment of the scapular muscles Mention the nerve supply & actions of the scapular muscles Describe the relations of deltoid muscle. Interpret clinical problem related to the nerve supply to deltoid. Cite the rotator cuff muscles MUSCLES OF THE SHOULDER REGION (Scapular Muscles) These are group of muscles surrounding the shoulder joint and extending from scapula to humerus (Fig. 44).They include the following muscles: a) Deltoid lat ". of davide b) Supraspinatus lat border. of acronion c) Infraspinatus d) Teres major e) Teres minor lower lip of crest of spine delloid tuberosity f) Subscapularis a) Deltoid (Figs. 45): it is a triangular thick muscle which forms the rounded contour of the shoulder. Origin : it has a V-shaped origin as follow: - Origin: Anterior border of the lateral third of the clavicle (anterior fibers). Lateral border of acromion (middle fibers). Lower lip of the crest of spine of scapula (posterior fibers). - Insertion Insertion:: it is inserted in the deltoid tuberosity at the middle of the lateral surface of the shaft of the humerus. - Nerve supply: Circumflex (axillary) nerve (C 5, 6).  Shoulder Region -Action: The anterior fibers flex and medially rotates the arm The posterior fibers extend and laterally rotate the arm. The middle fibers abduct the arm from 15 to 90 degrees. Clinical importance: Paralysis of the deltoid muscle results in flattening of the shoulder and loss of abduction of the shoulder joint from 15° to 9rf. Deltopectoral groove (Fig. 44): It is a groove between the contiguous borders of the pectoralis major and the deltoid and ends above, just below the clavicle, in the infraclavicular fossa. It lodges the following structures: Uppermost part of cephalic vein. Deltoid branch of thoraco-acromial artery. Deltopectorallymph nodes. b) Supraspinatus (Fig. 47): - Origin Origin:: from the medial two-third of the supraspinous fossa. - Insertion Insertion: into the highest impression on the greater tuberosity. - Nerve supply: suprascapular nerve (C5,6). -Action: Helps to steady the head of the humerus in the glenoid cavity. Abducts the arm from 0 to lS'thus initiates abduction medial of supraspinous fosse impression on highest tuberosity greater  Shoulder Region Long head of biceps brachii muscle (Anterior view) Fig. 44: Scapular muscles (Posterior view) Fig. 45: Attachments of deltoid muscle  Shoulder Region C) Infraspinatus (Fig. 47): Origin : -Origin: From the medial two-third of the infraspinous fossa. Insertion : into the middle impression on the back of the greater tuberosity. -Insertion: - Nerve supply: suprascapular nerve (C5,6). -Action: back of greater Luberosity It steadies the head of the humerus It rotates the arm laterally. med. 43 of infraspinous fossa D) Teres minor (Fig. 47): - Origin Origin:: from the upper two-third of the dorsal surface of the lateral border of the scapula. -Insertion: Insertion : into the lowest impression on the back of the greater.tuberosity. lowest impression - Nerve supply: axillary (circumflex) nerve (C 5, 6). ofgreater Iberosily -Action: lupper) let border of It steadies the head of the humerus.. scapula It adducts and laterally rotates the arm. E) Teres major: (Figs. 46) - Origin Origin:: from the lower third of the dorsal surface of the lateral border of the scapula. - Insertion Insertion:: into the medial lip of the bicipital groove of the humerus. - Nerve supply: lower subscapular nerve (C 5, 6). -Action: adduction, medial rotation and extension of the arm.. med lip of biciptal groove Lower s of lat border.  Shoulder Region nerve branch of superficial cervical artery suprascapular nerve and artery