Anatomy of Upper and Lower Limbs (ANAT 201) Lecture 04 PDF

Anatomy of Upper and Lower Limbs (ANAT 201) Lecture # 04 Professor BALA Usman [email protected] Usman BALA, PhD 1  MYOLOGY OF THE UPPER Usman BALA, PhD 2  The Muscles –...

Anatomy of Upper and Lower Limbs (ANAT 201) Lecture # 04 Professor BALA Usman [email protected] Usman BALA, PhD 1  MYOLOGY OF THE UPPER Usman BALA, PhD 2  The Muscles – Introduction Muscles are responsible for all types of body movement There are ~ 600 muscles in the body. Muscles are made of bundles of muscle fibers which are held together by connective tissue. When muscle fibers are stimulated by nerves, they contract or become short and thick. Usman BALA, PhD 3  Functions of Muscle Produce movement Bones = attachment points Internal organs (move nutrients, waste, etc.) Maintain posture Unique to Bipedalism Stabilize joints Allows for wider range of movement and use of force Generate heat During contraction Protect some internal organs Abdominal organs Usman BALA, PhD 4  Classification of Muscle n Basically, three basic muscle types are found in the body. 1. Skeletal muscle 2. Cardiac muscle 3. Smooth muscl n Muscles can also be classified based on: 1. Present / Absent of striation 1. Striated ( Skeletal & Cardiac muscle) 2. Unstriated (Smooth Muscle) 2. Control over its action 1. Voluntary (Skeletal Muscle 2. Involuntary (Smooth & Cardiac Muscle) 5  Classification of Muscle Striated Muscle Appearance of light and dark stripes. – Examples are Skeletal & Cardiac muscle) Striated Muscle Unstriated Muscle – Absent of the the of light and dark stripes – Examples Smooth Muscle Usman BALA, PhD Unstriated Muscle 6  Classification of Muscle Voluntary n Muscles that are willfully control n Eg. - Facial expressions, chewing, swallowing, and movement of the head Involuntary Muscle n Muscles that are not under our control n Eg. Heart muscles & blood vessels. Note: Some muscles are both voluntary and involuntary ~ Muscles of the eye Usman BALA, PhD 7  Classification of Muscle Skeletal Muscle n Striated muscle n Voluntary in action n Multinucleated Tubular fiber n They are attach to bones Striated Muscle n Main function - contraction and thus facilitate movement of our skeletons. Usman BALA, PhD 8  Classification of Muscle Smooth Muscle – Unstriated muscle – Involuntary – no conscious control – Has narrow tapered rod- shaped cells – Uninucleated cells – Found in the walls of GI organs and blood vessels. Usman BALA, PhD 9  Classification of Muscle Cardiac Muscle – Striated muscle – Involuntary in action – Has branched tubular uninucleated cells – Only found in the walls of the heart. – Joined to another muscle cell at an intercalated disc Note Similar to: – Skeletal muscle -striated – Smooth Usman BALA, PhDmuscle- involuntarily controlled 10  Special Features of Muscle Contractibility - ability to shorten when an adequate stimulus is received Irritability – ability to receive and respond to a stimulus Excitibility - nervous impulses travel through muscle plasma membrane to stimulate contraction Extensibility - after contraction muscle can be stretched back to original length by opposing muscle action Elasticity - after being stretched, muscle passively recoils to resume its resting length Usman BALA, PhD 11  Connective Tissue Wrappings of Skeletal Muscle Endomysium – around single muscle fiber Perimysium – around a fascicle (bundle) of fibers Epimysium – covers the entire skeletal muscle Fascia – on the outside of the epimysium Usman BALA, PhD 12  Skeletal Muscle Attachments Epimysium blends into a connective tissue attachment – Tendon – cord-like structure – Aponeuroses – sheet-like structure Sites of attachment include: – Bones – Cartilages – Connective tissue coverings Usman BALA, PhD 13  Muscle is Stimulated