Question

The small canal leading from pinna into the head in mammals is:
A. Haversian canal
B. Ext. auditory meatus
C. Inguinal canal
D. Eustachian tube

Answer 1

Hint: Pinna is an external organ which helps in auditory system. It helps in collecting sound from the surrounding. Choose the canal which is related to the auditory system.

Complete Step by Step Answer:
The pinna is made up of elastic cartilage. The helix is the most prominent outer ridge and a soft pliable part at its lower end is the lobule. The external auditory meatus (canal) is internally lined by hairy skin (stratified epithelium) and ceruminous glands (wax glands). The external auditory meatus is the canal which connects the outer pinna to the head of the mammal.

Haversian canal is observed in the bone region. It is a series of tubes around narrow channels formed by lamellae. The Haversian canals connect all osteocytes and surround blood vessels and nerve fibres throughout the bone. Osteocytes are mature bone cells.

The inguinal canal is a passage observed in the lower anterior abdominal wall. This canal is located above the inguinal ligament. The inguinal canal in males consists of the spermatic cord (with the genital branch of the genitofemoral nerve) and the ilioinguinal nerve. In females, the contents include the round ligament, the genital branch of the genitofemoral nerve, and the ilioinguinal nerve.

The eustachian tube connects the pharynx and the middle ear. It equalizes the pressure on both sides of the eardrums.

Hence, The correct option is B.

Note: The external auditory meatus canal is internally lined by ceruminous glands (wax glands). They are modified sweat glands which secrete a waxy substance- the cerumen (ear wax) which prevents foreign bodies from entering the ear.