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Lecture 11

CAS BI 106 Lecture 11: Anatomy Lecture 11

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Boston University
CAS BI 106
Dale Pasino

Lecture 11 22117 How to focus this material? Muscles of facial expression o Frontalis on forehead above eyes Raise eyebrows and frontalis will contract o Orbicularis oculi around the eye Squint eyes to contract o Zygomaticus major under zygomatic bone Smile to contract. To smile we use both zygomaticus major and orbicularis oculi o Masseter cheek towards jaw. Helps chew o Orbicularis oris around mouth o Depressor anguli oris under mouth muscle, near ends of lips Contracted when frown o Platysma neck muscle Muscles that keep our head up Muscles of breath o External intercostals o Internal intercostals o Central tendon of diaphragm Muscles that keep us upright as bipedal organisms 3 sets of intercostals (bring ribs up and out) Innermost intercostal o runs straight up and down o Superior to lateral Internal intercostal o inferiorlateral to superior medial (45 degree angle) External intercostal o Superior lateral to inferior medial (45 degree angle) Breathing Mechanics Inhale: the space inside the thoracic cage expands, drawing air in o When contracting, the diaphragm pulls down, flattens out, pushes on abdominal contents o 3 sets of intercostal muscles pull ribs superior laterally Exhale: the space inside the thoracic cage contracts, pushing air out o The diaphragms central tendon pulls it superiorly when relaxed o 3 sets of intercostal muscles relax, ribs return to original position Forcible exhale: abdominal muscles contract, pushing abdominal contents up against diaphragm further decreasing thoracic cage (coughing) Upper Body front Pectoralis major chest muscle Pectoralis minor under chest muscle, looks like 3 lines going to ribs Latissimus dorsi armpit goes to back too Serratus anterior next to armpit, under pectoral Rectus abdominis where your abs would be Rectus sheath white sheet on top of abdomen
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