by Nerve Skeletal muscles must be stimulated by a nerve to contract Motor unit One neuron Muscle cells stimulated by that neuron Usman BALA, PhD 14  Nerve Stimulus to Muscles Neuromuscular junctions (NMJ) – the site of nerve and muscle association Synaptic cleft – gap between nerve and muscle – Nerve and muscle do not make contact – Area between nerve and muscle is filled with interstitial fluid Usman BALA, PhD 15  Muscles and Body Movements Movement is attained due to a muscle moving an attached bone. Attachment can either be: – Direct - right onto bone – Indirect –via tendon or aponeurosis More common Leave bony markings such as tubercle, crest, ridge, etc. Usman BALA, PhD 16  Muscles and Body Movements Muscles are attached to at least two points Origin – attachment to a moveable bone Insertion – attachment to an immovable bone Usman BALA, PhD 17  Effects of Exercise on Muscle Results of increased muscle use 1. Increase in muscle size 2. Increase in muscle strength 3. Increase in muscle efficiency 4. Muscle becomes more fatigue resistant Usman BALA, PhD 18  Types of Muscles Agonist - primary mover of a muscle, with the major responsibility for a certain movement – Example - Biceps brachii is main flexor of forearm Antagonist – muscle that opposes or reverses the action of prime mover or prevent overshooting agonistic motion. – Example - Triceps brachii is antagonist to biceps brachii Usman BALA, PhD 19  Types of Muscles Synergist – Muscle that aids a prime mover in a movement, helps prevent rotation and reduce undesirable extra movement Example; muscles crossing 2 joints Fixator – stabilizes the origin of a prime mover / a synergist that holds bone in place to provide stable base for movement Example; joint stablilizers Usman BALA, PhD 20  Arrangement of muscle fibers Parallel: long axis of fascicles parallel to axis of muscle; straplike (eg) biceps, sternocleidomastoid Convergent: O = broad, I = narrow, via tendon; fan or triangle shaped (eg) pectoralis major Circular: fascicles arranged in concentric circles; sphincter (eg) around mouth Pennate: fascicles short + attached obliquely to tendon running length of muscle; – Unipennate = fascicles insert on only 1 side, (eg) flexor pollicis longus – Bipennate = fascicles insert both sides, (eg) rectus femoris – Multipennate = many bundles inserting together, (eg) deltoid Usman BALA, PhD 21  Arrangement of Muscle Fibers Usman BALA, PhD 22  Naming of Skeletal Muscles Location of the muscle Example: brachialis, temporalis, Frontalis Shape of the muscle Example: deltoid (triangular) Relative size of the muscle Example: maximus (largest) Direction of muscle fibers Example: rectus (straight), oblique Location of attachement (origin and insertion) Example: sternocleidomastoid (on the sternum), brachioradialis Number of origins Example: triceps (three heads), Biceps (2 heads) Action of the muscle Example: flexor and extensor (flexes or extends a bone) Usman BALA, PhD 23  Head and Neck Muscles Usman BALA, PhD 24  Trunk Muscles Usman BALA, PhD 25  Deep Trunk and Arm Muscles Usman BALA, PhD 26  Pelvis, Hip & Thigh Muscles Usman BALA, PhD 27  Muscles of the Lower Leg Usman BALA, PhD 28  Anterior Superficial Muscles Usman BALA, PhD 29  Posterior Superficial Muscles Usman BALA, PhD Figure30 6.22 BRACHIAL PLEXUS Usman BALA, PhD 31  Brachial plexus Nerves of the Upper limb — Formed by the anterior rami of C5- C8 in neck and T1 at thoracic inlet — Roots receive grey rami communicantes so carry post- ganglionic sympathetic fibres — In posterior triangle of the neck the roots pass between anterior and middle scalene muscles — Pass over 1st rib and enter the axilla  Brachial Plexus FORMATION ROOTS forms the TRUNKS The root unites to form the trunks, ( 3 trunks) Superior trunk - C5 & C6 Middle trunk - C7 Inferior trunk - C8 & T1 Each trunk divide in to Anterior and posterior divisions Note: Anterior divisions= Anterior compartment Posterior division = Posterior compartment  Brachial Plexus FORMATION TRUNK DIVIDES INTO DIVISIONS — Each trunk divides into an anterior and posterior divisions — The 3 anterior and posterior divisions ultimate pathway for fibres associated with anterior and posterior compartments of arm and forearm respectively. — Note: No peripheral nerves direct from divisions  Brachial plexus FORMATION DIVISIOS forms the CORDS Division re-unite to form cords (3 cords) LATERAL CORD: Anterior division of Superior & Middle trunk MEDIAL CORD: Anterior division of inferior trunk POSTERIOR CORD: Posterior divisions of all the 3 trunk  Brachial plexus CORDS Named in relation to the 2nd part of axillary artery — LATERAL = unites anterior divisions of superior and middle trunks therefore C5-7 fibres present, also origin of lateral pectoral nerve — POSTERIOR = unites all posterior divisions of ALL the trunks therefore C8-T1 fibres present, also origins of subscapular and thoracodorsal nerves — MEDIAL = continuation of anterior division of inferior trunk therefore C8-T1 fibres present, also origins of medial pectoral and cutaneous nerves  Brachial plexus CORDS relation to the axillary artery Brachial plexus  Brachial plexus Branches of Root and Trunks SUPRACLAVICULAR BRANCH 1. Dorsal scapular nerve C5 2. Long thoracic nerve C5-7 3. Nerve to subclavius 4. Suprascapular nerve Note: 1 & 2 from the Root 3 & 4 from the Superior trunk  Brachial plexus INFRACLAVICULAR BRANCH Terminal & Sides branches LATERAL CORD (1 SB, 2 TB) 1. Lateral pectoral nerve 2. Lateral root of median nerve 3. Musculocutaneous nerve  Brachial plexus INFRACLAVICULAR BRANCH Terminal & Sides branches MEDIAL CORD (3SB, 2TB) 1. Medial pectoral nerve 2. Medial cutaneous nerve of arm 3. Medial cutaneous nerve of forearm 4. Medial root of median nerve 5. Ulnar nerve  Brachial plexus INFRACLAVICULAR BRANCH Terminal & Sides branches POSTERIOR CORD (3SB, 2TB) 1. Thoracodorsal nerve 2. Upper subscapular nerves, 3. Lower subscapular nerves, 4. Axillary nerve 5. Radial nerve  Brachial plexus Terminal nerve branches  Brachial plexus Terminal nerve branches  Brachial plexus Terminal nerve branches  Nerves from the Lateral and Medial Cords Axillary nerve Musculocutaneous—main branch of the lateral cord Innervates the biceps brachii and brachialis Humerus Median—originates from both Radial nerve lateral and medial cords Musculocutaneous nerve Innervates anterior forearm Ulna muscles and lateral palm Radius Ulnar nerve Median nerve Ulnar—branches from the Radial nerve (superficial branch) medial cord Dorsal branch of ulnar nerve Innervates intrinsic hand Superficial branch of ulnar nerve muscles and skin of the medial Digital branch of ulnar nerve hand Muscular branch Median nerve Digital branch  Nerves from the Lateral and Medial Cords Muscular innervation Cutaneous innervation Musculocutaneous Median nerve Ulnar nerve nerve C5 C5 C6 C6 C7 C7 C8 C8 T1 T1 Anterior view Posterior view Coraco- brachialis Biceps brachii Brachialis Medial cutaneous nerves off medial cord Pronator teres Flexor carpi radialis Flexor Palmaris longus Flexor digitorum carpi superficialis ulnaris Flexor pollicis Musculocutaneous longus Flexor digitorum nerve profundus Pronator quadratus Adductor 3 Thenar muscles pollicis 7 Interossei3 Hypothenar Ulnar nerve muscles Lumbricals to Lumbricals to digits 2,3 digits 4,5 Indicates variable contribution Median nerve  Nerves from the Posterior Cord Musculocutaneous nerve Radial—continuation of the Axillary nerve Branches of axillary nerve posterior cord Radial nerve Largest branch of the Ulnar nerve (cut) brachial plexus Median nerve (cut) Innervates