Ex. 12: Skeletal Muscle

A. Characteristics of Three Muscle Types

1. Skeletal muscle– with striations; each skeletal muscle cell (fiber) has multiple and peripherally located nuclei

Location– primarily to bones by tendons Nuclei Striations Muscle fiber (b) 4

2. Cardiac muscle–striations; each muscle cell (fiber) has a single centrally located nucleus, branches, and intercalated discs at both ends

Location– the heart

3. Smooth muscle– without striations; each cell (fiber), with a single and centrally located nucleus, is thick in the middle and tapered at each end

Location– walls of viscera, airways, blood vessels, iris and ciliary body of eye Nuclei Muscle cells (b) 8

B. The Organization of Skeletal Muscle

A B C

C. The Neuromuscular Junction

The number of muscle fibers controlled by one neuron is called a motor unit. Spinal cord Motor neuron 1 Motor neuron 2 Neuromuscular junction Skeletal muscle fibers

      Neurotransmitter  

Ex. 13: Gross Anatomy of the Muscular System Required muscles/tendons are highlighted in green, the same 80 muscles and 3 tendons appeared in the lab manual. When highlighted in red, muscles’ actions, insertions, and origins are also required.

Anterior view 18 Frontalis Orbicularis oculi Zygomaticus minor Superficial Deep Galea aponeurotica Frontalis Corrugator supercilii Orbicularis oculi Nasalis Levator labii superioris Levator anguli oris Zygomaticus minor Masseter Zygomaticus major Risorius Buccinator Modiolus Orbicularis oris Depressor anguli oris Depressor labii inferioris Mentalis (cut) Platysma 18

Lateral view 19 Frontalis (cut) Temporalis Orbicularis oculi Galea aponeurotica Frontalis (cut) Corrugator supercilii Temporalis Orbicularis oculi Occipitalis Nasalis Levator labii superioris Zygomatic arch Zygomaticus minor O: Zygomatic arch & maxilla; I: Mandibular angle & ramus Action: Closes jaw & elevates mandible Zygomaticus major Orbicularis oris Masseter Sternocleidomastoid Modiolus Levator scapulae Risorius (cut) Inferior pharyngeal constrictor Mentalis Thyrohyoid Depressor labii inferioris Sternothyroid Omohyoid Depressor anguli oris Sternohyoid Buccinator 19

Lateral view Practice 20 Origin: Insertion: Action: Galea aponeurotica Corrugator supercilii Nasalis Levator labii superioris Zygomatic arch Origin: Insertion: Action: Modiolus Levator scapulae Inferior pharyngeal constrictor Thyrohyoid Depressor labii inferioris Depressor anguli oris Practice 20

Anterior view 21 Sternocleidomastoid Superficial Deep Digastric: Anterior belly Posterior belly Suprahyoid group Stylohyoid Mylohyoid Hyoid bone Common carotid artery Levator scapulae Internal jugular vein Thyrohyoid Sternohyoid Infrahyoid group Infrahyoid group Omohyoid: Sternothyroid Superior belly Inferior belly Sternocleidomastoid Clavicle O: Manubrium & medial clavicle; I: Mastoid process of temporal bone Action: Flexion in neck against resistance 21

Lateral view 22 Trapezius: Stylohyoid Digastric (posterior belly) O: Occipital bone, spine of C7 & all thoracic vertebrae; I: Acromion & spinous process of scapula Action: Extends heads, movement of scapula Stylohyoid Digastric (posterior belly) Hyoglossus Splenius capitis Mylohyoid Inferior pharyngeal constrictor Digastric (anterior belly) Sternocleidomastoid Hyoid bone Trapezius Thyrohyoid Levator scapulae Omohyoid (superior belly) Scalenes Sternothyroid Omohyoid (inferior belly) Sternohyoid 22

Lateral view Practice 23 Hyoglossus Splenius capitis Origin: Insertion: Action: Hyoglossus Splenius capitis Inferior pharyngeal constrictor Hyoid bone Thyrohyoid Levator scapulae Scalenes Sternothyroid Practice 23

