📖 Anatomy
Muscles of the larynx -Intrinsic muscles
AnatomyIntrinsic muscles
all innervated by recurrent laryngeal nerve except cricothyroid: external laryngeal nerve
adductors of vocal folds: bring folds together at midline
Transverse and oblique arytenoids: pull arytenoids together
Lateral cricoartenoids: spin and slide arytenoids up
only one abductor of vocal folds
Posterior cricoarytenoids—down and up
adjustors of shape and tension of vocal folds
Cricothyroid muscle
o superficial to lateral cricoarytenoid
o tenses vocal folds by tilting thyroid cartilage forward and sliding forward
Thyroartenoid and vocalis muscles
o vocalis: sometimes treated as medial most fibers of thyroartenoid muscle
o different fiber directions
lateral: adduct
medial: change shape of folds
control voice by bring bringing together different parts of folds
o as move from epithelium to vocalis muscle, fold becomes stiffer
o near connections, vocal folds are stiffer
o vocal fold: complex, multilayered vibrator
Muscles of the Forehead
AnatomyThe Frontalis Muscle
- The frontalis muscle is part of the scalp muscle called the occipitalfrontalis.
- The frontalis elevates the forehead, giving the face a surprised look, and produces transverse wrinkles in the forehead when one frowns.
Larynx
Anatomy3 basic functions
o protection of respiratory tract during swallowing food/air pathways cross.
epiglottis provides protection
o control intra-thoracic pressure (in coughing) - close off airway to build pressure then rapidly open to release stuff
o production of sound (in speaking, singing, laughing)
Important structures
o hyoid bone
o thyroid cartilage
o arytenoids cartilage: vocal and muscle process
sits on slope on posterior side of cricoid - spin and slide
o cricoid cartilage: signet ring
o thyroepiglottic ligament
Membranes and ligaments
o membrane: general; ligament: thickening of membrane
o folds: free edges of membranes or ligaments
o names: tell you where located
Important membranes:
quandrangular/vestibular membrane—from epiglottis to arytenoids
• inferior edge: false vocal fold
thyrohyoid membrane
conus elasticus = cricothyroid = cricovocal
• superior/medial edge = vocal fold
• vocal ligaments: true folds, top of cricothyroid membrane
Intramembranous ossification
AnatomyIntramembranous ossification
- Flat bones develop in this way (bones of the skull)
- This type of bone development takes place in mesenchymal tissue
- Mesenchymal cells condense to form a primary ossification centre (blastema)
- Some of the condensed mesenchymal cells change to osteoprogenitor cells
- Osteoprogenitor cells change into osteoblasts which start to deposit bone
- As the osteoblasts deposit bone some of them become trapped in lacunae in the bone and then change into osteocytes
- Osteoblasts lie on the surface of the newly formed bone
- As more and more bone is deposited more and more osteocytes are formed from mesenchymal cells
- The bone that is formed is called a spicule
- This process takes place in many places simultaneously
- The spicules fuse to form trabeculae
- Blood vessels grow into the spaces between the trabeculae
- Mesenchymal cells in the spaces give rise to hemopoetic tissue
- This type of bone development forms the first phase in endochondral development
- It is also responsible for the growth of short bones and the thickening of long bones