muscles of the posterior upper limb Posterior cutaneous nerve Deep radial nerve Axillary Superficial branch of radial nerve – Innervates the deltoid and teres minor Anterior Posterior divisions divisions Axillary and Radial Nerves Muscular innervation Cutaneous innervation Radial nerve Axillary nerve C5 C5 C6 C6 C7 C8 T1 Anterior view Posterior view Teres minor Deltoid Axillary Axillary nerve nerve Triceps brachii (long head) Triceps brachii Triceps brachii Radial Radial (lateral head) (medial head) nerve nerve Brachioradialis* Anconeus Extensor carpi radialis longus Extensor digitorum Extensor carpi radialis brevis Extensor digiti minimi Supinator Extensor carpi ulnaris Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis Radial nerve Indicates variable contribution *Functionally brachioradialis acts as a flexor of the forearm. It develops from the posterior compartment and thus is innervated by a posterior division nerve. Nerves from the Lateral and Medial Cords Anterior Roots (ventral rami) divisions C4 Posterior Dorsal scapular divisions C5 Nerve to Trunks subclavius Suprascapular C6 Roots Upper C7 Posterior Middle Trunks divisions C8 Lateral Lower T1 Cords Posterior Long thoracic Medial Medial pectoral Lateral pectoral Axillary Upper Musculo- subscapular cutaneous Lower Radial subscapular Median Thoracodorsal Medial cutaneous Ulnar nerves of the arm and forearm (b) Roots (rami C5–T1), trunks, divisions, and cords  Applied and Clinical Anatomy Injury to Brachial Plexus Mainly Due to – Disease, – Stretching, – Injury – Wounds in the neck or axilla Signs and symptoms depends on the part of the plexus involve Paralysis of the muscles – Complete – no movement – Incomplete - some movement Loss of sensation (Anesthesia)  Applied and Clinical Anatomy Injury to Brachial Plexus Brachial plexus neuritis - Inflammation of the BP Sudden onset of severe pain around the shoulder – follow by muscle weakness and muscle atrophy (sometimes) Cause – Unknown but is usually preceded by some events – (Vaccination, Upper respiratory infection or nonspecific trauma) Affecting the nerves derived from superior trunk Usman BALA, PhD  Applied and Clinical Anatomy Usman BALA, PhD  Applied and Clinical Anatomy Injury to Brachial Plexus COMPRESSION OF THE CORDS OF BP Due to prolonged hyperabduction of the arm Cords compress or impinged btw coracoid process and P. minor Symptoms - – Pain running down the arm – Numbness – Paresthesia (Tingling) – Erythema (redness of skin) – Weakness of the hand Signs and symptoms result from compression of axillary vessels and nerve – Hyperabduction syndrome of the UL  Applied and Clinical Anatomy INJURY TO THE TRUNKS ERB-DUCHENNE PALSY (C5,C6): UPPER TRUNK – C5 & C6 Sudden, violent stretch between head & shoulder. (trauma during birth, falling on neck & shoulder) Nerves Injured: MC, Suprascapular, Axillary, Phrenic Clinical: Pronated & medially rotated arm (WAITER’S TIP) Usman BALA, PhD  Applied and Clinical Anatomy INJURY TO THE TRUNKS KLUMPKE PARALYSIS LOWER – C8 & T1 (Not common) Due to: – Sudden pulling of the UL superiorly – During delivery – the baby UL is pulled excessively – Breech birth - baby’s limb is pulled over head Nerves Injured: Median, Ulnar, Sympathetic of T1 spinal nerve Clinical: Loss of function of wrist & hand. Wrist drop, Claw hand  Applied and Clinical Anatomy INJURY TO THE BRANCHES WRIST DROP RADIAL (C5, C6, C7, C8, T1) Due to: – Fracture at the mid shaft of humerus – Badly fitted crutch – Falling asleep with arm over chair (SAT NIGHT PALSY) Clinical: Can’t extend wrist or fingers; supination is compromised EXTENSION OF FOREARM IS OK. Why? (innervation to TRICEPS is intact) Sensory loss on posterior arm, post. forearm, and lateral dorsum of hand  THANK YOU FOR LISTENING QUESTIONS Usman BALA, PhD 58