Superficial muscles of the anterior abdominal wall Pectoralis major Latissimus dorsi Serratus anterior Tendinous intersections Rectus sheath (cut edges) Rectus sheath Transverse abdominal Umbilicus Internal abdominal oblique (cut) Linea semilunaris Linea alba External abdominal oblique (cut) Aponeurosis of external abdominal oblique Rectus abdominis Inguinal ligament 24

Deep muscles of the anterior abdominal wall Subclavius Pectoralis minor (cut) Pectoralis minor Internal intercostals Serratus anterior External intercostals Rectus abdominis (cut) Rectus sheath External abdominal oblique (cut) Internal abdominal oblique (cut) Internal abdominal oblique Posterior wall of rectus sheath (rectus abdominis removed) Inguinal ligament Transverse abdominal (cut) 25

External intercostals Deep muscles of the anterior abdominal wall Subclavius External intercostals Rectus sheath Posterior wall of rectus sheath (rectus abdominis removed) Inguinal ligament Practice 26

Action: Prime mover of inspiration Inferior view of diaphragm Lateral view of intercostal muscles External intercostals O: Xiphoid process of sternum Inferior vena cava O: Ribs Esophagus Insertion: Central tendon of diaphragm Internal intercostals O: Vertebral column Action: Prime mover of inspiration Inferior view of diaphragm 27

Neck, back, and gluteal muscles Superficial Deep Splenius capitis Sternocleidomastoid Levator scapulae Trapezius Rhomboideus major/minor Deltoid Supraspinatus O: Acromion and spine of scapula I: Deltoid tuberosity Action: Prime mover of arm abduction Infraspinatus Teres minor Teres major Erector spinae Serratus anterior Serratus posterior inferior Latissimus dorsi External abdominal oblique External abdominal oblique Internal abdominal oblique Thoracolumbar fascia Gluteus medius Gluteus minimus Gluteus maximus Lateral rotators 28

Serratus posterior inferior Neck, back, and gluteal muscles Superficial Deep Splenius capitis Origin: Insertion: Action: Erector spinae Serratus posterior inferior Thoracolumbar fascia Lateral rotators Practice 29

Anterior view Deltoid Pectoralis major Triceps brachii: Biceps brachii Clavicle Sternum Deltoid Pectoralis major Triceps brachii: Coracobrachialis Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis 30

Posterior view Supraspinatus Infraspinatus Teres minor Teres major Spine of scapula Greater tubercle of humerus Infraspinatus Humerus Teres minor Teres major Triceps brachii: Lateral head Long head O: glennoid cavity I: olecranon process of ulna Action: forearm extensor Latissimus dorsi 31

Anterior view Brachialis 32 Subscapularis Coracobrachialis O: Distal humerus I: coronoid process of ulna Action: Major flexor of forearm 32

Anterior view of the forearm Extensor carpi radialis Biceps brachii Triceps brachii Brachialis Common flexor tendon Common flexor tendon Pronator teres Supinator Anterior view Aponeurosis of biceps brachii Interosseous membrane Brachioradialis Flexor carpi radialis Flexor digitorum superficialis Flexor digitorum profundus Palmaris longus Flexor carpi ulnaris Extensor carpi radialis longus and brevis Flexor pollicis longus Flexor pollicis longus Flexor digitorum superficialis Flexor retinaculum Flexor digitorum superficialis tendons Flexor digitorum superficialis tendons Palmar aponeurosis Flexor digitorum profundus tendons Flexor digitorum profundus tendons (a) Superficial flexors (b) Intermediate flexor (c) Deep flexors 33

Anterior view of the forearm Common flexor tendon Common flexor tendon Anterior view Aponeurosis of biceps brachii Interosseous membrane Flexor digitorum profundus Flexor retinaculum Flexor digitorum superficialis tendons Flexor digitorum superficialis tendons Palmar aponeurosis Flexor digitorum profundus tendons Flexor digitorum profundus tendons (a) Superficial flexors (b) Intermediate flexor (c) Deep flexors Practice 34

Posterior view of the forearm Triceps brachii Brachioradialis Olecranon Anconeus Extensor carpi radialis longus Anconeus Supinator Extensor carpi radialis brevis Posterior view Flexor carpi ulnaris Abductor pollicis longus Extensor carpi ulnaris Extensor digitorum Abductor pollicis longus Extensor pollicis brevis Extensor digiti minimi Extensor pollicis longus Extensor pollicis brevis Extensor indicis Tendon of extensor indicis Extensor pollicis longus Tendons of extensor carpi radialis longus and brevis Tendons of extensor digitorum (a) Superficial extensors (b) Deep extensors 35

Supination Pronation 36 Lateral epicondyle Medial epicondyle Supinator Pronator teres Ulna Radius Pronator quadratus Biceps brachii Radius Bursa Supinator Ulna Muscle actions in supination 36

Anterior muscles of thigh, superficial view Iliac crest Iliopsoas: includes Iliacus L5 Psoas major Anterior superior iliac spine Medial compartment: Tensor fasciae latae Adductor magnus Pectineus Adductor brevis Iliotibial band Adductor longus Gracilis Anterior compartment: Sartorius Rectus femoris Vastus lateralis O: Iliac spine and superior acetabulum I: Tibial tuberosity and patella Action: Extend knee and flexes thigh at hip Vastus medialis Quadriceps femoris tendon Patella Patellar ligament Anterior muscles of thigh, superficial view 37

Anterior muscles of thigh, superficial view Iliac crest includes Iliacus L5 Psoas major Anterior superior iliac spine Medial compartment: Tensor fasciae latae Pectineus Adductor brevis Anterior compartment: Origin: Insertion: Action: Quadriceps femoris tendon Patella Patellar ligament Practice Anterior muscles of thigh, superficial view 38

Anterior muscles of the thigh, deep view Quadriceps femoris: Vastus intermedius Vastus lateralis Vastus medialis Quadriceps femoris tendon Patella Patellar ligament 39

Gluteal muscles, posterior view Deep Superficial Iliac crest Gluteus minimus Gluteus medius Sacrum Lateral rotators: Piriformis Gluteus maximus Gemellus superior Obturator internus Coccyx Obturator externus Ischial tuberosity Gemellus inferior Quadratus femoris 40

Posterior muscles of the hip and thigh Biceps femoris, long head Gluteus medius Gluteus maximus Gracilis Adductor magnus Iliotibial band Vastus lateralis Biceps femoris, long head: O: Ischial tuberosity I: Head of fibula & lateral condyle of tibia Action: Extends thigh, laterally rotates leg, & flexes knee Hamstring group: Biceps femoris, long head Short head Semitendinosus Semimembranosus 41

Posterior muscles of the hip and thigh Origin: Insertion: Action: Hamstring group: Short head Practice 42

Extensor digitorum longus Patella Patellar ligament Tibia Fibularis longus Gastrocnemius Soleus Fibularis brevis Tibialis anterior Extensor digitorum longus O: Lateral condyle of tibia I: First cuneiform and metatarsal 1 Action: Prime mover of dorsiflexion Extensor retinacula 43 (a)

Extensor hallucis longus Fibularis tertius 44 (c)

Extensor digitorum longus 45 (d)

Superficial muscles of the leg, posterior compartment Plantaris Gastrocnemius: Medial head Lateral head Tendon of gastrocnemius Calcaneal tendon Calcaneus 46

Deep muscles of the leg, posterior view Heads of gastrocnemius (cut) Plantaris Popliteus Fibularis longus Soleus Tendon of plantaris Gastrocnemius (cut) Fibularis longus Fibularis brevis Flexor digitorum longus Flexor hallucis longus 47

Flexor digitorum longus Calcaneal tendon (cut) Plantaris (cut) Gastrocnemius (cut) Popliteus Soleus (cut) Fibula Tibialis posterior Fibularis longus Flexor digitorum longus Flexor hallucis longus Fibularis brevis Calcaneal tendon (cut) Calcaneus 48 (a)